Transcript Animal Unit - Misc

Animal Unit – Chapters 40, 41, 42, 44, 50
• This power point is an accumulation of material
from various chapters. Please concentrate on the
key concepts as we cover this material. There is a
lot of overlap in the content of this power point.
Please refer to page and figure numbers to help
guide you through this unit.
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Surface Area to Volume Ratios – Key Concept
•
Surface area to volume ratios affect a biological system’s ability to
obtain necessary resources or eliminate waste products.
•
As cells increase in volume, the relative surface area decreases and
demand for material resources increases; more cellular structures are
necessary to adequately exchange materials and energy with the
environment. These limitations restrict cell size.
•
The surface area of their plasma membrane must be large enough to
adequately exchange materials; smaller cells have a more favorabl3e
surface area to volume ratio for exchanage of materials with the
environment.
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Fig. 6-8 – Page 99
Surface area increases while
total volume remains constant
A high surface area to volume ratio
facilitates the exchange of materials
between a cell and its environment.
5
1
1
Total surface area
[Sum of the surface areas
(height  width) of all boxes
sides  number of boxes]
Total volume
[height  width  length 
number of boxes]
Surface-to-volume
(S-to-V) ratio
[surface area ÷ volume]
6
150
750
1
125
125
6
1.2
6
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Fig. 35-3 – Page 739
In most plants, absorption of water
and minerals occurs near the root
hairs, where vast numbers of tiny
root hairs increase the surface
area. Root hairs are extensions of
the epidermal cells.
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Fig. 41-15 – Page 889
The small intestine has a huge amount of surface area. Large folds in the lining have
finger like projections called villi. In turn, each epithelial cell of a villus has on its
apical surface many microvilli, that are exposed to the intestinal lumen.
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
The enormous surface area presented by microvilli is an adaptation that greatly
increases the total capacity for nutrient absorption.
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Fig. 42-24 – Page 919
Gas exchange occurs in alveoli. Human lungs have a surface area fifty times that of
the skin.
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
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50 µm
Colorized
SEM
50 µm
Fig. 42-11 – Page 907
5,000
4,000
3,000
2,000
1,000
0
50
40
30
20
10
0
Systolic
pressure
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Venae cavae
Veins
Venules
Capillaries
Arterioles
Diastolic
pressure
Arteries
120
100
80
60
40
20
0
Aorta
Pressure
(mm Hg)
Velocity
(cm/sec)
Area (cm2)
The reduced
velocity of the
blood flow in
capillaries is
critical to the
function of the
circulatory system.
capillaries are
the only vessels
with walls thin
enough to permit
the transfer
of substances
between the blood.
Feedback Mechanisms – Key Concept
•
Organisms use feedback mechanisms to maintain their internal
environments and respond to external environmental changes.
•
Negative feedback mechanisms maintain dynamic homeostasis for a
particular condition (variable) by regulating physiological processes,
returning the changing condition back to its target set point.
•
Positive feedback mechanisms amplify responses and processes in
biological organisms. The variable initiating the response is moved
farther away from the initial set-point. Amplification occurs when the
stimulus is further activated which, in turn, initiates an additional
response that produces system change.
•
Alteration in the mechanisms of feedback often results in deleterious
consequences.
•
All of the following examples are physiological mechanisms that
organisms use to respond to changes in their environment.
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Fig. 1-13
Negative
feedback 
A
Enzyme 1
Negative feedback means that
as more of a product
Excess D
accumulates, the
blocks a step
process that creates
it slows and less of the product
is produced
B
D
D
Enzyme 2
D
C
Enzyme 3
D
(a) Negative feedback
Positive feedback means that as more of
a product accumulates, the process that
creates it speeds up and more of the
Positive
product is produced
feedback +
W
Enzyme 4
X
Enzyme 5
Excess Z
stimulates a
step
Z
Y
Z
Z
Enzyme 6
Z
(b) Positive feedback
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Fig. 45-12-5 – Page 983
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
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Fig. 40-8 – Page 861
Regulating room
temperature
depends on a
control center
(thermostat) that
detects
temperature
change and
activates
mechanisms that
reverse that
change.
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
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Fig. 40-16 – Page 868
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
increases; thermostat
shuts off warming
mechanisms.
Decreased body
temperature
Blood vessels in skin
constrict, reducing
heat loss.
Skeletal muscles contract;
shivering generates heat.
Thermostat in
hypothalamus
activates warming
mechanisms.
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Fig. 18-3 –
Pages 352 - 353
trp operon
Promoter
Promoter
Genes of operon
DNA
trpR
Regulatory
gene
mRNA
5
Protein
trpE
3
Operator
Start codon
mRNA 5
RNA
polymerase
Inactive
repressor
trpD
trpB
trpA
B
A
Stop codon
E
D
C
Polypeptide subunits that make up
enzymes for tryptophan synthesis
(a) Tryptophan absent, repressor inactive, operon on
DNA
No RNA made
mRNA
Active
repressor
Protein
trpC
Tryptophan
(corepressor)
(b) Tryptophan present, repressor active, operon off
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Fig. 18-2
Precursor
Feedback
inhibition
trpE gene
Enzyme 1
trpD gene
Enzyme 2
trpC gene
trpB gene
Enzyme 3
trpA gene
Natural selection
has favored
bacteria that
produce only
Regulation
the products
of gene
needed by
expression
that cell
A cell can regulate
the production
of enzymes by
feedback
inhibition or by
gene
regulation
Tryptophan
(a) Regulation of enzyme
activity
(b) Regulation of enzyme
production
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Fig. 18-2
Precursor
Feedback
inhibition
trpE gene
Enzyme 1
In pathway
“a”
tryptophan
works as a
“inhibitor” of
enzyme
activity
trpD gene
Enzyme 2
trpC gene
trpB gene
Enzyme 3
trpA gene
Tryptophan
(a) Regulation of enzyme
activity
Regulation
of gene
expression
In pathway “b”
the
expression of
the trpC gene
is inhibited by
the
accumulation
of tryptophan
(b) Regulation of enzyme
production
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Fig. 30-8 – Page
626
Tomato
Ruby grapefruit
Fruit
ripening is
an example
of positive
feedback.
The
gaseous
hormone
ethylene
triggers
ripening,
and ripening
triggers
more
ethylene
production.
(See “Fruit
Ripening –
Page 834
Nectarine
Hazelnut
Milkweed
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Feedback Mechanisms
•
Hemophilia is a sex-linked recessive disorder defined by the absence
of one or more of the proteins required for blood clotting. When a
person with hemophilia is injured, bleeding is prolonged because a firm
clot is slow to form, Small cuts in the skin are usually not a problem,
but bleeding in the muscles or joints can be painful and cal lead to
serious damage. Today, people with hemophilia are treated as
needed with intravenous inject5ions of the missing protein.
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Fig. 42-18-4
Red blood cell
Collagen fibers
Platelet
plug
Fibrin clot
Platelet releases chemicals
that make nearby platelets sticky
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Prothrombin
Thrombin
Fibrinogen
Fibrin
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5 µm
Organisms exhibit complex properties due to
interactions between their constituent parts. – Key
Concept
•
Interactions and coordination between organs provide essential
biological activities.
–
•
In this section we are covering the digestive system, specifically
the stomach and small intestines. One more example to review
for this section is the interactions between roots, stem, and
leaves.
Interactions and coordination between systems provide essential
biological activities.
–
In this section we are covering the respiratory and circulatory
systems. Two more examples to review for this section are the
interactions and coordination between the nervous and muscular
system and plant vascular tissue and leaf.
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Organs specialized for sequential stages of food processing form
the mammalian digestive system
•
The mammalian digestive system consists of an alimentary canal and
accessory glands that secrete digestive juices through ducts
•
Mammalian accessory glands are the salivary glands, the pancreas,
the liver, and the gallbladder
•
Food is pushed along by peristalsis, rhythmic contractions of muscles
in the wall of the canal
•
Valves called sphincters regulate the movement of material between
compartments
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Fig. 41-10 – Pages
884 - 888
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
Liver
Small
intestine
Small
intestine
Large
intestine
Rectum
Anus
Appendix
Cecum
Pancreas
Stomach
Small
intestine
Large
intestine
Rectum
Anus
A schematic diagram of the
human digestive system
Fig. 41-11-3
Food
Epiglottis
up
Tongue
Epiglottis
up
Pharynx
Esophageal
sphincter
contracted
Glottis
Larynx
Trachea
Epiglottis
down
Esophagus
To To
lungs stomach
Glottis up
and closed
Esophageal
sphincter
relaxed
Glottis
down
and open
Esophageal
sphincter
contracted
Relaxed
muscles
Relaxed
muscles
Contracted
muscles
Sphincter
relaxed
Stomach
Digestion in the Stomach
•
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
•
Gastric ulcers, lesions in the lining, are caused mainly by the bacterium
Helicobacter pylori
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Fig. 41-12a
Stomach Dynamics
Esophagus
Sphincter
Stomach
5 µm
Sphincter
Small
intestine
Folds of epithelial
tissue – increase
surface area
Interior surface
of stomach
• Coordinated contraction and relaxation of stomach muscle churn the
stomach’s contents
• Sphincters prevent chyme from entering the esophagus and regulate
its entry into the small intestine
Fig. 41-12b
Interior surface
of stomach
Epithelium
3
Pepsinogen
2
1
Chief cells
(secrete
Pepsingen)
Parietal cells
(secrete HCl)
1 Pepsinogen and HCl
are secreted.
HCl
Gastric gland
Mucus cells
Pepsin
H+
–
Cl
2 HCl converts
pepsinogen to pepsin.
3 Pepsin activates
more pepsinogen.
Chief cell
Parietal cell
Digestion in the Small Intestine
•
The small intestine is the longest section of the alimentary canal
•
It is the major organ of digestion and absorption!!!!!!
•
The first portion of the small intestine is the duodenum, where acid
chyme from the stomach mixes with digestive juices from the
pancreas, liver, gallbladder, and the small intestine itself
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 41-13
Carbohydrate digestion
Oral cavity,
pharynx,
esophagus
Protein digestion
Nucleic acid digestion
Fat digestion
Polysaccharides Disaccharides
(starch, glycogen)
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,
maltose
Stomach
Proteins
Pepsin
Small polypeptides
Lumen of
small intestine
Polysaccharides
Pancreatic amylases
Polypeptides
Pancreatic trypsin and
chymotrypsin
DNA, RNA
Fat globules
Pancreatic
nucleases
Bile salts
Maltose and other
disaccharides
Nucleotides
Fat droplets
Smaller
polypeptides
Pancreatic lipase
Pancreatic carboxypeptidase
Glycerol, fatty
acids, monoglycerides
Amino acids
Epithelium
of small
intestine
(brush
border)
Small peptides
Disaccharidases
Monosaccharides
Nucleotidases
Nucleosides
Dipeptidases, carboxypeptidase,
and aminopeptidase
Amino acids
Nucleosidases
and
phosphatases
Nitrogenous bases,
sugars, phosphates
Pancreatic Secretions
•
The pancreas produces proteases trypsin and chymotrypsin, proteindigesting enzymes that are activated after entering the duodenum
•
Its solution is alkaline and neutralizes the acidic chyme
Bile Production by the Liver
•
In the small intestine, bile aids in digestion and absorption of fats
•
Bile is made in the liver and stored in the gallbladder
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Secretions of the Small Intestine
•
The epithelial lining of the duodenum, called the brush border,
produces several digestive enzymes
•
Enzymatic digestion is completed as peristalsis moves the chyme and
digestive juices along the small intestine
•
Most digestion occurs in the duodenum; the jejunum and ileum function
mainly in absorption of nutrients and water
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Absorption in the Small Intestine
(Do not memorize red text!)
•
The small intestine has a huge surface area, due to villi and microvilli
that are exposed to the intestinal lumen
•
The enormous microvillar surface greatly increases the rate of nutrient
absorption
•
Each villus contains a network of blood vessels and a small lymphatic
vessel called a lacteal
•
After glycerol and fatty acids are absorbed by epithelial cells, they are
recombined into fats within these cells
•
These fats are mixed with cholesterol and coated with protein, forming
molecules called chylomicrons, which are transported into lacteals
•
Amino acids and sugars pass through the epithelium of the small
intestine and enter the bloodstream
•
Capillaries and veins from the lacteals converge in the hepatic portal
vein and deliver blood to the liver and then on to the heart
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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
Absorption in the Large Intestine
•
The colon of the large intestine is connected to the small intestine
•
The cecum aids in the fermentation of plant material and connects
where the small and large intestines meet
•
The human cecum has an extension called the appendix, which plays
a very minor role in immunity
•
A major function of the colon is to recover water that has entered the
alimentary canal, however most water is absorbed by the small int.
•
Wastes of the digestive tract, the feces, become more solid as they
move through the colon
•
Feces pass through the rectum and exit via the anus
•
The colon houses strains of the bacterium Escherichia coli, some of
which produce vitamins
•
Feces are stored in the rectum until they can be eliminated
•
Two sphincters between the rectum and anus control bowel
movements
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 41-17
Cooperative interactions within organisms
promote efficiency in the use of energy and
matter. – Key Concept
•
Organisms have areas or compartments that perform a subset of
functions related to energy and matter, and these parts contribute to
the whole.
–
At the cellular level, the plasma membrane, cytoplasm and, for
eukaryotes, the organelles contribute to the overall specialization
and functioning of the cell. (From chapter 7.)
–
Within multicellular organisms, specialization of organs
contributes to the overall function of the organism.
• Exchange of gases
• Circulation of fluids
• Digestion of food
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 42-24 – Page 919
Gas exchange occurs in alveoli. Human lungs have a surface area fifty times that of
the skin.
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
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
50 µm
Colorized
SEM
50 µm
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
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Capillaries of
abdominal organs
and hind limbs
Fig. 42-10
Vein
SEM
Valve
100 µm
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Red blood cell
Capillary
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Venule
15 µm
Arteriole
LM
The thicker
walls of
arteries are
very strong,
accommodatin
g blood
pumped at
high pressure
the heart, and
their elastic
recoil helps
maintain blood
pressure when
the heart
relaxes
between
contractions
Artery
The thinnerwalled veins
convey blood
back in the
heart at a
lower velocity
and pressure.
Valves in the
veins maintain
a
unidirectional
flow of blood
in these
vessels
Fig. 42-11 – Page 907
5,000
4,000
3,000
2,000
1,000
0
50
40
30
20
10
0
Systolic
pressure
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Venae cavae
Veins
Venules
Capillaries
Arterioles
Diastolic
pressure
Arteries
120
100
80
60
40
20
0
Aorta
Pressure
(mm Hg)
Velocity
(cm/sec)
Area (cm2)
The reduced
velocity of the
blood flow in
capillaries is
critical to the
function of the
circulatory system.
capillaries are
the only vessels
with walls thin
enough to permit
the transfer
of substances
between the blood.
Fig. 41-10 – Pages
884 - 888
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
Liver
Small
intestine
Small
intestine
Large
intestine
Rectum
Anus
Appendix
Cecum
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Pancreas
Stomach
Small
intestine
Large
intestine
Rectum
Anus
A schematic diagram of the
human digestive system
Evolutionary adaptations of vertebrate digestive
systems correlate with diet
•
Digestive systems of vertebrates are variations on a common plan
•
However, there are intriguing adaptations, often related to diet
•
Dentition, an animal’s assortment of teeth, is one example of structural
variation reflecting diet
•
Mammals have varying dentition that is adapted to their usual diet
•
The teeth of poisonous snakes are modified as fangs for injecting
venom
•
All snakes can unhinge their jaws to swallow prey whole
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 41-18
Carnivores
generally have
pointed incisors
and canines that
can be used to
kill prey and rip or
cut away pieces
of flesh. The
jagged premolars
and molars crush
and shred food.
Incisors
Canines
Premolars
(a) Carnivore
(b) Herbivore
(c) Omnivore
Molars
In contrast,
herbivorous
mammals usually
have teeth with
broad, ridges
surfaces that
grind tough plant
material. The
incisors and
canines are
generally
modified for biting
off pieces of
vegetation. In
some herviborous
mammals,
canines are
absent.
Fig. 41-18
Incisors
Canines
Premolars
(a) Carnivore
Humans, being
omnivores
adapted for
eating both
vegetation and
meat, have a
relatively
unspecialized
dentition. Human
have teeth for
biting, tearing,
grinding and
crushing.
(b) Herbivore
(c) Omnivore
Molars
Fig. 41-19
Herbivore
Carnivore
Small intestine
Stomach
Small
intestine
Cecum
Colon
(large
intestine)
• Herbivores generally have longer alimentary canals than carnivores,
reflecting the longer time needed to digest vegetation
Cooperative interactions within organisms
promote efficiency in the use of energy and
matter. – Key Concept (con’t)
•
Organisms have areas or compartments that perform a subset of
functions related to energy and matter, and these parts contribute to
the whole.
–
Interactions among cells of a population of unicellular organisms
can be similar to those of multicellular organisms, and these
interactions lead to increased efficiency and utilization of energy
and matter.
• Bacterial community in the rumen of animals
• Bacterial community in and around deep sea vents
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Mutualistic Adaptations
•
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
•
Microorganisms help herbivores digest plants. Much of the chemical
energy in herbivore diets comes from the cellulose of plant cell walls,
but animals do not produce enzymes that hydrolyze cellulose. Instead,
many vertebrates (as cell as termites, whose wood diets are largely
cellulose) house large populations of mutualistic bacteria and protists
in fermentation chambers in their alimentary canals. These
microorganisms have enzymes that can digest cellulose to simple
sugars and other compounds that the animal can absorb. In many
cases, the microorganisms also use the sugars from digested cellulose
to produce a variety of nutrients essential to the animals, such as
vitamins (K and several B) and amino acids.
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 41-20
1
Rumen
2
Reticulum
Intestine
Esophagus
4
Abomasum
3
Omasum
Fig. 52-18 – Page 1165
• Unique assemblages of organisms are associated with
deep-sea hydrothermal vents of volcanic origin on midoceanic ridges; here the autotrophs are chemoautotrophic
prokaryotes
A deep-sea hydrothermal vent community
Homeostatic mechanisms reflect both common
ancestry and divergence due to adaptation in
different environments.
•
•
Continuity of homeostatic mechanisms reflects common ancestry,
while changes may occur in response to different environmental
conditions.
–
DNA and RNA are carriers of genetic with major features of the
genetic code being shared by all living systems. Mutations are
the original source of different alleles which results in evolution.
–
Metabolic pathways are conserved across all currently recognized
domains. Ex. – Glycolysis is present in both aerobic and
anaerobic respiration
Organisms have various mechanisms for obtaining nutrients and
eliminating wastes.
–
Respiratory systems of aquatic and terrestrial animals
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Concept 42.5: Gas exchange occurs across
specialized respiratory surfaces – Pages 915 - 919
•
Gas exchange supplies oxygen for cellular respiration and disposes of
carbon dioxide
•
Gases diffuse down pressure gradients in the lungs and other organs
as a result of differences in partial pressure
•
Partial pressure is the pressure exerted by a particular gas in a
mixture of gases
•
A gas diffuses from a region of higher partial pressure to a region of
lower partial pressure
•
In the lungs and tissues, O2 and CO2 diffuse from where their partial
pressures are higher to where they are lower
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Respiratory Media
•
Animals can use air or water as a source of O2, or respiratory medium
•
In a given volume, there is less O2 available in water than in air
•
Obtaining O2 from water requires greater efficiency than air breathing
Respiratory Surfaces
•
Animals require large, moist respiratory surfaces for exchange of
gases between their cells and the respiratory medium, either air or
water
•
Gas exchange across respiratory surfaces takes place by diffusion
•
Respiratory surfaces vary by animal and can include the outer surface,
skin, gills, tracheae, and lungs
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Fig. 42-21
• Gills are outfoldings of the body that create a large surface area for gas
exchange
Coelom
Gills
Gills
Parapodium (functions as gill)
(a) Marine worm
Tube foot
(b) Crayfish
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(c) Sea star
•
Ventilation moves the respiratory medium over the respiratory surface
•
Aquatic animals move through water or move water over their gills for
ventilation
•
Fish gills use a countercurrent exchange system, where blood flows
in the opposite direction to water passing over the gills; blood is always
less saturated with O2 than the water it meets
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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
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Net diffusion of O2
from water
to blood
140 110 80 50 20
PO2 (mm Hg) in blood
Tracheal Systems in Insects
•
The tracheal system of insects consists of tiny branching tubes that
penetrate the body
•
The tracheal tubes supply O2 directly to body cells
•
The respiratory and circulatory systems are separate
•
Larger insects must ventilate their tracheal system to meet O2
demands
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Fig. 42-23
Air sacs
Tracheae
External
opening
Tracheoles
Mitochondria
Muscle fiber
Body
cell
Air
sac
Tracheole
Trachea
Air
Body wall
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2.5 µm
Lungs
•
Lungs are an infolding of the body surface
•
The circulatory system (open or closed) transports gases between the
lungs and the rest of the body
•
The size and complexity of lungs correlate with an animal’s metabolic
rate
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Mammalian Respiratory Systems: A Closer Look
•
A system of branching ducts conveys air to the lungs
•
Air inhaled through the nostrils passes through the pharynx via the
larynx, trachea, bronchi, bronchioles, and alveoli, where gas
exchange occurs
•
Exhaled air passes over the vocal cords to create sounds
•
Secretions called surfactants coat the surface of the alveoli
•
The process that ventilates the lungs is breathing, the alternate
•
http://www.youtube.com/watch?v=HiT621PrrO0&feature=related
(anatomy of human respiratory system)
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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
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50 µm
Colorized
SEM
50 µm
Homeostatic mechanisms reflect both common
ancestry and divergence due to adaptation in
different environments.
•
Homeostatic control systems in species of microbes, plants and
animals support common ancestry.
–
Circulatory systems in fish, amphibians and mammals – Natural
selection has modified the cardiovascular systems of different
vertebrates in accordance with their level of activity. Animals with
higher metabolic rates generally have more complex circulatory
systems and more powerful hearts than animals with lower
metabolic rates. These differences reflect the close fit of form to
function.
–
Thermoregulation in aquatic and terrestrial animals
(countercurrent exchange mechanisms)
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Circulatory Systems in Fish, Amphibians, and
Mammals
•
Every organism must exchange materials with its environment
•
Exchanges ultimately occur at the cellular level
•
In unicellular organisms, these exchanges occur directly with the
environment
•
For most cells making up multicellular organisms, direct exchange with
the environment is not possible
•
Gills are an example of a specialized exchange system in animals
•
Internal transport and gas exchange are functionally related in most
animals
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Fig. 42-1
How does a feathery fringe help this animal survive?
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Concept 42.1: Circulatory systems link exchange
surfaces with cells throughout the body
•
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
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Open and Closed Circulatory Systems
•
More complex animals have either open or closed circulatory systems
–
Open – blood leaves vessels and bathes body tissues before
returning
–
Closed – blood never leaves vessels
• The benefits of closed circulatory systems include relatively
high blood pressure, which enable the effective delivery of
oxygen and nutrients to the cells of larger and more active
animals.
•
Both systems have three basic components:
–
A circulatory fluid (blood or hemolymph)
–
A set of tubes (blood vessels)
–
A muscular pump (the heart)
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Organization of Vertebrate Circulatory Systems
•
Humans and other vertebrates have a closed circulatory system, often
called the cardiovascular system
•
The three main types of blood vessels are arteries, veins, and
capillaries
•
Arteries branch into arterioles and carry blood to capillaries
•
Networks of capillaries called capillary beds are the sites of chemical
exchange between the blood and interstitial fluid
•
Venules converge into veins and return blood from capillaries to the
heart
•
Vertebrate hearts contain two or more chambers
•
Blood enters through an atrium and is pumped out through a ventricle
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Fig. 42-4
• Bony fishes,
rays, and sharks
have single
circulation with
a two-chambered
heart
• In single
circulation, blood Heart
leaving the heart
passes through
two capillary
beds before
returning
• Fish are
ectotherms
Gill capillaries
Artery
Gill
circulation
Ventricle
Atrium
Systemic
circulation
Vein
Single Circulation
Systemic capillaries
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Double Circulation
•
Amphibian, reptiles, and mammals have double circulation
•
Oxygen-poor and oxygen-rich blood are pumped separately from the
right and left sides of the heart
•
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
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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
A
A
V
Left
Systemic capillaries
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Pulmonary
circuit
Left
systemic
aorta
A
V
V
Right
Left
Systemic
circuit
Systemic capillaries
Amphibians
•
Frogs and other amphibians have a three-chambered heart: two atria and one
ventricle
•
The ventricle pumps blood into a forked artery that splits the ventricle’s output
into the pulmocutaneous circuit and the systemic circuit
•
Underwater, blood flow to the lungs is nearly shut off
Mammals
•
Mammals have a four-chambered heart with two atria and two
ventricles
•
The left side of the heart pumps and receives only oxygen-rich blood,
while the right side receives and pumps only oxygen-poor blood
•
Mammals are endotherms and require more O2 than ectotherms
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Thermoregulation in aquatic and terrestrial animals - Concept
40.3: Homeostatic processes for thermoregulation involve
form, function, and behavior
•Thermoregulation is the process by which animals maintain an internal
temperature within a tolerable range
•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
•In general, ectotherms tolerate greater variation in internal temperature,
while endotherms are active at a greater range of external temperatures
•Endothermy is more energetically expensive than ectothermy
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The walrus is an
endotherm
The lizard is an
ectotherm
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Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation
Radiation
Convection
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Evaporation
Conduction
Heat regulation in mammals often involves the integumentary system:
skin, hair, and nails
Hair
Epidermis
Sweat
pore
Muscle
Dermis
Nerve
Sweat
gland
Hypodermis
Adipose tissue
Blood vessels
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Oil gland
Hair follicle
Five general adaptations help animals
thermoregulate:
•
Insulation is a major thermoregulatory adaptation in mammals and
birds. Skin, feathers, fur, and blubber reduce heat flow between an
animal and its environment
•
Circulatory adaptations - 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
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Five general adaptations help animals
thermoregulate:
•
Cooling by evaporative heat loss - 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. Many types of
animals lose heat through evaporation of water in sweat. Panting
increases the cooling effect in birds and many mammals. Sweating or
bathing moistens the skin, helping to cool an animal down
•
Behavioral responses - Both endotherms and ectotherms use
behavioral responses to control body temperature. Some terrestrial
invertebrates have postures that minimize or maximize absorption of
solar heat
•
Adjusting metabolic heat production - Some animals can regulate
body temperature by adjusting their rate of metabolic heat production.
Heat production is increased by muscle activity such as moving or
shivering. Some ectotherms can also shiver to increase body
temperature
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Fig. 40-12
Canada goose
Bottlenose
dolphin
Blood flow
Artery Vein
Vein
Artery
35ºC
33º
30º
27º
20º
18º
10º
9º
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