Cardiovascular
System
Circulation and Gas Exchange
Circulation
• Exchange of materials
must take place across
a wet membrane
Simple animals have
a gastrovascular
cavity (digestion
and circulation)
Phylum Cnidaria: gastrovascular cavity
Circulation
• Complex organisms are multi-layered & have
cells that are isolated and need transport
systems
• Special organs just for transport (circulation);
heart, vessels
Circulatory System Overview:
•
•
•
•
Open vs closed
Types of hearts in vertebrates
Double circulation
Structure and function of basic parts:
– Heart, vessels, blood
Open Circulatory
System
• No closed vascular tubes;
‘Blood’ (hemolymph)
circulates freely in sinuses
(spaces around organs)
• Hydrostatic pressure
returns the hemolymph to the heart
– Ex. Arthropods, clams; limited in size
Closed Circulatory
System
• Closed vessels; veins
• Blood travels to an exchange
surface (pulmonary), then to
body cells (systemic)
• Blood remains in vessels;
– Much more efficient
– Ex. Earthworms, vertebrates
Closed
Open
Vertebrate Phylogeny
Adaptations (Evolution) of the
Cardiovascular System
Structural Adaptations
• Heart has chambers
– Atria - Superior chambers - receive blood
– Ventricles - Inferior chambers; pump
blood away from the heart
Vertebrate Hearts
• Number of chambers is different, demonstrate
evolutionary adaptation
– 2 chambers = 1 atrium, 1 ventricle
– 3 chambers = 2 atria, 1 ventricle
– 4 chambers = 2 atria, 2 ventricles
Blood passes through
2 capillary beds;
pulmonary, (gill)
systemic
–Reduces blood
pressure
–Oxygen-rich blood
slower to circulate
Three Chambered Heart
• Double circulation: blood
travels separately to lungs
and system
• Oxygenated blood mixes
with deoxygenated blood
• Amphibians, reptiles
Double circulation;
pulmonary and systemic are
separated
Mammalian Heart
4-chambered, double
circulation
Systemic circuit
Pulmonary circuit
Systemic circuit
4 chambered: efficient,
double circulation,
homeothermic, lots of
energy; ex. Mammals,
birds
Structure and Function of the
Circulatory System
• Three basic parts:
– Heart
– Blood vessels
– Blood
Heart
• Cardiac muscle; Smooth (rhythmical, persistent)
+ striated (multinucleated, strength)
• Muscle tissue can change shape, in response to
electrical or chemical stimulation
Heart Structure
• Pericardium = sac that surrounds the
heart (?)
• 2 Atria; thin walled, receive blood, no
pressure, right/left side
– Right - receives systemic blood
(‘deox’)
– Left - receives blood from lungs
(‘oxed’)
Heart Structure
• 2 Ventricles; thicker walls, pump
blood to body/lungs,
– Right - pumps blood to lungs
(pulmonary)
– Left - pumps blood to body
(systemic); heaviest muscle
Blood Flow Through the Heart
4. O2 rich blood to body
2. O2 poor blood to lungs
3. O2 rich blood from
lungs
1. O2 poor systemic blood
Cardiac Cycle
• Heart cycle: sequence of events during heartbeat
• Systole
• Diastole
Systole
• Heart contraction
• Chambers ‘pump’ blood
• Atria contract first (0.1 seconds); atrial
systole
• Ventricles contract; force blood into
arteries; ventricular systole
Diastole
• Relaxation phase
– Ventricles refill with blood
– Valves prevent ‘backflow’
Heart Cycle
• Heart Rate = pulse; number of beats per
minute
– Avg. = 65-70/min. at rest
• Stroke volume amount of blood that the left
ventricle pumps systemically per minute;
– Average human = 75 ml
Cardiac Output
• Rate x volume
– vol. = 75ml
– 70 ‘beats’ /min.
– 75 ml x 70 = 5.25 l
– 70/min. x 60 x 24 x 365 x 70 =
• A lot
Heart Cycle
25
1560
Inverse relationship between size and heart rate;
Elephants = 25
Shrews = 1560
How Do We Keep Blood From
Going ‘Backwards’?
One-Way Valves
Structure
• Four valves: prevent ‘back flow’
• 2 Atrioventricular between atria and ventricles
• 2 Semilunar; between ventricles and arteries,
aorta and pulmonary
Atrioventricular valves
Left atrium
Right atrium
Tricuspid (‘three
points’)
Bicuspid (mitral
valve) MVP
Left Ventricle
Right ventricle
2 Semilunar; between ventricles and arteries
Aortic valve
Pulmonary valve
LV
RV
Heart Cycle
• Heart sounds: valves opening/closing;
“heart beat”
• Stethoscope
• “Lubb” = lower pitch, atrioventricular
valves closing (bicuspid/tricuspid);
ventricles contracting; just before systole
• “Dupp” = semilunar valves closing;
ventricles relax; just before diastole
Heart Cycle
• Heart Murmur: defect in valve causing
backflow. Serious, corrected with surgery
Normal
Murmurs
Control of the Heart Cycle
Control of Heart Cycle
• Intercalated disks = special areas between
cells; extraordinary cell-to-cell
communication; folds in between like
tongue-in-groove
– (Why is this important?) –
structure/function
Control of Heart Cycle
• Cardiac muscle is myogenic (self-excitable)
– Contracts without nervous input
• Tempo is controlled by nodes (knots of nervous
tissue + cardiac muscle)
• Two ‘nodes’ stimulate muscle contraction
– Sinoatrial Node (SA)
– Atrioventricular node (AV)
• Sinoatrial node (SA) - tempo
of contraction “Pacemaker”
• Starts a wave of contraction;
causes both atria to contract
together
Atrioventricular node
(AV)
•Impulse delayed 0.1
second (why)
•Impulse travels to
Purkinje fibers; cause
apex of heart to twist,
wringing all blood out
Electrocardiogram
• Detects tiny electrical changes; action potentials
• Depolarization/repolarization detected by
electrodes on surface of skin
• Length of time measurement indicates healthiness
• Protracted time = unhealthy heart
• Non-surgical procedure
Regulation of Heart Cycle
• Controlled by SA node
• Influenced by:
– Autonomic nervous system
– Hormones
– Temperature
– Exercise
• Balance controlled by medulla
Regulation of Heart Cycle
• Autonomic – ‘automatic’
– Causes release of norepinephrine (hormone)
• Increases heart rate (emotions; fear, ‘love’)
• Impulses come from cerebrum (memory)
• Other causes for heart rate change:
– Pressure
– Ions –potassium, Ca.
Blood Pressure
• Systole = contraction of chambers; blood
‘pumped’
• Diastole = relaxing of chambers, ventricles,
atria fill
Blood Pressure
•
•
•
•
Measured by a sphygmomanometer/stethoscope
First number is systole
Second is diastole
120/70 = ‘good’, normal
Blood Pressure
• The hydrostatic force that blood exerts against
a vessel wall
• Greater in arteries
• Greatest during systole (contraction)
• Peripheral resistance = impedance from
arterioles; blood enters arteries faster than it
can get out
• Always pressure (even during diastole)
Blood Pressure
• What would cause blood pressure?
• Cardiac output and peripheral resistance
• Stress causes neural and hormonal responses
which trigger smooth muscle to contract,
increases peripheral resistance
Blood Pressure
• Pressure is near zero in veins
–
–
–
–
Blood is returning to the heart
Movement of muscle
Valves in the veins
Breathing increases volume in the thoracic cavity
causing vena cavae to dilate
Structural Differences in Vessels
Arteries, veins, capillaries
Vessels: 2 Types
• Arteries; carry blood
away from the heart
• Branch out into
arterioles
• Branch into capillaries
(diffusion/osmosis)
Arteries
• 3 layers (tunics): connective epithelium,
smooth muscle and endothelium: thick walled;
deep in body
• Arteriole = smallest arteries with 3 tunics
Veins
• Veins; return blood to heart
• Capillaries rejoin to form venules
(microscopic)
• Venules rejoin to form
veins
• May have flap like valves
(back flow)
• Thin walls; low pressure
Blood Vessels
• Capillary: endothelial tissue, thin, branched
• Diffusion of O2 to individual cells
Water that escapes from capillary
diffuses back into lymph
Capillary Exchange
• Passive transport occurs by:
– Diffusion
– Osmosis
– Hydrostatic pressure; blood pressure
– Gap junctions = pores between cells
Capillary Exchange
• Capillary wall is ‘leaky’
• Materials may cross in
vesicles
– Active transport
(endocytosis, exocytosis)
Capillary Exchange
• Gases move by diffusion
• Fluids move by osmosis or vesicles
• Direction of fluid flow depends upon the amount
of pressure
• Pressure = hydrostatic + osmotic
Capillary Exchange
• At the arteriole end: hydrostatic pressure
outward is greater than the inward osmotic
pressure
• Fluids move OUT Hydrostatic
pressure
into the interstial
fluid (materials
move through in
dissolved from)
Capillary Exchange
• At the venule end: outward hydrostatic pressure
is less than the inward osmotic pressure
• Fluids move back
into the capillary Hydrostatic
Osmosis
pressure
Hydrostatic
pressure
Osmosis
Lymph System
•Return Fluids to the Body
•Immunity
Lymph
• 85% of fluids lost in capillary bed exchange is
recovered at the venous end of the bed
• Other 15% is recovered by Lymph
• Lymphatic fluid = similar to interstial fluid
(water, proteins, antigens)
Lymph
• Movement of skeletal muscle aids circulation of
lymph (stay active)
• Trauma or histamines may cause an increase in
permeability
• Lymphatic system cannot keep up
• Surrounding tissues swell
Lymph
•
•
•
•
Lymph fluid travels through nodes
‘checked’ for antigens (invaders)
Nodes may become swollen
Also carries fats from
digestion
Heart Problems
• Rheumatic heart disease = streptococcal
infection; inflamed endocardium; valves
damaged” MVP
• Aneurysm = swelling in blood vessel
• Embolism = moving clot
Heart Problems
• Coronary thrombosis = clot in
coronary artery; causes
infarction (area of damaged
tissue)
Heart Problems
• Arrhythmia = heart out of rhythm:
– Tachycardia = 100 +
– Brachycardia = less than 60
– Flutter = 250+
– Fibrillation = heart muscles not contracting
together; defribillator stops heart
Heart Problems
• Coronary heart disease = reduced flow to
coronary arteries; ½ of all deaths in U.S.
• Stress, hypertension (atherosclerosis)
• Enlarges left ventricle (overwork)
Heart Problems
• Atherosclerosis = hardening of arterial wall due to
build up of plaque (cholesterol); LDL = ‘bad’; HDL
= ‘good’
• Arteriosclerosis = type of
athersclerosis; addition of Ca
deposits
Arteriosclerosis
Plaque
Normal
Arteriosclerosis
Heart Problems
• Myocardial infarction (‘heart attack’); angina
pectoris = pain in chest, left arm, shoulder
• Constriction of chest (angina); crushing,
bursting (may fade/return)
• Pain in back, jaw, left arm
• Shortness of breath
• Nausea, sweat, dizzy, pallor
Heart Problems
• Scar tissue replaces cardiac muscle
• Rest, diet (animal fat) reduce stress
• Exercise; dilation of skeletal muscles allows
increased flow through systemic, increased
O2 flow; brain works better…
Heart Problems: Treatment
• Digitalis = slows, strengthens heart
contraction
• Nitroglycerin = dilates vessels
• Anticoagulants = prevent blood clotting
Heart Problems
• By-pass surgery; remove vessels (leg) and
splice in around coronary vessel that is
blocked (‘triple/quadruple by-pass’)
• Stent = ‘balloon’ in artery to swell and break
up thrombosis/clot
Heart Problems
• Congenital = from birth; septal defect, cyanosis
(‘blue baby’)
• Aging = heart failure: by 70, 30% decrease in
heart efficiency; earlier if infections, toxins,
anemia, hyperthyroidism, infarction, stress
Heart Problems
• Stroke = loss of blood supply; necrosis
(tissue death); Infarction
• Caused by:
– Thrombosis (stationary clot)
– Hemorrhage (blood leak)
– Arteriosclerosis
Blood
• Connective tissue; 2 parts:
– Plasma – fluid – 55%
– Formed elements = solids; 45%
• Makes up 8% of body mass
• Average = 4 to 6 liters of whole blood
Functions
• Transport - O2, nutrients, enzymes, etc.
remove CO2, wastes
• Endothermy - (homeostasis)
• Balance - fluid, electrolyte, pH (homeostasis)
• Protection - from diseases, infection
Plasma
•
•
•
•
•
Water = 90%
Dissolved gases (CO2, O2 N2)
Inorganic salts (electrolytes; salts)
Proteins
Other – urea, sugars, aa, hormones
Plasma
• Proteins = buffer blood, osmosis, viscosity
(thickness)
– Albumins = osmotic pressure
– Globulins = immune (antibodies)
– Fibrinogen = clotting agent
• Serum = plasma with no clotting factors;
Why serum?
Blood: Formed Elements
• Solids
– Erythrocytes = 95 %
– Leucocytes = varies
– Platelets = 5 %
Erythrocytes
• ‘Red cells’
– Biconcave discs, transport oxygen
– 25 trillion
– Lack nuclei and mitochondria
Hemoglobin
Sickle cell
• Iron-containing protein
pigment;
– 250 million molecules per
RBC; 1/3 of mass
– Reversibly binds with oxygen
– Oxyhemoglobin -Bright red
• Four heme groups; each contains an iron
atom with an affinity for oxygen
Sickle cell
RBC Production
• Hematopoeisis (‘blood make’)
• Red marrow of long bones
– Femur, humerus; skull,
ribs, pelvis, sternum,
vertebrae
• 2.5 million/sec.
• Nucleus lost during
development
RBC Production
• RBC production stimulated by Erythropoeitin
(hormone from kidney)
• Negative feedback mechanism
– Low oxygen = release of erythropoeitin
• Exercise, altitude (low partial pressure)
Blood: Physiology
• After hemoglobin releases oxygen, it has a
greater affinity for carbon dioxide
– Carbaminohemoglobin
– Reversible reaction
• Hemoglobin has a greater affinity for carbon
monoxide than oxygen or carbon dioxide
Loss Prevention
•
•
•
•
•
Vasoconstriction
Platelet plug
Clotting (coagulation)
Clotting factors inactive
Become active when:
– Connective tissue becomes exposed
– Chemicals released from injured tissue
• Positive feedback
Clotting
• Prothrombin (globulin protein) converted (by
Ca) into thrombin
• Thrombin converts fibrinogen into fibrin
(sticky, thread like)
• Fibrin forms a ‘mesh’ net
• Platelets and RBC’s clog up = clot
• Fragments of cells with membranes
• Stick to collagen fibers (connective tissue),
and each other to form platelet ‘plug’
Blood Agglutination
An Example of Immune Response,
Codominance, and Multiple Alleles
Blood Agglutination
• Clumping
• Agglutinogens (antigens);
– Glycoproteins on surface of RBC’s
– ‘Flags’
• Agglutinins (antibodies) in plasma
Blood Agglutination
• Antibodies ‘attack’ antigens if they don’t match
• Ex.
– Anti A clumps B antigens
– Anti B clumps A antigens
• A person with “A” blood cannot receive “B”
blood (?)
• A person with “B” blood cannot receive “A”
blood (?)
‘A’ antigens
A
‘B’ Antibodies
‘B’ antigens
B
‘A’ Antibodies
Person with
‘A’ blood:
given ‘B’
blood
transfusion
‘B’ Antibodies
‘B’ antigens
B
B antibodies attach
to B antigens; causes
blood to agglutinate
‘A’ antigens
Person with
‘B’ blood:
given ‘A’
blood
transfusion
‘A’ Antibodies
A
‘A’ antigens are
attacked by ‘A’
antibodies
Person with
AB blood:
A, B antigens
AB
No antibodies
What about “O”???
Person with
O blood:
No antigens
O
A and B antibodies
Blood Typing
• Type “AB” = ‘universal recipient’; has both
antigens so neither antibody is present
• Type “O” = ‘universal donor’; has no antigens so
nobody’s antibodies are ‘awakened’
• Multi-allelic (more than 2 possible alleles can be
inherited; A, B, or O (ABO blood groups)
• Codominant = both A and B are expressed if
present in the genes
Genetic Blood Problems
• Sickle-cell – globin molecule misshapen,
recessive genetic; advantage for carriers (less
malaria)
• Hemophilia – lack of clotting factors; sexlinked recessive
Other Blood Problems
• Anemia = deficiency of erythrocytes or
hemoglobin in the blood
– Lack of energy; tired, listless, pale
– Damage to marrow; inability to produce
RBC’s; drugs
– Pernicious anemia – lack of vitamin B12
(enables mitosis of RBC); lack of
intrinsic factor, absorb B12
• Leukemia – cancer of leukocytes; immature
(unable to function); overproduction of WBC
prevents normal production of RBC’s/platelets;
anemia, bleeding
• Malaria – protozoa carried by mosquito (vector)
• Septicemia – blood poisoning; surgery, decrease
in blood pressure
• AIDS – HIV; T-cell lymphocytes destroyed
• Hepatitis – virus affecting liver; virus carried by
blood after infection
Blood Problems: Infections
• Mononucleosis – lymphocytes are altered
by virus, immune system attacks, swelling
in lymph nodes
White Blood Cells
• Leukocytes = ‘white cell’; no hemoglobin
– Function in the immune system
– Amoeboid movement through tissues
• Spend most time there (fighting)
White Blood Cells
• Arise from stem cells in
bone marrow
• Mature in spleen, thymus,
lymph nodes, tonsils,
adenoids
• Normally 5-10,000 per mm3
5 Types of Leucocytes
• Monocytes – leaves blood
becomes macrophage (eats
microbes, dead cells)
• Neutrophils - most common;
‘pus’, eat antigen/antibody complexes
• Basophils – least common; release histamine
• Eosinophils – reduce inflammation, eat
parasites
• Lymphocytes – produce antibodies
Gas Exchange
Gas Exchange
• Gas exchange = exchange of oxygen and
carbon dioxide between the animal and the
environment
• CO2 + H2O
H2CO3
H++ HCO3-
Gas Exchange
• Environment supplies oxygen and removes
(recycles) carbon
dioxide
• Respiratory medium is
air for terrestrials
• Aquatics is water
Gas Exchange
• General knowledge:
• Air = 21% O2 78% N2
• Water = 6-8 ppm O2; mg/liter;
– Called Dissolved Oxygen
– D.O. dependent upon:
• Temperature of water
• Solute concentrations in the water
• Movement
Slow moving, warm water = low D.O.
Gas Exchange
• Respiratory surface = where gas exchange
takes place with environment
– Must be moist
– Diffusion
• Thin, moist, epithelial
tissue; highly
vascularized
• Single cell layer
separates gases from
blood
Respiratory Organs
• 4 types of respiratory surfaces:
– Skin
– Gills
– Tracheae
– Lungs
Gills
• Evaginations of the
body surface
• Skin is finely branched
to form a feathery
surface with large
surface area
• Often covered
Gills
• Have to be very efficient
– Water has less oxygen than air
• Ventilation = increase flow of the
respiratory medium over the
respiratory surface - brings fresh supply of O2
and removes CO2
• Water is dense; fish have to spend a lot of ATP
to ventilate water
• Surface is always moist
Gills
• Counter current exchange = blood flows in the
OPPOSITE direction than the water passing
over the gills
• More efficient because there is a constant
concentration gradient between blood and water
Tracheae
• Insects
• Air has higher O2 content
– Gases diffuse faster
– Surfaces do not have to be ventilated as
thoroughly
• Dessicated (dry out)
Tracheal System
• Trachea = tiny air tubes that branch over the
entire body
• Spiracles= pores in the exoskeleton of
animals for gas exchange
• Air enters via spiracles and diffuses into the
trachea into smaller branches which extend
to every cell
– Open circulatory system
Tracheal System
• Some ‘breathe’, ventilate (muscle
contractions)
• Others use
diffusion
Tracheal systems; may
have ‘pouches’ near
major organs
Lungs
• Invaginations of body surface
• Thoracic cavity
• Highly subdivided; many branches
– Surface area
• Two layers held together by surface tension of
fluid between layers
– Parietal pleura = thoracic wall
– Visceral pleura = lung surface
• Collapsed lung - broken surface
tension
Lungs
• Air enters nostrils; filtered by hairs, warmed,
humidified
• Pharynx, larynx (voice box with vocal cords)
• Cartilage lined trachea
• Forks into 2 bronchi
Lungs
• Bronchi branch into bronchioles
– Bronchitis
• Bronchioles dead
end into alveoli
• Alveoli (air sacs)
are lined with
epithelium which
is the respiratory
surface
Skin - Cutaneous
• Amphibians, frogs, salamanders
• Small, flat
• Lots of surface area
Lungs
• Oxygen dissolves in the moist film covering the
epithelium
• Diffuses into the capillaries surrounding each
alveolus
• Carbon dioxide goes opposite
Lungs
•
•
•
•
Vertebrates ventilate by BREATHING
Inhalation, exhalation
Positive = frogs
Negative = mammals
Frog Ventilation
•
•
•
•
•
Enlarge mouth by lowering the floor of the mouth
Close mouth and nostrils
Push floor up
Air forced into trachea
Primitive lungs; mostly skin
Fish Ventilation
• Exchange surfaces in their mouth
• Poor oxygen content of water
• Air ‘gulpers’
– Betta, lungfish, electric eel
Negative Ventilation
Ventilating Lungs: Mammals
• P = 1/V; inverse relationship
• Increase volume, decrease pressure
• Increase size of thoracic cavity decreases the
pressure (less than the 760 mm atmospheric
pressure)
Ventilating Lungs: Mammals
• Greater pressure on the outside causes air
to ‘push in’ to the lungs (less pressure)
• Diaphragm moves down, ribs expand
outward (increased volume)
Mammal Breathing
• Parietal pleura attached to the ribs
• Visceral pleura attached to the parietal
pleura (surface tension from the fluid
between)
• As ribs expand, the lungs expand
• Collapsed lung
Mammal Breathing
• Tidal volume = amount of air an organism
inhales and exhales w/ each breath; 500 ml
in humans
• Residual volume = amount of air left in the
lungs after exhalation
• Vital capacity = maximum volume when
forced (running); 4-5000 ml in college
males
Breathing: Birds
•
•
•
•
Lungs; P. 892
8-9 air sacs in abdomen, neck, wings
Reduces density (lighter)
Heat sink for heat produced by flying
(radiator)
Birds
• Parabronchi = small channels in the lungs
where gas exchange takes place
– More efficient; air moves in only one
direction; no dead ends
– Air is constantly pumped through
– Maximizes complete air exchange (no
residual volume)
– Very efficient; altitude
Control Centers in the Brain
Regulate Rate and Depth of
Breathing
Breathing Controls
• Automatic
• Breathing center of the medulla sends
impulses to the muscles (diaphragm, rib);
10-14 x min.
• Negative feedback system
Negative Feedback
• Stretch the lungs; pressure sensors send
messages back to medulla inhibiting
inspiration
Breathing
Controls:
Breathing Controls
• Breathing center monitors blood pH; if CO2
levels increase, pH drops (acidic, acidosis)
• CO2 + H2O  H2CO3
• Stimulates increase in tempo
Gas Exchange
• Gas enters or leaves depends upon:
Partial Pressure
• O2 = 21 % of atmosphere
• CO2 = 0.03 %
• Partial pressure = proportion of
pressure contributed by a gas in a mixture
of gases
• Air = gas mixture
Partial Pressure
• O2 = 21 % of 760 mm (atmospheric
pressure)
• Po2 = (760 x 21%) = 160 mm
• Pco2 = (760 mm x 0.03%) = 0.23mm
• Gases diffuse from ______to_____
Partial Pressure: p. 894
• In the alveoli, the PO2 is high and PCO2
is low
• In systemic cells, PO2 is low and PCO2 is
high
• O2 diffuses into systemic from the blood;
CO2 is opposite
pO = 104 mm
p CO2 = 40 mm
pO =40mm; CO2=45mm
pO=20;
pCO2=45
pO=95;
p CO2 = 40
Respiratory Pigments
• Oxygen is carried by pigments because
O2 does not diffuse easily into water
• Arthropods (insects, crabs) have
Hemocyanin;
• Copper not iron
Respiratory Pigments
• Dissolved in plasma
• Open circulatory
• Hemoglobin; vertebrates
Dissociation; p. 895
• Release of oxygen by hemoglobin is
dependent upon:
– Partial pressure
– pH
Dissociation
• At rest, PO2 in tissues is low;
• Hemoglobin releases only a portion of its O2
(28%)
• If the partial pressure goes down (exercising)
then hemoglobin releases more O2
Dissociation
curve
Bohr Shift
• pH causes a change in hemoglobin affinity for
oxygen
• During exercise, increased CO2 is dissolved in
the plasma
• CO2 becomes carbonic acid (decreases pH)
Bohr Shift
• Conformation of hemoglobin is sensitive to
pH change; loses affinity for O2
• BOHR SHIFT
• Active muscle causes Bohr Shift, hemoglobin
releases more O2
CO2
• Carbon dioxide carried by blood in 3 forms:
– Bicarbonate ions in blood (70%)
– Bound to amino groups (23%)
– Dissolved in plasma (7%)
CO2
• CO2 diffuses into erythrocytes
• Carbonic anhydrase converts CO2 into
bicarbonate
• CO2 + H2O H2CO3
H+ + HCO3-
Blood Chemistry
• CO2 + H2O H2CO3
H+ + HCO3(bicarbonate)
• Carbonic acid lowers pH; H+ is tied up by
hemoglobin molecule to prevent drastic
lowering of pH
Special Adaptations
• Seals, whales make lonnnggg underwater
dives; deep
• Myoglobin = oxygen storing pigment in
muscles
• More O2 in blood
• Twice the blood per kg as humans
Special Adaptations
• Very large spleen
– Contracts - releasing additional blood
• Diving reflex slows heart rate
– Oxygen consumption slows
• Blood routed to brain, eyes, glands, placenta
• Muscles shift to fermentation