circulation chapter 38. general function 1.transports nutrients (from digestion), wastes (to...
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Circulation
Chapter 38
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General Function
1. Transports nutrients (from digestion), wastes (to respiratory and urinary), hormone (endocrine) and gases (to and from respiratory) throughout the body
2. Helps fight infection
3. Helps regulate body temperature and pH
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Functional Connections
food, water intake oxygen intake
DIGESTIVESYSTEM
RESPIRATORYSYSTEM
eliminationof carbondioxide
nutrients,water,salts
oxygencarbondioxide
CIRCULATORYSYSTEM
URINARYSYSTEM
water,solutes
eliminationof foodresidues
rapid transportto and from allliving cells
elimination ofexcess water,salts, wastes
Figure 38.2Page 665
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Circulatory Systems
spaces orcavitiesin bodytissues
aorta heart
pump pump
Open System Closed System
Figure 38.3Page 666
•Arthropods and most mollusks •Vertebrates and anelids
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Circulation of higher animals- Heart- pump to move fluids-usually one way with a valve
Closed circulatory system- one that has vessels (veins and arteries) to move the blood
Open circulatory system- lacking vessels-allowing the blood to move in large sinuses
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Open circulatory systems:
Insect circulatory system (picture)
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Closed circulatory systems: Earthworm Anterior end--10 hearts (aortic arches) (5 on each side)
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Vertebrate Circulatory
Arteries- take blood away from the heart
Veins- take blood to the heart
Capillaries- connect arteries and veins (exchanges materials)
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Fish
1 circuit , 2 chambered heart
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Amphibians
2 circuits (to lungs and body), 3 chambered heart (blood mixes)
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3. Reptiles- 3 chambered heart; 2 atria, 1 ventricle but the ventricle is partial divided allowing very little mixing of blood
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Birds and mammals – 2 circuits (to lungs and body), 4 chambered heart (blood doesn’t mix)
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Functions of Blood
• Transports oxygen and nutrients to cells
• Carries carbon dioxide and wastes away
from cells
• Helps stabilize internal pH
• Carries infection-fighting cells
• Helps equalize temperature
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Components of Blood
Blood6-8%of body weight
Plasma portion (50-60% of total volume)• Water• Proteins• Ions, sugars, lipids, amino acids, hormones, vitamins, dissolved gases
Cellular portion (40-50% of total volume)• White blood cells (leukocytes) – involved in immune response Neutrophils-fast acting phagocytes, nonspecific Lymphocytes-B & T cells, specific Monocytes-call up immune response, slow, nonspecific Eosinophils-fast, secrete enzymes, nonspecific Basophils-fast, inflammatory response, nonspecific• Red blood cells (erythrocytes) – carry oxygen• Platelets – involved in clotting
Figure 38.5Page 668
See figure 38.7, page 669 also
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Erythrocytes (Red Cells)
• Most numerous cells in the blood
• Transport oxygen and carbon dioxide
• Colored red by oxygen-binding pigment
(hemoglobin)
• Have no nucleus when mature
• Develop from stem cells in bone marrow
• Good for about 120 days, ongoing
replacementBiconcave disc
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Leukocytes (White Cells)
• Function in housekeeping and defense
• Cell typesBasophils
Eosinophils B lymphocytes
Neutrophils T lymphocytes
Macrophages NK cells
Dendritic cells Mast cells
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Leukocytes (White Cells)
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Platelets (thrombocytes)
• Membrane-bound cell fragments
• Derived from megakaryocytes, which
arise from stem cells
• Release substances that initiate blood
clotting
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Blood Cell Development
• Stem cells in bone marrow are unspecialized cells that retain the capacity to divide
• Some daughter cells of stem cells differentiate to form blood cells
• Body must continually replace blood cells
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natural killer cells
eosinophils
neutrophils
basophils
mast cells
B lymphocytes (mature in bone
marrow)
T lymphocytes (mature in
thymus)
dendritic cells mature macrophages
platelets
red blood cells (ertyrocytes)
forerunners of the white blood
cells (leukocytes)
monocytes (immature
phagocytes)
stem cells that multiply and
differentiate in bone marrow
megakaryocytes
?
committed cell(proerythroblast)
Fig. 38-5, p.661
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Blood Disorders• Red blood cell disorders
– Anemia – to few red-blood cells, oxygen blood levels cannot be kept high enough
• Many different kinds, from many causes
– Polycythemias – too many red-blood cells, makes blood flow sluggish
• White blood cell disorders– Infectious mononucleosis – too many
monocytes and lymphocytes– Leukemias – cancer suppresses or impairs
white blood cell formation in bone marrow
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Blood Type in Transfusions
• Require that donor and recipient have
same blood type
• If bloods of incompatible types are mixed,
recipient’s immune system will attack,
clump up and destroy donor cells
• This is an agglutination reaction
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ABO Blood Type
• Type A red cells have one type of marker
at surface (can accept type A or O)
• Type B red cells have a different type of
marker (can accept type B or O)
• Type AB cells have both markers (tolerate
any donor)
• Type O cells have neither marker (can
only accept type O donor)
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Blood Type Compatibility
O A B AB
Blood type of donor
O
A
B
AB
Blood type of recipient
Figure 38.8Page 670
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Rh Blood Type
• Based on presence or absence of Rh marker on red cells– Rh+ has marker, Rh- doesn’t have marker
• Can cause problems during pregnancy – If mother is Rh negative,
– has previously carried Rh positive child,
– is carrying fetus that is Rh positive
– Mother’s antibodies can attack fetal cells
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Vessels•Blood flows from heart into arteries (large vessels that lead away from the heart)
•Then into arterioles (smaller vessels that lead away from the heart)
•Then into capillaries (smallest diameter, with thin walls that allow for diffusion of materials into and out of blood)
•Then into venules (small vessels that lead back toward the heart)
•And finally into veins (large diameter vessels that return blood to heart)
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Blood Vessels
• Arteries: main transporters of oxygenated blood, thick elastic walls to withstand high pressure
Figure 38.15 Page 676
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Blood Vessels
• Arteries: main transporters of oxygenated blood
• Arterioles: diameter is adjusted to regulate blood flow
• Capillaries: diffusion occurs across thin walls
Figure 38.17 Page 668
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Blood Vessels
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Human Heart Is a Double Pump
• Partition separates heart into
left and right sides
• Each pumps blood through a
different circuit
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Pulmonary Circuit
Short loop that
oxygenates
blood, pumps
blood to and
from lungs.
right pulmonary artery left pulmonary artery
capillarybed ofrightlung
pulmonarytrunk
capillary bedof left lung
(to systemic circuit)
pulmonary veins
lungs
(fromsystemiccircuit)
heart
Figure 38.10 Page 672
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Systemic Circuit
Longer loop that
carries blood to
and from body
tissues
capillary beds of headand upper extremities
(to pulmonarycircuit)
aorta
(frompulmonarycircuit)
heart
capillary beds of otherorgans in thoracic cavity
capillary bed of liver
capillary beds of intestines
Figure 38.10 Page 672
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Hepatic Portal System
• Carries blood from capillaries in
digestive organs to capillaries in the
liver
• Allows liver to detoxify substances from
digestive tract before they are carried to
the body
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jugular veins
superior vena cava
pulmonary veins
hepatic portal vein
renal vein
inferior vena cava
iliac veins
femoral vein
carotid arteries
ascending aorta
pulmonary arteries
coronary arteries
renal artery
brachial artery
abdominal aorta
iliac arteries
femoral artery
Major Vessels
Figure 38.11 Page 673
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Figure 38.12
Page 674
Location of the Heart
right lungleft lung
diaphragm
Pericardium – double sac of tough connectivetissue that protects and anchors the heart to nearby structures
rib cage
Figure 38.12 Page 674
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Four Chambers• Each side has two chambers
– Upper atrium
– Lower ventricle
• Valves between atria and
ventricles (AV valves)
• Valves between each ventrical
and artery (semilunar)
• Contraction of the ventricles is
the driving force for blood
circulation.
Figure 38.12 Page 674
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Heart Anatomy
superior vena cava
right semilunar valve
right pulmonary veins
right atrium
right AV valve
right ventricle
inferior vena cava
septum
myocardiumheart’sapex
arch of aorta
trunk of pulmonaryarteriesleft semilunar valve
left pulmonaryveinsleft atrium
left AV valve
left ventricle
endothelium and connective tissue
inner layer ofpericardium
Figure 38.12Page 674
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Blood Path
• From body in vena cava
• To right atrium
• To right ventricle
• To lungs (in pulmonary artery – deoxygenated)
• To left atrium from lungs (in pulmonary vein – oxygenated)
• To left ventricle
• To body in aorta
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Cardiac Muscle•Cardiac muscle is striated, like skeletal muscles.
•Sliding filament model like skeletal muscles.
•But cardiac muscle cells are branching, short and connected at their endings
•Lots of gap junctions are present allowing quick spread of action potentials.
•Also, 1% of cardiac muscles do not contract, they function in the cardiac conduction system (make the heart pump by rhythmic waves of excitation).
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intercalateddisk
mitochondrion
Fig. 38-15a,b, p.667
one sarcomere
Intercalated disk, a region of adhering cell junctions at the abutting ends of cardiac cells.
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c Gap junction. These communication junctions occur on the sides of cardiac muscle cells, where mechanical stress is not as great as at the ends. They connect the cytoplasm of adjoining cells. We removed one cell’s plasma membrane for clarity.
Fig. 38-15c, p.667
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Conduction and Contraction
• SA node in right atrium is pacemaker
• Electrical signals cause contraction of atria
• Signal flows to AV node and down septum to ventricles, causing the ventricals to contract.
• The nervous can only adjust the rate and strength of contractions.
SA node
Figure 38.14Page 675
AV node
•Systole – contraction
•Diastole - relaxation
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Blood Pressure
• Highest in arteries,
lowest in veins
• Systolic pressure is
peak pressure
(ventricular
contraction)
• Diastolic pressure is
the lowest Greatest pressure drop Greatest pressure drop
is in arteriolesis in arteriolesFigure 38.18 Page 668
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Controlling Blood Pressure• Cardiac output is adjusted by controls over rate and strength
of heartbeat (nervous system)
• Total resistance in vessels changes due to diameter changes
(vasoconstriction and vasodilation) which is controlled by the
nervous and endocrine system.
• Baroreceptor response is main short-term control of blood
pressure
– By triggering the sympathetic or parasympathetic nerves
that control the blood vessels and heart
• Kidneys are the main long-term control of blood pressure
– By regulating the volume and composition of the blood
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Velocity of Flow Varies
• Volume of blood flowing through vessels always has to equal heart’s output
• Flow velocity is highest in large-diameter transport vessels
• Flow velocity is slowest in capillary beds; blood spreads out into many vessels with greater total cross-sectional area
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Diffusion Zone
• Capillary beds are the site of exchange between blood and interstitial fluid
• Capillary is a single sheet of epithelial cells
• Flow is slow; allows gasses to diffuse across membranes of blood cells and across endothelium
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Movement in and out Capillaries• Capillary beds are the site of exchange between
blood and interstitial fluid
• Capillary is a single sheet of epithelial cells (very thin walls), some clefts between them, flow is slow
• allows gasses to diffuse across membranes of blood cells and across endothelium
• Some proteins leave and enter by endo and exocytosis
• Some ions leave at the clefts between the cells
• Bulk flow (in response to fluid pressure) also occurs– Ultrafiltration out and reabsorption in
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Bulk Flow in Capillary Bed
blood tovenule
inward-directedosmotic movement
cells oftissue
outward-directedbulk flow
blood from arteriole
Figure 38.21Page 670
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Net Bulk Flow
• Normally, ultrafiltration only slightly exceeds reabsorption
• Fluid enters interstitial fluid and is eventually returned to blood by way of the lymphatic system
• High blood pressure causes excessive ultrafiltration and results in edema
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The Venous System• Blood flows from capillaries into venules, then
on to veins
• Veins are large-diameter vessels with some smooth muscle in wall
• Valves in some veins prevent blood from flowing backward
Figure 38.17d Page 668
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Bicarbonate Formation
CO2 + H2O H2CO3
carbonic acid
HCO3–
bicarbonate
+ H+
• Most carbon dioxide is transported as bicarbonate• Some binds to hemoglobin• Small amount dissolves in blood
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Cardiovascular Disorder
Risk factors
• Smoking, Gender (maleness), Genetic factors, Old age, High cholesterol, Obesity, Lack of exercise, Diabetes mellitus
•Hypertension High Blood pressure (above 140/90)
Atherosclerosis• Arteries thicken, lose elasticity, and fill up with
cholesterol and lipidsArrhythmias• Irregular heartbeat
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Hemostasis – stops bloodloss
• Blood vessel spasm (contracts, slows bloodflow), platelet plug formation, blood coagulation (clotting)
• Clotting mechanism– Prothrombin is converted to thrombin– Fibrinogen is converted to fibrin– Fibrin forms net that entangles cells
and platelets
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Fig. 38-23, p.672
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Lymphatic System
• Collects and returns fluid to the bloodstream
– The circulatory system is leaky
– Some fluid is forced out of the smallest vessels and
into the interstitial fluid
– Vessels of the lymphatic system pick up this fluid,
filter it, and return it to the circulatory system
• Defends against infection
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Main Parts- See figure page 683
• Lymph nodes – organ acts as a filter for lymph, packed
with lymphocytes for immune response
• Lymph vessels – tubes that collect and deliver leaky
fluid back to vein in lower neck
• Lymph – the fluid
• Lymphoid organs – central to body’s defense
– Tonsils, Thymus, Spleen
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Lymph Nodes• Located at intervals
along lymph vessels
• Act as a filter for lymph
• Contain lymphocytes
that can recognize a
foreign invader
Figure 38.27c Page 674
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Lymphoid Organs
• Central to the
body’s defense
• Tonsils
• Spleen
• Thymus gland
Figure 38.27a Page 674