1) CVS Intro & Histology

Question 0

Rate of diffusion is affected by?

Answer 0

AREA (capillary density varies between tissues and perfusion controlled by sphincters) RESISTANCE (Size and polarity of molecule, size or pore, length of path) CONC GRAD+ (Depends on rate of usage, perfusion rate through capillary bed)

Question 1

Briefly describe the movement of different types of molecules in the vascular system

Answer 1

• Via diffusion at capillaries between endothelial cells (simple squamous) and intracellular spaces - O2 and CO2 can diffuse freely across - Hydrophilic (glucose, lactate, AA) diffuse through small pores - All move along their diffusion grad+ - time for diffusion is proportional to distance2

Question 2

Briefly describe how the perfusion rates at diff organs in the body vary

Answer 2

• Brain & Kidneys HIGH, CONSTANT AND ABSOLUTE (0.75 & 1.2L/min) - Skeletal muscle and cardiac muscle increase during VPA - GI and skin vary and are reduced during VPA - total 5L/min

Question 3

Describe capacitance in the vascular system

Answer 3

• acts as a blood STORE to cope with increased CO - regulates temporary imbalances to the heart - veins have thin distensible walls that can collapse easily and act as a reservoir of blood

Question 4

% blood distribution in the body?

Answer 4

67 Veins 17 heart and lungs 11 arteries and Arterioles 5 capillaries

Question 5

Describe the structure of arteries

Answer 5

• elastic conducting - expand with the heart on contraction - thick muscular walls - branch into Arterioles to regulate flow - controlled via ANS

Question 6

Describe the structure of capillaries

Answer 6

• single cell thick - continuous or fenestrated (pores) - sinusoids are larger and contain an incomplete basal lamina to allow WBCs to fit through in liver, spleen and at bone marrow - Pericytes can divide into muscle/fibroblasts during angiogenesis

Question 7

Describe the structure of veins

Answer 7

• thinner walls, wider lumen - valves to prevent back flow - distensibility - muscle pumping

Question 8

Describe the histological layers of blood vessels

Answer 8

• Tunica INTIMA, endothelial narrow CT and discontinuous internal elastic lamina - Tunica MEDIA, 40-70 fenestrated elastic membrane with SM and collagen - Tunic ADVENTITIA, fibroelastic CT with ‘Vasa vasorum’ lymph and nerves. SM in larger veins

Question 9

Describe the pericardial layers and their innervation

Answer 9

• Phrenic nerve (C3-5) passes over pericardium on its course to innervate the diaphragm - Fibroserous sac - OUTER FIBROUS LAYER - PARIETAL LAYER - PERICARDIAL FLUID (lubricant) - VISCERAL/EPICARDIAL LAYER

Question 10

Describe the attachments of the pericardium

Answer 10

Anchored at - sternum - diaphragm - tunica adventitia of great vessels - mediastinal portions of left and right pleurae

Question 11

What is the function of the pericardium?

Answer 11

Prevent heart from overfilling (inextensibility) Protect from infection (physical barrier) Frictionless movement

Question 12

What is the function of the papillary muscles?

Answer 12

Project into ventricles forming CHORDAE TENDINAE These attach to the tricuspid and mitral valves Tighten during contraction to help keep valves closed (prevents inversion) Prevents regurgitation and outflow through pulmonary and aortic valves only

Question 13

What are the branches of the aorta and the area they supply? (Medial to lateral)

Answer 13

• Brachiocephalic (R arm and R side of head and neck) - LCC (L side of head and neck) - LSC (L arm)

Question 14

What is the transverse pericardial sinus and what is its use?

Answer 14

-separates the outflow vessels (aorta and PT) -bypass during heart surgery

Question 15

What is cardiac tamponade, give a possible cause and it’s treatment and what would hear on auscultation? When is there an exception to this outcome?

Answer 15

• pericardial effusion, accumulation of fluid within pericardial cavity leading to compression of the heart itself due to inextensibility of pericardium, leading to reduced CO) - hypothyroidism, physical trauma, pericarditis, iatrogenic, post-op - pericardialcentesis (aspiration of fluid) - only when rapid, if effusion is slow then the pericardium is able to expand to accommodate the extra fluid - muffled sounds on auscultation

Question 16

Show the areas in which the sounds of the heart valves can be best heard

Answer 16

Question 17

Describe what makes up the 4 borders of the heart

Answer 17

Right border – Right atrium

Inferior border – Left ventricle and right ventricle

Left border – Left ventricle (and some of the left atrium)

Superior border – Right and left atrium and the great vessels