Transcript Human Systems

2014 AP Exam Body systems updated
 Anatomy is the study of the biological form of an
organism
 Physiology is the study of the biological functions
an organism performs
 The comparative study of animals reveals that
form and function are closely correlated
Table 40-1
 Different tissues have different structures that
are suited to their functions
 Tissues are classified into four main categories:
epithelial, connective, muscle, and nervous
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Epithelial tissue covers the outside of the body
and lines the organs and cavities within the body
 It contains cells that are closely joined
 The shape of epithelial cells may be cuboidal (like
dice), columnar (like bricks on end), or
squamous (like floor tiles)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-5a
Epithelial Tissue
Cuboidal
epithelium
Simple
columnar
epithelium
Pseudostratified
ciliated
columnar
epithelium
Stratified
squamous
epithelium
Simple
squamous
epithelium
 Connective tissue mainly binds and supports
other tissues
 It contains sparsely packed cells scattered
throughout an extracellular matrix
 The matrix consists of fibers in a liquid, jellylike,
or solid foundation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-5c
Connective Tissue
Loose
connective
tissue
Chondrocytes
Cartilage
Elastic fiber
Chondroitin
sulfate
Nuclei
Fat droplets
Adipose
tissue
Osteon
150 µm
Fibrous
connective
tissue
30 µm
100 µm
120 µm
Collagenous fiber
White blood cells
Blood
55 µm
700 µm
Bone
Central canal
Plasma
Red blood
cells
 Muscle tissue consists of long cells called
muscle fibers, which contract in response to
nerve signals
 It is divided in the vertebrate body into three
types:
 Skeletal muscle, or striated muscle, is responsible for
voluntary movement
 Smooth muscle is responsible for involuntary body
activities
 Cardiac muscle is responsible for contraction of the heart
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-5j
Muscle Tissue
Multiple
nuclei
Muscle fiber
Sarcomere
Skeletal
muscle
Nucleus
100 µm
Intercalated
disk
50 µm
Cardiac muscle
Nucleus
Smooth
muscle
Muscle
fibers
25 µm
 Vertebrate skeletal muscle is characterized by a
hierarchy of smaller and smaller units
 A skeletal muscle consists of a bundle of long
fibers, each a single cell, running parallel to the
length of the muscle
 Each muscle fiber is itself a bundle of smaller
myofibrils arranged longitudinally
 Skeletal muscle is also called striated muscle
because the regular arrangement of
myofilaments creates a pattern of light and dark
bands
 The functional unit of a muscle is called a
sarcomere, and is bordered by Z lines
Fig. 50-25
Muscle
Bundle of
muscle fibers
Nuclei
Single muscle fiber
(cell)
Plasma membrane
Myofibril
Z lines
Sarcomere
TEM
M line
0.5 µm
Thick
filaments
(myosin)
Thin
filaments
(actin)
Z line
Z line
Sarcomere
Fig. 50-26
Sarcomere
Z
M
Relaxed
muscle
Contracting
muscle
Fully contracted
muscle
Contracted
Sarcomere
Z
0.5 µm
Fig. 50-27-4
Thick filament
Thin
filaments
Thin filament
Myosin head (lowenergy configuration
ATP
ATP
Thick
filament
Thin filament moves
toward center of sarcomere.
Actin
ADP
Myosin head (lowenergy configuration
ADP
+ Pi
Pi
ADP
Pi
Cross-bridge
Myosin
binding sites
Myosin head (highenergy configuration
Fig. 50-29
Motor
neuron axon
Synaptic
terminal
T tubule
Mitochondrion
Sarcoplasmic
reticulum (SR)
Myofibril
Plasma membrane
of muscle fiber
Ca2+ released from SR
Sarcomere
Synaptic terminal
of motor neuron
T Tubule
Synaptic cleft
ACh
Plasma membrane
SR
Ca2+
ATPase
pump
Ca2+
ATP
CYTOSOL
Ca2+
ADP
Pi
 Nervous tissue senses stimuli and transmits
signals throughout the animal
 Nervous tissue contains:
 Neurons, or nerve cells, that transmit nerve impulses
 Glial cells, or glia, that help nourish, insulate, and
replenish neurons
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-5n
Nervous Tissue
40 µm
Dendrites
Cell body
Glial cells
Axon
Neuron
Axons
Blood vessel
15 µm
 Control and coordination within a body depend
on the endocrine system and the nervous system
 The endocrine system transmits chemical signals
called hormones to receptive cells throughout
the body via blood
 A hormone may affect one or more regions
throughout the body
 Hormones are relatively slow acting, but can have
long-lasting effects
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-6
Stimulus
Stimulus
Endocrine
cell
Neuron
Axon
Signal
Hormone
Signal travels
along axon to
a specific
location.
Signal travels
everywhere
via the
bloodstream.
Blood
vessel
Signal
Axons
Response
(a) Signaling by hormones
Response
(b) Signaling by neurons
 A regulator uses internal control mechanisms to
moderate internal change in the face of external,
environmental fluctuation
 A conformer allows its internal condition to
vary with certain external changes
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-7
40
Body temperature (°C)
River otter (temperature regulator)
30
20
Largemouth bass
(temperature conformer)
10
0
10
20
30
40
Ambient (environmental) temperature (ºC)
 Organisms use homeostasis to maintain a
“steady state” or internal balance regardless of
external environment
 In humans, body temperature, blood pH, and
glucose concentration are each maintained at a
constant level
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-8
Response:
Heater
turned
off
Room
temperature
decreases
Stimulus:
Control center
(thermostat)
reads too hot
Set
point:
20ºC
Stimulus:
Control center
(thermostat)
reads too cold
Room
temperature
increases
Response:
Heater
turned
on
 The dynamic equilibrium of homeostasis is
maintained by negative feedback, which helps
to return a variable to either a normal range or a
set point
 Most homeostatic control systems function by
negative feedback, where buildup of the end
product shuts the system off
 Positive feedback loops occur in animals, but
do not usually contribute to homeostasis
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Endothermic animals generate heat by
metabolism; birds and mammals are endotherms
 Ectothermic animals gain heat from external
sources; ectotherms include most invertebrates,
fishes, amphibians, and non-avian reptiles
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-9
(a) A walrus, an endotherm
(b) A lizard, an ectotherm
Fig. 40-11
Hair
Epidermis
Sweat
pore
Muscle
Dermis
Nerve
Sweat
gland
Hypodermis
Adipose tissue
Blood vessels
Oil gland
Hair follicle
 Regulation of blood flow near the body surface
significantly affects thermoregulation
 Many endotherms and some ectotherms can alter
the amount of blood flowing between the body
core and the skin
 In vasodilation, blood flow in the skin increases,
facilitating heat loss
 In vasoconstriction, blood flow in the skin
decreases, lowering heat loss
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 The arrangement of blood vessels in many
marine mammals and birds allows for
countercurrent exchange
 Countercurrent heat exchangers transfer heat
between fluids flowing in opposite directions
 Countercurrent heat exchangers are an
important mechanism for reducing heat loss
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-12
Canada goose
Bottlenose
dolphin
Blood flow
Artery Vein
Vein
Artery
35ºC
33º
30º
27º
20º
18º
10º
9º
 Some bony fishes and sharks also use
countercurrent heat exchanges
 Many endothermic insects have countercurrent
heat exchangers that help maintain a high
temperature in the thorax
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-16
Sweat glands secrete
sweat, which evaporates,
cooling the body.
Body temperature
decreases;
thermostat
shuts off cooling
mechanisms.
Thermostat in hypothalamus
activates cooling mechanisms.
Blood vessels in
skin dilate:
capillaries fill;
heat radiates
from skin.
Increased body
temperature
Homeostasis:
Internal
temperature of 36–
38°C
Body temperature
Decreased body
increases; thermostat
temperature
shuts off warming
mechanisms.
Blood vessels in skin
constrict, reducing
heat loss.
Skeletal muscles contract;
shivering generates heat.
Thermostat in
hypothalamus
activates warming
mechanisms.
 Kidney, Neurons, Salt and Water…
 Recall the concepts of Osmosis and Diffusion.
 Hyper/hypo/iso-TONIC
 And, Active transport..
 Osmoconformers, consisting only of some
marine animals, are isoosmotic with their
surroundings and do not regulate their
osmolarity
 Osmoregulators expend energy to control
water uptake and loss in a hyperosmotic or
hypoosmotic environment
Fig. 44-3
Fig. 44-4
Gain of water and
salt ions from food
Excretion
of salt
ions
from gills
Gain of water
and salt ions from
drinking seawater
Excretion of salt ions and
small amounts of water in
scanty urine from kidneys
(a) Osmoregulation in a saltwater fish
Osmotic water
loss through gills
and other parts
of body surface
Uptake of water and
some ions in food
Uptake
Osmotic water
of salt ions gain through gills
by gills
and other parts
of body surface
Excretion of large
amounts of water in
dilute urine from kidneys
(b) Osmoregulation in a freshwater fish
Fig. 44-6
Water
balance in a
kangaroo rat
(2 mL/day)
Ingested
in food (0.2)
Water
gain
(mL)
Water
balance in
a human
(2,500 mL/day)
Ingested
in food (750)
Ingested
in liquid
(1,500)
Derived from
metabolism (250)
Derived from
metabolism (1.8)
Feces (0.09)
Water
loss
(mL)
Urine
(0.45)
Evaporation (1.46)
Feces (100)
Urine
(1,500)
Evaporation (900)
 Most excretory systems produce urine by
refining a filtrate derived from body fluids
 Key functions of most excretory systems:
 Filtration: pressure-filtering of body fluids
 Reabsorption: reclaiming valuable solutes
 Secretion: adding toxins and other solutes from the
body fluids to the filtrate
 Excretion: removing the filtrate from the system
 Each segment of an earthworm has a pair of
open-ended metanephridia
 Metanephridia consist of tubules that collect
coelomic fluid and produce dilute urine for
excretion
Fig. 44-12
Coelom
Capillary
network
Components of
a metanephridium:
Internal opening
Collecting tubule
Bladder
External opening
Fig. 44-14
Renal
medulla
Posterior
vena cava
Renal artery
and vein
Aorta
Renal
cortex
Kidney
Renal
pelvis
Ureter
Urinary
bladder
Urethra
Ureter
(a) Excretory organs and major
associated blood vessels
Juxtamedullary
nephron
Section of kidney
from a rat
(b) Kidney structure
Cortical
nephron
10 µm
4 mm
Afferent arteriole Glomerulus
from renal artery
Bowman’s
capsule
SEM
Proximal
tubule
Peritubular capillaries
Renal
cortex
Efferent
arteriole from
glomerulus
Collecting
duct
Renal
medulla
Branch of
renal vein
Collecting
duct
Descending
limb
To
renal
pelvis
Loop of
Henle
(c) Nephron types
Distal
tubule
Ascending
limb
(d) Filtrate and blood flow
Vasa
recta
Fig. 44-14a
Posterior
vena cava
Renal artery
and vein
Aorta
Ureter
Urinary
bladder
Urethra
(a) Excretory organs and major
associated blood vessels
Kidney
Fig. 44-14b
Renal
medulla
Renal
cortex
Renal
pelvis
Ureter
(b) Kidney structure
Section of kidney
from a rat
4 mm
Fig. 44-14cd
Juxtamedullary
nephron
Cortical
nephron
10 µm
Afferent arteriole Glomerulus
from renal artery
Bowman’s capsule
SEM
Proximal tubule
Peritubular capillaries
Renal
cortex
Efferent
arteriole from
glomerulus
Collecting
duct
Renal
medulla
Branch of
renal vein
Collecting
duct
Descending
limb
To
renal
pelvis
Loop of
Henle
(c) Nephron types
Distal
tubule
Ascending
limb
(d) Filtrate and blood flow
Vasa
recta
 The nephron, the functional unit of the
vertebrate kidney, consists of a single long
tubule and a ball of capillaries called the
glomerulus
 Bowman’s capsule surrounds and receives
filtrate from the glomerulus
Fig. 44-14c
Juxtamedullary
nephron
Cortical
nephron
Renal
cortex
Collecting
duct
To
renal
pelvis
(c) Nephron types
Renal
medulla
Fig. 44-14d
10 µm
Afferent arteriole
from renal artery
SEM
Glomerulus
Bowman’s capsule
Proximal tubule
Peritubular capillaries
Efferent
arteriole from
glomerulus
Distal
tubule
Branch of
renal vein
Collecting
duct
Descending
limb
Loop of
Henle
(d) Filtrate and blood flow
Ascending
limb
Vasa
recta
 Filtration occurs as blood pressure forces fluid
from the blood in the glomerulus into the lumen
of Bowman’s capsule
 Filtration of small molecules is nonselective
 The filtrate contains salts, glucose, amino
acids, vitamins, nitrogenous wastes, and other
small molecules
 From Bowman’s capsule, the filtrate passes
through three regions of the nephron: the
proximal tubule, the loop of Henle, and the
distal tubule
 Fluid from several nephrons flows into a
collecting duct, all of which lead to the renal
pelvis, which is drained by the ureter
 Cortical nephrons are confined to the renal
cortex, while juxtamedullary nephrons have
loops of Henle that descend into the renal
medulla
 Each nephron is supplied with blood by an
afferent arteriole, a branch of the renal artery
that divides into the capillaries
 The capillaries converge as they leave the
glomerulus, forming an efferent arteriole
 The vessels divide again, forming the
peritubular capillaries, which surround the
proximal and distal tubules
 The mammalian kidney conserves water by
producing urine that is much more concentrated
than body fluids
Proximal Tubule
 Reabsorption of ions, water, and nutrients takes
place in the proximal tubule
 Molecules are transported actively and
passively from the filtrate into the interstitial
fluid and then capillaries
 Some toxic materials are secreted into the
filtrate
 The filtrate volume decreases
Animation: Bowman’s Capsule and Proximal Tubule
Descending Limb of the Loop of Henle
 Reabsorption of water continues through
channels formed by aquaporin proteins
 Movement is driven by the high osmolarity of
the interstitial fluid, which is hyperosmotic to the
filtrate
 The filtrate becomes increasingly concentrated
Ascending Limb of the Loop of Henle
 In the ascending limb of the loop of Henle, salt
but not water is able to diffuse from the tubule
into the interstitial fluid
 The filtrate becomes increasingly dilute
Distal Tubule
 The distal tubule regulates the K+ and NaCl
concentrations of body fluids
 The controlled movement of ions contributes to
pH regulation
Animation: Loop of Henle and Distal Tubule
Collecting Duct
 The collecting duct carries filtrate through the
medulla to the renal pelvis
 Water is lost as well as some salt and urea, and
the filtrate becomes more concentrated
 Urine is hyperosmotic to body fluids
Animation: Collecting Duct
Fig. 44-15
Proximal tubule
NaCl Nutrients
HCO3–
H2O
K+
H+
NH3
Distal tubule
H2O
NaCl
K+
HCO3–
H+
Filtrate
CORTEX
Loop of
Henle
NaCl
H2O
OUTER
MEDULLA
NaCl
Collecting
duct
Key
Active
transport
Passive
transport
Urea
NaCl
INNER
MEDULLA
H2O
 Mammals control the volume and osmolarity of
urine
 It’s the Pituitary gland at the base of the skull
that accomplishes this.
 ADH: Antidiuretic Hormone released by the
Pituitary prevents water loss by increasing the
osmolarity of the collecting ducts
Fig. 44-19
Osmoreceptors in
hypothalamus trigger
release of ADH.
Thirst
INTERSTITIAL
FLUID
COLLECTING
DUCT
LUMEN
Hypothalamus
COLLECTING
DUCT CELL
ADH
cAMP
Drinking reduces
blood osmolarity
to set point.
ADH
Increased
permeability
Second messenger
signaling molecule
Pituitary
gland
Storage
vesicle
Distal
tubule
Exocytosis
Aquaporin
water
channels
H2O
H2O reabsorption helps
prevent further
osmolarity
increase.
Collecting duct
Homeostasis:
Blood osmolarity
(300 mOsm/L)
(a)
H2O
STIMULUS:
Increase in blood
osmolarity
(b)
ADH
receptor
 The kidneys (nephrons) are also responsible for waste
EXCRETION.
 Excretion is removal of nitrogenous waste from the
blood (urea in us, uric acid in reptiles, and ammonia in
fish and Amphibians.)
 This is really important, and the reason for dialysis in
people with non-functional kidneys (they need a
transplant)
 Animals harvest chemical energy from food
 Energy-containing molecules from food are
usually used to make ATP, which powers cellular
work
 After the needs of staying alive are met,
remaining food molecules can be used in
biosynthesis
 Biosynthesis includes body growth and repair,
synthesis of storage material such as fat, and
production of gametes
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-17
External
environment
Animal
body
Organic molecules
in food
Digestion and
absorption
Heat
Energy lost
in feces
Nutrient molecules
in body cells
Carbon
skeletons
Cellular
respiration
Energy lost in
nitrogenous
waste
Heat
ATP
Biosynthesis
Cellular
work
Heat
Heat
 Metabolic rate is the amount of energy an
animal uses in a unit of time
 One way to measure it is to determine the
amount of oxygen consumed or carbon dioxide
produced
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-18
 Basal metabolic rate (BMR) is the metabolic
rate of an endotherm at rest at a “comfortable”
temperature
 Standard metabolic rate (SMR) is the
metabolic rate of an ectotherm at rest at a
specific temperature
 Both rates assume a nongrowing, fasting, and
nonstressed animal
 Ectotherms have much lower metabolic rates
than endotherms of a comparable size
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Metabolic rates are affected by many factors
besides whether an animal is an endotherm or
ectotherm
 Two of these factors are size and activity
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
 Metabolic rate per gram is inversely related to
body size among similar animals
 Researchers continue to search for the causes of
this relationship
 The higher metabolic rate of smaller animals
leads to a higher oxygen delivery rate, breathing
rate, heart rate, and greater (relative) blood
volume, compared with a larger animal
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 40-19
103
BMR (L O2/hr) (Iog scale)
Elephant
Horse
102
Human
Sheep
10
Cat
Dog
1
10–1
Rat
Ground squirrel
Shrew
Mouse
Harvest mouse
10–2
10–3
10–2
10
10–1
1
102
Body mass (kg) (log scale)
103
(a) Relationship of BMR to body size
8
Shrew
BMR (L O2/hr) (per kg)
7
6
5
4
3
2
1
Harvest mouse
Mouse
Rat
Sheep
Cat
Dog
Human Elephant
Horse
Ground squirrel
0
10–3 10–2
102
10–1
1
10
Body mass (kg) (log scale)
103
(b) Relationship of BMR per kilogram of body mass to body size
 Digestive systems
 Circulatory systems
 Nervous systems
 Endocrine systems
 Excretory systems
*ALL OF THESE WORK TOGETHER!!!
 Find food
 Maintain safety
 Don’t eat poisonous foods
 Or get eaten
 Detect mates (and convince them to participate)
Enter the
Nervous System…
 The transmission of information depends on the
path of neurons along which a signal travels
 Processing of information takes place in simple
clusters of neurons called ganglia or a more
complex organization of neurons called a brain
Fig. 48-2
Nerves
with giant axons
Ganglia
Brain
Arm
Eye
Nerve
Mantle
 Sensors detect external stimuli and internal
conditions and transmit information along
sensory neurons
 Sensory information is sent to the brain or
ganglia, where interneurons integrate the
information
 Motor output leaves the brain or ganglia via
motor neurons, which trigger muscle or gland
activity
 Many animals have a complex nervous system
which consists of:
 A central nervous system (CNS) where integration takes
place; this includes the brain and a nerve cord
 A peripheral nervous system (PNS), which brings
information into and out of the CNS
Fig. 48-3
Sensory input
Integration
Sensor
Motor output
Effector
Peripheral nervous
system (PNS)
Central nervous
system (CNS)
 Most of a neuron’s organelles are in the cell
body
 Most neurons have dendrites, highly branched
extensions that receive signals from other
neurons
 The axon is typically a much longer extension
that transmits signals to other cells at synapses
 An axon joins the cell body at the axon hillock
Fig. 48-4
Dendrites
Stimulus
Nucleus
Cell
body
Axon
hillock
Presynaptic
cell
Axon
Synapse
Synaptic terminals
Postsynaptic cell
Neurotransmitter
 A synapse is a junction between an axon and
another cell
 The synaptic terminal of one axon passes
information across the synapse in the form of
chemical messengers called neurotransmitters
 Every cell has a voltage (difference in electrical
charge) across its plasma membrane called a
membrane potential
 Messages are transmitted as changes in
membrane potential
 The resting potential is the membrane
potential of a neuron not sending signals
 In a mammalian neuron at resting potential, the
concentration of K+ is greater inside the cell, while
the concentration of Na+ is greater outside the cell
 Sodium-potassium pumps use the energy of ATP
to maintain these K+ and Na+ gradients across the
plasma membrane
 These concentration gradients represent chemical
potential energy
 The opening of ion channels in the plasma
membrane converts chemical potential to
electrical potential
 A neuron at resting potential contains many
open K+ channels and fewer open Na+ channels;
K+ diffuses out of the cell
 Anions trapped inside the cell contribute to the
negative charge within the neuron
Animation: Resting Potential
Fig. 48-6
Key
Na+
K+
OUTSIDE
CELL
OUTSIDE [K+]
CELL
5 mM
INSIDE [K+]
CELL 140 mM
[Na+]
[Cl–]
150 mM 120 mM
[Na+]
15 mM
[Cl–]
10 mM
[A–]
100 mM
INSIDE
CELL
(a)
(b)
Sodiumpotassium
pump
Potassium
channel
Sodium
channel
 In a resting neuron, the currents of K+ and Na+
are equal and opposite, and the resting potential
across the membrane remains steady
Fig. 48-7b
+62 mV
150 mM
NaCI
15 mM
NaCI
Cl–
Na+
Sodium
channel
(b) Membrane selectively permeable to Na+
(
ENa = 62 mV log
) = +62 mV
150 mM
15 mM
 Neurons contain gated ion channels that open
or close in response to stimuli
Fig. 48-9
Stimuli
Stimuli
Strong depolarizing stimulus
+50
+50
+50
0
–50
Threshold
Membrane potential (mV)
Membrane potential (mV)
Membrane potential (mV)
Action
potential
0
–50
Resting
potential
Threshold
0
–50
Resting
potential
Resting
potential
Depolarizations
Hyperpolarizations
–100
–100
0
1
2 3 4 5
Time (msec)
(a) Graded hyperpolarizations
Threshold
–100
0
1 2 3 4
Time (msec)
(b) Graded depolarizations
5
0
(c) Action potential
1
2 3 4 5
Time (msec)
6
 Other stimuli trigger a depolarization, a
reduction in the magnitude of the membrane
potential
 For example, depolarization occurs if gated Na+
channels open and Na+ diffuses into the cell
 Graded potentials are changes in polarization
where the magnitude of the change varies with
the strength of the stimulus
 Voltage-gated Na+ and K+ channels respond to a
change in membrane potential
 When a stimulus depolarizes the membrane, Na+
channels open, allowing Na+ to diffuse into the
cell
 The movement of Na+ into the cell increases the
depolarization and causes even more Na+
channels to open
 A strong stimulus results in a massive change in
membrane voltage called an action potential
 An action potential occurs if a stimulus causes
the membrane voltage to cross a particular
threshold
 An action potential is a brief all-or-none
depolarization of a neuron’s plasma membrane
 Action potentials are signals that carry
information along axons
Fig. 48-10-5
Key
Na+
K+
3
4
Rising phase of the action potential
Falling phase of the action potential
Membrane potential
(mV)
+50
Action
potential
–50
2
2
4
Threshold
1
1
5
Resting potential
Depolarization
Extracellular fluid
3
0
–100
Sodium
channel
Time
Potassium
channel
Plasma
membrane
Cytosol
Inactivation loop
5
1
Resting state
Undershoot
Fig. 48-11-3
Axon
Plasma
membrane
Action
potential
Cytosol
Na+
K+
Action
potential
Na+
K+
K+
Action
potential
Na+
K+
Fig. 48-12
Node of Ranvier
Layers of myelin
Axon
Schwann
cell
Axon
Nodes of
Myelin sheath Ranvier
Schwann
cell
Nucleus of
Schwann cell
0.1 µm
Fig. 48-15
5
Synaptic vesicles
containing
neurotransmitter
Voltage-gated
Ca2+ channel
Postsynaptic
membrane
1 Ca2+
4
2
Synaptic
cleft
Presynaptic
membrane
3
Ligand-gated
ion channels
6
K+
Na+
 After release, the neurotransmitter
 May diffuse out of the synaptic cleft
 May be taken up by surrounding cells
 May be degraded by enzymes
Table 48-1
 All stimuli represent forms of energy
 Sensation involves converting energy into a
change in the membrane potential of sensory
receptors
 Sensations are action potentials that reach the
brain via sensory neurons
 The brain interprets sensations, giving the
perception of stimuli
 Functions of sensory pathways: sensory
reception, transduction, transmission, and
integration
 For example, stimulation of a stretch receptor in
a crayfish is the first step in a sensory pathway
Membrane
potential (mV)
Slight bend:
weak
stimulus
–50
Weak
receptor
potential
–70
Dendrites
2
1
3
1 Reception
Membrane
potential (mV)
Muscle
Large bend:
strong
stimulus
–50
Strong receptor
potential
–70
2 Transduction
Action potentials
0
–70
0 1 2 34 5 6 7
Time (sec)
Stretch
receptor
Brain perceives
slight bend.
4
Axon
Membrane
potential (mV)
Membrane
potential (mV)
Fig. 50-2
Brain
Action potentials
Brain perceives
large bend.
0
–70
0 1 2 34 5 6 7
Time (sec)
3 Transmission
4 Perception
 Sensations and perceptions begin with sensory
reception, detection of stimuli by sensory
receptors
 Sensory receptors can detect stimuli outside
and inside the body
 Sensory transduction is the conversion of
stimulus energy into a change in the membrane
potential of a sensory receptor
 This change in membrane potential is called a
receptor potential
 Many sensory receptors are very sensitive: they
are able to detect the smallest physical unit of
stimulus
 For example, most light receptors can detect a photon of
light
 After energy has been transduced into a receptor
potential, some sensory cells generate the
transmission of action potentials to the CNS
 Sensory cells without axons release
neurotransmitters at synapses with sensory
neurons
 Larger receptor potentials generate more rapid
action potentials
 Integration of sensory information begins when
information is received
 Some receptor potentials are integrated through
summation
 Based on energy transduced, sensory receptors
fall into five categories:
 Mechanoreceptors
 Chemoreceptors
 Electromagnetic receptors
 Thermoreceptors
 Pain receptors
Fig. 50-3
Heat
Gentle
touch
Pain
Cold
Hair
Epidermis
Dermis
Hypodermis
Nerve
Connective
tissue
Hair
movement
Strong
pressure
 General chemoreceptors transmit information
about the total solute concentration of a solution
 Specific chemoreceptors respond to individual
kinds of molecules
 When a stimulus molecule binds to a
chemoreceptor, the chemoreceptor becomes
more or less permeable to ions
 The antennae of the male silkworm moth have
very sensitive specific chemoreceptors
0.1 mm
Fig. 50-4
 Electromagnetic receptors detect
electromagnetic energy such as light, electricity,
and magnetism
 Photoreceptors are electromagnetic receptors
that detect light
 Some snakes have very sensitive infrared
receptors that detect body heat of prey against a
colder background
Fig. 50-5
Eye
Infrared
receptor
(a) Rattlesnake
(b) Beluga whales
 Thermoreceptors, which respond to heat or
cold, help regulate body temperature by
signaling both surface and body core
temperature
 Hearing and perception of body equilibrium are
related in most animals
 Settling particles or moving fluid are detected by
mechanoreceptors
Fig. 50-8a
Middle
ear
Outer ear
Skull
bone
Inner ear
Stapes
Incus
Malleus
Semicircular
canals
Auditory nerve
to brain
Cochlea
Pinna
Auditory
canal
Oval
window
Round
Tympanic
window
membrane
Eustachian
tube
Fig. 50-12
Lateral line
Surrounding water
Scale Lateral line canal
Epidermis
Opening of
lateral line canal
Cupula
Sensory
hairs
Hair cell
Supporting
cell
Segmental muscles
Fish body wall
Lateral nerve
Axon
Fig. 50-18
Ciliary body
Sclera
Choroid
Retina
Suspensory
ligament
Fovea (center
of visual field)
Cornea
Iris
Optic
nerve
Pupil
Aqueous
humor
Lens
Vitreous humor
Central artery and
vein of the retina
Optic disk
(blind spot)
 The human retina contains two types of
photoreceptors: rods and cones
 Rods are light-sensitive but don’t distinguish
colors
 Cones distinguish colors but are not as sensitive
to light
 In humans, cones are concentrated in the fovea,
the center of the visual field, and rods are more
concentrated around the periphery of the retina
And they need to “develop”
The ENDOCRINE SYSTEM does this…
 Animal hormones are chemical signals that are
secreted into the circulatory system and
communicate regulatory messages within the
body
 Hormones reach all parts of the body, but only
target cells are equipped to respond
 Insect metamorphosis is regulated by hormones
 Two systems coordinate communication
throughout the body: the endocrine system and
the nervous system
 The endocrine system secretes hormones that
coordinate slower but longer-acting responses
including reproduction, development, energy
metabolism, growth, and behavior
 The nervous system conveys high-speed
electrical signals along specialized cells called
neurons; these signals regulate other cells
Fig. 45-UN1
Fig. 45-1
 Chemical signals bind to receptor proteins on
target cells
 Only target cells respond to the signal
 Secreted chemical signals include
 Hormones
 Local regulators
 Neurotransmitters
 Neurohormones
 Pheromones
 Endocrine signals (hormones) are secreted into
extracellular fluids and travel via the
bloodstream
 Endocrine glands are ductless and secrete
hormones directly into surrounding fluid
 Hormones mediate responses to environmental
stimuli and regulate growth, development, and
reproduction
Fig. 45-2
Blood
vessel
Response
(a) Endocrine signaling
Response
(b) Paracrine signaling
Response
(c) Autocrine signaling
Synapse
Neuron
Response
(d) Synaptic signaling
Neurosecretory
cell
Blood
vessel
(e) Neuroendocrine signaling
Response
 Exocrine glands have ducts and secrete
substances onto body surfaces or into body
cavities (for example, tear ducts)
 Signaling by any of these hormones involves
three key events:
 Reception
 Signal transduction
 Response
Fig. 45-5-2
Fat-soluble
hormone
Watersoluble
hormone
Transport
protein
Signal receptor
TARGET
CELL
Cytoplasmic
response
OR
Signal
receptor
Gene
regulation
Cytoplasmic
response
(a)
NUCLEUS
(b)
Gene
regulation
 The hormone epinephrine has multiple effects
in mediating the body’s response to short-term
stress
 Epinephrine binds to receptors on the plasma
membrane of liver cells
 This triggers the release of messenger molecules
that activate enzymes and result in the release of
glucose into the bloodstream
Fig. 45-6-2
Epinephrine
Adenylyl
cyclase
G protein
G protein-coupled
receptor
GTP
ATP
cAMP
Inhibition of
glycogen synthesis
Promotion of
glycogen breakdown
Protein
kinase A
Second
messenger
 The response to a lipid-soluble hormone is
usually a change in gene expression
 Steroids, thyroid hormones, and the hormonal
form of vitamin D enter target cells and bind to
protein receptors in the cytoplasm or nucleus
 Protein-receptor complexes then act as
transcription factors in the nucleus, regulating
transcription of specific genes
Animation: Lipid-Soluble Hormone
Fig. 45-7-2
Hormone
(estradiol)
Estradiol
(estrogen)
receptor
Plasma
membrane
Hormone-receptor
complex
DNA
Vitellogenin
mRNA
for vitellogenin
 The same hormone may have different effects on
target cells that have
 Different receptors for the hormone
 Different signal transduction pathways
 Different proteins for carrying out the response
 A hormone can also have different effects in
different species
Fig. 45-8-2
Same receptors but different
intracellular proteins (not shown)
Different receptors
Epinephrine
Epinephrine
Epinephrine
receptor
receptor
receptor
Glycogen
deposits
Glycogen
breaks down
and glucose
is released.
(a) Liver cell
Vessel
dilates.
(b) Skeletal muscle
blood vessel
Vessel
constricts.
(c) Intestinal blood
vessel
Fig. 45-9
(a)
(b)
 In paracrine signaling, nonhormonal chemical
signals called local regulators elicit responses in
nearby target cells
 Types of local regulators:
 Cytokines and growth factors
 Nitric oxide (NO)
 Prostaglandins
Fig. 45-10
Major endocrine glands:
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Organs containing
endocrine cells:
Thymus
Heart
Adrenal
glands
Testes
Liver
Stomach
Pancreas
Kidney
Kidney
Small
intestine
Ovaries
 A negative feedback loop inhibits a response by
reducing the initial stimulus
 Negative feedback regulates many hormonal
pathways involved in homeostasis
 Insulin and glucagon are antagonistic
hormones that help maintain glucose
homeostasis
 The pancreas has clusters of endocrine cells
called islets of Langerhans with alpha cells that
produce glucagon and beta cells that produce
insulin
Fig. 45-12-5
Body cells
take up more
glucose.
Insulin
Beta cells of
pancreas
release insulin
into the blood.
Liver takes
up glucose
and stores it
as glycogen.
STIMULUS:
Blood glucose level
rises.
Blood glucose
level declines.
Homeostasis:
Blood glucose level
(about 90 mg/100 mL)
STIMULUS:
Blood glucose level
falls.
Blood glucose
level rises.
Alpha cells of pancreas
release glucagon.
Liver breaks
down glycogen
and releases
glucose.
Glucagon
 Insulin reduces blood glucose levels by
 Promoting the cellular uptake of glucose
 Slowing glycogen breakdown in the liver
 Promoting fat storage
 Glucagon increases blood glucose levels by
 Stimulating conversion of glycogen to glucose in the liver
 Stimulating breakdown of fat and protein into glucose
 Diabetes mellitus is perhaps the best-known
endocrine disorder
 It is caused by a deficiency of insulin or a
decreased response to insulin in target tissues
 It is marked by elevated blood glucose levels
 Type I diabetes mellitus (insulin-dependent) is an
autoimmune disorder in which the immune
system destroys pancreatic beta cells
 Type II diabetes mellitus (non-insulindependent) involves insulin deficiency or
reduced response of target cells due to change in
insulin receptors
Table 45-1
Table 45-1a
 Survive anyone???
 This had to be evolved by prey species…
 Epinephrine and norepinephrine
 Trigger the release of glucose and fatty acids into the blood
 Increase oxygen delivery to body cells
 Direct blood toward heart, brain, and skeletal muscles,
and away from skin, digestive system, and kidneys
 The release of epinephrine and norepinephrine
occurs in response to nerve signals from the
hypothalamus
Fig. 45-21a
Stress
Spinal cord
Nerve
signals
Releasing
hormone
Nerve
cell
Hypothalamus
Anterior pituitary
Blood vessel
ACTH
Adrenal
medulla
Adrenal
cortex
Adrenal
gland
Kidney
Fig. 45-21b
Adrenal medulla
Adrenal
gland
Kidney
(a) Short-term stress response
Effects of epinephrine and norepinephrine:
1. Glycogen broken down to glucose; increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood flow patterns, leading to increased
alertness and decreased digestive, excretory, and
reproductive system activity
 The adrenal cortex releases a family of steroids
called corticosteroids in response to stress
 These hormones are triggered by a hormone
cascade pathway via the hypothalamus and
anterior pituitary
 Humans produce two types of corticosteroids:
glucocorticoids and mineralocorticoids
Fig. 45-21c
Adrenal cortex
Adrenal
gland
Kidney
(b) Long-term stress response
Effects of
mineralocorticoids:
Effects of
glucocorticoids:
1. Retention of sodium
ions and water by
kidneys
1. Proteins and fats broken down
and converted to glucose, leading
to increased blood glucose
2. Increased blood
volume and blood
pressure
2. Possible suppression of
immune system
 Glucocorticoids, such as cortisol, influence
glucose metabolism and the immune system
 Mineralocorticoids, such as aldosterone, affect
salt and water balance
 The adrenal cortex also produces small amounts
of steroid hormones that function as sex
hormones
 The gonads, testes and ovaries, produce most of
the sex hormones: androgens, estrogens, and
progestins
 All three sex hormones are found in both males
and females, but in different amounts
 The testes primarily synthesize androgens,
mainly testosterone, which stimulate
development and maintenance of the male
reproductive system
 Testosterone causes an increase in muscle and
bone mass and is often taken as a supplement to
cause muscle growth, which carries health risks
 THE IMMUNE SYSTEM
Fig. 43-1
1.5 µm
 Barriers help an animal to defend itself from the
many dangerous pathogens it may encounter
 The immune system recognizes foreign bodies
and responds with the production of immune
cells and proteins
 Two major kinds of defense have evolved: innate
immunity and acquired immunity
 Innate immunity is present before any exposure
to pathogens and is effective from the time of
birth
 It involves nonspecific responses to pathogens
 Innate immunity consists of external barriers
plus internal cellular and chemical defenses
 Acquired immunity, or adaptive immunity,
develops after exposure to agents such as
microbes, toxins, or other foreign substances
 It involves a very specific response to pathogens
Fig. 43-2
Pathogens
(microorganisms
and viruses)
INNATE IMMUNITY
• Recognition of traits
shared by broad ranges
of pathogens, using a
small set of receptors
• Rapid response
ACQUIRED IMMUNITY
• Recognition of traits
specific to particular
pathogens, using a vast
array of receptors
• Slower response
Barrier defenses:
Skin
Mucous membranes
Secretions
Internal defenses:
Phagocytic cells
Antimicrobial proteins
Inflammatory response
Natural killer cells
Humoral response:
Antibodies defend against
infection in body fluids.
Cell-mediated response:
Cytotoxic lymphocytes defend
against infection in body cells.
Fig. 43-3
Microbes
This is
A form of Innate
immunity
PHAGOCYTIC CELL
Vacuole
Lysosome
containing
enzymes
 The immune system of mammals is the best
understood of the vertebrates
 Innate defenses include barrier defenses,
phagocytosis, antimicrobial peptides
 Additional defenses are unique to vertebrates:
the inflammatory response and natural killer
cells
 Barrier defenses include the skin and mucous
membranes of the respiratory, urinary, and
reproductive tracts
 Mucus traps and allows for the removal of
microbes
 Many body fluids including saliva, mucus, and
tears are hostile to microbes
 The low pH of skin and the digestive system
prevents growth of microbes
 White blood cells (leukocytes) engulf pathogens
in the body
 Groups of pathogens are recognized by TLR,
Toll-like receptors
Fig. 43-6
EXTRACELLULAR
Lipopolysaccharide
FLUID
Helper
protein
TLR4
WHITE
BLOOD
CELL
Flagellin
TLR5
VESICLE
CpG DNA
TLR9
TLR3
ds RNA
Inflammatory
responses
 A white blood cell engulfs a microbe, then fuses
with a lysosome to destroy the microbe
 There are different types of phagocytic cells:
 Neutrophils engulf and destroy microbes
 Macrophages are part of the lymphatic system and are
found throughout the body
 Eosinophils discharge destructive enzymes
 Dendritic cells stimulate development of acquired
immunity
Fig. 43-7
Interstitial fluid
Adenoid
Tonsil
Blood
capillary
Lymph
nodes
Spleen
Tissue
cells
Lymphatic
vessel
Peyer’s patches
(small intestine)
Appendix
Lymphatic
vessels
Lymph
node
Masses of
defensive cells
 Following an injury, mast cells release
histamine, which promotes changes in blood
vessels; this is part of the inflammatory
response
 These changes increase local blood supply and
allow more phagocytes and antimicrobial
proteins to enter tissues
 Pus, a fluid rich in white blood cells, dead
microbes, and cell debris, accumulates at the site
of inflammation
Fig. 43-8-3
Pathogen
Splinter
Chemical Macrophage
signals
Mast cell
Capillary
Red blood cells Phagocytic cell
Fluid
Phagocytosis
 White blood cells called lymphocytes recognize
and respond to antigens, foreign molecules
 Lymphocytes that mature in the thymus above
the heart are called T cells, and those that
mature in bone marrow are called B cells
 B cells and T cells have receptor proteins that can
bind to foreign molecules
 Each individual lymphocyte is specialized to
recognize a specific type of molecule
 An antigen is any foreign molecule to which a
lymphocyte responds
 A single B cell or T cell has about 100,000
identical antigen receptors
Fig. 43-9
Antigenbinding
site
Antigenbinding site
Antigenbinding
site
Disulfide
bridge
C
C
Light
chain
Variable
regions
V
V
Constant
regions
C
C
Transmembrane
region
Plasma
membrane
Heavy chains
chain
chain
Disulfide bridge
B cell
(a) B cell receptor
Cytoplasm of B cell
Cytoplasm of T cell
(b) T cell receptor
T cell
 All antigen receptors on a single lymphocyte
recognize the same epitope, or antigenic
determinant, on an antigen
 B cells give rise to plasma cells, which secrete
proteins called antibodies or
immunoglobulins
Fig. 43-10
Antigenbinding
sites
Antigen-binding sites
Antibody A Antigen Antibody C
C
C
Antibody B
Epitopes
(antigenic
determinants)
 The acquired immune system has three
important properties:
 Receptor diversity
 A lack of reactivity against host cells
 Immunological memory
 In the body there are few lymphocytes with
antigen receptors for any particular epitope
 The binding of a mature lymphocyte to an
antigen induces the lymphocyte to divide rapidly
 This proliferation of lymphocytes is called clonal
selection
 Two types of clones are produced: short-lived
activated effector cells and long-lived memory
cells
Fig. 43-14
Antigen molecules
B cells that
differ in
antigen
specificity
Antigen
receptor
Antibody
molecules
Clone of memory cells
Clone of plasma cells
 The first exposure to a specific antigen represents
the primary immune response
 During this time, effector B cells called plasma
cells are generated, and T cells are activated to
their effector forms
 In the secondary immune response, memory
cells facilitate a faster, more efficient response
Animation: Role of B Cells
 Acquired immunity has two branches: the
humoral immune response and the cell-mediated
immune response
 Humoral immune response involves activation
and clonal selection of B cells, resulting in
production of secreted antibodies
 Cell-mediated immune response involves
activation and clonal selection of cytotoxic T
cells
 Helper T cells aid both responses
Fig. 43-16
Humoral (antibody-mediated) immune response
Cell-mediated immune response
Key
Antigen (1st exposure)
+
Engulfed by
Gives rise to
Antigenpresenting cell
+
Stimulates
+
+
B cell
Helper T cell
+
Cytotoxic T cell
+
Memory
Helper T cells
+
+
+
Antigen (2nd exposure)
Plasma cells
Memory B cells
+
Memory
Cytotoxic T cells
Active
Cytotoxic T cells
Secreted
antibodies
Defend against extracellular pathogens by binding to antigens,
thereby neutralizing pathogens or making them better targets
for phagocytes and complement proteins.
Defend against intracellular pathogens
and cancer by binding to and lysing the
infected cells or cancer cells.
Fig. 43-18-3
Released cytotoxic T cell
Cytotoxic T cell
Perforin
Granzymes
CD8
TCR
Class I MHC
molecule
Target
cell
Dying target cell
Pore
Peptide
antigen
Fig. 43-19-3
Antigen-presenting cell
Bacterium
Peptide
antigen
B cell
Class II MHC
molecule
TCR
Clone of plasma cells
+
CD4
Helper T cell
Cytokines
Activated
helper T cell
Clone of memory
B cells
Secreted
antibody
molecules
 Active immunity develops naturally in response
to an infection
 It can also develop following immunization,
also called vaccination
 In immunization, a nonpathogenic form of a
microbe or part of a microbe elicits an immune
response to an immunological memory
 Passive immunity provides immediate, short-
term protection
 It is conferred naturally when IgG crosses the
placenta from mother to fetus or when IgA passes
from mother to infant in breast milk
 It can be conferred artificially by injecting
antibodies into a nonimmune person
Fig. 43-22
 Antigens on red blood cells determine whether a
person has blood type A (A antigen), B (B
antigen), AB (both A and B antigens), or O
(neither antigen)
 Antibodies to nonself blood types exist in the
body
 Transfusion with incompatible blood leads to
destruction of the transfused cells
 Recipient-donor combinations can be fatal or
safe
 MHC molecules are different among genetically
nonidentical individuals
 Differences in MHC molecules stimulate
rejection of tissue grafts and organ transplants
 Chances of successful transplantation increase if
donor and recipient MHC tissue types are well
matched
 Immunosuppressive drugs facilitate
transplantation
 Lymphocytes in bone marrow transplants may
cause the donor tissue to reject the recipient
 Allergies are exaggerated (hypersensitive)
responses to antigens called allergens
 In localized allergies such as hay fever, IgE
antibodies produced after first exposure to an
allergen attach to receptors on mast cells
Fig. 43-23
IgE
Histamine
Allergen
Granule
Mast cell
 Inborn immunodeficiency results from
hereditary or developmental defects that prevent
proper functioning of innate, humoral, and/or
cell-mediated defenses
 Acquired immunodeficiency results from
exposure to chemical and biological agents
 Acquired immunodeficiency syndrome
(AIDS) is caused by a virus
 Some Digestion
 Some Circulation
 Some Gas Exchange
Digestive system
mmm,mmm
good
(Campbell’s Soup)
Fig. 41-10
Tongue
Sphincter
Salivary
glands
Oral cavity
Salivary glands
Mouth
Pharynx
Esophagus
Esophagus
Sphincter
Liver
Stomach
Ascending
portion of
large intestine
Gallbladder
Gallbladder
Duodenum of
small intestine
Pancreas
Small
intestine
Small
intestine
Large
intestine
Rectum
Anus
Appendix
Cecum
Liver
Pancreas
Stomach
Small
intestine
Large
intestine
Rectum
Anus
A schematic diagram of the
human digestive system
 The stomach stores food and secretes gastric
juice, which converts a meal to acid chyme
 Gastric juice is made up of hydrochloric acid and
the enzyme pepsin
 Parietal cells secrete hydrogen and chloride ions
separately
 Chief cells secrete inactive pepsinogen, which is
activated to pepsin when mixed with
hydrochloric acid in the stomach
 Mucus protects the stomach lining from gastric
juice
Surface
Area !!!!!
Fig. 41-12
Esophagus
Sphincter
Stomach
5 µm
Sphincter
Interior surface
of stomach
Small
intestine
Folds of
epithelial
tissue
Epithelium
3
Pepsinogen
1 Pepsinogen and HCl
are secreted.
Pepsin
2
HCl
Gastric gland
2 HCl converts
pepsinogen to pepsin.
1
Mucus cells
Cl–
3 Pepsin activates
more pepsinogen.
H+
Chief cells
Chief cell
Parietal cells
Parietal cell
Fig. 41-15
Microvilli (brush
border) at apical
(lumenal) surface Lumen
Vein carrying blood
to hepatic portal vein
Blood
capillaries
Muscle layers
Epithelial
cells
Basal
surface
Large
circular
folds
Villi
Epithelial cells
Lacteal
Key
Nutrient
absorption
Intestinal wall
Villi
Lymph
vessel
 Many herbivores have fermentation chambers,
where symbiotic microorganisms digest cellulose
 The most elaborate adaptations for an
herbivorous diet have evolved in the animals
called ruminants
Fig. 41-20
1
Rumen
2
Reticulum
Intestine
Esophagus
4
Abomasum
3
Omasum
 Heart
 Arteries
 Capillaries
 Veins
And, of course…
* The lungs (gas exchange)
Fig. 42-2
These guys need no Circulatory System…
DiffusionCircular
suffices…
canal
Mouth
Pharynx
Mouth
Radial canal
(a) The moon jelly Aurelia, a cnidarian
5 cm
2 mm
(b) The planarian Dugesia, a
flatworm
Fig. 42-1
 In small and/or thin animals, cells can
exchange materials directly with the
surrounding medium
 In most animals, transport systems connect the
organs of exchange with the body cells
 Most complex animals have internal transport
systems that circulate fluid
 In insects, other arthropods, and most
molluscs, blood bathes the organs directly in an
open circulatory system
 In an open circulatory system, there is no
distinction between blood and interstitial fluid,
and this general body fluid is more correctly
called hemolymph
 In a closed circulatory system, blood is
confined to vessels and is distinct from the
interstitial fluid
 Closed systems are more efficient at
transporting circulatory fluids to tissues and
cells
Fig. 42-3
Heart
Hemolymph in sinuses
surrounding organs
Pores
Heart
Blood
Interstitial
fluid
Small branch vessels
In each organ
Dorsal vessel
(main heart)
Tubular heart
(a) An open circulatory system
Auxiliary hearts
Ventral vessels
(b) A closed circulatory system
Fig. 42-5
Amphibians
Reptiles (Except Birds)
Mammals and Birds
Lung and skin capillaries
Lung capillaries
Lung capillaries
Pulmocutaneous
circuit
Atrium (A)
Right
systemic
aorta
Atrium (A)
Ventricle (V)
Left
Right
Systemic
circuit
Systemic capillaries
Pulmonary
circuit
A
V
Right
Pulmonary
circuit
A
A
V
Left
Systemic capillaries
Left
systemic
aorta
A
V
V
Right
Left
Systemic
circuit
Systemic capillaries
 In reptiles and mammals, oxygen-poor blood
flows through the pulmonary circuit to pick up
oxygen through the lungs
 In amphibians, oxygen-poor blood flows
through a pulmocutaneous circuit to pick up
oxygen through the lungs and skin
 Oxygen-rich blood delivers oxygen through the
systemic circuit
 Double circulation maintains higher blood
pressure in the organs than does single
circulation
Fig. 42-6
Superior
vena cava
Capillaries of
head and
forelimbs
7
Pulmonary
artery
Pulmonary
artery
Capillaries
of right lung
Aorta
9
3
Capillaries
of left lung
3
2
4
11
Pulmonary
vein
Right atrium
1
Pulmonary
vein
5
Left atrium
10
Right ventricle
Left ventricle
Inferior
vena cava
Aorta
8
Capillaries of
abdominal organs
and hind limbs
Ok, so, we don’t think you really need to know these
specifics for the AP Exam, but I can’t conscientiously
finish this powerpoint ithout putting this in… All
educated people should have an idea about this thing,
since heart disease is so pervasive in our society…
Fig. 42-7
Pulmonary artery
Aorta
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Right
ventricle
Left
ventricle
Fig. 42-8
2 Atrial systole;
ventricular
diastole
Semilunar
valves
closed
0.1 sec
AV
valves
open
1 Atrial and
ventricular
diastole
0.4 sec
Semilunar
valves
open
0.3 sec
AV valves
closed
3 Ventricular systole;
atrial diastole
Fig. 42-9-5
1 Pacemaker
generates wave of
signals to contract.
SA node
(pacemaker)
ECG
2 Signals are
delayed at
AV node.
AV
node
3 Signals pass
to heart apex.
Bundle
branches
Heart
apex
4 Signals spread
throughout
ventricles.
Purkinje
fibers
Fig. 42-10
Artery
Vein
SEM
Valve
100 µm
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Capillary
15 µm
Red blood cell
Venule
LM
Arteriole
 Systolic pressure is the pressure in the
arteries during ventricular systole; it is the
highest pressure in the arteries
 Diastolic pressure is the pressure in the
arteries during diastole; it is lower than systolic
pressure
 A pulse is the rhythmic bulging of artery walls
with each heartbeat
 Blood pressure is determined by cardiac output
and peripheral resistance due to constriction of
arterioles
 Vasoconstriction is the contraction of smooth
muscle in arteriole walls; it increases blood
pressure
 Vasodilation is the relaxation of smooth
muscles in the arterioles; it causes blood
pressure to fall
Fig. 42-13-3
Blood pressure reading: 120/70
Pressure in cuff
greater than
120 mm Hg
Rubber
cuff
inflated
with air
Pressure in cuff
drops below
120 mm Hg
120
Pressure in
cuff below
70 mm Hg
120
70
Artery
closed
Sounds
audible in
stethoscope
Sounds
stop
Fig. 42-16
Body tissue
INTERSTITIAL FLUID
Capillary
Net fluid
movement out
Net fluid
movement in
Direction of
blood flow
Pressure
Blood pressure
Inward flow
Outward flow
Osmotic pressure
Arterial end of capillary
Venous end
Fig. 42-17
Plasma 55%
Constituent
Major functions
Water
Solvent for
carrying other
substances
Cellular elements 45%
Cell type
Number
per µL (mm3) of blood
Erythrocytes
(red blood cells)
5–6 million
Transport oxygen
and help transport
carbon dioxide
Leukocytes
(white blood cells)
5,000–10,000
Defense and
immunity
Ions (blood electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering, and
regulation of
membrane
permeability
Functions
Separated
blood
elements
Plasma proteins
Albumin
Osmotic balance
pH buffering
Lymphocyte
Basophil
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Eosinophil
Neutrophil
Monocyte
Substances transported by blood
Nutrients (such as glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Platelets
250,000–
400,000
Blood clotting
 We need Oxygen…
 We need to get rid of Carbon Dioxide…
 Animals do this with “respiratory surfaces”
 Places where the blood gets really close to the air or
water.
 Think: thin membranes (simple squamous Epithelium)
and INCREASED SURFACE AREA…
Fig. 42-21
Coelom
Gills
Gills
Parapodium (functions as gill)
(a) Marine worm
Tube foot
(b) Crayfish
(c) Sea star
Fig. 42-22
Fluid flow
through
gill filament
Oxygen-poor blood
Anatomy of gills
Oxygen-rich blood
Gill
arch
Lamella
Gill
arch
Gill filament
organization
Blood
vessels
Water
flow
Operculum
Water flow
between
lamellae
Blood flow through
capillaries in lamella
Countercurrent exchange
PO2 (mm Hg) in water
150 120 90 60 30
Gill filaments
Net diffusion of O2
from water
to blood
140 110 80 50 20
PO2 (mm Hg) in blood
Fig. 42-24
Branch of
pulmonary
vein
(oxygen-rich
blood)
Branch of
pulmonary
artery
(oxygen-poor
blood)
Terminal
bronchiole
Nasal
cavity
Pharynx
Larynx
Alveoli
(Esophagus)
Left
lung
Trachea
Right lung
Bronchus
Bronchiole
Diaphragm
Heart
SEM
50 µm
Colorized
SEM
50 µm
Fig. 42-25
Rib cage
expands as
rib muscles
contract
Air
inhaled
Rib cage gets
smaller as
rib muscles
relax
Air
exhaled
Lung
Diaphragm
INHALATION
Diaphragm contracts
(moves down)
EXHALATION
Diaphragm relaxes
(moves up)
Fig. 42-28
Alveolus
PCO2 = 40 mm Hg
PO2 = 100 mm Hg
PO2 = 40
Alveolus
PO2 = 100
PCO2 = 46
Circulatory
system
PO2 = 40
PCO2 = 40
Circulatory
system
PO2 = 100
PO2 ≤ 40 mm Hg
PCO2 = 46
PCO2 ≥ 46 mm Hg
Body tissue
(a) Oxygen
PCO2 = 40
Body tissue
(b) Carbon dioxide
 You are a devoted AP Biology student
 You know a heck of a lot about your body (the inner
workings, at least)
 You are ready to tackle the AP Bio Exam!
 Now: go and study your review books and make me
proud in May!!!
 With love, J.Ship