Title: 1
1Lecture 10 Animal Circulation and Gas Exchange
Systems
2Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
3Animals use O2 and produce CO2
- All animals are aerobic
- Lots of oxygen is required to support active
mobility - Some animals use lots of oxygen to maintain body
temperature - All animals produce CO2 as a byproduct of
aerobic respiration - Gasses must be exchanged
- Oxygen must be acquired from the environment
- Carbon dioxide must be released to the environment
4Animals use O2 and produce CO2
- Circulation systems move gasses (and other
essential resources such as nutrients, hormones,
etc) throughout the animals body - Respiratory systems exchange gasses with the
environment
5Circulation systems have evolved over time
- The most primitive animals exchange gasses and
circulate resources entirely by diffusion - Process is slow and cannot support 3-D large
bodies - Sponges, jellies and flatworms use diffusion alone
6Critical Thinking
- Why isnt diffusion adequate for exchange in a 3D
large animal???
7Critical Thinking
- Why isnt diffusion adequate for exchange in a 3D
large animal???
8Critical Thinking
- But..plants rely on diffusion for gas
exchange..how do they get so big???
9Critical Thinking
- But..plants rely on diffusion for gas
exchange..how do they get so big???
10Circulation systems have evolved over time
- The most primitive animals exchange gasses and
circulate resources entirely by diffusion - Process is slow and cannot support 3-D large
bodies - Surface area / volume ratio becomes too small
- Sponges, jellies and flatworms use diffusion alone
11Virtually every cell in a sponge is in direct
contact with the water little circulation is
required
Diagram of sponge structure
12- Jellies and flatworms have thin bodies and
elaborately branched gastrovascular cavities - Again, all cells are very close to the external
environment - This facilitates diffusion
- Some contractions help circulate (contractile
fibers in jellies, muscles in flatworms)
Diagram of jellyfish structure, and photos
13Circulation systems have evolved over time
- Most invertebrates (esp. insects) have an open
circulatory system
- Metabolic energy is used to pump hemolymph
through blood vessels into the body cavity - Hemolymph is returned to vessels via ostia
pores that draw in the fluid as the heart relaxes
Diagram of open circulatory system in a
grasshopper
14Circulation systems have evolved over time
- Closed circulatory systems separate blood from
interstitial fluid
- Metabolic energy is used to pump blood through
blood vessels - Blood is contained within the vessels
- Exchange occurs by diffusion in capillary beds
Diagram of a closed circulatory system, plus a
diagram showing an earthworm circulatory system
15Open vs. Closedboth systems are common
- Open systems.
- Use less metabolic energy to run
- Use less metabolic energy to build
- Can function as a hydrostatic skeleton
- Most invertebrates (except earthworms and larger
mollusks) have open systems
- Closed systems.
- Maintain higher pressure
- Are more effective at transport
- Supply more oxygen to support larger and more
active animals - All vertebrates have closed systems
16All vertebrates have a closed circulatory system
- Chambered heart pumps blood
- Atria receive blood
- Ventricles pump blood
- Vessels contain the blood
- Veins carry blood to atria
- Arteries carry blood from ventricles
- Capillary beds facilitate exchange
- Capillary beds separate arteries from veins
- Highly branched and very tiny
- Infiltrate all tissues in the body
Well go over these step by step
17Chambered heart pumps blood
- Atria receive blood
- Ventricles pump blood
- One-way valves direct blood flow
Diagram of a chambered heart
18Critical Thinking
- Atria receive blood ventricles pump
- Given that function, what structure would you
predict???
19Critical Thinking
- Atria receive blood ventricles pump
- Given that function, what structure would you
predict???
20Chambered heart pumps blood
- Atria receive blood
- Soft walled, flexible
- Ventricles pump blood
- Thick, muscular walls
- One-way valves direct blood flow
Diagram of a chambered heart
21Vessels contain the blood
- Arteries carry blood from ventricles
- Always under pressure
- Veins carry blood to atria
- One-way valves prevent back flow
- Body movements increase circulation
- Pressure is always low
Diagram showing artery, vein and capillary bed
22Note that blood vessel names reflect the
direction of flow, NOT the amount of oxygen in
the blood
- Arteries carry blood AWAY from the heart
- Arterial blood is always under pressure
- It is NOT always oxygenated
- Veins carry blood TO the heart
Diagram of blood circulation pattern in humans
23Capillary beds facilitate exchange
- Capillary beds separate arteries from veins
- Highly branched and very tiny
- Infiltrate all tissues in the body
- More later
Diagram showing artery, vein and capillary bed
24Arteriovenous Malformation (AVM)
- This is a congenital disease where the vascular
system forms incorrect connections that persist
all through life - The arteries become piped directly into the
veins with a hard tube called a shunt, and blood
moves freely between them - AVMs form most commonly in the brain or spinal
cord, two very sensitive areas of the body
From Brandon Mizroch, 2008
25AVM Pathology
- The tissues around the AVM is called a nidus, and
because there are no capillaries, blood moves too
fast to take up waste and deposit nutrients and
oxygen - Tissues around the AVM essentially starve
- Also the veins are too weak to contain the high
pressure of arterial blood and there is great
risk of an aneurism or hemorrhage
From Brandon Mizroch, 2008
26AVM (cont.)
Improper Vessel Connection
Bulging Aneurism
Good
Bad
27AVM Symptoms
- There are about 300,000 people in America with
this condition, but only about 12 show any
symptoms - When the AVM is present in the brain the most
common symptoms are headache, a constant
whooshing noise called a bruit, and seizures - Unfortunately, this condition is often not
diagnosed until a person dies as a result of it
From Brandon Mizroch, 2008
28All vertebrates have a closed circulatory system
REVIEW
- Chambered heart pumps blood
- Atria receive blood
- Ventricles pump blood
- Vessels contain the blood
- Veins carry blood to atria
- Arteries carry blood from ventricles
- Capillary beds facilitate exchange
- Capillary beds separate arteries from veins
- Highly branched and very tiny
- Infiltrate all tissues in the body
29Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
30Evolution of double circulation not all
animals have a 4-chambered heart
Diagram showing progression from a 1-chambered
heart to a 4-chambered heart. This diagram is
used in the next 12 slides.
31Fishes have a 2-chambered heart
- One atrium, one ventricle
- A single pump of the heart circulates blood
through 2 capillary beds in a single circuit - Blood pressure drops as blood enters the
capillaries (increase in cross-sectional area of
vessels) - Blood flow to systemic capillaries and back to
the heart is very slow - Flow is increased by swimming movements
32Two circuits increases the efficiency of gas
exchange double circulation
- One circuit goes to exchange surface
- One circuit goes to body systems
- Both under high pressure increases flow rate
33Amphibians have a 3-chambered heart
- Two atria, one ventricle
- Ventricle pumps to 2 circuits
- One circuit goes to lungs and skin to release CO2
and acquire O2 - The other circulates through body tissues
- Oxygen rich and oxygen poor blood mix in the
ventricle - A ridge helps to direct flow
- Second pump increases the speed of O2 delivery to
the body
34Most reptiles also have a 3-chambered heart
- A partial septum further separates the blood flow
and decreases mixing - Crocodilians have a complete septum
- Point of interest reptiles have two arteries
that lead to the systemic circuits - Arterial valves help direct blood flow away from
pulmonary circuit when animal is submerged
35Critical Thinking
- What is a disadvantage of a 3 chambered heart???
36Critical Thinking
- What is a disadvantage of a 3 chambered heart???
37Mammals and birds have 4-chambered hearts
- Two atria and two ventricles
- Oxygen rich blood is completely separated from
oxygen poor blood - No mixing ? much more efficient gas transport
- Efficient gas transport is essential for both
movement and support of endothermy - Endotherms use 10-30x more energy to maintain
body temperatures
38Mammals and birds have 4-chambered hearts
- Mammals and birds are NOT monophyletic
- What does this mean???
39Mammals and birds have 4-chambered hearts
- Mammals and birds are NOT monophyletic
Phylogenetic tree showing the diversification of
vertebrates
40Mammals and birds have 4-chambered hearts
- Mammals and birds are NOT monophyletic
- Four-chambered hearts evolved independently
41Mammals and birds have 4-chambered hearts
- Mammals and birds are NOT monophyletic
- Four-chambered hearts evolved independently
42Review evolution of double circulation
43Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
44Blood Circulation
- Blood vessels are organs
- Outer layer is elastic connective tissue
- Middle layer is smooth muscle and elastic fibers
- Inner layer is endothelial tissue
- Arteries have thicker walls
- Capillaries have only an endothelium and basement
membrane
45Critical Thinking
- Arteries have thicker walls than veins
- Capillaries have only an endothelium and basement
membrane - What is the functional significance of this
structural difference???
46Critical Thinking
- Arteries have thicker walls than veins
- Capillaries have only an endothelium and basement
membrane - What is the functional significance of this
structural difference???
47Form reflects function
- Arteries are under more pressure than veins
- Capillaries are the exchange surface
Diagram showing artery, vein and capillary bed
48Blood pressure and velocity drop as blood moves
through capillaries
Graph showing relationships between blood
pressure, blood velocity, and the cross-sectional
area of different kinds of blood vessels
arteries to capillaries to veins. This same
graph is on the next 3 slides.
49Total cross-sectional area in capillary beds is
much higher than in arteries or veins slows flow
50Velocity increases as blood passes into veins
(smaller cross-sectional area) pressure remains
dissipated
51One-way valves and body movements force blood
back to right heart atrium
52Critical Thinking
- What makes rivers curl on the Coastal Plain???
53Critical Thinking
- What makes rivers curl on the Coastal Plain???
54Capillary Exchange
- Gas exchange and other transfers occur in the
capillary beds - Muscle contractions determine which beds are
open - Brain, heart, kidneys and liver are generally
always fully open - Digestive system capillaries open after a meal
- Skeletal muscle capillaries open during exercise
- etc
55Bed fully openBed closed, through-flow
onlyNote scale capillaries are very tiny!!
Diagram showing sphincter muscle control over
capillary flow. Micrograph of a capillary bed.
56Capillary Transport Processes
- Endocytosis ? exocytosis across membrane
- Diffusion based on electrochemical gradients
- Bulk flow between endothelial cells
- Water potential gradient forces solution out at
arterial end - Reduction in pressure draws most (85) fluid back
in at venous end - Remaining fluid is absorbed into lymph, returned
at shoulder ducts
57Capillary Transport Processes
- Endocytosis ? exocytosis across membrane
- Diffusion based on concentration gradients
- Bulk flow between endothelial cells
- Water potential gradient forces solution out at
arterial end - Reduction in pressure draws most (85) fluid back
in at venous end - Remaining fluid is absorbed into lymph, returned
at shoulder ducts
58Bulk Flow in Capillary Beds
- Remember water potential ? P s
- Remember that in bulk flow P is dominant
- No membrane
- Plus, in the capillaries, s is stable (blood
proteins too big to pass) - P changes due to the interaction between arterial
pressure and the increase in cross-sectional area
59Bulk Flow in Capillary BedsRemember ? P s
Diagram showing osmotic changes across a
capillary bed
60Capillary Transport Processes
- Endocytosis ? exocytosis across membrane
- Diffusion based on concentration gradients
- Bulk flow between endothelial cells
- Water potential gradient forces solution out at
arterial end - Reduction in pressure draws most (85) fluid back
in at venous end - Remaining fluid is absorbed into lymph, returned
at shoulder ducts
61Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
62Blood structure and function
- Blood is 55 plasma and 45 cellular elements
- Plasma is 90 water
- Cellular elements include red blood cells, white
blood cells and platelets
63Blood Components
Chart listing all blood components both liquid
and cellular
64Plasma Solutes 10 of plasma volume
- Solutes
- Inorganic salts that maintain osmotic balance,
buffer pH to 7.4, contribute to nerve and muscle
function - Concentration is maintained by kidneys
- Proteins
- Also help maintain osmotic balance and pH
- Escort lipids (remember, lipids are insoluble in
water) - Defend against pathogens (antibodies)
- Assist with blood clotting
- Materials being transported
- Nutrients
- Hormones
- Respiratory gasses
- Waste products from metabolism
65Cellular Elements
- Red blood cells, white blood cells and platelets
- Red blood cells carry O2 and some CO2
- White blood cells defend against pathogens
- Platelets promote clotting
66Red Blood Cells
- Most numerous of all blood cells
- 5-6 million per mm3 of blood!
- 25 trillion in the human body
- Biconcave shape
- No nucleus, no mitochondria
- They dont use up any of the oxygen they carry!
- 250 million molecules of hemoglobin per cell
- Each hemoglobin can carry 4 oxygen molecules
- More on hemoglobin later
67Critical Thinking
- Tiny size and biconcave shape do what???
68Critical Thinking
- Tiny size and biconcave shape do what???
69White Blood Cells
- All function in defense against pathogens
- We will cover extensively in the chapter on
immune systems
70Platelets
- Small fragments of cells
- Formed in bone marrow
- Function in blood clotting at wound sites
71The Clotting Process
Diagram showing the clotting process
72Blood Cell Production
- Blood cells are constantly digested by the liver
and spleen - Components are re-used
- Pluripotent stem cells produce all blood cells
- Feedback loops that sense tissue oxygen levels
control red blood cell production
Diagram showing blood cell production from stem
cells in bone marrow
Fig 42.16, 7th ed
73Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
74Gas Exchange
- Gas Exchange ? Respiration ? Breathing
- Gas exchange delivery of O2 removal of CO2
- Respiration the metabolic process that occurs
in mitochondria and produces ATP - Breathing ventilation to supply the exchange
surface with O2 and allow exhalation of CO2
75Diagram showing indirect links between external
environment, respiratory system, circulatory
system and tissues.
76Gas Exchange Occurs at the Respiratory Surface
- Respiratory medium the source of the O2
- Air for terrestrial animals air is 21 O2 by
volume - Water for aquatic animals dissolved O2 varies
base on environmental conditions, especially
salinity and temperature always lower than in air
77Gas Exchange Occurs at the Respiratory Surface
- Respiratory surface the site of gas exchange
- Gasses move by diffusion across membranes
- Gasses are always dissolved in the interstitial
fluid - Surface area is important!
78Evolution of Gas Exchange Surfaces
- Skin
- Must remain moist limits environments
- Must maintain functional SA / V ratio limits 3D
size - Gills
- Large SA suspended in water
- Tracheal systems
- Large SA spread diffusely throughout body
- Lungs
- Large SA contained within small space
79Skin Limits
- Sponges, jellies and flatworms rely on the skin
as their only respiratory surface
80Evolution of Gas Exchange Surfaces
- Skin
- Must remain moist limits environments
- Must maintain functional SA / V ratio limits 3D
size - Gills
- Large SA suspended in water
- Tracheal systems
- Large SA spread diffusely throughout body
- Lungs
- Large SA contained within small space
81Invertebrate Gills
- Dissolved oxygen is limited
- Behaviors and structures increase water flow past
gills to maximize gas exchange
Diagrams and photos of gills in different animals.
Fig 42.20, 7th ed
82Countercurrent Exchange in Fish Gills
- Direction of blood flow allows for maximum gas
exchange maintains high gradient
Diagram of countercurrent exchange in fish gills
Fig 42.21, 7th ed
83How countercurrent flow maximizes diffusion
Figure showing countercurrent vs co-current flow
effects on diffusion
84Evolution of Gas Exchange Surfaces
- Skin
- Must remain moist limits environments
- Must maintain functional SA / V ratio limits 3D
size - Gills
- Large SA suspended in water
- Tracheal systems
- Large SA spread diffusely throughout body
- Lungs
- Large SA contained within small space
85Tracheal Systems in Insects
- Air tubes diffusely penetrate entire body
- Small openings to the outside limit evaporation
- Open circulatory system does not transport gasses
from the exchange surface - Body movements ventilate
Diagram and micrograph of insect tracheal system.
86Tracheal Systems in InsectsRings of chitinLook
familiar???
87Critical Thinking
- Name 2 other structures that are held open by
rings
88Critical Thinking
- Name 2 other structures that are held open by
rings
89Evolution of Gas Exchange Surfaces
- Skin
- Must remain moist limits environments
- Must maintain functional SA / V ratio limits 3D
size - Gills
- Large SA suspended in water
- Tracheal systems
- Large SA spread diffusely throughout body
- Lungs
- Large SA contained within small space
90Lungs in Spiders, Terrestrial Snails and
Vertebrates
- Large surface area restricted to small part of
the body - Single, small opening limits evaporation
- Connected to all cells and tissues via a
circulatory system - Dense capillary beds lie directly adjacent to
respiratory epithelium - In some animals, the skin supplements gas
exchange (amphibians)
91Mammalian Lungs
- Highly branched system of tubes trachea,
bronchi, and bronchioles - Each ends in a cluster of bubbles the alveoli
- Alveoli are surrounded by capillaries
- This is the actual site of gas exchange
- Huge surface area (100m2 in humans)
- Rings of cartilage keep the trachea open
- Epiglottis directs food to esophagus
92Figure and micrograph of lung and alveolus
structure.
93Mammalian Lungs
- Highly branched system of tubes trachea,
bronchi, and bronchioles - Each ends in a cluster of bubbles the alveoli
- Alveoli are surrounded by capillaries
- This is the actual site of gas exchange
- Huge surface area (100m2 in humans)
- Rings of cartilage keep the trachea open
- Epiglottis directs food to esophagus
94Figure of vascularized alveolus
95Mammalian Lungs
- Highly branched system of tubes trachea,
bronchi, and bronchioles - Each ends in a cluster of bubbles the alveoli
- Alveoli are surrounded by capillaries
- This is the actual site of gas exchange
- Huge surface area (100m2 in humans)
- Rings of cartilage keep the trachea open
- Epiglottis directs food to esophagus
96Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
97Breathing Ventilates Lungs
- Positive pressure breathing amphibians
- Air is forced into trachea under pressure
- Mouth and nose close, muscle contractions force
air into lungs - Relaxation of muscles and elastic recoil of lungs
force exhalation
98Breathing Ventilates Lungs
- Positive pressure breathing amphibians
- Air is forced into trachea under pressure
- Mouth and nose close, muscle contractions force
air into lungs - Relaxation of muscles and elastic recoil of lungs
force exhalation - Negative pressure breathing mammals
- Air is sucked into trachea under suction
- Circuit flow breathing birds
- Air flows through entire circuit with every breath
99Negative Pressure Breathing
Diagram of negative pressure breathing
100Breathing Ventilates Lungs
- Positive pressure breathing amphibians
- Air is forced into trachea under pressure
- Mouth and nose close, muscle contractions force
air into lungs - Relaxation of muscles and elastic recoil of lungs
forces exhalation - Negative pressure breathing mammals
- Air is sucked into trachea under suction
- Circuit flow breathing birds
- Air flows through entire circuit with every breath
101Flow Through Breathing
- No residual air left in lungs
- Every breath brings fresh O2 past the exchange
surface - Higher lung O2 concentration than in mammals
Diagram of circuit flow breathing in birds
102Critical Thinking
- What is the functional advantage of flow-through
breathing for birds???
103Critical Thinking
- What is the functional advantage of flow-through
breathing for birds???
104Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments
105Respiratory pigments tying the two systems
together
- Respiratory pigments are proteins that reversibly
bind O2 and CO2 - Circulatory systems transport the pigments to
sites of gas exchange - O2 and CO2 molecules bind or are released
depending on gradients of partial pressure
106Partial Pressure Gradients Drive Gas Transport
- Atmospheric pressure at sea level is equivalent
to the pressure exerted by a column of mercury
760 mm high 760 mm Hg - This represents the total pressure that the
atmosphere exerts on the surface of the earth - Partial pressure is the percentage of total
atmospheric pressure that can be assigned to each
component of the atmosphere
107Atmospheric pressure at sea level is equivalent
to the pressure exerted by a column of mercury
760 mm high 760 mm Hg (29.92 of mercury)
108Partial Pressure Gradients Drive Gas Transport
- Atmospheric pressure at sea level is equivalent
to the pressure exerted by a column of mercury
760 mm high 760 mm Hg - This represents the total pressure that the
atmosphere exerts on the surface of the earth - Partial pressure is the percentage of total
atmospheric pressure that can be assigned to each
component of the atmosphere
109Partial Pressure Gradients Drive Gas Transport
- Each gas contributes to total atmospheric
pressure in proportion to its volume in the
atmosphere - Each gas contributes a part of total pressure
- That part the partial pressure for that gas
- The atmosphere is 21 O2 and 0.03 CO2
- Partial pressure of O2 is 0.21x760 160 mm Hg
- Partial pressure of CO2 is 0.0003x760 0.23 mm Hg
110Partial Pressure Gradients Drive Gas Transport
- Each gas contributes to total atmospheric
pressure in proportion to its volume in the
atmosphere - Each gas contributes a part of total pressure
- That part the partial pressure for that gas
- The atmosphere is 21 O2 and 0.03 CO2
- Partial pressure of O2 is 0.21x760 160 mm Hg
- Partial pressure of CO2 is 0.0003x760 0.23 mm Hg
111Partial Pressure Gradients Drive Gas Transport
- Atmospheric gasses dissolve into water in
proportion to their partial pressure and
solubility in water - Dynamic equilibriums can eventually develop such
that the PP in solution is the same as the PP in
the atmosphere - This occurs in the fluid lining the alveoli
112Critical Thinking
- If a dynamic equilibrium exists in the alveoli,
will the partial pressures be the same as in the
outside atmosphere???
113Critical Thinking
- If a dynamic equilibrium exists in the alveoli,
will the partial pressures be the same as in the
outside atmosphere???
114Diagram showing partial pressures of gasses in
various parts of the body. This diagram is used
in the next 3 slides.
- Inhaled air PPs atmospheric PPs
- Alveolar PPs reflect mixing of inhaled and
exhaled air - Lower PP of O2 and higher PP of CO2 than in
atmosphere
115- O2 and CO2 diffuse based on gradients of partial
pressure - Blood PPs reflect supply and usage
- Blood leaves the lungs with high PP of O2
- Body tissues have lower PP of O2 because of
mitochondrial usage - O2 moves from blood to tissues
116- Same principles with CO2
- Blood leaves the lungs with low PP of CO2
- Body tissues have higher PP of CO2 because of
mitochondrial production - CO2 moves from tissues to blood
117- When blood reaches the lungs the gradients favor
diffusion of O2 into the blood and CO2 into the
alveoli
118Oxygen Transport
- Oxygen is not very soluble in water (blood)
- Oxygen transport and delivery are enhanced by
binding of O2 to respiratory pigments
Diagram of hemoglobin structure and how it
changes with oxygen loading. This diagram is
used in the next 3 slides.
Fig 42.28, 7th ed
119Oxygen Transport
- Increase is 2 orders of magnitude!
- Almost 50 times more O2 can be carried this way,
as opposed to simply dissolved in the blood
120Oxygen Transport
- Most vertebrates and some inverts use hemoglobin
for O2 transport - Iron (in heme group) is the binding element
121Oxygen Transport
- Four heme groups per hemoglobin, each with one
iron atom - Binding is reversible and cooperative
122Critical Thinking
- Binding is reversible and cooperative
- What does that mean???
123Critical Thinking
- Binding is reversible and cooperative
- What does that mean???
124Oxygen Transport
- Reverse occurs during unloading
- Release of one O2 induces shape change that
speeds up the release of the next 3
125Oxygen Transport
- More active metabolism (ie during muscle use)
increases unloading - Note steepness of curve
- O2 is unloaded quickly when metabolic use
increases
Graph showing how hemoglobin oxygen saturation
changes with activity.
126Oxygen Transport the Bohr Shift
Graph showing the Bohr Shift
- More active metabolism also increases the release
of CO2 - Converts to carbonic acid, acidifying blood
- pH change stimulates release of additional O2
Fig 42.29, 7th ed
127Carbon Dioxide Transport
Figure showing how carbon dioxide is transported
from tissues to lungs. This figure is used in
the next 3 slides.
- Red blood cells also assist in CO2 transport
- 7 of CO2 is transported dissolved in plasma
- 23 is bound to amino groups of hemoglobin in the
RBCs - 70 is converted to bicarbonate ions inside the
RBCs
128Carbon Dioxide Transport
- CO2 in RBCs reacts with water to form carbonic
acid (H2CO3) - H2CO3 dissociates to bicarbonate (HCO3-) and H
129Carbon Dioxide Transport
- Most H binds to hemoglobin
- This limits blood acidification
- HCO3- diffuses back into plasma for transport
130Carbon Dioxide Transport
- Reverse occurs when blood reaches the lungs
- Conversion back to CO2 is driven by diffusion
gradients as CO2 moves into the lungs
131REVIEW Key Concepts
- Circulation and gas exchange why?
- Circulation spanning diversity
- Hearts the evolution of double circulation
- Blood circulation and capillary exchange
- Blood structure and function
- Gas exchange spanning diversity
- Breathing spanning diversity
- Respiratory pigments