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Proefdiercursus 2022 > 5. Circulation > Flashcards

5. Circulation Flashcards

1
Q

What are the three buffer systems of the circulation?

A
  • phosphate system
  • carbonic acid/bicarbonate system
  • protein buffer

Together, they maintain a pH between 7.35 and 7.45 in the blood

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2
Q

What is the RBC stem cell?

A

A hemocytoblast

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3
Q

What does hemorrhage mean?

A

Bleeding

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4
Q

How does blood coagulation occur?

A

Blood coagulation occurs when a clot of insoluble fibrin is formed from fibrinogen. The transformation of fibrinogen is produced by the enzyme thrombin

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5
Q

How does the blood flow through a four chambered heart?

A

Oxygen-depleted blood enters the right atrium via the vena cavae and moves to the right ventricle by passing the tricupsid valve.

Right ventricle pumps blood through the pulmonary valve into the pulmonary trunk (pulmonary artery) from where it flows into the lungs

The now oxygen-rich blood travels via the pulmonary veins into the left atrium and to the left ventricle by passing the mitralis/mitral valve.

Left ventricle contracts to pump the same amount of blood through the aortic valve into the aorta from where it flows throughout systemic circulation.

Ventricle power/strength of the left ventricle thus has to be greater than the right ventricle

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6
Q

What are the four main blood vessels that enter or leave the heart?

A

Leave: aorta (oxygen-rich) and pulmonary valve (oxygen-depleted)

Incoming: vena cava caudalis and vena cava cranialis (both enter the right atrium

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7
Q

What is systole and diastole?

A

Ssystole is a cycle of contraction, diastole is a cycle of relaxation. The systole and diastole is performed by the myocardium

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8
Q

What are baroreceptors and what do they do?

A

Baroreceptors are located in the walls of arteries at strategic positions in the body. Over teh short term, if blood pressure falls, baroreceptor reflexes increase heart rate and force of contraction and promote vasoconstriction. The reverse happens if blood pressure rises.

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9
Q

What are chemoreceptors and what do they do?

A

Chemoreceptors respond to CO2. When CO2 rises and pH decreases, chemoreceptors transmit signals to the vasomotor center which excites it to produce vasoconstriction, this increases blood pressure. They also signal to the cardioaccelerator center which increases cardiac output –> more blood moves through the lungs and this allows the excretion of CO2 and the intake of CO2 to increase

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10
Q

What is the role of kidneys in blood pressure regulation?

A

IN mammals, kidneys alter the amount of water that is filtered from blood and excreted in ureine. Water loss in urine decreases the volume of blood and this in turn decreases blood pressure.

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11
Q

What are the four hormones that regulate urine volume?

A

angiotensin II
ADH
aldosterone
ANP

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12
Q

Which compounds are essential for the clotting process?

A

Calcium and vitamin K. Any deficiency in either of these may lead to clotting problems. Vit K is needed for the liver to produce prothrombin (inactive thrombin).

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13
Q

What is the function of the spleen?

A

It has a rich blood supply and acts as a reservoir of red blood cells. When there is a sudden loss of blood, as happens when a haemorrhage occurs, the spleen contracts to release large numbers of red blood cells into the circulation. The spleen also destroys old red cells and makes new lymphocytes but it is not an essential organ because its removal in adult life seems to cause few problems.

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14
Q

What is the vessel that carries blood to the main organs of the body?

A

Aorta

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15
Q

What is the vessel that carries blood to the brain?

A

Carotid artery

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16
Q

What is the vessel that carries blood to the kidneys?

A

renal artery

17
Q

What is the vessel that carries blood from the intestines to the liver?

A

hepatic portal vessel

18
Q

What is the vessel that carries blood to the heart muscle?

A

coronary artery?

19
Q

In haemostasis, which molecule polymerises to become the insoluble blood clot?

A

Fibrin. Fibrin is a monomer that polymerises to form a “soft clot”, then crosslinking between fibrin produces a stable, web-like “hard clot”.

20
Q

Which enzyme converts fibrinogen to fibrin?

A

Thrombin is the enzyme. It is not present until prothrombinase converts prothrombin to thrombin.

21
Q

In blood clotting, what activates “factor X”

A

Factor X is a plasma protein produced by the liver. In the extrinsic pathway, factor III combines with factor VII to form an “enzyme complex” that activates Factor X.

22
Q

The Frank-Starling law of the heart describes the proportional relationship between which of the following pairs?

A

The blood volume in the ventricles and stroke volume. States that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart. That is, stroke volume increases so that all the blood that enters the heart is pumped out.

23
Q

What will cause the sinoatrial (SA) node to depolarize more frequently?

A

Norepinephrine (released by the sympathetic nervous system) acting on the SA node increases heart rate and blood pressure. Parasympathetic stimulation along the vagus nerve decreases heart activity.

24
Q

How are cardiac cells mechanically attached to each other?

A

By their intercalated discs

25
Q

Which structure in the heart acts as a pacemaker?

A

The SA node, in the right atrial wall sets the pace of the heart rate = sino-atrial node

26
Q

What is the name given to the remnant of the opening in the foetal heart that allowed the foetal lungs to be bypassed?

A

The fossa ovalis is the slight depression that remains when the foramen ovale closes.

27
Q

In a normal ECG trace, what does a QRS wave indicate?

A

QRS is produced when the cells of the ventricles depolarise.

28
Q

What would be a possible consequence of the SA node failing to depolarise?

A

The heart rate will decrease. The SA node contains cells that will depolarise at a faster rate than others in the heart. If it fails, these other places will depolarise, but their rate will be slower than that of the SA node.

29
Q

What does an ECG display?

A

The ECG also displays the depolarisation of the atria (the P wave), the depolarisation of the ventricles results in the QRS wave.

30
Q

When listening to the “lub-dup” sound of the heart with a stethoscope, what is the cause of the “dup” sound?

A

The turbulent blood flow through closing semilunar valves. Turbulent blood flow generates audible sound that can be heard with a stethoscope placed on the skin above the heart. Such turbulent flow is produced when blood flow out of the heart is impeded by the cusps of the semilunar
valves as they close.

31
Q

Which capillaries are found in the brain?

A

The blood supply to the brain has continuous capillaries (in the blood-brain barrier)

32
Q

Which capillary type is found in the small intestine?

A

the SI has fenestrated capillaries (to facilitate absorption
of digestion products)

33
Q

Which capillary type is found in the liver?

A

the liver has sinusoids. Sinusoidal capillaries have gaps between the endothelial cells of their walls which are large enough to allow proteins to enter the blood.

34
Q

What is the advantage of having a wide lumen in veins?

A

It provides less resistance to the blood on its way to heart

35
Q

Which capillaries allow cells and plasma proteins to enter or leave their lumen?

A

Sinusoidal capillaries have some gaps between the adjacent endothelial cells (and a thin or absent basement membrane). The gaps are large enough for plasma proteins and some cells to pass through.

36
Q

By which muscles is vasoconstriction and vasodilation facilitated?

A

By smooth muscle cells. Contraction and relaxation of smooth muscle produces constriction and dilation of blood vessels. This is under the control of the sympathetic
nervous system.

37
Q

The wall of a capillary consists of one layer (or coat). What is it called?

A

Tunica intima. Tunica means “coat” while “intima” means inner most. In the case of capillaries this is the only tunica.

38
Q

Fenestrated capillaries permit the exchange of nutrients and wastes between cells and the blood because of which feature of their structure?

A

their endothelium has pores (windows) to allow the rapid movement of water and solutes. The pores (holes) in the endothelium allows passage of material through the capillary wall

Proefdiercursus 2022 (12 decks)

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