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Physiology > Circulatory System > Flashcards

Circulatory System Flashcards

1
Q

The blood is carried through the lungs. In the lungs the blood like a sponge sucks in oxygen from the inspired air.

A

Pulmonary Circulation

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2
Q

This oxygen is then carried in a “sponge” to all tissues. In the tissues the “sponge is soaked” and oxygen is released into tissues. The path from the heart into the tissues and back supplies all systems with oxygen, hence the name: systemic circulation.

A

Systemic circulation

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3
Q

What is blood pressure?

A

Blood pressure is the force of blood pushing against blood vessel walls

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4
Q

Where are the two receptors for blood pressure (Pa)?

A 
Carotid arteries (external, internal and common)
Aortia
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5
Q

The Pa (BP) sensors are ____ receptors

A

Stretch

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6
Q

How can fainting from low BP be alleviated?

A

Massaging the carotid sinuses

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7
Q

The right half of the heart pumps blood through the _____ circulation and the left half of the heart pumps blood through the ____ circulation.

A

Pulmonary

Systemic

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8
Q

Path of blood in the the pulmonary system

A

Carries blood from the right ventricle through the pulmonary arteries to the lungs, and back to the left atrium through the pulmonary veins

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9
Q

What are the major functions of the pulmonary system?

A

Oxygenate the blood and release CO2 into air. The process occurs in the smallest blood vessels, the capillaries

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10
Q

What are the smallest blood vessels?

A

Capillaries

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11
Q

How does oxygen enter into and CO2 leave the blood?

A

Following the concentration gradient, O2 diffuses from the air through the capillary wall into blood where it binds to hemoglobin contained in RBC’s; CO2 diffuses in the opposite direction-from the blood into the air

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12
Q

Path of blood in systemic circulation

A

carries oxygenated blood from the left ventricle via large artery, the aorta, to all body organs except the lungs. The aorta distributes blood through a number of arteries-> arterioles-> capillaries. Capillaries then unite to form larger diameter vessels, venules-> veins->two large veins, the inferior vena cava and superior and vena cava right->carries deoxygenated blood to the right atrium

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13
Q

What is the major function of the systemic system?

A

to deliver oxygen and nutrients to tissues and to remove carbon dioxide and metabolic end products from them. These processes take place in capillaries.

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14
Q

What are the two sets of valves in the heart?

A 
atrioventricular valves (separate atriums and ventricles)
semilunar valves
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15
Q

The right AV valve is also known as the ____.

The left AV valve is also known as the _____.

A

Tricuspid

Bicuspid or mitral

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16
Q

Papillary muscles connect the AV valves to what?

A

The ventricular walls

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17
Q

Papillary muscles contract when?

A

The ventricular walls contract

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18
Q

The function of the papillary muscles is to:

A

Pull the vanes of the atrioventricular valves toward the ventricles in order to prevent the valves from bulging backward during ventricular contraction

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19
Q

What mechanism controls the opening and closing of the AV valves?

A

Passive process from pressure on across the valves

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20
Q

What causes the “lubb” heart sounds

A

Closure of the atrioventicular valves

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21
Q

What causes the “dubb” heart sounds

A

Closure of the semilunar valves

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22
Q

Cardiac muscles are ____x shorter than skeletal muscle and ____x smaller in diameter than skeletal muscle

A

3000

6

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23
Q

The resting membrane potential of the cardiac muscle

A

-90

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24
Q

Longitudinally adjacent muscle cells are separated by membranes called

A

intercalated discs

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25
Q

Cardiac muscle is said to be a ____of many individual muscle cells, so that when one muscle cell fires an action potential, the action potential could spread to all the cells, jumping from cell to cell through gap junctions.

A

syncytium

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26
Q

interconnected muscle cells forming the walls of two atria constitute

A

atrial syncytium

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27
Q

interconnected muscle cells forming the walls of two ventricles constitute

A

ventricular syncytium.

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28
Q

The heart is composed of two syncytia called:

A

atrial and ventricular syncytium

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29
Q

The atrial syncytium is separated from the ventricular syncytium by:

A

fibrous tissue that does not conduct electrical current

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30
Q

Action potential can be conducted from atrial syncytium to ventricular syncytium only by way of;

A

bundle of his (AV bundle)

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31
Q

Electrical pathway of the heart:

A

Sinoatrial node (cardiac pacemaker) ->wall of atria and internodal pathways that lead to the
AV Node/Bundle of His->
Purkinje Fibers

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32
Q

Speeds action potentials in electrical pathways of the heart:

A

SA node=1 m/s
AV node/bundle of his=0.05 m/s (causes a delay which allows atria to contract and empty its contents into the ventricles)
Purkinje fibers=3m/s
ventricular muscle fibers=.4m/s

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33
Q

Ventricles contract from:

A

The apex up

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34
Q

The cardiac muscle action potential is how long?

A

300 ms

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35
Q

Why is the action potential of the cardiac muscle so long?

A

The initial 1ms is comprised of an inward flow of sodium, but the plateau phase is sustained by the inward flow of calcium.

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36
Q

ECG

A

, the voltmeter connected to the surface of the body should measure voltage drop created by current flowing from one part of the heart to the other in the conductive medium surrounding the heart

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37
Q

P wave

A

spread of depolarization through atria and beginning of atrial contraction

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38
Q

QRS complex

A

corresponds to spread of depolarization in ventricles and beginning of ventricular contraction

39
Q

T wave

A

Repolarization of ventricles, i.e. decrease of the cell membrane potential to its resting value is responsible for T wave. The ventricles remain contracted until a few milliseconds after the end of repolarization

40
Q

Systole

A

Heart cycle is separated in two phases based on the events in ventricles. The period of ventricular contraction, from S to the T-wave=

41
Q

Diastole

A

The period of ventricular relaxation, from T wave of one heart cycle to S of a consequent heart cycle is called

42
Q

cardiac muscle cells use _____ as a source of energy

A

oxidative phosphorylation

43
Q

a disease of the arterial wall characterized by the development of localized plaques protruding into the lumen of the artery. The plaques are present to a small degree in adolescence, but increase in size and number with age. Their development is facilitated by smoking, hypertension, high blood cholesterol, and diabetes.

A

Atherosclerosis

44
Q

Thrombus

A

Blood clot

45
Q

Two problems that may result in ischemia:

A
  1. atherosclerotic plaques decrease blood flow through an artery
  2. the thrombus (blood clot) forms. Thrombus could grow on a plaque within minutes. When it is big, it detaches and is carried away by blood flow
46
Q

Way to resolve atherosclerotic plaque:

A

Stent

47
Q

How can a myocardial infarction be detected?

A

On ECG by the shift of S-T segment and confirmed by measuring plasma concentration of enzymes released by infarcted tissue.

48
Q

The dying cardiac muscle can become an ectopic pacemaker.

It could cause ventricles to beat rapidly and independently of atria

A

Ventricular fibrillation

49
Q

Ventricular fibrillation is caused by:

A

An action potential traveling in circles through the cardiac tissue.

50
Q

Cardiac output is measured by:

A

Heart rate X stroke volume

51
Q

Stroke volume is controlled by:

A

End diastolic volume (Frank Starling’s Law)

SNS-via NE/Epi

52
Q

How does control of stroke volume by SNS work?

A

A)Increased SNS (NE/Epi) ->Increased contractility (power of contraction) -> at the same end-diastolic volume, contraction is more powerful
B)Reduce the duration of contraction and relaxation by increasing conduction velocity in the atrioventricular node

53
Q

ventricular fibrillation

A

The dying cardiac muscle can become an ectopic pacemaker.

It could cause ventricles to beat rapidly and independently of atria.

54
Q

What is the life-threatening consequence of myocardial infarction?

A

Ventricular fibrillation

55
Q

How does ventricular fibrillation becomes “its own ectopic pacemaker”

A

Fibrillation is caused by an action potential traveling in circles through the cardiac tissue. Short action potentials allow some muscle cells to quickly emerge from refractory period and recycle action potentials.

56
Q

How does defibrillation work?

A

The electrical shock depolarizes all cardiac muscle cells at the same time causing them to synchronize again.
The sinoatrial node can assume pacemaker function again and the heart can start pumping normally

57
Q

Cardiac Output

A

Heart Rate x Stroke Volume (i.e.72 bpm x 0.07 L/b=5 L)

58
Q

Cardiac output can increase __xduring exercise

A

5x

59
Q

Stroke volume is controlled by the SNS or PNS?

A

SNS

60
Q

How does SNS control the stroke volume?

A

A) Increase contractility (power of contraction) -> at the same end-diastolic volume contraction is more powerful B)Reduce the duration of contraction and relaxation by increasing conduction velocity in the atrioventricular node

61
Q

How is blood flow redistributed?

A

blood flow is regulated by smooth muscles on arterioles and by precapillary sphincters

62
Q

Precapillary sphincters tension is decreased (and blood flow in muscles is increased) by:

A

1) decrease in partial pressure of oxygen (PO2)
2) PCO2
3) increase H+ (from lactic acid)
4) increase of osmolarity (one Glucose molecule->glycolysis in fast muscles->2 lactic acid molecules)
5) increase of [adenosine]

63
Q

Central regulation of SNS

A

Smooth muscles of precapillary sphincters have NE receptors:
1)NE increases smooth muscle tension->blood flow ↓
2)NE ↓ blood flow
Vasopressin (=antidiuretic hormone) ↓ b.f.
Angiotensin II ↓ b.f.
nitric oxide (NO) ↑ b.f.
Atrial naturatic enzyme ↑ b.f.

64
Q

Explain shock:

A

high NE
high Angiotensin II
but high Nictric Oxide (Pneumonia, meningitis cause cells to synthesize NO
Vasopressin is initially high but is released completely over 2 hours (by pituitary gland)
Dramatic reduction of vasopressin
-smooth muscles of precapillary sphincters relax
- Pa plunges
-lack of O2 in the brain
-death

65
Q

How is BP kept constant?

A

Both (1) changes in cardiac output and (2) blood flow redistribution due to regulation by smooth muscles on arterioles and smooth muscles in precapillary sphincters keep Pa=const

66
Q

Capillaries are very leaky except where?

A

The brain-blood brain barrier

67
Q

What are the only molecules that can diffuse through the walls of the capillaries in the brain?

A

Only nonpolar, noncharged membrane-permeable molecules

68
Q

Why is heroin more potent than morphine?

A

Morphine is polar and heroin is non-polar. Therefore, heroin can more easily cross the blood brain barrier

69
Q

Drugs that can go through the blood brain barrier:

A 
Heroin
Barbiturate
Nicotine
Caffeine
Alcohol
70
Q

What ensures one way flow of blood in veins?

A

Valves-need to walk/move in order for valves to work

71
Q

At rest, 70% of the blood is where?

A

Veins

72
Q

Purpose of lymph nodes:

A

The lymphatic vessels also ferry antigens (substances capable of inducing an immune response) from the tissues to lymph nodes, where they are presented to immune cells.
Lymph nodes act as filters that trap foreign particles.
They contain white blood cells.
On detecting a problem, such as an injury or an infection in the tissue, the immune cells activate and migrate to the affected tissue to try to resolve the problem.
During an infection lymph nodes are enlarged.

73
Q

Speed of blood flow in arteries, capillaries and veins

A

Notice, that the blood is quickly propelled through the arteries at an average speed of 25cm/s, slowed down in capillaries of the hand to a speed less than 1cm/s, and accelerated again to average speed of 15cm/s in veins.

74
Q

Large number of ____ are inserted into intercalated discs. They provide a low resistance path for electrical current to travel between the cells.

A

Gap junctions

75
Q

Why are there gap junctions in cardiac cells?

A

This allows action potential to travel from one muscle cell to another, past the intercalated discs, with minimal delay.

76
Q

Similarities between cardiac and skeletal muscles?

A 
Oxidative phosphorylation
T-tubules 
Both stimulated by action potentials
Both are striated 
Calcium from the sarcoplasmic reticulum
77
Q

Differences between cardiac and skeletal muscles?

A
  1. 3,000-times shorter than skeletal muscle: 100µm vs. ~30cm
  2. 6-times smaller diameter than skeletal muscle: 15µm vs. 100µm
  3. Predominantly contain only one nucleus, although populations with two to four nuclei do exist
  4. Have several branching processes
    Contain intercalated discs which contain gap junctions
    Cardiac muscles act in syncytium
78
Q

What waves are measured in an ECG?

A

depolarization wave and repolarization wave

79
Q

SNS activation of smooth muscles increases____->increases venous return-> increases cardiac output.

A

venomotor tone

80
Q

How can venous return impacted by constricting the chest?

A

Example: hyperventilate->reduce [CO2] -> constriction of blood vessels -> reduction of blood supply to the brain -> compress chest -reduce venous return ->reduction in cardiac output -> reduction of blood flow in the brain -> fainting

81
Q

Plasma by weight

A

91% H2O
2% other solutes (urea, K+, Na+, bicarbonate, …)
7% plasma proteins:

82
Q

RBC lifepsan

A

120 days

83
Q

Plasma color is due to ___ - a waste product of hemoglobin breakdown.

A

bilirubin

84
Q

Why do RBC’s have a donut shape?

A

Gases diffusion:
Gas exchange occurs passively by diffusion (Brownian motion). In a sphere, gas exchange is slow.
In a donut, gas exchange is much quicker.
Many capillaries are smaller than 7.5 micron in diameter.
Donut shaped RBCs behave like paper: they bend
Spherical cells, on the other hand, have maximum volume for their surface area: they cannot be deformed

85
Q

Electrical current goes from the SA node to the wall of the atria at a speed of___

A

0.3 m/s

86
Q

Small specialized muscle bundles that connect sinoatrial and atrioventricular nodes

A

Internodal pathways

87
Q

HR is controlled by:

A

PNS and SNS innervation of SA node.

88
Q

Perfusion to the muscles must increase ___fold during peak muscle performance

A

30

89
Q

How do you accomplish an increase of 30 fold during peak muscle performance?

A

The vascular system must redistribute blood flow from nonessential organs to skeletal muscles during heavy exertion activity.

90
Q

What do lymphatic muscles do?

A

remove toxins and other waste materials (called lymph)

ferry antigens from tissues to lymph nodes where they are presented to immune cells

91
Q

Lymph nodes contain ____ cells

A

white blood

92
Q

What happens if lymph nodes are blocked?

A

Elephantiasis

93
Q

Where is e. coli found on the human body?

A

The intestines

94
Q

Most e. coli is harmless, but some strains are pathogenic and cause diarrheal illness. T/F?

A

True

Physiology (8 decks)

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