Transcript Unit 12 Animal Anatomy and Physiology Part 1

UNIT 12
ANIMAL ANATOMY AND
PHYSIOLOGY
Introduction, Digestive, Circulatory,
and Respiratory Systems
(Chapters 40, 41, and 42)
Epithelial
Tissue
Stratified
= multiple layers
Tightly
packed
Simple
= single layer
Connective Tissue
Sparse in
extracellular matrix
Osteoblasts
Ca, Mg, P
Collagen Fibers=
Nonelastic/tensil strength
Elastic Fibers =
Elastin
Holds organs
In place
Tendons = Muscle  Bone
Ligaments = Bone  Bone
Reticular Fiber =
Joins to Tissues
Nervous Tissue
Muscle Tissue
Long “Contracting” Cells/ Fibers
Heart Contraction
Voluntary Movements
Involuntary Activities
Walls of Digestive Tract, Bladder, Arteries, etc.
Interstitial
Fluid
Biofeedback Circuits
Negative Feedback =
The change in the variable being monitored triggers the
control mechanism to counteract further change in the same direction
1. Receptor (detects change)
2. Control Center
(processes information)
3. Effector
(response)
Positive Feedback =
A change in a variable that triggers
mechanisms that amplify the change
Child Birth
Contractions
Pressure of baby’s head on Uterus Contractions 
+ Pressure  More Contractions
Bioenergetics of an Animal
Metabolic Rate = the sum of all the energy-requiring
biochemical reactions occurring over a given time interval
“The amount of energy an animal uses per unit time”
Energy measured in:
calories (c)
kilocalories (kcal or C)
Inverse relationship with size:
Smaller = Higher Metabolic Rate
Higher breathing rate and heart rate
Eat more food per unit body mass
Surface Area to Volume = Maintaining Temp
Maximum Metabolic Rates
Total Annual Energy Expenditures
Energy Expenditures per Unit Mass
Basal Metabolic Rate (BMR) = Endotherm at Rest, Fasting, No Stress
Standard Metabolic Rate (SMR) = Ectotherm at Rest, Fasting, No Stress
Male Human BMR = 1,600-1,800 kcal/day
Female Human BMR = 1,300-1,500 kcal/day
CHAPTER 41: ANIMAL NUTRITION
Homeostatic Regulation
“Essential Nutrients”
Essential Amino Acids
Pancreas secretes Insulin
Blood Glucose is High
Insulin enhances the transport of glucose
into body cells and stimulates the liver and
muscle cells to store glucose as glycogen
= blood glucose level drops
Glucagon promotes the
breakdown of glycogen
and the release of glucose
Blood Glucose is Low
into the blood
= blood glucose level rises
Pancreas secretes Glucagon
Essential Fatty Acids
(Synthesize Most that are Needed)
Glucose energy surplus stored as Glycogen in Liver and Muscle Cells
Liver glycogen expended first, then fat glycogen, then muscle glycogen
Vitamins =
organic molecules
needed in small quantities
Minerals =
simple inorganic
molecules needed
in small quantities
Feces
Caterpillar
Heterotrophic
-Herbivores
-Carnivores
-Omnivores
Ingestion Adaptations
4 Stages of Food Processing
-Suspension Feeders
-Substrate Feeders
-Fluid Feeders
-Bulk Feeders
-Ingestion
-Digestion
Enzymatic Hydrolysis
-Absorption
-Elimination
Specialized Compartments
for Digestion
“Intracellular”
(Don’t Digest Yourself)
Sponges and
Heterotrophic Protist
= Food Vacuole
“Extracellular”
Hydra (Cnidarian)
Gastrovascular Cavity
Complete Digestive Tract
“Alimentary Canal”
Specialized Compartments
Directional Flow
The Mammalian Digestive System
Physical and Chemical Digestion
Salivary Amylase =
Hydrolyzes Starch
and Glycogen
Swallow Reflex
Dentition
Voluntary
Bolus
Saliva =
+ 1 Liter/day of Saliva
Mucin – Glycoprotein protects cells and lubricates
Buffers – Neutralize food for tooth decay
Antibacterial Agents
Salivary Amylase
Windpipe moves upward
Glottis and Epiglottis
“Went down wrong pipe”
Peristalsis
Involuntary
Stomach
Upper Abdominal Cavity
Elastic/Accordianlike Folds
Store 2 Liters of food
Chemical Digestion:
Gastric Juice
-Secreted from the Epithelium Lining
-HCl (pH 2)
Secreted by the Parietal cells
Disrupt Extracellular Matrix that binds cells together
Kills most bacteria from food
Denatures (unfolds) proteins
-Pepsin – begins hydrolysis of proteins (peptide bonds)
Pepsinogen- Inactive form secreted from Chief cells
Activated by the HCl in the lumen of the stomach (+ feedback)
Mechanical Digestion:
-“Churning” from smooth muscle tissue
-Hunger Pangs when stomach is empty
-Acid Chyme – contents of the food in the stomach
Mucus:
-Secreted by the Epithelium cells
-Protect stomach lining
-Mitosis replaces stomach lining every 3 days
Cardiac Sphincter – “Heartburn”
Pyloric Sphincter – 2-6 hours for stomach to empty
Small Intestine
~6 meters in human
Most of the enzymatic hydrolysis
Most of the nutrient absorption
Duodenum
-First 25 cm
-Chyme mixes with digestive juices
from the pancreas, liver, gallbladder
and gland cells from the intestinal wall
Bile Salts
-Digestion of Fats
-Pigments “Brown”
Maltase
Sucrase
Lactase
Emulsification – keep fats from coalescing
Pancreatic Enzymes
-Inactive Form
-Enteropeptidase Activates Trypsin
-Trypsin Activates the others
Hydrolytic Enzymes
Alkaline Solution (Bicarbonate)
Buffer acidity of Chyme
Rest of the Small Intestine
-Jejunum
-ileum
Most of the Nutrient Absorption
-A few nutrients in stomach and large intestine
Animals expend 3-30% of the chemical energy contained in
food during digestion and absorption
Large Surface Area
~300m2 (size of a tennis court)
-Villi = fingerlike projections in lining
-Microvilli = microscopic extensions of the villi
Absorption across epithelial cells  blood vessels
Blood Vessels (Capillaries)
Lacteal – small vessel of the lymphatic system
Passive Diffusion – some simple sugars like fructose
Active Transport – amino acids, small peptides, vitamins, glucose
The Large Intestine: “Colon”
-1.5 meters long
-U-shaped
-Water Absoption (90% efficient)
Cecum
- Appendix (Lymphoid Tissue)
Feces
-Peristalsis
-12-24 hours for feces to travel its length
-Diarrhea = Irritation of the lining and less water absobed
-Constipation = Feces moved too slowly (+ water absorption)
-Fiber = helps move along
Rectum
-Stores Feces
-Sphincters: Involuntary and Voluntary
- “Bowel Movement”
Microorganisms
-E.coli as an example
-Gases: Methane and Hydrogen Sulfide
-Produce Vitamins: Biotin, Folic Acid, K, B
-Indicators of contaminated water supply
Hormones Regulate Digestion
Gastrin
-Stimulated by food
-Secretion of Gastric Juice
Enterogastrones
-Secretin
From Duodenum lining
Secretion of Bicarbonate (Pancreas)
-Cholecystokinin (CCK)
Gall Bladder to release bile into Duodenum
Length of Intestines
Structural Adaptations
Dentition
Fermentation
chamber
Microorganisms (Ruminant)
Water Removal
Bacteria and Protists
cud
Chapter 42: Circulation and Gas Exchange
Gastrovascular Cavities for Transport
Thin Tissue
Diffusion
Circulatory System
Open Circulatory System
Closed Circulatory System
Common Features:
1. Circulatory Fluid
2. A Set of Tubes
3. A Muscular Pump
4. Fluid Pressure
Hemolymph – blood and
interstitial fluid mix
Blood – not mixed with interstitial fluid
Sinuses – spaces
surrounding the organs
Vessels branch into smaller vessels
Insects, other Arthropods,
and most Mollusk
Earthworms, Squid,
Octopus, Vertebrates
Cardiovascular System (Vertebrates)
High Metabolic Rate = More Complex Circulatory System
and More Powerful Hearts
Heart Chambers:
-Atria = Receiving Chambers
-Ventricles = Pumping Chambers
Vessels:
-Arteries = Carry Oxygenated Blood
-Veins = Carry Deoxygenated Blood
-Capillaries = Infiltrate Tissue/Diffusion
Two Chambered Heart:
Three Chambered Heart:
-Gill Circulation = Blood/Respiratory
-Systemic Circulation = Blood/Body
-Two capillary beds lowers pressure
-Pulmocutaneous Circuit= lungs/skin
-Systemic Circuit= body
-Double Circulation= pumped twice/
Maintains pressure
-Ventricle= some mixing of blood but
a ridge diverts most of the blood
into the correct circuit
Pathway of Blood:
Heart  Arteries  Arterioles  Capillaries  Tissue
Tissue  Capillaries  Venules  Veins  Heart
Four Chambered Heart:
-No Mixing of Blood
-Pulmonary Circuit = lugs
-Systemic Circuit = body
-Double Circulation
-Allowed Endothermic (use
10% more energy)
Mammalian Double Circulation
Systemic Circuit
(Body)
Arteries = Oxygen Rich
Veins = Oxygen Poor
Pulmonary Circuit
(Lungs)
Mammalian Heart
-Below sternum
-Size of a fist
-Mostly cardiac tissue
Systemic Circuit
(Body)
-Chambers
-Vessels
-Valves
Atria:
-Thin walls
-Collection chambers for
returning blood
-Pump only to the ventricles
Ventricles:
-Thick walls
-Pumping chambers
-Right Ventricle  Lungs
-Left Ventricle  Body
(AV)
The Cardiac Cycle
-One complete sequence of pumping and filling (rhythmic)
-Contracts = Pumps
-Relaxes = Chambers fill
Systole = Contraction phase
Diastole = Relaxation phase
Cardiac Output = volume of blood per minute from the left ventricle
Dependent upon:
Heart Rate (number of beats per minute)
Stroke Volume (amount of blood pumped by left ventricle)
Avg ~75mL
If stroke volume is 75mL and heart rate 70bpm then
Cardiac Output = 5.25 L/min
Equivalent to the total volume of blood in the body
Increases during exercise
Valves (4):
-Connective tissue
-Prevent backflow
-Atrioventricular (AV) valves – between atria and ventricle
Close during ventricular contraction
-Semilunar valves – anterior ends of the ventricles
Open during ventricular contraction
Close following contraction
Pulse = rhythmic stretching of arteries caused by the pressure of blood driven by ventricle contraction
Measure heart rate by measuring your pulse
Heart Sounds:
-Closing of the valves
-“Lub-dup”
-Lub –created by the recoil of blood against the closed AV valves
-Dup –recoil of blood against the semilunar valves
Heart Murmur:
-Defect of one of the valves
-Hissing sound when a stream of blood squirts backwards through a valve
-Born with or damaged by infection (rheumatic fever)
-Usually do not reduce the efficiency of blood enough to warrant surgery
Maintaining the Rhythmic Beat of the Heart
-Brain cells within a few minutes without oxygen
-Maintaining the beat is critical for survival
Sinoatrial (SA) Node:
-Self excitable (contract w/o nervous system)
-”Pacemaker”
-Sets the rate and timing in which all cardiac muscles contract
-Anterior wall of right atrium
-Produces electrical impulses
-Contract atria in unison (both at the same time)
Atrioventricular (AV) Node:
-Between wall of right atrium and right ventricle
-Impulses delayed ~0.1 second (ensures atria are completely empty)
-Impulse relayed to ventricles in unison via the bundle branches
Bundle Branches and Purkinje Fibers (muscle fibers):
Atria Systole
Ventricle Systole
-Conduct the signal from the AV node to the apex of the heart
-Ventricles contract from the apex toward the atria
re-priming of ventricles
Electrocardiogram (ECC or EKG):
-Use electrodes to record the heart cycle
-Measures heart impulses that are conducted through body fluids to the skin
Physiological Cues Influence SA node:
-2 sets of nerves (1 speeds up the pacemaker and 1 slows it down)
-Hormones: Epinephrine “fight or flight” from adrenal gland speeds it up
-Body Temperature: increase in 1oC raises heart rate by ~10 beats/min (fever=+rate)
-Exercise
Vessel Structure
Similarities between Arteries and Veins:
-Connective tissue with elastic fibers (exterior)
-Smooth muscle tissue with elastic fibers
-Endothelium – single layer of flattened cells; minimizes flow resistance
Differences between Arteries and Veins:
-Arteries
Thicker middle and outer layers = higher velocity and pressure
Highly elastic
Blood moves due to pressure
-Veins
Thinner walls = lower velocity and pressure
Blood moves due to skeletal muscles pinching the veins and
smooth muscle tissue contractions (peristalsis)
Valves that allow unidirectional flow to heart
Vein
Artery
Capillaries:
-Lack the outer two layers
-Very thin walls with basement membrane
-Facilitates the exchange of substances between the blood and interstitial fluid
Blood Flow Velocity
Vessel Area increases due to the increase in the
total number of vessels = Total Area
Velocity decreases as the vessel area increases
Blood travels over a thousand times faster in the
aorta (~30 cm/sec) than in capillaries (~0.026 cm/sec)
Blood Pressure
= the hydrostatic force that blood exerts against the wall
of a vessel and that propels blood
Fluids exert a force called hydrostatic pressure against surfaces they contact
Fluids flow from areas of high pressure to low pressure
Peaks in blood pressure corresponding to ventricular systole
alternate with lower blood pressures corresponding to diastole
Resistance to flow through the arterioles and capillaries, due
to contact of the blood with a greater surface area of endothelium,
reduces blood pressure and eliminates pressure peaks
Healthy 20 year old = 120 mm Hg/ 70 mm Hg
Sphygmomanometer cuff inflated to
+120 mm Hg (pressure of cuff exceeds pressure of artery)
Cuff is further loosened until the blood flows
freely (no sound) = Diastolic Pressure
-Stethoscope s used to listen for sounds of blood flow
-Cuff is gradually deflated until blood pressure exceeds cuff pressure
(hear blood pulsing) = Systolic Pressure
Capillary Exchange
Lymphatic System
-So much blood passes through the capillaries that the cumulative
loss of fluid adds up to about 4 L per day
-There is also some leakage of blood proteins
Lymphatic System:
-Returns blood fluids and blood proteins back to the blood
-Fluid enters by diffusing into tiny lymph capillaries intermingled among capillaries of the cardiovascular system
-Lymph – the fluid in the lymph capillaries
-Drains into the circulatory system near the junction of the venae cavae with the right atrium
-Lymph vessels have veins to prevent backflow
-Depend on skeletal/smooth muscle contractions for movement
-Lymph nodes = connective tissue filled with white blood cells specialized for defense (filter pathogens)
Blood
-Connective Tissue
-Specialized cells suspended in a liquid matrix (plasma)
Ions:
-Inorganic salts in the form of ions
-“blood electrolytes”
-Maintain osmotic balance
-Help buffer = pH 7.4
-Muscle and nerves depend upon
-Kidney helps maintain electrolytes
Erythrocyte (Red Blood Cells):
-Most numerous – 25 trillion in body’s 5L of blood
-Structure = Function
Small 7-8.5 micrometers in diameter
Biconcave disks –thinner in the center
Greater surface area for carrying/diffusing oxygen
Mammalian cells lack nuclei = more space for hemoglobin
Lack mitochondria = use anaerobic metabolism (+ efficiency)
Hemoglobin – the iron containing protein for oxygen transport
~250 million molecules per cell
Each hemoglobin can bind 4 oxygen molecules
One erythrocyte can transport ~1 billion oxygen molecules
90%
Plasma Proteins:
-Buffers against pH changes
-Maintain osmotic balance
-Contribute to viscosity (thickness)
-Some are escorts for lipids
-Immunoglobulins = fight pathogens
-Fibrinogens = clotting factors
Leukocytes (White Blood Cells):
-5 types (see diagram)
-Collective function = fight infections
-Monocytes and Neutrophils are phagocytes (engulf and digest bacteria and debris)
-Spend most of their time outside of circulatory system patrolling in the interstitial fluid
-Numbers increase temporarily when body is fighting an infection
Platelets:
-Fragments of cells about 2-3 microns in diameter
-No nuclei
-Originate as pinched-off cytoplasmic fragments of large cell in the bone marrow
-Function in blood clotting
Replacement of Cellular Elements in Blood
-Cellular elements of blood wear out and are replaced constantly
-Erythrocytes usually circulate for only ~3-4 months and then are destroyed by phagocytic cells in the liver and spleen
Components are recycled into new erythrocyte cells through biosynthetic processes
-These cellular elements develop from pluripotent stem cells in the red marrow of bones, particularly the ribs, vertebrae, breastbone, and pelvis
-Pluripotent = have the ability to differentiate into any type of blood cell or into cells that produce platelets
Leukemia:
-A cancerous line of the stem cells that produce leukocytes
-The cancerous stem cells crowd out cells that make red blood cells and produce an unusually
high number of leukocytes, many of which are abnormal
-Treatment is to remove pluripotent stem cells from a patient, destroy the bone marrow, and
restock it with noncancerous pluripotent cells
-As few as 30 of these cells can repopulate the bone marrow
Blood Clotting
-Fibrinogen = sealant (inactive form)
-Fibrin (active form) aggregates into threads  Clot
-Clotting factors, derived from platelets, begin the process
-Clotting factors activate fibrin from fibrinogen
Thrombus:
-Spontaneous clot that develops when platelets clump and fibrin
coagulates within a vessel
-Normally, anticlotting factors in blood prevent spontaneous clotting
-Potentially dangerous (cardiovascular disease)
-”Throw a clot”  Stroke if brain oriented or Heart Attack if heart oriented
Hemophilia:
-Inherited defect in any step of the clotting process
-Treated by injections correcting the defected step
Cardiovascular Disease
-Diseases of the heart and blood vessels
-Cause more than half the deaths in the US
Heart Attack:
= the death of cardiac muscle tissue resulting from prolonged
blockage of one or More coronary arteries (the vessels supplying
the heart muscle with oxygen/nutrients)
Stroke:
= the death of nervous tissue in the brain, usually resulting from
rupture or blockage of arteries in the head
Both frequently result from a thrombus that dislodges and clogs
an artery
Normal Artery
Artery partially closed by plaque
Atherosclerosis:
= build up of plaque on the inner walls of the arteries, narrowing their bore
-Can be caused by cholesterol
-Encourage the development of thrombus formation
Arteriosclerosis:
= the plaque becomes hardened by calcium deposits (“hardening of the arteries”)
Hypertension (high blood pressure):
-Encouraged by atherosclerosis (narrowing vessels and reducing elasticity)
-Can be controlled by diet, exercise, medication, or a combination of these
-Diastolic pressure greater than 90 = concern
-200/120 = courting disaster
-These conditions can be inherited
-Nongenetic factors such as smoking, lack of exercise,
diet rich in animal fat, high cholesterol
Cholesterol:
-Low-density lipoproteins (LDL’s) = “bad” cholesterol
-High-density lipoproteins (HDL’s) = “good” cholesterol by
reducing deposition
-Exercise increases HDL’s
-Smoking increases LDL’s
Gas Exchange in Animals: The Respiratory System
Role of Gas Exchange in Bioenergetics
Diversity of Gill Structures
Gills = outfoldngs of the body surface that are suspended in the water
Total surface area often exceeds that of the rest of the body
Distributed over most of the body
-O2 in and CO2 out
-Respiratory medium: atmosphere (terrestrial) and water (aquatic)
Dissolved oxygen in water is always less than atmospheric oxygen
-Respiratory surface = where gases are exchanged with environment
Tend to be thin and have large surface areas
Moist for diffusion
Endotherms have a larger respiratory surface area than similar sized ectotherms
Simple animals (sponges, cnidarians, flatworms) every cell is close enough to
the external environment for diffusion = usually small, thin, flat, large surface area
In more complex animals, the bulk of the body doesn’t have direct external access
= respiratory organs
Flip-like covering one segment
Restricted to a local body region
Structure and Function of the Gill
-
Oxygen concentration is very low in water
Gills must be very effective
Ventilation:
-Increases the flow of medium over the gill
-Crayfish/Lobsters have paddlelike appendages that drive the current
-Fish Mouth Pharynx  Gill  Exits = pulled by operculum
Countercurrent Exchange:
-Blood flows in opposite direction to the movement of water past the gill
-Allows efficient transfer of oxygen to blood
-As blood moves through a gill capillary, it becomes more and more loaded with oxygen,
but it simultaneously encounters water with ever higher oxygen concentrations
-Diffusion gradient favors the transfer of oxygen from the water to blood
-Efficiency = 80% of dissolved oxygen is removed
Terrestrial Adaptations
Gills are unsuitable for terrestrial life:
-Too much evaporation from moistened surface
-Gills would collapse and cling together
-Terrestrial animals have respiratory surfaces within the body
with tubes opening to the atmosphere
Atmospheric Air
Advantages:
-Higher concentration = ~210 mL/L compared to ~6 mL/L in water
-Oxygen and carbon dioxide diffuse much faster = less ventilation required
-Less energy needed to ventilate due to air being lighter and easier to pump
Disadvantages:
-Desiccation of the large and moist respiratory structures – moved internally
Tracheal System (Insects)
-Made up of air tubes (tracheae), opened to the outside, that branch throughout the body
-Gas exchange is through diffusion
-Virtually every cell is within a short distance of the respiratory medium
-The open circulatory system is not involved in transporting gases
Lungs
-Lungs are restricted to one location
-Circulatory system is needed to transport gases
-Size and complexity is correlated with the animal’s metabolic rate
-Amphibians have relatively small lungs
-Rely on diffusion through skin to supplement
Insect Flight:
-Demands of gas exchange are heightened (10-200 times)
-Alternating contractions/relaxation of flight muscles pump air through tracheae (ventilation)
-Flight muscles are packed with mitochondria (bioenergetics)
-Reptiles, Birds, and Mammals rely entirely on lungs
Mammalian Respiratory Systems
Lungs:
-Located in the Thoracic (chest) cavity
-Spongy texture
-Honeycombed with a moist epithelium (respiratory surface)
Air Passage:
Nostrils  Nasal Cavity  Pharynx  Larynx  Trachea  Bronchi 
Bronchioles  Alveoli  Exchange
Reversed for carbon dioxide
Nostrils/ Nasal Cavity– filtered by hairs, warmed, humidified, and sampled for odors
Larynx:
-Cartilage
-Voicebox with vocal cords
-High pitch = cords are stretched tight and vibrate rapidly
-Low pitch = less tightly and vibrate slowly
Trachea:
-Cartilage
-”Windpipe”
Epithelium Lining:
-Covered by cilia and a thin film of mucus
-Mucus traps contaminants (dust, pollen, etc)
-Cilia beat and move the mucus upward to the pharynx
where it is swallowed
Alveoli (SEM)
Alveoli (Alveolus = singular):
-Site of gas exchange
-Millions in humans
-Total surface area of 100 m2
-Oxygen dissolves and rapidly diffuses into capillaries
-Carbon dioxide is reversed
Negative Pressure Breathing
Breathing = the alternate inhalation and exhalation of air that ventilates the lungs
Negative Pressure Breathing :
-Works like a suction pump, pulling air instead of pushing it into the lungs
Tidal Volume:
-The volume of air an animal inhales
and exhales with each breath
-Average ~500 mL at rest in humans
Vital Capacity:
-The maximum tidal volume during
forced breathing
-Approx 3.4 L and 4.8 L for college age male
and females respectively
Residual Volume:
-The air remaining in the lungs after we
forcefully exhale as much as we can
-Due to the lungs ability to hold more air
than the vital capacity
-Mixing of oxygen-rich and oxygen depleted
air = decrease efficiency
Inhalation:
Exhalation:
-Lung volume increases as a result of contraction of the rib cage muscles
and the diaphragm
-Contraction of the rib muscles expands the rib cage by pulling the ribs
upward and the breastbone outward
-At the same time, the chest cavity expands as the diaphragm contracts
and descends like a piston
-All these changes increase the lung volume, and as a result, air pressure
within the alveoli becomes lower than atmospheric pressure
-Because air flows from a region of higher pressure to lower pressure,
air rushes through the respiratory tract to the alveoli
-Rib muscles and diaphragm relax
-Lung volume is reduced
-The increase of air pressure within the alveoli forces air up the tract
Vigorous Exercise:
-Other muscles of the neck, back, and chest further increase ventilation volume
-Raise the rib cage even more
Ventilation in Birds
-Much more complex than in mammals
-Birds have eight or nine air sacs that penetrate the abdomen, neck, and even the wings
-These air sacs act as bellows that keep air flowing through the lungs
-Air flows through the interconnected system in a circuit that passes through the lungs in one direction only, regardless of inhalation or exhalation
-Parabronchi = tiny channels through which air flows in one direction (not dead ends like alveoli)
-This system completely exchanges the air in the lungs with every breath (maximizing lung oxygen concentrations)
-Allows them to perform better at high altitudes (+9,000 meters during migration)
Breathing Control
-We can hold our breath for a short period of time
-We can consciously breath faster and deeper
-Most of the time automatic mechanism regulate our breathing
-This ensures coordination with the cardiovascular system
Breathing Control Centers
Medulla Oblongata:
-Sets the rhythm
-Inhibited during conscious breathing
-Monitors CO2 levels
Monitors cerebrospinal fluid
pH drops due to carbonic acid
Increases depth and rate of breathing
Aorta and Carotid Arteries:
-Monitor CO2 levels and relay to Medulla
-Monitor O2 levels and relay to Medulla
(high altitudes)
Coordination with circulatory system
-During exercise, increase cardiac output is
matched to the increased breathing rate,
which enhances O2 uptake and CO2 removal
as blood flows through the lungs
Oxygen Transport:
-Hemoglobin (quaternary protein)
-4 subunits each with a “heme” group
-Each heme group has an iron molecule at its center
-The iron binds oxygen
-Each hemoglobin can carry 4 oxygen molecules
-Hemoglobin binds oxygen reversibly (load and unload)
-The binding of oxygen to one subunit induces shape
change in other subunits
-This change increases oxygen affinity
-This process is reversed at the tissue due to the low
concentration of oxygen in the tissue (gradient) and the pH of
carbonic acid causing a confirmation change in the subunits
Carbon Dioxide Transport:
-7% of CO2 released by respiring cells travels in plasma
-23% binds to the amino groups of hemoglobin
-70% is transported in the blood in the form of bicarbonate ions
-CO2 diffuses into plasma and then into rbc’s
-Inside the rbc’s it is converted into bicarbonate
-Carbon dioxide first reacts with water (assisted by carbonic anhydrase) to form carbonic acid
-The carbonic acid then dissociates into a hydrogen ion and a bicarbonate ion
-Most of the hydrogen ions attach to hemoglobin and therefore do not change the pH
-The bicarbonate ions diffuse into the plasma
-The process is reversed at the other end
Adaptations to Deep-Diving
-Humans can hold breath 2-3 minutes and swim to depths of 20 m or so
-Weddell seal can swim to 200-300 m and hold breath for ~20 minutes
(sometimes for more than an hour)
-Penguins can do about the same
-Elephant seals can reach depths of 1,500 m (almost a mile) and stay
submerged for as much as 2 hours
-Some whales can make even more impressive dives
Store large amounts of oxygen (twice as much as humans)
-Store it in blood and muscles
-About 36% of our total oxygen is in our lungs and 51% is in our blood
-Weddell seal holds only about 5% in lungs while stockpiling 70% in blood
-It has twice the volume of blood per kg of body mass as a human
Weddell seal has a huge spleen
-The spleen can store about 24 L of blood.
High concentration of myoglobin (an oxygen-storing protein) in their muscles
-Store about 25% of its oxygen in muscle, compared to only 13% in humans
Conserve oxygen
-Swim with little muscular effort
-Use buoyancy changes to glide passively upward or downward
-Heart rate and oxygen consumption rate decrease during a dive
-Blood is routed to the brain, spinal cord, eyes, and adrenal glands
-Blood supply is altogether shut off to muscles during the longest dives
-Derive their ATP from fermentation after deplete oxygen stored in myoglobin