S13) Cardiovascular System Flashcards Preview

ESA1: Body Logistics > S13) Cardiovascular System > Flashcards

Flashcards in S13) Cardiovascular System Deck (35)
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1
Q

What are the functions of the cardiovascular system?

A
  • Circulate and transport nutrients, hormones, O2 and CO2
  • Fight disease
  • Maintain homeostasis (temperature & pH)
2
Q

What are the components of the cardiovascular system?

A
  • Heart
  • Blood
  • Blood vessels
3
Q

What is pulmonary circulation?

A

Pulmonary circulation is a “loop” through the lungs where blood is oxygenated

4
Q

What is systematic circulation?

A

Systemic circulation is a “loop” through the rest of the body to provide oxygenated blood and receive deoxygenated blood

5
Q

An average adult has 5.0 litres of circulating blood.

Explain the distribution of this blood in the human body

A
  • 3.25 litres ⇒ veins
  • 1.0 litre ⇒ heart and lungs
  • 0.5 litres ⇒ peripheral arteries
  • 0.25 litres ⇒ capillaries
6
Q

What is collateral circulation?

A

Collateral circulation is the alternate circulation around a blocked artery or vein via another path, such as nearby minor vessels

7
Q

What is an end artery?

A

An end artery is a terminal artery supplying all or most of the blood to a body part without significant collateral circulation

8
Q

What happens when end arteries are occluded?

Why does this happen?

A
  • If occluded, there is insufficient blood supply to the dependent tissue
  • End arteries undergo progressive branching without the development of channels connecting with other arteries
9
Q

Identify some examples of end arteries

A
  • Coronary arteries
  • Splenic artery
  • Cerebral arteries
  • Renal arteries
10
Q

What happens during systole?

A

In systole, the left ventricle contraction causes the blood pressure in the aorta to rise to approx. 120 mm Hg (systolic pressure) and the walls of the aorta expand

11
Q

What happens during diastole?

A

In diastole, the aortic semilunar valve closes and the walls of the aorta recoil, causing pressure to drop to 80 mmHg (diastolic pressure), moving blood towards the heart and smaller vessels

12
Q

What are the three layers of arteries and veins?

A
  • Tunica intima
  • Tunica media
  • Tunica adventitia/externa
13
Q

What do smooth muscle cells do in blood vessel walls?

A

Produce elastin, collagen and matrix

14
Q

What is an aneurysm?

A

An aneurysm is a dilatation of a blood vessel

15
Q

Why are most abdominal aortic aneurysms infrarenal?

A
  • The mechanical tension in the abdominal aortic wall is higher than in the thoracic aortic wall
  • The diameter decreases from the root to the aortic bifurcation
  • The infrarenal aorta contains a less elastin
16
Q

Describe the properties of the tunica intima of muscular arteries

A
  • Endothelium
  • Subendothelial layer
  • Thick internal elastic lamina
17
Q

Describe the features of the tunica media of muscular arteries

A
  • Many layers of smooth muscle cells
  • Cells are connected by gap junctions for coordinated contraction
  • Prominent external elastic lamina
18
Q

Describe the features of the tunica adventitia of muscular arteries

A
  • Thin layers of fibroelastic connective tissue
  • Contains vasa vasorum, lymphatic vessels and nerve fibres
19
Q

What are arterioles?

A

Arterioles are arteries with a diameter of less than 0.1 mm

20
Q

Describe the wall of arterioles

A
  • Tunica intima: endothelial cells and subendothelial connective tissue
  • Tunica media: 1 layer of smooth muscle cells
  • Tunica adventitia: layers of fibroblasts
21
Q

What are metarterioles?

A

Metarterioles are arteries that supply blood to capillary beds

22
Q

What are precapillary sphincters?

A

Precapillary sphincters are individual muscle cells that each encircle the endothelium of a capillary arising from the metarteriole

23
Q

What do precapillary sphincters do?

A
  • Each smooth muscle cell is believed to function as a precapillary sphincter
  • They contract to control blood flow into the capillary bed (regulators)
24
Q

What do lymphatic capillaries do?

A

Lymphatic capillaries drain way excess extracellular fluid, returning it to the blood at the junctions of the internal jugular and subclavian veins

25
Q

Describe the role of arterioles during strenuous physical exertion

A
  • Blood flow to skeletal muscles is increased by dilation of arterioles
  • Blood flow to the intestine is decreased by constriction of arterioles
26
Q

Describe the role of arterioles after the ingestion of a large meal

A
  • Blood flow to intestine is increased by dilation of arterioles
  • Blood flow to skeletal muscles is decreased by constriction of arterioles
27
Q

Where is blood velocity at its lowest and why?

A

Blood velocity is lowest in the capillaries to allow time for gas and nutrient exchange with surrounding tissues

28
Q

What are pericytes and what do they do?

A

- Pericytes are cells which form a branching network on the outer surface of the endothelium

  • They can divide into muscle cells/ fibroblasts during angiogenesis, tumour growth and wound healing
29
Q

What do post-capillary venules do?

A

Post-capillary venules receive blood from capillaries (lower pressure, more permeable)

30
Q

Describe the general features of veins in relation to their accompanying arteries

A
  • Veins have a larger diameter
  • Veins have a thinner wall with more connective tissue
  • Veins have fewer elastic and muscle fibres in their walls
31
Q

Veins are also called capacitance vessels.

What is capacitance?

A

Capacitance is the ability of a blood vessel to increase the volume of blood it holds without a large increase in pressure (inversely proportional to elasticity)

32
Q

How does venous blood get from the legs back to the heart in a standing human?

A
  • Valves in the veins of the lower limbs that prevent the backflow of blood
  • The calf muscle acts as a pump for deep leg veins
33
Q

What is pulmonary oedema?

A
  • Pulmonary oedema is a condition wherein fluid accumulates in the lungs
  • It is often a consequence of congestive heart failure
34
Q

What is orthopnea?

A

Orthopnea is shortness of breath (dyspnea) that occurs when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair

35
Q

What is Paroxysmal nocturnal dyspnoea (PND)?

A

- PND refers to attacks of severe shortness of breath and coughing that generally occur at night

  • It usually awakens the person from sleep, and may be quite frightening