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Biology 1 > Lecture 18- Circulatory system > Flashcards

Lecture 18- Circulatory system Flashcards

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1
Q

What does a circulatory system consist of?

A

A muscular pump (heart)
A fluid (blood)
A series of conduits (blood vessels)

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2
Q

What is the heart, blood and blood vessels known collectively as?

A

Cardiovascular system

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3
Q

What is the function of circulatory systems?

A

To transport things around the body- heat, hormones, respiratory gases, blood cells, platelets, immune system, nutrients, waste products

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4
Q

What organisms do not have circulatory systems?

A

Single celled organisms, multicellular organisms with cells close to the external environment

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5
Q

Why do some animals not need circulatory systems?

A

Exchange can occur directly with the external environment due to structures and body shapes (such as gastrovascular cavities)

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6
Q

What are gastrovascular cavities?

A

Highly branched central cavities

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7
Q

In larger animals, what environment do cells exchange with?

A

The extracellular fluid

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8
Q

What does the extracellular fluid consist of?

A

Fluid in the circulatory system (blood plasma)

Fluid around the cells (interstital fluid)

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9
Q

What is an open circulatory system?

A

Where extracellular fluid combines with fluid of the circulatory system and squeezes through intercellular spaces when the animal moves.

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10
Q

How does fluid return to the heart in an open circulatory system?

A

In arthropods- through ostia

In mollusks- open vessels

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11
Q

What is a closed circulatory system?

A

Where blood is kept separate from the interstital fluid

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12
Q

How does blood move through a closed circulatory system?

A

Blood is pumped through the vascular system by one or more hearts

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13
Q

What are the three main advantages of a closed circulatory system?

A
  • Faster transport through vessels than intercellular spaces
  • Blood directed to specific tissues
  • Specialized carriers travel in vessels and transport hormones or nutrients to specific sites
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14
Q

What does the right side of the heart do?

A

Pumps blood through the pulmonary circuit

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15
Q

What does the left heart do?

A

Pumps blood through the systemic circuit

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16
Q

What are the two types of chambers?

A

Atria, ventricles

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17
Q

What is the purpose of valves in the heart?

A

To prevent backflow of blood

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18
Q

What valve lies between the atria and ventricles?

A

Atrioventricular valves

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19
Q

What do atrioventricular valves do?

A

Prevent backflow when ventricles contract

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20
Q

What valves lie between the ventricles and major arteries?

A

The pulmonary valve

The aortic valve

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21
Q

What is the purpose of the pulmonary valve and the aortic valve?

A

Prevent backflow when ventricles relax

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22
Q

What are the three steps of blood flow through the right side of the heart?

A

Deoxygenated blood from tissues enters the right atrium
Flows through atrioventricular valve into right ventricle
Right ventricle pumps blood through pulmonary valve into pulmonary circuit

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23
Q

What veins does the right atrium receive blood from?

A
  • Superior vena cava (from upper body)

- Inferior vena cava (from lower body)

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24
Q

What veins does oxygenated blood return to the heart in?

A

Pulmonary veins

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25
Q

What are the two phases of of the cardiac cycle?

A

Systole

Diastole

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26
Q

What is systole?

A

When ventricles contract

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27
Q

What is diastole?

A

When ventricles relax

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28
Q

What is the 1st step in the cardiac cycle?

A

The atria contract

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29
Q

What is the next step after the atria contract?

A 
'lub'
Ventricles contract
AV valves close
Pressure in ventricle builds
Pulmonary/aortic valve opens
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30
Q

What happens after the ‘lub’ stage?

A

Blood is pumped out of the ventricles, into the aorta and pulmonary artery.

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31
Q

What happens after blood is pumped out of the ventricles into the aorta and pulmonary arteries?

A

‘Dup’
Ventricles relax
Pressure in ventricle falls at the end of sytole
Aortic/pulmonary arteries shut

The the ventricles fill with blood again

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32
Q

How are blood pressure changes measured?

A

Sphygmomanometer and a stethoscope

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33
Q

What is the systolic value?

A

The pressure needed to compress an artery so blood does not flow

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34
Q

What is diastolic value?

A

Pressure needed to allow intermittent flow through the artery

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35
Q

What are healthy blood pressure values?

A

120 mm Hg over 70 mm Hg

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36
Q

What is blood?

A

A connective tissue made of cells in a liquid extracellular matrix called plasma

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37
Q

What is the name of the part of the blood made up of cells?

A

Packed cell volume or hematocrit

38
Q

What are most of the cells in the hematocrit?

A

Erythrocytes- red blood cells- that transport gases

39
Q

Where are red blood cells generated?

A

Bone marrow

40
Q

What is hypoxia?

A

Deficiency in the amount of oxygen reaching tissues

41
Q

What is produced in response to hypoxia?

A

Erythropoietin- a hormone released by the kidneys

42
Q

What activates the genes for erythropoietin in the kidneys?

A

Hypoxia-inducible factor 1 (HIF-1) a transcription factor

43
Q

How are red blood cells formed?

A

Immature red blood cells divide and produce hemoglobin while in the bone marrow,
At 30% hemoglobin the organelles break down
The cell enters circulation

44
Q

How long do red blood cells circulate?

A

About 120 days

45
Q

What happens to red blood cells after 120 days?

A

They rupture as the pass through narrow capillaries, as in the spleen

46
Q

Other than red blood cells, what else does bone marrow produce?

A

Megakaryocytes

47
Q

What do megakaryocytes do?

A

Break off cell fragments called platelets

48
Q

What do platelets do?

A

Initiate blood clotting when activated by collagen exposed in damaged blood vessels

49
Q

What do platelets do once activated?

A

Release chemical clotting factors which activate other platelets

50
Q

What are the 4 main steps in blood clotting?

A
  • Cell damage and platelet activation
  • Inactive enzyme prothrombin converts to active form, thrombin
  • Thrombin cleaves fibrinogen and forms fibrin
  • Fibrin threads form mesh that clots blood and seals vessels
51
Q

Where is prothrombin and fibrinogen found?

A

Circulating in the plasma

52
Q

What does plasma contain?

A 
Gases
Ions
Nutrients
Proteins
Other molecule: hormones, vitamins
53
Q

What type of vessel are arteries and arterioles?

A

Resistance vessels because their resistance can vary

54
Q

How does the resistance of arteries and arterioles vary?

A
  • Walls have elastin and collagen- stretch and recoil

- Smooth muscle cells in the walls allow them to dilate/constrict.

55
Q

What other feature of a resistance vessel can change its resistance?

A

Its diameter

56
Q

How is the resistance of an artery or arteriole controlled?

A

By neuronal and hormonal mechanisms by influencing smooth muscle cells

57
Q

Why is pressure reduced in smaller vessels such as capillaries?

A
  • Arterioles are highly branched

- Capillaries contribute an enormous surface area

58
Q

What is the structure of a capillary?

A

Walls are a single layer of endothelial cells, tiny holes called fenestrations

59
Q

What are capillary beds permeable to?

A

Water, ions, small molecules

Not large proteins

60
Q

What are Starling’s forces?

A

Two opposing forces that maintain water balance in capillaries

61
Q

How do starling’s forces work?

A
  • Blood pressure: forces water and small solutes out

- (Colloidal) Osmotic pressure: created by large molecules that cannot leave

62
Q

Explain how blood pressure changes across a capillary bed.

A

Blood pressure is higher at the arterial end and drops at the venous end

63
Q

How does osmotic pressure change across a capillary?

A

It does not change- it is constant

64
Q

How does blood pressure and osmotic pressure work together in a capillary?

A

Blood pressure is higher than osmotic pressure: fluid leaves

Blood pressure is lower than osmotic pressure: fluid returns

65
Q

What is Edema?

A

An accumulation of fluid in the extracellular space.

66
Q

What can cause edema?

A
  • Fall in blood protein levels (disease)
  • Histamine release: increases capillary permeability, relaxes smooth muscle in arterioles, raises blood pressure in capillaries
67
Q

Other than changes in blood pressure, what else draws water back into capillaries?

A

Bicarbonate ions (HCO3-) converted from CO2 contribute to the osmotic pressure- more at the venous end raises osmotic pressure.

68
Q

What is the blood-brain barrier?

A

Highly selective brain capillaries which do not have fenestrations

69
Q

What are veins also known as?

A

Capacitance vessels

70
Q

Why are veins called capacitance vessels?

A

Because they are very expandable so blood will accumulate in them

71
Q

How is blood returning from below the heart assisted?

A

Skeletal muscle contractions that squeeze the veins

72
Q

How is backflow prevented in veins?

A

One-way valves

73
Q

What is the Frank-Starling law?

A

A property of cardiac muscle cells that increases cardiac output

74
Q

What are the implications of the Frank-Starling law?

A

Cells contract more forcefully if stretched by an increase in the volume of returning blood

75
Q

What does the lymphatic system do?

A

Returns interstital fluid to the blood

76
Q

What is it called when fluid enters the vessels?

A

lymph

77
Q

Where do lymphatic capillaries go?

A

Merge into thoracic ducts- they empty into veins in the neck

78
Q

What are lymph nodes?

A

Sites of lymphocyte production

79
Q

What do lymph nodes do?

A

Remove microorganisms and foreign material by phagocytosis and act as filters.

80
Q

What is atherosclerosis?

A

Hardening of the arteries

81
Q

How does atherosclerosis form?

A

-Endothelial lining is damaged by high blood pressure, smoking, diet, microorganisms
Plaque forms at site of damage
Damaged cells attract migration of smooth muscle cells

82
Q

What happens once smooth muscle cells have been attracted to damaged cells?

A

Smooth muscle cells have cholesterol deposits to make the plaque fatty
Connective tissue and calcium deposits make the artery wall less elastic

83
Q

What can happen if platelets stick to plaque on artery walls?

A

A thrombus may form

84
Q

What do coronary arteries do?

A

Supply blood to the heart muscle

85
Q

What are the symptoms of atherosclerosis?

A

Chest pain, shortness of breath (reduced blood flow in coronary arteries)

86
Q

What happens if a thrombus forms in the coronary artery?

A

Coronary thrombus: myocardial infarction (heart attack)

87
Q

What is an embolus?

A

A piece of thrombus

88
Q

what can an embolus cause?

A

Embolism if it lodges in a blood vessel

89
Q

What happens if the embolism is in the brain?

A

Cells fed by that artery die: a stroke

90
Q

What are some of the causes of atherosclerosis?

A
  • Genetic predisposition
  • Age
  • Environmental risk (smoking, high-fat diet, sedentary)
  • Medical conditions (hypertension, obesity, diabetes)

Biology 1 (16 decks)

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