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Circulatory Systems

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Human Circulatory System. circulation ... Human Circulatory System. heartbeat is myogenic. pacemaker cells occur at sinoatrial node ... – PowerPoint PPT presentation

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Title: Circulatory Systems


1
Circulatory Systems
  • Transport Maintenance

2
Circulatory Systems
  • transport to from tissues
  • nutrients, O2 waste, CO2
  • hormones
  • maintain electrolyte balance of intercellular
    fluid
  • transport to/from homeostatic organs
  • small intestine delivers nutrients
  • liver removes wastes, controls nutrients
  • kidney controls electrolytes, dumps wastes

3
Circulatory Systems
  • some animals lack circulatory systems
  • aquatic environment fulfills same functions
  • some animals have open circulatory systems
  • the heart pumps interstitial fluid
  • vessels deliver interstitial fluid to tissues
  • interstitial fluids leave the vessels bathe the
    cells of the tissues
  • interstitial fluids return to the heart
  • other animals have closed circulatory systems

4
open circulatory systemsFigure 49.1
5
closed circulatory system of earthwormFigure
49.2
6
Closed Circulatory Systems
  • components of closed circulatory systems
  • heart(s) - pump
  • vessels - transport conduits
  • blood -
  • transport medium
  • distinct from interstitial fluid
  • advantages over open system
  • speed
  • control of blood flow
  • cellular elements of blood remain in vessels

7
Circulatory Systems
  • hearts
  • vertebrates have chambered hearts
  • valves impose one-way flow
  • number of chambers varies with phylogeny
  • blood circulates through one or two circuits
  • H G.E.M. B
  • H G.E.M. H B
  • pulmonary systemic
  • circuit circuit

8
Closed Circulatory Systems
  • vessels
  • arteries
  • transport blood away from heart
  • veins
  • transport blood toward heart
  • arterioles/venules
  • small arteries/veins
  • capillaries
  • connect arterioles to venules

9
Closed Circulatory Systems
  • systems with two-chambered hearts - fish
  • one circuit
  • atrium ventricle gills aorta body
    atrium
  • ventricular pressure is dissipated in gill
    capillaries

10
fish circulation schematicp. 943
11
Closed Circulatory Systems
  • systems with two-chambered hearts - lungfish
  • modified for breathing air or water
  • out-pocketing of gut acts as a lung
  • some gill arteries supply blood to lung
  • some gill arteries deliver blood to aorta
  • gills exchange gases with water
  • partially separated atrium
  • right side oxygenated blood body
  • left side deoxygenated blood gills/lungs

12
lungfish circulation schematicp. 943
one pair of gill arteries delivers blood to
lung two gill arches deliver blood directly to
aorta gilled gill arches exchange gases with
blood
13
Closed Circulatory Systems
  • systems with three-chambered hearts - amphibians
  • two atria
  • left atrium receives pulmonary blood
  • right atrium receives systemic blood
  • ventricle anatomy limits mixing
  • deoxygenated blood travels to lung
  • oxygenated blood travels to body

14
amphibian circulation schematicp. 943
15
Closed Circulatory Systems
  • reptilian hearts provide further control
  • two atria receive blood from pulmonary systemic
    circuits
  • partially separated ventricle supplies three
    vessels
  • pulmonary artery two aortas
  • when breathing, the right aorta carries
    deoxygenated blood to the pulmonary circuit
  • when not breathing, both aortas carry blood to
    the systemic circuit

16
reptilian circulation schematicp. 944
17
Closed Circulatory Systems
  • crocodilian hearts have four chambers
  • two atria, two ventricles, two aortas
  • two aortas are bridged near their origins
  • when breathing, the left ventricle ( aorta)
    pressure is higher
  • deoxygenated blood goes to lungs
  • when not breathing, right aorta pressure is
    higher
  • pulmonary circuit is bypassed

18
crocodilian schematicp. 944
19
Closed Circulatory Systems
  • endotherm hearts have four chambers and one aorta
  • systemic/pulmonary circuits are separated
  • tissues receive highest possible O2 (?P1) under
    high pressure
  • lungs receive lowest possible O2 (?P2) under
    lower pressure

20
endotherm schematicp. 945
21
human circulatory systemFigure 49.3
22
Human Circulatory System
  • circulation
  • deoxygenated blood arrives at right atrium from
    inferior superior vena cava
  • atrium pumps blood to right ventricle
  • ventricle pumps blood to pulmonary artery
  • backflow is prevented by atrioventricular valve
  • ventricle relaxes
  • backflow is prevented by pulmonary valve

23
human heart anatomyFigure 49.3
24
Human Circulatory System
  • circulation
  • oxygenated blood arrives at left atrium through
    pulmonary veins
  • atrium pumps blood into left ventricle
  • ventricle pumps blood to aorta
  • backflow is prevented by atrioventricular valve
  • ventricle relaxes
  • backflow is prevented by aortic valve

25
human heart anatomyFigure 49.3
26
Human Circulatory System
  • cardiac cycle
  • systole - contraction of ventricles
  • maximum pressure generated
  • major electrical event
  • diastole - relaxation of ventricles
  • minimum pressure
  • characteristic electrical signatures

27
ventricular pressures volumesFigure 49.4
28
measuring blood pressureFigure 49.5
29
Human Circulatory System
  • heartbeat is myogenic
  • pacemaker cells occur at sinoatrial node
  • resting membrane potential depolarizes
  • at threshold, voltage gated Ca2 channels open
  • K channels open to repolarize cells
  • K channels close slowly, allow gradual
    depolarization
  • autonomic nervous system regulates the rate of
    depolarization

30
autonomic control of heart rateFigure
49.6Figure 49.8Figure 44. 9
norepinephrine
acetylcholine
31
Human Circulatory System
  • contraction
  • the pacemaker action potential spreads across the
    atrial walls
  • atria contract
  • action potential is transmitted to ventricles
    through the atrioventricular node and the bundle
    of His
  • the action potential spreads to Purkinje fibers
    in ventricular muscle
  • ventricles contract

32
origin and spread of cardiac
contractionFigure 49.7
33
Human Circulatory System
  • vascular system
  • arteries carry blood from heart
  • elastic tissues absorb pressure of heart
    contractions
  • smooth muscle allows control of blood flow by
    neural and hormonal signals

34
artery structureFigure 49.10
35
Human Circulatory System
  • vascular system
  • capillaries
  • fed by arterioles drained by venules
  • exchange materials between blood intercellular
    fluids
  • high total capacity slow flow
  • thin walls

36
capillary bedFigure 49.10
37
Human Circulatory System
  • vascular system
  • capillaries
  • exchange materials by filtration, osmosis
    diffusion
  • water solutes move through capillary walls
    under pressure on the arteriole side
  • remaining solutes diffusing CO2 produce a low
    osmotic potential
  • water returns to capillaries on the venule side

38
water movement balanced between blood pressure
osmotic potentialFigure 49.12
39
Human Circulatory System
  • lymphatics
  • lymph vessels return excess tissue fluid to
    blood
  • lymphatic capillaries collect lymph
  • capillaries merge into larger vessels
  • vessels contain one-way valves
  • the major lymph vessel, the thoracic duct,
    empties into the superior vena cava
  • lymph nodes participate in lymphocyte production
    phagocyte activity

40
vein structureFigure 49.10
41
Human Circulatory System
  • veins
  • receive blood from capillaries under low pressure
  • contain one-way valves
  • blood is propelled by skeletal muscle contraction
    or gravity

42
venous return by skeletal muscle contraction and
one-way valves
43
Human Circulatory System
  • blood - a fluid connective tissue
  • fluid matrix - plasma
  • dissolved gases, ions, proteins, nutrients,
    hormones, etc.
  • many components found in tissue fluid
  • cellular elements
  • red blood cells (erythrocytes)
  • white blood cells (leukocytes)
  • platelets

44
blood componentsFigure 49.15
45
human blood samplesbeforeand aftercentrifugati
on to separate red blood cells from serum
46
Human Circulatory System
  • control regulation of circulation
  • capillaries are subject to auto-regulation
  • pre-capillary sphincters and arterial smooth
    muscle are sensitive to
  • O2 CO2 concentrations
  • accumulated waste materials

47
local control of blood flowFigure 49.17
48
Human Circulatory System
  • control regulation of circulation
  • simultaneous auto-regulation of capillary beds
    produces systemic responses
  • changes in breathing, heart rate
  • changes in blood distribution
  • systemic control is neural or hormonal
  • sympathetic stimulation contracts most arteries
    dilates skeletal muscle arteries
  • hormones constrict arteries in targeted tissues

49
circulatory regulation at two levelsFigure 49.18
50
Human Circulatory System
  • control regulation of circulation
  • autonomic control of circulation originates in
    medulla of brain stem
  • inputs arrive from
  • stretch receptors
  • chemosensors
  • higher brain centers
  • responses may be
  • direct - artery relaxation or contraction
  • indirect - release of epinephrine

51
neural control of circulation is centered in
the medullaFigure 49.19
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