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Body Logistics > 8. Cardiovascular & Muscle > Flashcards

8. Cardiovascular & Muscle Flashcards

1
Q

How much blood does the average human have, and what is its composition?

A

5L of blood. 2L of plasma and 3L erythrocytes.

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2
Q

Where does most of our blood lie ?

A

65% in our capillaries
20% heart and lungs
10% peripheral arteries
5% capillaries

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3
Q

What are the major arteries which supply the heart and where do they stem from?

A

The L and R coronary arteries which emerge from the aorta and divide further to supply the heart.

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4
Q

What is the only proper example of an absolute end artery?

A

Central artery to the retina

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5
Q

What are end arteries?

A

When a terminal artery supplies all or most of the blood to a body part without significant collateral circulation
E.g splenic artery, renal arteries, cerebral arteries and coronary arteries.

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6
Q

What develops in response to stenosis or blockage of an end artery?

A

Branching of the arteries to build collateral circulation.

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7
Q

Where is the tricuspid valve?

A

Right atrioventricular valve

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8
Q

Where is the mitral valve?

A

Left atrioventricular valve

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9
Q

What is the significant of atrioventricular delay?

A

The AV node delays nerve impulses to the ventricles to allow them to fill before stimulating contraction

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10
Q

What branches from the brachiocephalic trunk?

A

The right subclavian artery and the R carotid artery

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11
Q

What happens during systole?

A

The left ventricle contracts, causing blood pressure in the aorta to rise to 120 mmHg. The aortic walls stretch, elastic properties.

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12
Q

What happens during diastole?

A

The aortic semilunar valve closes and the aortic walls recoil, pressure drops to 80 mmHg.

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13
Q

Which layer of the arteries contains smooth muscle?

A

Tunica media

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14
Q

How do elastic arteries act as ‘pressure resovoirs’ or capacitor vessels?

A

During diastole, they act as auxiliary pumps, giving back the elastic energy stored during systole.

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15
Q

What is an aneurysm and where is the commonist site and why?

A

Dilation of a blood vessel. Most common in the infrarenal abdominal aorta because the junction of suprarental and infrarenal aorta contains less elastic fibres, making it weaker.

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16
Q

What is in the tunica adventitia?

A

Connective tissue containing lymphatic vessels, nerve fibres and vasa vasorum (blood vessels)

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17
Q

What is the different between arteries and arterioles in terms of their smooth muscle layer?

A

In tunica media of arteries there are 40 layers of smooth muscle, only 1-2 in arterioles

18
Q

What structure regulates the flow of blood to the capillary beds?

A

Pre-capillary sphincters open and close to increase and reduce blood flow to the capillary beds.

19
Q

How is blood flow regulated in arteries?

A

Most arteries can dilate 60-100% of their resting diameter. This can direct blood flow to where it is most needed. E.g during exercise increased blood flow to skeletal muscle.

20
Q

Outline the structure of capillaries and how this is related to their function.

A

Single layer of endothelium and its basement membrane - think barrier for diffusion.
Large SA
small lumen - RBC’s virtually fill the entire lumen

21
Q

Where are pericytes found?

A

They form a branching network on the outer surface of the endothelium in capillaries and postcapillary venues.

22
Q

What are the properties of pericytes?

A

Capable of dividing into muscle cells and fibroblasts during angiogenesis, wound healing and tumour growth.

23
Q

What is the role of post-capillary venules?

A

Receive blood from the capillaries and are even more permeable than capillaries with a lower pressure, so fluid is drawn into them.
They are the preferred location for leukocyte emigration from the blood.

24
Q

Explain how veins act as capacitance vessels.

A

Capacitance is inversely proportional to elasticity. Veins have thin NON-ELASTIC so they can stretch a great deal but do not recoil.
Ability of the vessels to increase the volume of blood without increasing blood pressure.

25
Q

What are 3 mechanisms which help venous return to the heart from the legs?

A
  1. Calf muscle pump
  2. Pressure changes in the thorax act as a ‘vacuum’ by increasing and decreasing atrial pressure
  3. One-way valves in veins of lower limbs, upper limbs and heart
26
Q

Which veins contain NO valves?

A

Intrabdominal, intrathoracic and neck veins

27
Q

What does the frank starling curve represent?

A

Stroke volume of the heart increases in response to increased filling.
As sarcomeres are more stretched, due to more filling, they can pump more effectively…up to a certain point when ‘over-stretched’ and cannot contract.

28
Q

What is the consequence of calf muscle pump failure?

A

Venous hypertension

29
Q

Why does left ventricular heart failure lead to pulmonary oedema?

A

It will lead to a back up of blood in the pulmonary arteries which will increase hydrostatic pressure,

30
Q

Why is pulmonary oedema worse when lying flat?

A

More blood is returning to the heart

31
Q

A symptom of LVF is Orthopnea, what does this mean?

A

Shortness of breath when lying flat

32
Q

What are some causes of LVF?

A

Aortic stenosis - age related

Hypertension - increased ‘afterload’

33
Q

What are 3 indicators of muscle injury?

A 
Troponin 1 (cardiac muscle) - HF indicator 
Creatine Kinase (skeletal muscle, heart muscle) - MI indicator
Myoglobin
34
Q

What are some diseases caused by smooth muscle dysfunction?

A

Asthma, irritable bowel syndrome, primary hypertension

35
Q

What is the first symptom of right sided heart failure?

A

Pitting oedema around the ankles. Back up of blood in vena cava, increased venous hydrostatic pressure.

36
Q

What is the significance of fixed mottling?

A

indicated there is absolutely no circulation whatsoever, irreversible ischaemia.

37
Q

What normally happens in post-capillary venules?

A

Fluid enters the vessel, as they are much lower pressure

38
Q

What happens in post-capillary venules during infection?

A

Emigration of leukocytes and fluid

39
Q

When would you see skin staining?

A

Venous hypertension, as red blood cells leave the capillaries and iron is oxidised to stain skin - dark appearance.

40
Q

What does calf muscle pump failure cause?

A

venous hypertension

Body Logistics (12 decks)

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