Transcript Homeostasis, Circulation and Respiration.

Homeostasis and the
Organization of the
Animal Body
Homeostasis
 Homeostasis
(“steady state”)
–Maintenance of nearly constant
internal conditions
–Snakes are cold-blooded
(ectothermic or poikilothermic)
Heat
& thus their body temperature is
absorbed from environment
–Humans are warm-blooded
(endothermic or homeothermic)
Body
temperature is generated
internally
Feedback Systems
 Homeostasis
is controlled by
feedback
 Feedback loops used by organisms to
help maintain homeostasis & have 3
major components:
– Receptors - respond to various stimuli to
which organism may be exposed
– Control center - decides to which stimuli
organism should respond to & what is the
right response
– Effectors - receive instructions from
control center
Homeostasis

A. Negative feedback is used to



Slow down, shut off, or reverse a
physiological process &
Return it to an optimal condition
B. Positive feedback enhances or
intensifies a process
signal
(temperature to
control center)
Negative feedback
signal to turn off effector
signal to turn on effector
thermometer
(sensor)
heater
(effector)
heat output decreases
signal to
control
center
nerve signal
to turn off
effector
nerve signal
(temperature) to
control center
control
center
heat output
increases
hypothalamus
(control center)
nerve endings
(sensor)
heat output
(shivering)
decreases
Positive feedback
nerve signal to
control center
signal to turn
on effector
Skeletal
muscles
(effector)
hypothalamus
(control center)
uterine muscles
(effector)
uterus
output level
increases
stretch receptors
in cervix (sensor)
nerve
signal to
turn on
effector
heat output
(shivering)
increases
oxytocin
release
(signal to
turn on
effector)
output level
(contraction)
increases
Circulation and
Respiration
II. Circulatory systems

A. Circulatory system basics
•
•
•
1. Fluid—blood
2. Channels—vessels
3. A pump—the heart
III. The vertebrate circulatory
system

A. Functions
•
•
3.
•
•
•
1. Transport of O2 and CO2
2. Distribution of nutrients
Transport of waste
4. Distribution of hormones
5. Regulation of body temperature
6. Protection of the body against
blood loss
The vertebrate circulatory system
B. The heart
1. Structure
a. Atria
b. Ventricles
aorta
pulmonary artery
(to left lung)
superior
vena cava
pulmonary artery
(to right lung)
left atrium
pulmonary veins
(from right lung)
pulmonary
veins (from left
lung)
atrioventricular valve
right
atrium
semilunar valves
atrioventricular valve
right
ventricle
inferior
vena cava
descending aorta
(to lower body)
left ventricle
ventricular septum
heart muscle
The vertebrate circulatory system

Function
•
a. The cardiac cycle
•
•
•
1) Systole—period of ventricle
contraction
2) Diastole—relaxation of all the
chambers followed by
contraction of the atria
Oxygenated blood
from lungs enters
left ventricle.
Deoxygenated
blood from
body enters
right ventricle.
Oxygenated
blood is pumped
to the body.
(a) Atria contract, forcing
blood into the ventricles.
Deoxygenated blood is
pumped to the lungs.
Blood fills the
atria and begins
to flow passively
into the ventricles.
(b) Then the ventricles contract,
(c) The cycle ends as
forcing blood through arteries
the heart relaxes.
to the lungs and the rest of the
body.
III. The vertebrate circulatory
system

Function
•
b. Coordination of heart activity
•
1) Atrioventricular and semilunar
valves
•
2) The sinoatrial node (SA node)
•
3) The atrioventricular node (AV
node)
aorta
pulmonary artery
(to left lung)
superior
vena cava
pulmonary artery
(to right lung)
left atrium
pulmonary veins
(from right lung)
pulmonary
veins (from left
lung)
atrioventricular valve
right
atrium
semilunar valves
atrioventricular valve
right
ventricle
inferior
vena cava
descending aorta
(to lower body)
left ventricle
ventricular septum
heart muscle
sinoatrial
(SA) node
atrioventricular
(AV) node
excitable
fibers
The vertebrate circulatory system
. Coordination of heart activity
4) Influences on heart rate
a) Parasympathetic nervous system decreases heart rate
b) Sympathetic nervous system increases heart rate
c) Hormones
The vertebrate circulatory system
 C.
Blood
• 1. Functions
•
•
a. Transport of nutrients, gases,
hormones, wastes
b. Immune response
The vertebrate circulatory system
• 2. Composition
•
a. Plasma—55% to 60%
• 1) 90% water
• 2) Molecules of dissolved proteins, hormones,
nutrients, gases, ions, and urea as a waste
•
b. Red blood cells—erythrocytes
• 1) 99% of the total cellular component in the blood
• 2) Carry oxygen bound to hemoglobin from the lungs
to the tissue and buffer CO2 carried from the tissues
•
c. White blood cells—leukocytes
• 1) 1% of the total cellular component of blood
• 2) Five white blood cell types
•
d. Platelets
• 1) Cellular fragments from megakaryocyte in the bone
marrow
• 2) Function in blood clotting
platelets
trapped red
blood cell
fibrin network
The vertebrate circulatory system

D. Blood vessels
• 1. Arteries and arterioles
•
•
a. Thick walls, smooth muscle with elastic tissue to
withstand high pressure
b. Carry blood away from the heart
• 2. Capillaries
•
•
a. Tiniest vessels; thin, single-cell thick for easy
diffusion
b. Exchange of materials between blood and body
cells
• 3. Venules and veins
•
•
a. One-way valves in thin-walled vessels surrounded
by thin layer of smooth muscle giving low resistance
to blood flow, which is assisted by skeletal muscle
b. Returns blood to the heart
capillaries
arteriole
venule
endothelium
capillary
connective tissue
(external layer)
artery
smooth muscle
(middle layer)
connective tissue
endothelium
(inner layer)
vein
Red blood cells must
pass through capillaries
in single file.
Capillary walls are thin and permeable
to gases, nutrients, and cellular wastes.
III. The vertebrate circulatory
system
• 4. Distribution of blood flow
•
•
a. Regulated by muscular walls of the
arterioles
b. Influenced by autonomic nerves,
hormones, and other chemicals released
from nearby tissues
jugular vein
carotid artery
aorta
superior
vena cava
inferior
vena cava
lung capillaries
pulmonary artery
heart
liver
kidney
intestine
femoral vein
femoral artery
valve
open
valve
closed
relaxed
muscle
muscle
contraction
compresses
vein
valve
closed
(b)
(a)
endothelium
smooth muscle
cholesterol in
blood
fatty core
fibrous cap
plaque
Heart Attack
(Myocardial Infarction)
A heart attack (myocardial infarction)
occurs when heart muscle is
damaged or destroyed because it
does not get enough oxygen-rich
blood to sustain life. Just as the heart
supplies oxygen and nutrients to
other parts of the body, blood vessels
called coronary arteries supply
needed blood to the heart. If one or
more coronary arteries or the blood
vessels that feed blood into the
major arteries are blocked or
narrowed, the heart muscle is
deprived of oxygen. If the oxygen
supply is cut off for more than
several minutes, the heart cells suffer
permanent injury or death.
Lymphatic system

1. Structure
•
a. Complex network of thin-walled
vessels
•
b. In proximity to the capillary
network
•
c. Composed of cells with
openings between them that act
as one-way valves
(a)
superior
vena cava
thoracic duct enters
vein to vena cava
thymus
heart
spleen
thoracic duct
lymph vessels
lymph nodes
valve
prevents
backflow
white
blood cells
(b) lymph node
Lymph is transported
into larger lymph
vessels.
interstitial
fluid
Blood capillaries leak
fluid filtered from
blood plasma.
Interstitial fluid enters
through valvelike
openings between
lymph capillary cells.
Lymphatic system
• 2. Functions
•
•
•
a. Removal of excess fluid
b. Transport of fats from the intestine
c. Cellular body defense
The respiratory system

A. Functions of the respiratory
system
•
1. Works in conjunction with the
circulatory system
•
2. Provides oxygen for cellular
respiration
Respiratory systems and
gas exchange
 A.
Interrelated with circulatory
system
 B.
Mechanisms of gas movement
• 1. Bulk flow from areas of higher
pressure to areas of lower pressure
• 2. Simple diffusion at the tissue or
lung level
1. Gases move in and out
of the lungs by breathing.
2. O2 and CO2
are exchanged
in the lungs
by diffusion.
right
atrium
alveoli
(air
sacs)
left
atrium
right
ventricle
left ventricle
3. Gases
dissolved
in blood are
transported
by the
circulatory
system.
4. O2 and CO2 are
exchanged in the
tissues by diffusion.
VII. Human respiratory system
 A.
The conducting portion
• 1. Carries air to the lungs
• 2. Warms and moistens air moving
through it
• 3. Cilia that line the trachea, bronchi,
and bronchioles filter dust particles
(a)
nasal cavity
pharynx
epiglottis
larynx
esophagus
trachea
bronchi
branch of
pulmonary vein
bronchiole
alveoli
branch of
pulmonary
artery
bronchioles
pulmonary artery
pulmonary vein
(b)
capillary
network
VII. Human respiratory system

B. Gas exchange portion
•
•
•
1. The alveoli have an enormous
surface area
2. Capillaries surround the alveoli
3. The mechanism of gas exchange
and transport
•
•
a. Oxygen and hemoglobin
b. Carbon dioxide and bicarbonate
ions
interstitial fluid
capillary
fluid layer
alveolar
cell
nucleus
air in
alveolus
alveolar
membrane
capillary
cell
nucleus
red
blood
cell
plasma
capillary wall
VII. Human respiratory system
 C.
Mechanics of breathing
• 1. Inspiration—active inhalation of air
•
•
a. Diaphragm and rib muscles contract,
making the chest cavity larger
b. Chest expansion causes the lungs to
expand; vacuum draws in air
• 2. Expiration—passive exhalation of air
when muscles are relaxed
air moves in
air moves out
ribcage
contracts
ribcage
expands
lungs
compress
lungs
expand
diaphragm
contracts downward
(a) Inhalation
diaphragm
relaxes upward
(b) Exhalation
VII. Human respiratory system
 D.
Control of respiration
• 1. Description of breathing
• 2. Regulation of breathing by carbon
dioxide
(a)
(b)