Circulation Flashcards

(47 cards)

1
Q

Circulatory system components

A

pumps, vessels, and circulatory fluid

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2
Q

Circulatory system functions

A
  • maintenance of homeostasis
  • mass transport of solutes and cells
  • transport of heat
  • transmission of force
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3
Q

Mammalian circulation; two circuits (double circulation)

A
  • separate pulmonary and systemic circuits

- pressure differences possible

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4
Q

Systole

A

heart muscle contracts and chambers pump blood

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5
Q

Diastole

A

heart muscle is relaxed and chamber fills with blood

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6
Q

cardiac cycle

A

inherent activity of the heart and can be modified by outside influences

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7
Q

Arteries

A

carry blood away from the heart towards capillaries

- Arterioles (small branches of arteries, that convey blood to capillaries)

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8
Q

Capillaries

A
  • microscopic vessels that penetrate the tissues

- consist of single layer of cells that allow exchange between the blood and interstitial fluid

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9
Q

Veins

A

return blood to heart from capillaries

- Venules (convey blood between a capillary bed and a vein)

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10
Q

Blood pressure and blood flow

A

velocity varies inversely with total cross - sectional area of vessels

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11
Q

systolic pressure

A

ventricles contracting

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12
Q

diastolic pressure

A

ventricle relaxing

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13
Q

Blood pressure

A

force of the heartbeat falls almost to zero in veins, venules

  • returns to heart due to contraction of skeletal muscles
  • one way valves in veins ensure direction of blood flow towards heart
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14
Q

Measurement of blood pressure

A
  • record as two numbers; the first is systolic pressure and the second is diastolic pressure
  • in healthy resting human; 120mm Hg at systole and 70mm Hg at diastole
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15
Q

Regulation of blood flow

A
  • blood volume < systemic capacity
  • blood flow is directed to active tissue
  • relaxing/ contracting of precapillary sphincters (control mechanism)
  • constriction/ dilation of arterioles (control mechanism)
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16
Q

Lymphatic system functions

A
  • fluid balance, net leakage of fluid and proteins from blood capillaries, lymph capillaries collect lost fluid and return blood circulation
  • defense; lymph nodes have defense cells
  • lymph capillaries pick up fats absorbed by the small intestines, transfer it to blood
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17
Q

Lymphatic system Movement

A
  • one way valves, contraction of skeletal muscles

- lymph does not circulate in a closed circuit

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18
Q

Lymphatic system thymus

A

the site of maturation of T lymphocytes (of the immune system)

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19
Q

Lymphatic system tonsils

A

handle infections in the mouth

20
Q

Lymphatic system spleen function

A
  • defense
  • red blood cell destruction
  • blood reservoir
21
Q

Blood composition

A
  • cellular elements

- plasma; blood minus the cells

22
Q

Blood volume

A

heart rate (70 beats/min at rest) X stroke volume (75ml) = 5.25L/ min

23
Q

Blood Hematocrit

A
  • packed cell volume
  • normal value (45%) is regulated
  • departures are either adaptive or pathological
24
Q

Leukocytes

A
  • 5000-10 000 / mm3

- defense and immunity

25
Erythrocytes
- 5 -6 million / mm3 | - O2 and CO2 transport
26
Platelets
- 250 000 - 400 000/ mm3 | - blood clotting
27
Erythrocytes - shape
-biconcave disc (oval in camels) -small size (mammals 5-10um) = large surface area
28
Erythrocytes- Contents
- hemoglobin - spectrin; predominant component of the membrane skeleton - glycolytic enzymes; active carbohydrates metabolism (anaerobic) - carbonic anhydrase; catalyze CO2 - bicarbonate - no organelles or ribosomes - mammals; no nucleus = more space for hemoglobin
29
Formation of Erythrocytes- erythropoiesis Process
- takes 4 days from stem cell to erythrocytes - begins in bone marrow, completed in circulating blood - initiated when not enough O2 reaches tissues
30
Formation of Erythrocytes- erythropoiesis Rate
- 100 million cells per minute - normally balanced with erythrocytes destruction - can exceed destruction under conditions of tissue oxygen deficiency
31
Destruction of Erythrocytes
- break apart in capillaries due to mechanical stress | - eaten by macrophages (defensive phagocytes) in spleen and liver
32
Human red blood cells
- responsible for transport of O2 around body - 5-6 million - bioconcave shape - lack nucleus - lack mitochondria - life time of 120 days - manufactured in red marrow of certain bones - age or damaged cells phagocytosed by white blood cells in spleen and liver
33
Severe blood loss
- v blood pressure- v blood flow from damaged area - constriction of blood vessel- v blood flow - coagulation
34
Blood loss can be halted by
- platelet plugs (from early) | - fibrin clots (from later)
35
Platelets
- small, short lived fragments of cells - 2 - 3 um (150 000 - 300 000mm) - Do not respond to undamaged endothelial wall
36
Platelets are activated by
- exposed collagen fibres in damaged tissue of vessel walls - foreign surfaces - thrombin
37
Platelets upon activation ...
- form of platelet plug - release of clotting factor - change shape
38
Platelets contain
- actin and myosin (help them contract) - chemicals that help coagulation process to begin - chemicals that attract other platelets - chemicals that stimulate blood vessel repair - chemicals that stabilize a blood clot
39
Blood clot formation
-takes place via an activation cascade; cascades amplify signals
40
Blood clot steps -1
- tissue damage (endothelium); exposed to foregin substance= exposure to collagen - clotting factors; release from platelets and injured tissue, plasma protein synthesized liver, circulate in inactive form
41
Blood clot steps -2
- thrombin; enzyme, absent from circulating blood - prothrombin circulates in plasma - activation of blood factor= prothrombin= thrombin - thrombin=fibrinogen= fibrin
42
Blood clot steps -3
- platelets; release substance that cause contraction of blood vessels - sticky platelets form plug - initiate formation of fibrin clot - clot seals wound until vessel wall heals
43
Clotting dynamics
- opposing clotting; anticlotting agents (heparin) | - favouring clotting; activated platelets, activated blood factors, thrombin, fibrin
44
Clotting dissolution
- fibrinolysis | - dissolution of fibrin and thrombus
45
Plasmin
- main enzyme in fibrinolysis - cleaves fibrin in multiple locations - acts to dissolve a firbin clot - produced in inactive form (plasminogen) in the liver
46
Plasminogen
- cannot cleave fibrin, but has an affinity for it | - incorporated into the clot when it is formed
47
Clot lysis
complex process involving proteolytic enzymes, activators and inhibitors of plasmin and other proteases