Lecture 14: Cardiovascular System

Question 1

what are the valves of the heart

Answer 1

atrioventricular
- bicuspid (left atrium) 
- tricuspid (right atrium)
semilunar
- pulmonary 
- aortic

Question 2

what is the rate of contraction modified by

Answer 2

• sympathetic nervous system increases heart rate
• parasympathetic nervous system decreases heart rate
  together forms the cardiac plexus

Question 3

what are the layers of the heart wall

Answer 3

• epicardium, visceral pericardium
• myocardium, thickest layer, cardiac muscle
• endocardium, innermost layer that lines the chambers of the heart

Question 4

what are the microstructure features of cardiac muscle

Answer 4

• striated appearance
• branching pattern
• normally 1 nucleus per cell
• intercalated discs made up of fascia adherens, desmosomes and gap junctions

Question 5

what are the lobes of the left lung

Answer 5

• 2 lobes
• oblique fissure
• has a cardiac notch for the heart
• has a lingula (tongue)

Question 6

what are the lobes of the right lung

Answer 6

• 3 lobes

- horizontal and oblique fissure

Question 7

what is the smooth muscle like microscopically

Answer 7

• not striated
• spindle shaped
• one single central nucleus

Question 8

what does the endothelium look like microscopically

Answer 8

• monolayer of squamous epithelial cells

- covers entire vascular system

Question 9

functions of the endothelium

Answer 9

• control vascular tone and vessel diameter
• regulate permeability
• angiogenesis
• regulate clotting
• regulate immune response

Question 10

what are the layers of blood vessel tissue from innermost to outermost

Answer 10

• tunica intima, connective tissue
• tunica media, connective tissue: elastic and collagen fibres
• tunica externa/adventitia, outer connective tissue layer, primarily collagenous

Question 11

features of capillaries

Answer 11

• one endothelial layer
• no tunica media or externa, only one cell thick
• are fenestrated (porous)

Question 12

features and function of venules

Answer 12

• progressively increase lumen diameter
• no elastin
• very thin tunica media and externa
• drain capillary beds

Question 13

what are venous valves

Answer 13

• inner projection of tunica intima, strengthened by elastin and collagen fibres
• semi lunar cusps
• absent in thorax and abdomen
• dilation of veins can mean valves don’t close, resulting in varicose veins

Question 14

what is the relationship between arteries and veins

Answer 14

• big arteries are associated with a single vein, eg aorta, axillary and femoral arteries
• smaller ones are flanked by 2 arteries enclosed in a sheath
• superficial veins do not have corresponding arteries

Question 15

what factors aid the return of blood against gravity

Answer 15

• valves
• arteriovenous pumps: pulsation of the artery aids venous return
• musculovenous pumps: skeletal muscle contraction compresses vein

Question 16

what is anastomosis

Answer 16

• when an artery connects directly to another artery or a vein connects directly to another vein
• creates uninterrupted circulation, eg around joints
• require time to open sufficiently
• can provide collateral circulation

Question 17

what is the hepatic venous portal system

Answer 17

• venous blood is high in the products of digestion
• veins from the spleen, stomach and intestines drain into the liver via the hepatic portal vein
• filtered by the liver, blood then drains into the hepatic veins and inferior vena cava to be returned to the heart