Calendar
Contact Teacher
Labs:
nothing
nothing
nothing
Links
Notes:
Animal Body
Arthropods
Biochem
Cell Cycle
Cell Interactions
Cell Structure
Circulation
Respiration
Communities
Digestion
DNA
Ecosystems
Energy
Evolution Evidence
Future of
Biosphere
Genetic Engineering
Gene Function
Genetics
Hormones
Human Evolution
Immunity
Species
Interaction
Kidneys
Locomotion
Membranes
Mollusks
Mutation
Nervous
Non-Coelmic
Photosynthesis
Plant Physiology
Population Genetics
Population
Dynamics
Cellular Respiration
Sensory
Speciation
Taxonomy
Vertebrates
Vertebrate
Org
Vocabulary:
1,2,3,4,5,6,7,8,9,10,
11,12,13,14,15,
16,17,18,19,20,
21,22,23,24,25,
26,27,28,29,30,
31,32,33,34,35,
36,37,38,39,40,
41,42,43,44,45,
46,47,48,49,50,
51,52,53,54
Circulation & Respiration
I. Introduction
A. Heterotrophs Obtain Energy by Oxidizing Carbon Compounds
1. Called aerobic cell respiration
2. Remove electrons from organic compounds
a) Channel electrons
along series of proton pumps in mitochondria
b) Generates ATP
Electrons (accompanied by proton s)
donated to oxygen gas to form water
c) Carbon atoms
cleaved, released as carbon dioxide
B. Process Consumes Oxygen and Generate Carbon Dioxide
and Water
1. Called metabolic water to emphasize
its source
a) Provides sole
source of water for some desert vertebrates
b) Diluted into
body internal water in other organisms
2. Carbon dioxide can lower pH of
body fluid and must be eliminated
3. External respiration: uptake of
oxygen and release of carbon dioxide
II. The Composition Of Air
A. Composition and Properties of Air
1. All oxygen in the air is a result
of photosynthesis
2. Dry air = 78.09% N2 + 20.95% O2
+ 0.93% (argon + inert gase s)
+ 0.03 CO2
3. Amount of air present decreases
at high altitudes
4. At sea level, air pressure measures
760 mm of mercury
a) Equals the barometric
pressure of air
b) Equivalent to
one atmosphere of pressure
5. Each gas within the air exerts
a partial pressure = 760 x % gas
a) Nitrogen + inert
gases = 760 x 79.02% = 600.6 mm Hg
b) Oxygen = 760
x 20.95% = 159.2 mm Hg
c) Carbon dioxide
= 760 x 0.03% = 0.2 mm Hg
6. Less air, therefore less oxygen
present at high altitudes
a) Barometric pressure
above 6000 meters = 380 mm Hg
b) Partial pressure
of oxygen (PO2)= 380 x 20.95% = 80 mm Hg
c) Only half the
oxygen is available compared to sea level
B. The Diffusion of Gases Across Cell Membranes
1. Cell membranes of terrestrial organisms
freely permeable to oxygen
2. Cell membranes cannot exist without
a surrounding layer of water
3. Oxygen concentration in cytoplasm
lower than liquid surrounding cells
4. Net diffusion of oxygen from environment
into cells
5. Net diffusion of carbon dioxide
in opposite direction
6. Gases redistributed by circulatory
system
C. Fick's Law of Diffusion
1. Diffusion of oxygen into the epithelial
aqueous layer is passive
2. Driven by the difference in oxygen
concentration between the interior of the organism and the external environment
3. Mathematical relationship called
Fick`s Law of Diffusion
a) R = D x A x Δp
/ d
b) R = rate of diffusion
c) D = diffusion
constant
d) A = area over
which diffusion takes place
e) Δp = difference
in partial pressures on each side
f) d = distance
across which diffusion takes place
4. Evolutionary changes optimize R
by favoring certain parameters
a) Increase surface
area
b) Decrease distance
d
c) Increase concentration
difference Δp
III. The Evolution Of External Respiration
A. Simple Diffusion
1. Oxygen diffuses too slowly to be
efficient over more than 0.5 mm
a) Severely limits
size of organisms
b) Protists are
small enough to utilize simple diffusion
2. As size increases, surface area-to
volume ratio decreases
a) Surface area
proportional to radius squared (r2)
b) Volume proportional
to radius cubed (r 3)
c) Surface area-to-volume
ratio proportional to r2/r3 or 1/r
d) As the radius
increases the ratio decreases
3. Metabolism may be slowed down to
compensate
4. Increase in size must be accompanied
by facilitation of diffusion of oxygen into organism
B. Creating a Water Current
1. Most primitive phyla possess no
special respiratory organs
2. Can obtain oxygen via diffusion
by increasing Δp in Fick`s equation
a) Increase difference
in O2 concentration by creating a water current
b) Constantly replace
water over diffusion surface Δp does not decrease as diffusion proceeds
c) Keep exterior
O2 concentration high
d) Results in higher
realized value of R, rate of diffusion
C. Increasing the Diffusion Surface Area
1. More advanced invertebrates and
vertebrates possess respiratory organs
a) Increase surface
area over which diffusion occurs
b) Provides contact
between external environment and internal circulating fluids
c) Increase A and
decreasing d
2. Aquatic organs (gill s)
project from body into water
a) Simple gills
like papulae of echinoderms
b) Convoluted gills
of fish
3. Increase in diffusion surface area
enables aquatic organisms to extract more oxygen
D. Enclosing the Gills
1. Disadvantage of external gills
a) Difficult to
constantly circulate water past diffusion surface
b) Neotenic amphibian
larvae physically move gill through water
c) Inefficient,
highly branched gills offer resistance against movement
2. Special branchial chambers in other
organisms pump water past gills
a) Internal mantle
cavity of mollusks opens to outside, contains gills
b) Contraction of
muscular walls draws water in and expels it
c) Crustacean cavity
lies between body and hard exoskeleton
d) Movement of limbs
draws water through branchial chamber
IV. The Fish Gill As An Aquatic Respiratory Machine
A. Most Successful Branchial Chamber Evolved in Bony
Fishes
1. Water passes through mouth into
two opercular cavities
a) Gills are located
between mouth and entrance to cavity
b) Water then passes
out of body after passing over gills and through cavity
c) One-way flow
of water over gills
d) Maintains high
concentration of oxygen outside gills
2. Continuously swimming fish have
nearly immovable gill covers
a) Water constantly
forced over gills as fish swim
b) Process is a
form of ram ventilation
3. Most bony fish have flexible gill
covers
a) Inhales water
into mouth
b) Exhales water
over gills and through opercular cavities
B. Effects of Gill Construction on Parameters of Diffusion
1. Structure of gills
a) Each gill composed
of two rows of gill filaments that project into flow of water
b) Filaments divided
into thin, disk-like lamellae that lie parallel to water flow
c) Direction of
blood circulation runs opposite that of water flow
d) Countercurrent
flow maximizes Δp between water and blood
2. Advantage of countercurrent exchange
a) Least oxygenated
blood meets least oxygenated water at back of gill
b) Most oxygenated
blood meets most oxygenated water at front of gill
c) Diffusion occurs
along entire length of gill
3. If water and blood flowed in the
same direction
a) Oxygen-free blood
would meet highly oxygenated water
b) Diffusion would
initially be high
c) Oxygenated blood
would meet less oxygenated water at back of gill
d) Diffusion would
cease, only front part of gill would be functional
4. Fish gills are up to 85% efficient
V. From Aquatic To Atmospheric Breathing
A. More Oxygen Present in Air Than in Water
1. Water = 5-10 ml O2 per 1 liter
water
2. Air = 210 ml of O2 per 1 liter
air
3. Many aquatic animals use air as
their oxygen source
B. Gills Not Adaptable for Terrestrial Use
1. Air is less buoyant than water
a) Lamellae lack
structural support, collapse without water buoyancy
b) Collapse reduces
diffusion surface area
c) Internal air
passages remain open due to structural support
2. Water diffuses into air through
evaporation
a) Terrestrial organisms
constantly lose water to atmosphere
b) Gills provide
an enormous surface area for water loss
3. Evolved two main kinds of terrestrial
respiratory organs
4. Both systems sacrifice efficiency
to reduce water loss
a) Tracheae of insects
(1)
Extensive series of air-filled passages within body
(2)
Oxygen diffuses directly from trachea to cells, no circulatory intervention
(3)
Openings close when CO2 levels are below certain point to limit water
loss
b) Lungs of terrestrial
vertebrates
(1)
Air enters and exits through one tube, minimizes evaporation
(2)
Two-way flow of air replaces one-way flow
(3)
Diffusion surfaces not exposed to pure fresh air Δp is far from maximal,
lungs are less efficient than gills
C. Amphibians
1. Low efficiency of lungs offset
by high concentration of oxygen
2. Efficiency not a critical problem
to early land vertebrates
3. Structure of the amphibian respiratory
system
a) Lung is a simple
convoluted sac
b) Connected by
trachea (windpip e)
to rear of oral cavity (mout h)
c) Opening controlled
by glottis, sinuses connect oral cavity to nose
4. Much oxygen obtained by diffusion
across moist skin, cutaneous respiration
D. Reptiles
1. More active, greater metabolic
need for oxygen
2. Cannot obtain oxygen through watertight
skin surface
3. Changes within the reptile respiratory
system
a) Lungs possess
small air chambers
b) Larger surface
area for diffusion
E. Mammals
1. Metabolic demands even greater
due to maintaining constant body temperature
2. Lungs more highly branched with
more alveoli clusters
a) Each alveoli
cluster connected to main air passageway by short bronchiole
b) All gas exchange
occurs across walls of alveoli
c) Branching and
alveoli vastly increase total surface area
(1)
Humans have 300 million alveoli in two lungs
(2)
Area about 42 times the surface area of body
3. Active mammals do not have greater
lung mass
a) Have smaller,
more numerous alveoli
b) Thinner epithelial
layer separates alveoli from blood
F. Birds
1. Metabolism of flying necessitates
a more efficient respiratory system
2. Avian lung works like a two-cycle
pump
a) With inhalation
air passes into posterior air sacs
b) With exhalation
air flows into lung
c) With next inhalation,
that air passes from lung to anterior air sacs
3. Air flow is unidirectional from
posterior to anterior
a) Birds have no
"dead volume" of air remaining in lungs as do mammals
b) Air at the diffusing
surface of the lung is fully oxygenated
4. Direction of air flow is different
from the flow of blood
a) Flow of air and
blood are at 90% angles to one another
b) Called cross-current
flow
c) Less efficient
than fish, more efficient than mammals
5. Birds can survive in much higher
altitudes than mammals
6. Birds increase Δp value in
Fick`s equation
VI. The Structure And Mechanics Of The Human Circulatory System
A. Structure of the Respiratory Tree
1. Air normally enters through nostrils
a) Lined with hairs
to filter out dust
b) Extensive array
of cilia further cleans and moistens air
2. Air passes through glottis
a) Slit in larynx
(voice box)
b) Enters trachea,
branches into two bronchi one for each lung
c) Bronchi further
branch into smaller tubes, narrowest called bronchioles
3. Trachea and bronchi reinforced
with cartilaginous rings
4. Bronchioles have only smooth muscle
in walls
a) Smooth muscle
lining adjusts size of passageway
b) Contraction stimulated
by parasympathetic division of the nervous system
c) Decrease in diameter
by half increases resistance sixteen fold
d) Sympathetic division
relaxes smooth muscle, causes bronchodilation, decreases resistance
(1)
Bronchodilation also caused by epinephrine
(2)
Drug used to treat symptoms of asthma triggered by release of histamine
B. The Structure of the Lung
1. Terminal bronchioles deliver air
to respiratory bronchioles
a) Contain alveoli
where gas exchange occurs
b) Alveoli are outpouchings
surrounded by capillaries
c) Lines by epithelium
only one cell layer thick
2. Outside of lungs covered by visceral
pleural membrane
3. Inner wall of thoracic cavity lined
by parietal pleural membrane
4. Space between membranes called
the pleural cavity
a) Normally small
and filled with fluid
b) Fluid links membranes
together like water film holds two sheets of cellophane together
c) Lungs held tight
to thoracic cavity
d) Each lung has
own pleural cavity, if one punctured other lung functional
C. Air Flow in the Lung
1. Human lung functions as one-cycle
pump
a) During inhalation
or inspiration
(1)
Rib external intercostal muscles contract raising the ribs
(2)
Diaphragm contracts, lowers and flattens
(3)
Increases volume of thorax
(4)
Due to coupling of pleural membranes, volume of lungs also increases
(5)
Pressure of air in lungs decreases, air drawn into lungs
b) During exhalation
or expiration
(1)
Diaphragm and external intercostal muscles relax
(2)
Structures of thorax return to previous condition
(3)
Volume of thorax and lungs decreases
(4)
Increases pressure of air in lungs, air forced out
c) Extra air can
be forced out of lungs
(1)
Contraction of internal intercostal muscles lowers ribs
(2)
Diaphragm pushed further up into thoracic cavity
2. Air volumes of human lungs
a) Tidal volume:
volume inspired and expired in a single breath
(1)
About 500 ml of air
(2)
Anatomical dead space: 150 ml within air passages
(3)
Can be increased to 3000 ml during exercise
(4)
Diffusion surface of lungs exposed to mixture of fresh and oxygen-depleted
air
b) Functional residual
capacity (FRC): volume in lung after normal resting expiration
c) Residual volume:
volume in lung after maximal expiration
d) Vital capacity:
amount of air expired after forceful, maximum inspiration
(1)
Emphysema reduces vital capacity
(2)
Alveoli destroyed by cigarette smoking
e) Respiratory rate:
number of breaths per unit time
f) Minute respiratory
volume (MRV)
(1)
Equals tidal volume x respiratory rate per minute
(2)
Air entering and leaving lung per minute
(3)
Normally 5 liters/minute, can be as high as 130 liters/minute
3. Conditions associated with abnormal
P CO2
a) Hyperventilation
(1)
MRV extremely high
(2)
CO2 removed from blood by ventilation faster than its produced by tissues
b) Hypoventilation
(1)
MRV unusually low
(2)
Elevated P CO2 level
c) Hyperpnea
(1)
High MRV, high metabolic rate
(2)
Normal blood P CO2 level
VII. Gas Transport And Exchange
A. Association of Respiratory and Circulatory Systems
1. Transport of oxygen extremely slow
if only by diffusion
2. Transported through circulatory
system via carrier
a) Blood plasma
holds maximum of 3 ml O2/liter
b) Whole blood is
able to carry 200 ml O2/liter
3. Hemoglobin: oxygen carrier protein
within the blood of most animals
a) Four polypeptide
subunit protein
b) Each subunit
combines with iron containing heme group
c) Hemoglobin picks
up oxygen in lungs
(1)
Bright red color when bound with oxygen
(2)
Called oxyhemoglobin
d) Hemoglobin releases
oxygen at tissues
(1)
Called deoxyhemoglobin
(2)
Dark red color, looks blue under skin
e) Hemoglobin widely
distributed oxygen carrier protein throughout animal kingdom
4. Hemocyanin: second carrier protein
found in many invertebrates
a) Uses copper instead
of iron
b) Does not occur
within blood cells, exists free in hemolymph
B. Oxygen Transport
1. At P O2 of 100 mm Hg, 97% bound
to hemoglobin in red blood cells
2. Percent saturation in arterial
blood is 97% at sea level
3. Extracellular fluid surrounding
tissues has lower P O2
a) Oxygen diffuses
from capillaries into tissues
b) P O2 of venous
blood is 40 mm hg, percent saturation is 75%
4. Graphical representation is an
oxyhemoglobin dissociation curve
a) At rest, 22%
(97-75) of the oxyhemoglobin releases oxygen to tissues
b) One fifth of
oxygen unloaded in tissues, four-fifths in blood as reserve
(1)
Blood can additionally supply oxygen needs at exercise
a) If venous blood
P O2 is 20 mm Hg, saturation is 35%
b) Amount unloaded
now 62% (97-35)
(2)
Blood contains reserves for 4-5 minutes without breathing
5. Presence of CO2 at metabolizing
tissues
a) Combines with
water to form carbonic acid, lowers pH of blood
b) Occurs in red
blood cells, hemoglobin has less affinity for oxygen
c) Hemoglobin releases
oxygen more readily
d) Dissociation
curve shifted to right, called Bohr effect
6. 2,3 diphosphoglycerate (DPG) also
shifts curve to right
a) Also augments
unloading of oxygen
b) Production inhibited
by oxyhemoglobin
c) Anything that
reduces oxyhemoglobin causes production of DPG
d) Example: high
altitudes
(1)
Low P O2 of air lowers level of oxyhemoglobin
(2)
Immediately causes rapid fatigue
(3)
Red cells produce DPG after a few days, shifts curve to right
(4)
Stimulates unloading of oxygen, lessens fatigue
(5)
After a few weeks, kidneys produce erythropoietin
(6)
Stimulates bone marrow to produce more red cells
7. Hemoglobin binds to carbon monoxide
(CO)
a) Binding to CO
more efficient than to O2
b) CO not readily
dissociated; small amounts cause respiratory failure
C. Carbon Dioxide Transport
1. As red blood cells unload oxygen,
blood absorbs CO2 from tissues
a) 20% binds to
hemoglobin, 8% dissolved in plasma, 72% binds to red cell cytoplasm
b) Carbonic anhydrase
catalyzes formation of carbonic acid
(1)
Carbonic acid dissociates to form bicarbonate and hydrogen ions
(2)
CO2 removed from plasma, allows loading of greater amounts
2. Blood carry CO2 back to lungs
3. Lower concentration of CO2 in alveoli
a) Carbonic anhydrase
reaction proceeds in reverse
b) Gaseous CO2 released,
diffuses into alveoli
c) Leaves body with
next exhalation
VIII. How The Brain Controls Breathing
A. Breathing Initiated by Respiratory Center in Brain
1. Sends nerve signals to diaphragm
and intercostal muscles
a) Expansion of
chest causes inspiration
b) Expiration proceeds
when neurons stop producing impulses
2. Breathing muscles are skeletal,
but are under involuntary control
3. Can be voluntarily over-ridden
in hypo- or hyperventilation
B. Reflex Pathway Prevents Life Threatening Alterations
in Breathing
1. No breathing causes increase in
blood P CO2
a) Causes increase
in carbonic acid, lowers blood pH
b) Peripheral chemoreceptors
in aortic and carotid bodies are sensitive to pH
c) Send impulses
to respiratory control center to reinitiate breathing
2. Central chemoreceptors detect changes
in pH of cerebrospinal fluid (CSF)
3. Peripheral chemoreceptors are responsible
for immediate changes
4. Central chemoreceptors are responsible
for sustained changes
5. Indefinite hyperventilation also
prevented by chemoreceptors
IX. The Evolution of Circulatory Systems
A. All Organisms Must Capture Nutrients and Gases from
the Environment
1. Simple organisms transport materials
across membrane of each cell
2. Interior of large organisms cannot
communicate with environment
a) Fluids within
body cavity facilitate movement of materials
b) Circulation:
transport of materials through an internal fluid
B. Types of Circulatory Systems
1. Closed system: blood enclosed within
vessels
a) Circulating fluid
does not mix with other body fluids
b) Materials pass
across by diffusion through walls of vessels
c) Annelids have
a closed system
d) Movement of fluid
in vessels assisted by muscle contraction
e) All vertebrates
have closed circulatory system
2. Open system: no distinction between
circulating fluid and body fluid
a) Arthropods have
an open system
b) Muscular tube
in body cavity pumps fluid through network of channels
c) Fluid drains
back into central cavity
3. Advantage of closed systems
a) Can change diameter
of individual muscle-encased vessels
b) Regulate fluid
flow in specific parts of body independently
X. The Functions Of The Vertebrate Circulatory System
A. Nutrient and Waste Transport
1. Nutrients enter blood through wall
of small intestine
2. Carried to liver for storage or
metabolism
3. Dissolved glucose and metabolites
carried to all body cells
4. Metabolizing cells release wastes
into blood
5. Wastes carried to kidney for removal
6. Constitutes metabolic circuit or
systemic circulation
B. Oxygen and Carbon Dioxide Transport
1. Oxygen diffuses into blood through
gills or lungs
2. Oxygen accumulates in hemoglobin
of red blood cells
3. Oxygen released at metabolizing
cells
4. Carbon dioxide, a metabolic product,
is released by cells into blood
5. Waste carbon dioxide carried back
to gills or lungs and released
6. Constitutes respiratory circuit
or pulmonary circulation
C. Temperature Regulation
1. Most vertebrates are poikilotherms,
body temperature varies with environmental temperature
2. Mammals and birds are homeotherms,
maintain constant body temperature
3. Heat distributed by circulating
blood
4. Temperature adjusted by directing
flow to interior or extremities
a) Decrease body
temperature by dissipating heat to environment
b) Retain heat by
directing blood from extremities to interior
c) Some animals
use countercurrent heat exchange system
D. Hormone Circulation
1. Body activities coordinated by
hormones produced in endocrine glands
2. Hormones transported to target
tissues throughout body
3. Hormones persist only a short time,
are destroyed by body enzymes
XI. The Cardiovascular System
A. Three Elements in a Vertebrate Closed Circulatory
System
1. Heart: muscular pump
2. Blood vessels: tubes located through
the body
3. Blood: fluid circulating within
vessels
4. Heart and blood vessels comprise
cardiovascular system
a) Arteries: direct
blood away from heart
b) Arterioles: large
network of smaller vessels, lead away from heart
c) Capillaries:
exchange with cells occurs across this fine network
d) Venules: small
vessels that collect blood from capillaries
e) Veins: large
vessels carry blood back to heart
B. Anatomy of a Blood Vessel
1. Similar structures found in arteries,
arterioles, veins and venules
2. Walls are composed of four layers
of tissue
a) Innermost endothelium:
epithelial sheet of cells
b) Thick layer of
elastic fibers
c) Layer of smooth
muscle
d) Encased in connective
tissue
3. Walls too thick to permit exchange
of materials
4. Exchange occurs in capillaries,
have only endothelium
C. Arteries and Arterioles Carry Blood Away from the
Heart
1. Elastic fibers allow large artery
to expand and recoil when receiving blood from heart
2. Smaller arteries and arterioles
are less elastic, but have thicker smooth muscle
3. Network of small vessels provides
flow resistance
a) Inversely proportional
to radius of the tube to the fourth power
b) Small diameter
arteries and arterioles cause greatest resistance to blood flow
c) Contraction of
smooth muscle causes vasoconstriction
(1)
Increases resistance
(2)
Decreases flow
d) Relaxation of
smooth muscle causes vasodilation
(1)
Decreases resistance
(2)
Increases flow
e) Blood around
some organs regulated by precapillary sphincters
(1)
Rings of smooth muscle around arterioles where they empty into capillaries
(2)
Close off specific capillary beds to all blood flow
D. Exchange Takes Place in the Capillaries
1. Heart provides sufficient pressure
to pump against resistance of arterial tree and into capillaries
2. Every cell within 100 µm of a capillary
3. Average capillary 1 mm long, 8
µm wide, just larger than red blood cell
4. Capillaries have greatest cross-sectional
area of all types of vessels
a) Blood velocity
decreases in capillary beds fig 46.27
b) Provides greater
time for exchange of materials with extracellular fluid
c) Blood releases
oxygen and nutrients, picks up carbon dioxide and wastes
d) Blood pressure
greatly reduced when blood enters veins
E. Veins and Venules Return Blood to the Heart
1. Two main veins return systemic
blood to heart
2. Four veins return pulmonary blood
back to heart (two from each lun g)
3. Veins and venules have thinner
layer of smooth muscle than arteries
4. Pressure one-tenth that of arteries
a) Most blood in
body held in veins
b) Can expand to
hold greater quantities
5. Venous pressure not sufficient
to return blood to heart from feet and legs
a) Aided by contraction
of skeletal muscles
b) One-way venous
valves direct flow toward heart
F. The Lymphatic System Recovers Lost Fluid
1. Circulatory system open to diffusion
through capillary walls
a) Filtration driven
by pressure of blood, supplies cells with oxygen and nutrients
b) Most fluid returned
by osmosis due to concentration of protein in blood
2. Open lymphatic system collects
rest of fluid and returns it to blood
a) Composed of lymphatic
capillaries, lymphatic vessels, lymph nodes and lymphatic organs like
spleen and thymus
b) Fluid in tissues
drains into open-ended lymph capillaries
c) Lymph passes
into progressively larger vessels
d) Lymphatic vessels
contain vein-like one-way valves fig 46.32
e) Right lymphatic
duct and thoracic duct drain into veins on side of neck
f) Blockage of lymphatic
systems leads to edema
3. Lymph fluid movement assisted by
movement of muscles
a) Some lymph vessels
contract rhythmically
b) Some animals
have lymph hearts
4. Lymph modified by phagocytic cells
in nodes and lymphatic organs
a) Contain germinal
centers for production of lymphocytes
b) Thymus plays
central role in immune system
XII. Blood
A. The Plasma Is the Blood`s Fluid
1. Blood plasma is a complex solution
of three major components in water
2. Metabolites and wastes
a) Dissolved within
are glucose, amino acids, vitamins
b) Also includes
wastes and hormones
3. Ions
a) Plasma is a dilute
salt solution
b) Primarily sodium,
chloride and bicarbonate
c) Trace amounts
of calcium, magnesium and metallic ions
4. Proteins
a) Liver produces
most plasma proteins, including albumin
b) Alpha and beta
globin proteins are carriers of lipids and steroid hormones
c) Fibrinogen associated
with blood clotting
d) Serum is blood
fluid minus the fibrinogen
e) Plasma protein
concentration maintain osmotic balance
B. Erythrocytes Transport Oxygen
1. Each milliliter of blood contains
5 billion erythrocytes or red blood cells
2. Hematocrit: volume of blood composed
of red blood cells, 45% of blood volume
a) Each cell is
a flat disk with a central depression
b) Collection of
polysaccharides on outer membrane identify blood groups
3. Mature mammal cells lack nuclei
and protein-synthesis machinery
a) Can not repair
selves, have short life span of four months
b) Removed by spleen,
bone marrow, liver
c) Cells produced
in bone marrow during erythropoiesis
C. Leukocytes Defend the Body
1. Less than 1% of total blood cells
2. Larger than red cells, contain
no hemoglobin, virtually colorless
3. Circulate in blood, present in
interstitial fluid
4. Function to defend body against
microbes and foreign substances
a) Granular leukocytes
include neutrophils, basophils, eosinophils
b) Nongranular leukocytes
include monocytes and lymphocytes
5. Role in inflammatory response
a) Injured cells
release histamine
b) Dilation of arterioles
increases blood flow, makes area red and warm
c) Neutrophils leave
capillaries, accumulate at site of injury
d) Joined by monocytes
which are converted into macrophages
e) Neutrophil and
macrophages entrap microorganisms and foreign particles
f) Lymphocytes play
key role in antibody production
g) Eosinophils may
help defend against parasitic infections
D. Platelets Help Blood to Clot
1. Platelets are cell fragments that
pinch off from megakaryocytes, no nuclei
2. Play important role in blood clotting
a) Ruptured vessel
constricts due to contraction of smooth muscle in wall
b) Platelets accumulate
and form plug with tissues
c) Fibrin protein
glues platelets together
d) Plug of platelets,
fibrin and trapped red cells constitutes a blood clot
3. Injury to tissues causes inactive
clotting proteins in blood to become active
a) Activated proteins
are called clotting factors
b) Cause cascade
of reactions that produces thrombin from prothrombin
c) Thrombin catalyzes
conversion of fibrinogen to fibrin
XIII. THE EVOLUTION OF THE VERTEBRATE HEART
A. Reflects Two Transitions in History of Vertebrates
1. Shift from filter feeding to active
capture of prey
2. Invasion of land
a) Evolved new breathing
apparatus
b) Decrease of pressure
from sea to air
c) Development of
homeothermy
B. The Early Chordate Heart Was a Peristaltic Pump
1. Peristaltic contractions of muscular
wall of ventral artery
2. Pumps blood in both directions,
greater flow in direction of wave
C. The Fish Heart Is a One-Cycle Chamber Pump
1. Four consecutive chambers
a) Two collection
chambers: sinus venosus and atrium
b) Two pumping chambers:
ventricle and conus arteriosus
2. Heartbeat sequence: sinus venosus,
atrium, ventricle, conus arteriosus
3. Blood delivered to body tissues
is fully oxygenated
4. Flow: heart 9 gills 9 tissues 9
heart
5. Circulation to body is sluggish
due to resistance in gill capillaries
D. Amphibian and Reptile Hearts Reflect the Evolution
of Pulmonary Circulation
1. Evolution of large veins from lungs
called pulmonary veins
2. Altered blood flow: blood from
lungs returns to heart for repumping
3. Advantage: blood pumped to tissues
at higher pressure
4. Disadvantage: oxygenated blood
mixed with unoxygenated blood
5. Structure of the amphibian heart
a) Atrium divided
into right and left chambers
b) Conus arteriosus
partially separated by a septum
c) Imperfect separation
of blood flow into pulmonary and systemic circulations
d) Deficiency partly
compensated for by cutaneous respiration
6. Structure of the reptile heart
a) Ventricle partially
divided by a septum
b) Conus arteriosus
absent, fully subdivided into arteries leaving heart
c) Greater separation
of aerated/nonaerated blood, greater efficiency
d) Complete separation
in crocodiles
E. Mammal and Bird Hearts Are True Two-Cycle Pumps
1. Independent evolution in birds
and mammals
2. Advent of a double circulatory
system
a) Ventricular septum
prevents mixing of aerated/nonaerated blood
b) Left side of
heart pumps oxygenated blood to body tissues
c) Right side of
heart pumps unoxygenated blood to lungs
3. Evolution related to development
of endothermy
4. Same volume of blood moves through
each circuit
a) Left ventricle
pumps blood through higher resistance pathway than right
b) Left ventricle
is more muscular and generates more pressure than right one
F. The Pacemaker of Mammalian and Bird Hearts is a Remnant
of the Sinus Venosus
1. Sinus venosus served as collection
chamber and pacemaker in early vertebrates
2. Remaining tissue is site of origin
of the heartbeat in mammals
a) Located in wall
of right atrium
b) Called sinoatrial
node (SA node)
XIV. The Human Heart
A. Double Pump System Operates Within a Single Organ
1. Right side sends blood to lungs
2. Left side sends blood to rest of
body
B. Circulation Through the Heart
1. Cardiac cycle: complete journey
of blood through body and heart
2. Oxygenated blood from lungs carried
through pulmonary veins to left atrium
3. Blood flows from atrium to opening
in left ventricle
a) Movement occurs
while ventricle is relaxing
b) Period called
ventricular diastole
c) Ventricle about
80% full
d) Contraction of
right atrium produces final 20 % of blood volume to ventricle
4. Ventricle contracts, called ventricular
systole
a) Blood forced
out of left ventricle
b) Bicuspid or mitral
valve prevents backflow
5. Blood moves one-way through aortic
valve to aorta
a) Backpressure
of aorta closes aortic valve
b) Prevents blood
from reentering ventricle
6. Aorta branches into systemic arteries
a) Carry oxygen-rich
blood to all parts of body
b) Heart receives
blood via coronary arteries, not through ventricle
7. Blood from body returns to heart
via systemic veins
a) The superior
and inferior vena cava are collecting vessels
b) Empty oxygen-depleted
blood into right atrium
8. Blood moves from right atrium through
tricuspid valve to right ventricle
9. Blood moves out of contracting
right ventricle through pulmonary valve
10. Blood pumped to lungs through
pulmonary arteries
1 1. Blood returns from lungs to left
side of heart to complete cycle
C. How the Heart Is Stimulated to Contract
1. Contraction stimulated by membrane
depolarization, reversal of electrical polarity
2. Contraction triggered by SA node
a) SA node is pacemaker
b) Membrane of cells
depolarize spontaneously with regular rhythm
3. Depolarization passes from one
cardiac muscle cell to another
4. Spreads because cardiac cells are
electrically coupled by gap junctions
5. Ventricular wave of depolarization
delayed by nearly 0.1 second
a) Atria and ventricles
separated by connective tissue
b) Connective tissue
cannot propagate depolarization
c) Wave passes via
atrioventricular node (AV nod e)
d) Delay permits
atria to completely empty before ventricles contract
6. Depolarization conducted over both
ventricles via bundle of His
7. Transmitted by Purkinje fibers
that stimulate ventricle myocardial cells
8. Right and left ventricles contract
almost simultaneously
D. Monitoring the Heart`s Performance
1. Monitor heart sounds caused by
closing of heart valves
a) First (lub):
closing of mitral and tricuspid valves at start of ventricular systole
b) Second (dub):
closing of pulmonary and aortic valves at start of ventricular diastole
c) Turbulence from
improper closing of valve causes heart murmur
2. Can also monitor changes in blood
pressure
a) Ventricles are
relaxed during diastole
(1)
Pressure in arteries at lowest
(2)
Called diastolic pressure
b) Contraction of
ventricle during systole
(1)
Pressure in arteries at highest
(2)
Called systolic pressure
c) Normal values:
diastolic/systolic = 70-90 mm Hg/110-130 mm Hg
3. Monitor electrocardiogram that
records waves of depolarization
4. Human body conducts electricity
quite well
5. Depolarization in heart generates
electrical signals that spread throughout body
6. Recording of signals called electrocardiogram
7. First deflection (P wave): depolarization
associated with atrial contraction
8. Second deflection (QRS): depolarization
of ventricles
9. Last deflection (T wave): ventricular
repolarization
E. Cardiac Output
1. Output is the volume pumped by
each ventricle per minute
2. Calculated by: rate of heart beat
x volume of blood ejected (stroke volum e)
3. Cardiac output is increased with
exercise
a) Heart rate increases:
SA node is less inhibited by parasympathetic nervous system
b) Sympathetic division
stimulates heart rate to increase further
c) Skeletal muscles
squeeze on veins, returning blood to heart more rapidly
d) Increases rate
at which heart fills and ejects blood
e) Sympathetic division
and epinephrine make ventricles contract more strongly
f) Ventricles empty
more completely
XV. Blood Flow, Pressure And Volume
A. Two Factors Control Arteriolar Smooth Muscle Tension
1. Extrinsic control by autonomic
nervous system
2. Intrinsic control, autoregulation
a) Each organ gets
enough blood for its own activities
b) Increases blow
flow to heart and skeletal muscles during exercise
c) Ensures brain
has continuous supply of blood
B. Baroreceptor Reflex
1. Baroreceptors located in walls
of carotic artery and aortic arch
a) Respond to changes
in systemic arterial blood pressure
b) Connected to
cardiovascular control center in medulla
c) Firing rate decreases
when blood pressure falls
d) Stimulates sympathetic
activity, inhibits parasympathetic activity
e) Results in increased
rate and force of heart contraction
f) Restores normal
pressure and cardiac output
2. Baroreceptors act to maintain blood
flow to brain with rapid standing
a) Changes venous
pressure in lower body, reduces pressure above heart
b) Increases volume
of blood in lower body
c) Pressure in veins
at right side of heart decreased
d) Decreases cardiac
output and blood flow to brain = fainting
e) Reflex rapidly
increases heart rate, constricts arterioles
f) Maintains normal
blood pressure values
3. Effects of hemorrhage
a) Severe blood
loss reduces venous return, cardiac output gets dangerously low
b) Reflex causes
faster heart rate, vasoconstriction in skin and viscera
c) Diverts blood
to heart and brain
4. Reverse action of baroreceptor
reflex
a) Rise in blood
pressure promotes slowing of heart and vasodilation
b) Lowers blood
pressure toward normal values
C. Volume Receptors
1. Blood pressure depends partly on
blood volume
2. Higher blood volume means higher
blood pressure
3. Volume regulation via three homeostatic
systems
a) Antidiuretic
hormone (ADH) system
(1)
ADH secreted by posterior pituitary with increased osmotic concentration
of blood plasma
(2)
Example: dehydration decreases volume, increases plasma concentration
(3)
Stimulated thirst and ADH secretion
(4)
ADH stimulates kidneys to reduce amount of water lost in urine
b) Renin-angiotensin-aldosterone
(RAA) system
(1)
Secretion of aldosterone controlled by cascade that begins in kidney
(2)
When blood flow through kidney is decreased, endocrine cells secrete renin
(3)
Renin initiates conversion of plasma proteins to angiotensin I
(4)
Converted to angiotensin II by enzyme in walls of blood vessels
(5)
Angiotensin II has two effects
a) Promotes vasoconstriction
(raises blood pressur e)
b) Stimulates production
of aldosterone by adrenal cortex
(6)
Aldosterone increases total body Na+, reduces water loss
c) Atrial natriuretic
hormone (ANH) system
(1)
Responds to need to excrete Na+ and lower blood volume
(2)
Inhibits aldosterone secretion
(3)
ANH secreted by endocrine cells in atrial walls when atrium is stretched
by high blood volume
(4)
Inhibits secretion of renin by kidney, inhibits aldosterone release
(5)
More Na+ excreted in urine, water follows, blood volume lowered
XVI. The Central Importance Of Circulation
A. Ability to Circulate Materials to All Cells in the
Body
B. Other Body Systems Depend on Circulatory Systems
to Integrate Activities