Transcript diving accessory

Animal Nutrition
41.1 & 41.2
Nutrient Needs
• Nutrients- Some are essential for animal functioning.
• A good source of organic carbon and nitrogen.
• Amino acids- Nine amino acids are required in a diet.
• Fatty acids- Some unsaturated fatty acids cannot be self synthesized.
Vitamins
• “It makes you ill if you don’t eat it.”
• Needed in small amounts for diverse functions.
• Divided into water and fat soluble categories.
• Include B1, B12, and C.
Minerals
• Inorganic substances (i.e. iron and iodine) used for a variety of jobs.
• Cofactors, hormones, osmotic regulation.
• Very small amounts.
Digestion
• Four steps in food breakdown:
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Ingestion
Digestion
Absorprtion
Elimination
• Digestion can be either inter or extracellular.
Getting the Food In
Cellular Digestion
• Food enters the cell through a vacuole, merges with lysosomes, and
gets broken up.
• Used exculisvely in simple organisms.
41.3
Organs Specialized for Sequential Stages of
Food Processing form the Mammalian Digestive
System
{
Nicholas St. Laurent
Mr. Reis
AP Biology
11 March 2014
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Accessory Glands are used to aid the process of digestion
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3 pairs of salivary glands
Pancreas
Liver
Gallbladder
Mouth
Esophagus
Gallbladder
Mammalian digestive system also has an alimentary canal
Food is moved through contractions and relaxations in the
digestive system called peristalsis
Liver
Sphincters regulate exchange of food between compartments of Pancreas
the body
Salivary
glands
Stomach
Small
intestine
Large
intestine
Rectum
Anus
Schematic diagram
Intro
Carbohydrate digestion
Oral cavity,
pharynx,
esophagus
Polysaccharides
Salivary amylase
Smaller
Maltose
polysaccharides
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First stage of digestion begins here, the mouth
Salivary glands aid in chemical digestion and lubrication of food
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Amylase—initiates glucose polymer breakdown
Mucus—mainly a matter of protection
Teeth allow an increase in surface area of food by mashing and
grinding
The Oral Cavity
Tongue
Oral cavity
Salivary
glands
Pharynx
Carbohydrate digestion
Oral cavity,
pharynx,
esophagus
Polysaccharides
Salivary amylase
Smaller
Maltose
polysaccharides
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After the food is mashed into a lubricated ball, the bolus, it is
pushed into the pharynx
This is the throat region; consisting of:
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Esophagus—leads to stomach
Trachea—leads to lungs
Bolus of
food
Tongue
Epiglottis
up
Pharynx
Swallowing causes a flap of cartilage, epiglottis, to cover the
trachea opening, the glottis
Glottis
Larynx
Trachea
To lungs
Pharynx
Esophageal
sphincter
contracted
Esophagus
To stomach
Tongue
Bolus of
food
Pharynx
Epiglottis
up
Glottis
Larynx
Trachea
To lungs
Esophageal
sphincter
contracted
Esophagus
To stomach
Relaxed
muscles
Contracted
muscles
Sphincter
relaxed
Stomach
Stomach
Protein digestion
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Located below the diaphragm the stomach stores food and begins digestion
of proteins
Aided by the release of gastric acids; mixture of acid and food is called
chyme
 Hydrochloric acid—denatures peptide bonds
 Protease called pepsin—cleaves proteins into smaller polypeptides
Parietal cells secrete hydrogen and chloride ions separately into the lumen
(cavity) of the stomach
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
Digestion in Stomach
Proteins
Pepsin
Small polypeptides
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Most enzymatic hydrolysis of the macromolecules from food
occurs in the small intestines
Alimentary canal’s longest compartment at over 20ft in humans
First 10 inches (25cm) form the duodenum where chyme mixes
with the digestive juices from the accessory glands
Digestion in the Small Intestine
Pancreatic Secretions
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Produces alkaline solution rich in bicarbonate as well as several
enzymes
Neutralizes acidity of the chyme; acts as a buffer
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Trypsin
Chymotrypsin
Activate similar to pepsin
Bile Production by the Liver
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Digestion of fats and and other lipids relies heavily on bile
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Mixture of substances made in the liver
Aid in digestion and absorption by use of bile salts
Bile is stored and concentrated in the gallbladder
Digestion in the Small Intestine
[Pancreatic]
Small polypeptides
Small
intestine
(enzymes
from
pancreas)
Nucleic acid digestion
DNA, RNA
Pancreatic amylases
Pancreatic trypsin and
chymotrypsin
Fat digestion
Fat (triglycerides)
Pancreatic
nucleases
Disaccharides
Smaller
polypeptides
Nucleotides
Pancreatic lipase
Pancreatic carboxypeptidase
Small peptides
Glycerol, fatty acids,
monoglycerides
Vein carrying
blood to liver
Villi
Microvilli (brush
border) at apical
(lumenal) surface
Epithelial
cells
Blood
capillaries
Epithelial
cells
Muscle layers
Villi
Intestinal wall
Large
circular
folds
Basal
surface
Lacteal
Key
Nutrient
absorption
Lymph
vessel
Lumen
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Nutrients in the lumen, cavity, must first cross the lining of the
alimentary canal to reach body tissues
Villi and microvilli are an evolutionary adaptation to increase
nutrient absorption
Capillaries and veins that carry nutrient-rich blood away from the
villi all converge into the Hepatic Portal Vein—leads directly to
liver then the heart
The liver regulates nutrient distribution, interconverts many
organic molecules, and detoxifies many organic molecules
Absorption in the Small Intestine
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Alimentary canal ends here:
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Colon
Cecum
Rectum
The colon’ s primary purpose is to absorb water from chyme
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
>90% of water reabsorbed (colon)
 not enough water absorbed
back to body
 diarrhea
 too much water absorbed back to body
 constipation
Ascending
portion
of colon
Small
intestine
Cecum
Absorption in the Large Intestine
Appendix
Jake Clarke
How Evolutionary Adaptations of Vertebrate
Digestive Systems Correlate with Diet
Various Adaptations
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Dental Adaptations
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Stomach and Intestinal Adaptations
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Mutualistic Adaptations
Dental adaptations
Carnivores- Teeth have adapted to supply carnivorous
organisms with the ability to rip flesh or kill its prey
effectively
Herbivores- Teeth have adapted to make it easier for
herbivorous animals to chew tougher plants
Omnivores- Omnivores commonly have an equal
distribution of teeth common between herbivores and
carnivores
Dental Adaptations
Intestinanl Adaptations
Carnivorous have adapted longer small intestines to process the
large amounts of nutrients, and their colon is smaller.
 Reversed in herbivores due to the nutrients that come from plants,
the colon absorbs more waters and electrolytes and the small
intestine has less proteins and nutrients to absorb
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Mutualistic Adaptations
Mutualistic adaptations have allowed for evolution in a species.
 Bacteria in animals absorb simple sugars and compounds for
animals that can’t break down cellulose

Jake Clarke
Animals have intervals between times of eating and
digestion does not happen continuously.
The arrival of food to a compartment causes substances to
start the next process of chemical digestion.
When done, another stage of digestion occurs that tightens,
opens, or causes secretion for the food to continue
passing through.
 When
an animal takes in more energy rich molecules
than it needs for metabolism and activity, it stores the
excess energy.
 The first to get energy are muscle cells and the liver.
When there is excess energy it is stored in glycogen.
 If nutrient deprived, fat deposits are first taken from liver
glycogen then muscle glycogen.
 Leptin-
helps regulate appetite. And after eating, Leptin
would increase and tell the brain to suppress appetite.
 When there is not enough fat Leptin decreases and that
tells the brain to increase appetite of the individual.
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 42
Circulation and Gas Exchange
Lectures by
Erin Barley
Kathleen Fitzpatrick
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Every organism must exchange materials with its environment
Exchanges ultimately occur at the cellular level by crossing the
plasma membrane
In unicellular organisms, these exchanges occur directly with the
environment
© 2011 Pearson Education, Inc.
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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
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O2 diffuses from the water into blood vessels
CO2 diffuses from blood into the water
Internal transport and gas exchange are functionally related in
most animals
© 2011 Pearson Education, Inc.
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Diffusion time is proportional to the square of the distance
Diffusion is only efficient over small distances
In small and/or thin animals, cells can exchange materials directly
with the surrounding medium
In most animals, cells exchange materials with the environment via a
fluid-filled circulatory system
© 2011 Pearson Education, Inc.
Circular
canal
Mouth
Radial canals
(a) The moon jelly Aurelia, a cnidarian
5 cm
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Some animals lack a circulatory system
Some cnidarians, such as jellies, have elaborate gastrovascular
cavities
A gastrovascular cavity functions in both digestion and
distribution of substances throughout the body
The body wall that encloses the gastrovascular cavity is only two
cells thick
Flatworms have a gastrovascular cavity and a large surface area to
volume ratio
© 2011 Pearson Education, Inc.
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A circulatory system minimizes the diffusion distance in animals
with many cell layers
© 2011 Pearson Education, Inc.
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A circulatory system has
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A circulatory fluid
A set of interconnecting vessels
A muscular pump, the heart
The circulatory system connects the fluid that surrounds cells with
the organs that exchange gases, absorb nutrients, and dispose of
wastes
Circulatory systems can be open or closed and vary in the number
of circuits in the body
© 2011 Pearson Education, Inc.
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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 called
hemolymph
© 2011 Pearson Education, Inc.
(a) An open circulatory system
Heart
Hemolymph in sinuses
surrounding organs
Pores
Tubular heart
Closed Circulatory Systems
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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
Annelids, cephalopods, and vertebrates have closed circulatory
systems
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(b) A closed circulatory system
Heart
Interstitial fluid
Blood
Small branch
vessels in
each organ
Dorsal
vessel
(main heart)
Auxiliary
hearts
Ventral vessels
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Humans and other vertebrates have a closed circulatory system
called the cardiovascular system
The three main types of blood vessels are arteries, veins, and
capillaries
Blood flow is one way in these vessels
© 2011 Pearson Education, Inc.
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Arteries branch into arterioles and carry blood away from the
heart 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
© 2011 Pearson Education, Inc.
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Arteries and veins are distinguished by the direction of blood flow,
not by O2 content
Vertebrate hearts contain two or more chambers
Blood enters through an atrium and is pumped out through a
ventricle
© 2011 Pearson Education, Inc.
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Bony fish, rays, and sharks have single circulation with a twochambered heart
In single circulation, blood leaving the heart passes through two
capillary beds before returning
© 2011 Pearson Education, Inc.
(a) Single circulation
Gill
capillaries
Artery
Heart:
Atrium (A)
Ventricle (V)
Vein
Body
capillaries
Key
Oxygen-rich blood
Oxygen-poor blood
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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
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(b) Double circulation
Pulmonary circuit
Lung
capillaries
A
V
Right
A
V
Left
Systemic
capillaries
Key
Systemic circuit
Oxygen-rich blood
Oxygen-poor blood
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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
© 2011 Pearson Education, Inc.
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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
When underwater, blood flow to the lungs is nearly shut off
© 2011 Pearson Education, Inc.
Amphibians
Pulmocutaneous circuit
Lung
and skin
capillaries
Atrium
(A)
Atrium
(A)
Right
Left
Ventricle (V)
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
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Turtles, snakes, and lizards have a three-chambered heart: two atria
and one ventricle
In alligators, caimans, and other crocodilians a septum divides the
ventricle
Reptiles have double circulation, with a pulmonary circuit (lungs)
and a systemic circuit
© 2011 Pearson Education, Inc.
Reptiles (Except Birds)
Pulmonary circuit
Lung
capillaries
Right
systemic
aorta
Atrium
(A)
Ventricle
(V)
A
Right
V
Left
Left
systemic
aorta
Incomplete
septum
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
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Mammals and birds 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 and birds are endotherms and require more O2 than
ectotherms
© 2011 Pearson Education, Inc.
Mammals and Birds
Pulmonary circuit
Lung
capillaries
A
Atrium
(A)
Ventricle
(V)
Right
V
Left
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
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The mammalian cardiovascular system meets the body’s continuous
demand for O2
© 2011 Pearson Education, Inc.
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Blood begins its flow with the right ventricle pumping blood to the
lungs
In the lungs, the blood loads O2 and unloads CO2
Oxygen-rich blood from the lungs enters the heart at the left atrium
and is pumped through the aorta to the body tissues by the left
ventricle
The aorta provides blood to the heart through the coronary arteries
© 2011 Pearson Education, Inc.
Capillaries of
head and forelimbs
Superior vena cava
Pulmonary
artery
Capillaries
of right lung
Pulmonary
vein
Right atrium
Right ventricle
Pulmonary
artery
Aorta
Capillaries
of left lung
Pulmonary vein
Left atrium
Left ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and hind limbs
Aorta
Pulmonary artery
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Right
ventricle
Left
ventricle
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The heart contracts and relaxes in a rhythmic cycle called the cardiac
cycle
The contraction, or pumping, phase is called systole
The relaxation, or filling, phase is called diastole
© 2011 Pearson Education, Inc.
Atrial systole and ventricular
diastole
2
Atrial and
ventricular diastole
1
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
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The heart rate, also called the pulse, is the number of beats per
minute
The stroke volume is the amount of blood pumped in a single
contraction
The cardiac output is the volume of blood pumped into the systemic
circulation per minute and depends on both the heart rate and stroke
volume
© 2011 Pearson Education, Inc.
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Four valves prevent backflow of blood in the heart
The atrioventricular (AV) valves separate each atrium and
ventricle
The semilunar valves control blood flow to the aorta and the
pulmonary artery
Backflow of blood through a defective valve causes a heart murmur
© 2011 Pearson Education, Inc.
1
SA node
(pacemaker)
ECG
2
AV
node
3
Bundle
branches
4
Heart
apex
Purkinje
fibers
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Impulses from the SA node travel to the atrioventricular (AV)
node
At the AV node, the impulses are delayed and then travel to the
Purkinje fibers that make the ventricles contract
© 2011 Pearson Education, Inc.
42.3 Patterns of Blood
Pressure and Flow Reflect the
structure and arrangement of
blood vessels
Thursday & Friday!
Dylan Jardon
Question 
What kind of blood vessels
would maximize blood flow
and control of blo0d pressure?
Which blood vessels do
you think are larger,
arteries or veins?
Question  How can the velocity of blood in the capillaries be so much less than
blood in other vessels? Why is this important?
the velocity of
Changes in Blood Pressure
During the Cardiac Cycle
• A pulse is the rhythmic bulging of artery walls with each
heartbeat
• Systolic pressure—pressure in the arteries during
ventricular systole; it is the highest pressure in the
arteries
• Diastolic pressure—pressure in the arteries during
diastole; it is lower than systolic pressure
Blood is moved through veins by smooth muscle contraction, skeletal
muscle contraction, and expansion of the vena cava with inhalation
One-way valves in veins prevent backflow of blood
What happens if you stop moving right after
workout?
Regulation of Blood
Pressure
• Vasoconstriction- smooth muscles in arterioles contract
increasing blood pressure upstream of arteries
• Vasodilation- smooth muscles relax, decreasing blood
pressure of arteries
Capillary Function
•
Blood flows through only 510% of the body’s capillaries at a
time
•
Two mechanisms regulate distribution of blood in capillary
beds
o
Contraction of the smooth muscle layer in the wall of an arteriole
constricts the vessel
o
Precapillary sphincters control flow of blood between arterioles and
venules
•
Blood flow is regulated by nerve impulses, hormones, and
other chemicals
© 2011 Pearson Education, Inc.
The lymphatic system returns fluid that leaks
out from the capillary beds
Review!
• What’s the importance of smooth muscle in blood
vessels?
• What is the advantage of having precapillary
sphincters?
• What is the difference between capillaries and
other blood vessels?
CONCEPT 42.4
Blood components function in exchange, transport, and defense.
BLOOD COMPOSITION AND
FUNCTION
PLASMA
• In open circulatory system, fluid pumped comes into direct contact w/all
cells; vertebrates have closed circulatory system
• Vertebrate blood is a connective tissue consisting of cells suspended in a
liquid matrix called plasma (90% water)
• Plasma proteins influence blood pH, osmotic pressure, viscosity
• Function in lipid transport, immunity (antibodies) and blood clotting
• Contain dissolved salts (ions) known as electrolytes
CELLULAR ELEMENTS
• Erythrocytes, Leukocytes, & Platelets
• Platelets: fragments of cells that are involved in the clotting process
• 2 classes of cells
• Red blood cells: transport oxygen
• White blood cells: defense
ERYTHROCYTES
• Red blood cells-most numerous
• Contain hemoglobin: iron-containing protein that transports oxygen;
each molecule of hemoglobin can bond w/4 oxygen molecules
• Lack mitochondria; generate ATP anaerobically
• In mammals, lack nucleus-leaves more room for hemoglobin
• Sickle-cell disease: abnormal form of hemoglobin polymerizes into
aggregates
• Large enough to distort erythrocyte into elongated, curved shape
LEUKOCYTES
• White blood cells; 5 major types
• Fight infection
• Some are phagocytic-engulf & digest microorganisms as well as debris
from dead cells
• Also found outside circulatory system; interstitial fluid & lymphatic system
BLOOD CLOTTING
• Break in a blood vessel wall exposes proteins that attract platelets &
initiate coagulation: conversion of liquid components of blood into a solid
clot
• Sealant circulates in an inactive form called fibrinogen
• in response to a broken blood vessel, platelets release clotting factors that
trigger reactions leading to formation of thrombin
• Thrombin converts fibrinogen to fibrin-aggregates into threads that form the
framework of the clot
• works through positive feedback
FIBRIN CLOT FORMATION
STEM CELLS AND THE FORMATION
OF CELLULAR ELEMENTS
• Erythrocytes, leukocytes, & platelets all develop from multipotent stem
cells
• hormone erythropoietin (EPO) stimulates erythrocyte production when
O2 delivery is low
CARDIOVASCULAR DISEASE
• Inflammation: body’s reaction to injury can trigger flow of fluid out of
blood vessels at the sight of the injury
• Cholesterol metabolism plays central role in cardiovascular disease
• Low-density lipoprotein (LDL): delivers cholesterol to cells for membrane
production
• High-density lipoprotein (HDL): scavenges extra cholesterol for return to liver
• Individuals w/ high LDL to HDL ratio are at high risk for cardio. Disease
ATHEROSCLEROSIS, HEART
ATTACKS, AND STROKE
• Atherosclerosis: hardening of arteries by accumulation of fatty deposits
heart attack: damage/death of cardiac muscle due to blockage of
coronary arteries
• Stroke: death of nervous
tissue in the brain due to
lack of oxygen (result of
rupture/blockage of
arteries in the head)
RISK FACTORS AND TREATMENT OF
CARDIOVASCULAR DISEASE
high LDL to HDL ratio increases the risk of cardiovascular disease
Smoking, consuming trans fat increase ratio of LDL to HDL
Exercise decreases ration
Drugs called statins lower LDL levels
Aspirin inhibits inflammatory response—has been found to prevent
recurrence of heart attacks & stroke
• Hypertension: high blood pressure, contributes to heart attack & stroke
•
•
•
•
•
• Chronic high blood pressure damages lining of arteries, promoting plaque
formation
CONCLUSION
• Inactivating 1 copy of the PCSK9 gene lowers average plasma LDL level
40%--decreasing PCSK9 activity reduces risk for heart disease
• Search is currently being conducted for molecules that inhibit PCSK9 as
potential drugs to prevent heart disease
Gas exchange occurs across
specialized respiratory surfaces
42.5 STEVEN IANNUCCI
Partial Pressure
The pressure of a dissolved gas inside of a solution, will try to
create an equilibrium with the other mixture.
Applies to the gases inside of a liquid (i.e. Water, blood, etc...)
Respiratory Media
Oxygen can be obtain from either water or air
By ppm, there is less oxygen available in water than in air
Water is more dense and more vicious: requiring greater
efficiency
Respiratory Surfaces
More surface area, more efficiency
Gas exchange occurs by diffusion across the membrane due
to Partial Pressure
Gills in Aquatic Animals
Effectiveness of gills in increased by Ventilation and
Countercurrent Exchange
- Because blood is always less saturated than
water, blood flows in the opposite direction to
water passing over the gills
Countercurrent exchange system
TIME FOR WICKED
AWESOME
ACTIVITY
Everyone get up and form two parallel single file lines about
an arms length apart
Tracheal Systems in Insects
Lungs
•
•
•
Localized respiratory systems
Can only occur with the presence of a circulatory system
Size and complexity of lungs directly correlates with animals
metabolic rate
Avioli
Lack cilia therefore very susceptible to contamination
Surfactants are secreted in Avioli to moisten and allow for
better diffusion, protection, reduce surface tension
Absence of surfactants causes Respiratory Distress
Syndrome
•
Conclusion: In the lungs of infants over 1,200g, contain a substance that reduces
surface tension. The substance is missing in infants with RDS, and tiny alveoli cannot
stand under that pressure
How an Amphibian Breathes
• An amphibian such as a frog ventilates its lungs by
positive pressure breathing, which forces air
down the trachea
© 2011 Pearson Education, Inc.
How a Bird Breathes
• Birds have eight or nine air sacs that function as
bellows that keep air flowing through the lungs
• Air passes through the lungs in one direction only
• Every exhalation completely renews the air in the
lungs
© 2011 Pearson Education, Inc.
Figure 42.27
Anterior
air sacs
Posterior
air sacs
Lungs
Airflow
Air tubes
(parabronchi)
in lung
1 mm
Posterior
air sacs
Lungs
3
Anterior
air sacs
2
4
1
1 First inhalation
2 First exhalation
3 Second inhalation
4 Second exhalation
How a Mammal Breathes
• Mammals ventilate their lungs by negative
pressure breathing, which pulls air into the lungs
• Lung volume increases as the rib muscles and
diaphragm contract
• The tidal volume is the volume of air inhaled with
each breath
© 2011 Pearson Education, Inc.
Figure 42.28
1
Rib cage
expands.
2
Air
inhaled.
Lung
Diaphragm
Rib cage gets
smaller.
Air
exhaled.
• The maximum tidal volume is the vital capacity
• After exhalation, a residual volume of air remains
in the lungs
© 2011 Pearson Education, Inc.
Control of Breathing in Humans
• In humans, the main breathing control centers
are in two regions of the brain, the medulla
oblongata and the pons
• The medulla regulates the rate and depth of
breathing in response to pH changes in the
cerebrospinal fluid
• The medulla adjusts breathing rate and depth to
match metabolic demands
The
pons
regulates the tempo
© 2011•Pearson
Education,
Inc.
• Sensors in the aorta and carotid arteries monitor
O2 and CO2 concentrations in the blood
• These sensors exert secondary control over
breathing
© 2011 Pearson Education, Inc.
Figure 42.29
Homeostasis:
Blood pH of about 7.4
CO2 level
decreases.
Response:
Rib muscles
and diaphragm
increase rate
and depth of
ventilation.
Stimulus:
Rising level of
CO2 in tissues
lowers blood pH.
Sensor/control center:
Cerebrospinal fluid
Medulla
oblongata
Carotid
arteries
Aorta
Concept 42.7: Adaptations for gas exchange
include pigments that bind and transport
gases
• The metabolic demands of many organisms
require that the blood transport large quantities of
O2 and CO2
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Coordination of Circulation and Gas
Exchange
• Blood arriving in the lungs has a low partial
pressure of O2 and a high partial pressure of CO2
relative to air in the alveoli
• In the alveoli, O2 diffuses into the blood and CO2
diffuses into the air
• In tissue capillaries, partial pressure gradients
favor diffusion of O2 into the interstitial fluids and
CO
into
the
blood
2
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1 Inhaled air
8 Exhaled air
Alveolar
epithelial
cells
CO2
O2
2 Alveolar
spaces
Alveolar
capillaries
3 Pulmonary
veins
7 Pulmonary
arteries
6 Systemic
veins
4 Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
5 Body tissue
(a) The path of respiratory gases in the circulatory
system
Partial pressure (mm Hg)
Figure 42.30
160
120
Inhaled
air
PO
PCO2
Exhaled
air
80
40
0
2
1
2
3
4
5
6
7
8
(b) Partial pressure of O2 and CO2 at different points in the
circulatory system numbered in (a)
Respiratory Pigments
• Respiratory pigments, proteins that transport
oxygen, greatly increase the amount of oxygen that
blood can carry
• Arthropods and many molluscs have hemocyanin
with copper as the oxygen-binding component
• Most vertebrates and some invertebrates use
hemoglobin
• In vertebrates, hemoglobin is contained within
erythrocytes
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Education, Inc.
Hemoglobin
• A single hemoglobin molecule can carry four
molecules of O2, one molecule for each ironcontaining heme group
• The hemoglobin dissociation curve shows that a
small change in the partial pressure of oxygen can
result in a large change in delivery of O2
• CO2 produced during cellular respiration lowers
blood pH and decreases the affinity of hemoglobin
for O2;Inc.this is called the Bohr shift
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Figure 42.UN01
Iron
Heme
Hemoglobin
100
O2 unloaded
to tissues
at rest
80
60
40
O2 unloaded
to tissues
during exercise
20
0
0
20
40
60
Tissues during Tissues
at rest
exercise
PO2 (mm Hg)
80
100
Lungs
(a) PO2 and hemoglobin dissociation at pH 7.4
O2 saturation of hemoglobin (%)
O2 saturation of hemoglobin (%)
Figure 42.31
100
pH 7.4
80
pH 7.2
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration)
60
40
20
0
0
20
40
60
80
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
100
Carbon Dioxide Transport
• Hemoglobin also helps transport CO2 and assists
in buffering the blood
• CO2 from respiring cells diffuses into the blood and
is transported in blood plasma, bound to
–)
hemoglobin,
or
as
bicarbonate
ions
(HCO
Animation: O from Blood to Tissues3
2
Animation: CO2 from Tissues to Blood
Animation: CO2 from Blood to Lungs
Animation: O2 from Lungs to Blood
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Animation: O2 from Blood to Tissues
Right-click slide / select “Play”
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Animation: CO2 from Tissues to Blood
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Animation: CO2 from Blood to Lungs
Right-click slide / select “Play”
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Animation: O2 from Lungs to Blood
Right-click slide / select “Play”
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Figure 42.32
Body tissue
CO2 produced
CO2 transport
from tissues
Interstitial
CO2
fluid
Plasma
CO2
within capillary
H2O
Capillary
wall
CO2
Hemoglobin (Hb)
H2CO3
Hb
picks up
Carbonic
+
CO
2 and H .
acid
Red
blood
cell
HCO3 
Bicarbonate
HCO3
H+
To lungs
CO2 transport
to lungs
HCO3
HCO3 
H2CO3
H2O
H+
Hb
Hemoglobin
releases
CO2 and H+.
CO2
CO2
CO2
CO2
Alveolar space in lung
Respiratory Adaptations of Diving Mammals
• Diving mammals have evolutionary adaptations
that allow them to perform extraordinary feats
– For example, Weddell seals in Antarctica can
remain underwater for 20 minutes to an hour
– For example, elephant seals can dive to 1,500 m
and remain underwater for 2 hours
• These animals have a high blood to body volume
ratio
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• Deep-diving air breathers stockpile O2 and deplete
it slowly
• Diving mammals can store oxygen in their muscles
in myoglobin proteins
• Diving mammals also conserve oxygen by
– Changing their buoyancy to glide passively
– Decreasing blood supply to muscles
– Deriving ATP in muscles from fermentation once
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Inc.
oxygen
is depleted