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Physiology 2001 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

What fluids make up the extracellular fluid?

A

Lymph, plasma and interstitial fluid

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2
Q

What is serum?

A

Serum is blood fluid that has had the cells and clotting factors removed

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3
Q

What are the major cells in blood?

A

Erythrocytes
Leukocytes
Thrombocytes (Platelets)

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4
Q

What is a Reticulocyte?

A

An immature blood cell that hasn’t lost it’s nucleus yet

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5
Q

Describe the general structure of a RBC

A

Biconcave disc with no nucleus
7-8 um diameter
No organelles
Has haemoglobin and metabolic enzymes

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6
Q

What is the function of a RBC?

A

Transport of oxygen and carbon dioxide via haemoglobin

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7
Q

What is Carbonic Anhydrase?

A

An enzyme in RBC’s that catalyses the slow reaction of carbon dioxide and water

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8
Q

Describe the structure of Haemoglobin

A

4 poly-peptide sub-units (globin) (2a and 2B globin chains)

4 Haeme units

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9
Q

Explain how oxygen is transport via haemoglobin?

A
  • Each haeme unit can bind 1 oxygen at the Fe2+ site
  • Oxygen binds to haemoglobin via a reversible reaction
  • 4 oxygen molecules can be bound at once due to the presence of 4 haeme units
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10
Q

Why does foetal haemoglobin have a greater affinity for oxygen?

A

It is to assist in the transport across the placenta

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11
Q

Describe what stimulates the production of RBC’s

A
  1. low oxygen causes hypoxic environment
  2. Erythropoietin is secreted by the kidneys
  3. Erythropoietin increased the production of RBC’s in the bone marrow

N.B. Testosterone, Growth hormone and Thyroid hormone also stimulate production

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12
Q

What is Packed Cell Volume (PCV) or haematocrit?

A

The percentage of RBC in a given volume. Normal values are 45% for men and 42% for women

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13
Q

What are the 3 main types of WBC?

A

Granulocytes (Polymorphonuclear leukocytes)
Lymphocytes
Monocytes

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14
Q

What is the function of an Eosinophil?

A

It destroys parasites via extracellular means (it is weakly Phagocytic).
Also has a role in allergies and inflammation

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15
Q

What is the function of a Neutrophil?

A

Consume debris and pathogens, especially bacteria, they are first responders

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16
Q

What is the function of a Basophil?

A

Contribute to allergic reactions and inflammation

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17
Q

What is the role of Monocytes?

A

They become Macrophages, they are powerful phagocytes and release cytokines that enhance the immune response

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18
Q

What are Thrombocytes?

A

Cytoplasmic fragments of Megakaryocytes (large cell in the bone marrow)
They are small flat discs about 1-4um wide
They have a cell membrane and organelles but no nucleus

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19
Q

What is the function of Thrombocytes?

A

They clump together to plug gaps in the blood vessel
They respond to exposed collagen
Release growth factors and iniate repair

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20
Q

What are the functions of the Cardiovascular System?

A

Delivery of nutrients to active tissues
Removal of waste products from active tissue
Transport of metabolites
Transport of hormones, antibodies and other substances to their active sites

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21
Q

What is Pulmonary Circulation?

A

Circulation that goes to the lungs

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22
Q

What is Systemic Circulation?

A

Circulation through the rest of the body

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23
Q

What is Systole?

A

The period of contraction of the heart

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24
Q

Whats is Diastole?

A

The period of relaxtion of the heart

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25
Q

What is Systolic Pressure?

A

The highest pressure in the systemic arteries during sytole, usually 120mmHg

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26
Q

What is Diastolic Pressure?

A

The lowest pressure in the systemic arteries during diastole, usually 80mmHg

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27
Q

How is blood pressure written?

A

Sytolic BP over Diastolic BP

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28
Q

What is pulse pressure?

A

The pressure difference between the Systolic and Diastolic BP, usually 40mmHg

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29
Q

What is mean arterial pressure (MAP)?

A

The arterial pressure averaged over the cardiac cycle, usually 90-95mmHg

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30
Q

What is the formula for MAP?

A 
MAP = 2/3 DBP + 1/3 SBP
MAP = CO x total resistance
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31
Q

Blood flows from an area of ______ pressure to _____ pressure. Flow through the vascular system is produced by _______ to ________ blood pressure

A

Flows from high pressure to low pressure

Flow in the vascular system is produced by arterial to venous blood pressure

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32
Q

What is the Cardiac Output? What is it’s formula?

A

The amount of blood pumped per minute, 5L/min at rest

CO = SV x HR

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33
Q

What is the Frank-Starling Law of the heart?

A

Within physiological limits the heart pumps all the blood it receives

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34
Q

Increased venous return ______ ventricular volume which ________ the pressure that can be generated by the ventricles which ________ stroke volume

A

Increases, Increases, Increases

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35
Q

Why are myocardial cells connected by gap junctions?

A

Gap junction is a gap in the cell membrane that connect one cells cytosol with another’s. It allows action potentials to move through a low resistance pathway. This means electrical signals are conducted smoothly

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36
Q

What is Annulus Fibrosus and what is it’s function?

A

It is a fibrous “skeleton” that isolates the atria and ventricles electrically

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37
Q

What is the Sino-Atrial node?

A

A cluster of electrically active cells found where the sinus venosus joins the right atrium that generates the action potential that causes a heartbeat

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38
Q

What is the Atrio-Ventricular node?

A

A cluster of cells located at the top of the septum where the right atrium joins the ventricle. It delays and then conducts the impulse sent from the SA node

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39
Q

Which node has the faster pacemaker potential?

A

SA node, 90-100bpm

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40
Q

What is an ectopic beat?

A

A beat generated outside the normal pacemaker

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41
Q

Agents that alter the heart rate are called…..

A

Chronotropic agents

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42
Q

Positive chronotropic agents __________ the heart rate. For example _________

A

Increase the heart rate

Adrenaline and Noradrenaline

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43
Q

Negative chronotropic agents __________ the heart rate. For example _________

A

Decrease the heart rate

Acetylcholine

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44
Q

What happens during the P-wave on an ECG?

A

The atria depolarise

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45
Q

What happens during the QRS complex on an ECG?

A

The ventricles depolarise and the atria repolarise

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46
Q

What happens during the T-wave on an ECG?

A

The ventricles repolarise

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47
Q

Why does the QRS complex go down and then quickly up?

A

Because the heart contracts from the bottom upwards

48
Q

Blood doesn’t flow into the arteries until…….

A

Ventricular pressure exceeds the arterial pressure

49
Q

What produces the heart sounds?

A

The closing of the valves

50
Q

What is S1?

A

The first and loudest heart sound caused by the abrupt closure of the Atrioventricular valves

51
Q

What is S2?

A

The second heart sound caused by the closure of the semi-lunar valves

52
Q

What stage on a ECG does S1 occur?

A

The QRS complex

53
Q

What stage on a ECG does S2 occur?

A

The start/middle of the T-wave

54
Q

The thick and elastic walls of the arteries maintain ________ and _________ during diastole

A

Arterial pressure and blood flow

55
Q

What is the formula for Mean Arterial Pressure?

A 
MAP = CO x total resistance
MAP = 2/3 DBP + 1/3 SBP
56
Q

Arterial resistance is controlled by __________

A

Sympathetic tone, directly proportional

57
Q

__________ control the flow in a vascular bed by _______________

A

Arterioles by vasoconstriction and vasodilation

58
Q

What is venoconstriction?

A

The constriction of veins to decrease capacitance, this increase venous return

59
Q

Veins have a ____ capacitance and hold ____ of the volume of blood at rest

A

High capacitance and hold 2/3 of the blood volume at rest

60
Q

What is the normal range for central venous pressure?

A

2-5mmHg

61
Q

What is the normal Pulmonary Blood pressure? Why is it this value?

A

22/8 mmHg. It is less than systemic BP because there is less total resistance in the pulmonary circuit

62
Q

The microcirculatory system consists of:

A

Arterioles, Venules, Metarterioles (aka preferred channels) Capillaries and Arteriovenous shunts

63
Q

How do substances move across the capillary wall?

A

There are fenestrations between cells that allow the passage of small water soluble substances. Substances can also move through the cell.

64
Q

What is Para-cellular transport?

A

Transport through the gaps between cells

65
Q

What is Trans-cellular transport?

A

Transport through the cell via channels or endo/exocytosis

66
Q

What is a colloid?

A

A relatively large particle that stays in constant suspension

67
Q

What is colloidal osmotic/oncotic pressure?

A

The osmotic pressure formed by large proteins, like albumin, in the blood that tends to pull water into the vessel. It is about 25mmHg

68
Q

What is Hydrostatic pressure?

A

The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.

69
Q

What is Starling equilibrium?

A

The point at which inward and outward pressure are equal and there is no net fluid movement

70
Q

How is lymph circulated?

A

Peristaltic contractions move lymph along the lymphatic vessels and valves prevent back flow

71
Q

What is Hyperaemia?

A

Increased blood flow

72
Q

What is Ischemia?

A

Lack of blood flow

73
Q

What is Active Hyperaemia?

A

The increase of blood flow due to increase metabolic rate

74
Q

Following Ischemia, ________ occurs when flow is re-established. This is called___________

A

Hyperaemia occurs and we call this Reactive Hyperaemia

75
Q

What metabolites cause Vasoconstriction?

A

O2 (except in pulmonary circuit)

Glucose

76
Q

What metabolites cause Vasodilation?

A

K+ in low doses
CO2 (except in pulmonary circuit)
Adenosine
H+

77
Q

What is Angiogenesis?

A

The formation of new blood vessels

78
Q

Increasing sympathetic tone ________ vascular smooth muscle

A

constricts

79
Q

Vaso-constriction _________ total peripheral resistance

A

Increases

80
Q

Veno-constriction __________ venous return

A

Increases

81
Q

Vaso- and Veno-Constriction are controlled by the __________ nervous system

A

Sympathetic

82
Q

Most sympathetic fibers release _________ that acts on the __________ on the smooth muscle producing contraction

A

Noradrenaline which acts on the alpha receptors

83
Q

What affect does the parasympathetic nervous system have on the control of blood vessels

A

Not much, most vessels are not innervated by the parasympathetics

84
Q

Sympathetic stimulation _______ cardiac contractility

A

Increases

85
Q

Parasympathetic stimulation _________ cardiac contractility because ____________

A

Has little effect on contractility because the ventricles are not innervated by parasympathetic fibers

86
Q

Venous return provides ________ regulation of the cardiac contraction

A

Intrinisic

87
Q

Intrinsic regulation gives a _______________________

A

Constant ejection fraction

88
Q

What are some extrinsic regulators of cardiac contraction?

A

Autonomic stimulation
Drugs
Hormones

89
Q

Ionotropic Agents alter _________________________

A

The contractilitiy of the heart

90
Q

Increased Ionotropy causes_______________

A

an icrease in the ejection fraction

91
Q

Sympathetic nerve stimulation to the heart is a _________ and a _________ agent

A

Ionotropic and Chronotropic

92
Q

Adrenaline is a _________ and a _________ agent when stimulating the heart

A

Ionotropic and Chronotropic

93
Q

Sympathetic nerves innervate the __________ and stimulate positive ___________ and _________ actions

A

The whole heart and stimulate positive Chronotropic and Ionotropic actions

94
Q

Baroreceptors are sensitive to changes in __________ and can be found in _______ and ______ arteries

A

Central Arterial Pressure and can be found in the aorta and carotid

95
Q

Aortic baroreceptors are _____ sensitive than carotid baroreceptors

A

less

96
Q

Outline the Cardiac Baroreceptor reflex:

A
  1. Central arterial pressure is low
  2. Decrease in parasympathetic tone to the heart increases heart rate
  3. Increase in sympathetic tone to the heart increases heart rate
  4. Sympathetic increase contractility and stroke volume
  5. Increased cardiac output and blood pressure
97
Q

Outline the Vascular Barororeceptor reflex:

A
  1. Central arterial pressure is low
  2. Increase in vasotone and total peripheral resistance (coronary and cerebral circulation largely unaffected)
  3. Increased venous tone and return
  4. Increased stroke volume and cardiac output
  5. Increased Blood Pressure
98
Q

How does ADH increase blood pressure?

A
  1. Decreased BP leads to ADH secretion
  2. ADH increases resorption of water which increases blood volume
  3. Causes Vasoconstriction and increases total peripheral resistance
  4. Blood pressure increases
99
Q

What is the Central Ischemic Response?

A

A response activated when the blood supply to the brain is decreased and blood pressure drops below 60 mmHg.
It mimics the baroreceptor reflex but is much more potent, can raise pressure to 200 mmHg and block blood flow to everything except brain, heart and lungs

100
Q

How is blood flow to skeletal muscles controlled?

A

During excercise local metabolites controls the flow via vaso- constriction/dilation. Flow can increase to about 15-20L/min

101
Q

The heart receives ___% of Cardiac Output. During systole flow _______ and during flow______

A

5%, flow stops, flow occurs

102
Q

_________ is an important metabolite in coronary flow . _________ and _________ have little effect on coronary flow

A

Adenosine

Sympathetic stimulation and hormones

103
Q

What does Autoregulation of blood flow do?

A

Keeps blood flow constant as pressure changes

104
Q

What is the myogenic mechanism of autoregulation?

A

Pressure stretches smooth muscle and it contracts in response, this causes an increase in resistance

105
Q

Fall in blood pressure ________ blood vessels and maintains flow

A

dilates

106
Q

Increase in blood pressure ________ arterioles which keeps capillary flow and pressure constant

A

constricts

107
Q

Cerebral blood flow maintains constant from ___mmHg to ___mmHg

A

60mmHg to 160mmHg

108
Q

Increasing skin blood flow _________ heat loss

A

increases

109
Q

Decreasing skin blood flow _________ heat loss

A

decreases

110
Q

A large fall in temperature (to temperatures

A

Increases

111
Q

___________ sympathetics activate sweat glands. Sweat glands release _________ a potent vasodilator

A

Cholinergic, Bradykinin

112
Q

What is heat exhaustion?

A

When the cardiovascular system is unable to supply blood to both working muscles and the skin

113
Q

What is heat stroke?

A

When the body is unable to cool and temperature rise until death occurs

114
Q

Blood vessels constrict when exposed to ________

A

Cold

115
Q

Blood vessels relax when exposed to ________

A

Heat

116
Q

Explain the 3 ways blood flow to the skin is regulated when temperature changes

A
  1. Vessels dilate when warm and contract when cold
  2. Sensory nerves measure skin temperature and activate the reflex control of sympathetics via the Hypothalamus
  3. Hypothalamus measures core temperature and controls sympathetic nerves to the skin

Physiology 2001 (7 decks)

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