Histology of the heart

Question 1

what are the layers of the heart inside the parietal pericardium

Answer 1

epicardium
myocardium
endocardium

Question 2

what is the epicardium(5)

Answer 2

single layer squamous tissue
underlying connective tissue and fat
nerves (vagus and sympathetic)
coronary arteries which penetrate the myocardium

Question 3

what is the myocardium and where is it thickest

Answer 3

relay of specialised cells
intercalated discs
gap junctions
thickest in L ventricle

Question 4

what is heart endothelium (endocardium)

Answer 4

flattened endothelial cells
layer of supportive “tissue F” containing many elastic fibres which are continuous with connective tissue around myocytes and valves

Question 5

do heart valves have any muscle

Answer 5

no

Question 6

describe the tissue of heart valved

Answer 6

continous from the endothelium
less elastic, more dense collagen
LAMINA FIBROSA

Question 7

re: tissue, why is it easier for blood to flow one way rather than the other through the aortic and pulmonary valves

Answer 7

3 layers of tissue:
ventricularis (elastic fibres, loose collagen)
spongiosa (proteoglycans and loose collagen)
fibrosa (dense and tough collagen)
makes it harder for backflow

Question 8

where is the SAN located

Answer 8

between superior vena cava and right atrium

Question 9

what staining is good to see specialised myocytes

Answer 9

trichrome

Question 10

what colour are specialised myocytes when stained with trichome

Answer 10

pale pink

Question 11

what does trichrome stain

Answer 11

connective tissue - blue
myocytes and AVN SAN pale pink

Question 12

what are Purkinje fibres

Answer 12

massive myocytes

Question 13

what are Purkinje fibres not

Answer 13

nerves

Question 14

where is the AVN and why

Answer 14

embedded in connective tissue to delay the electrical signal getting to the ventricles

Question 15

what organelles do PUrkinje fibres have a lot of

Answer 15

mitochondria

Question 16

what do chordae tindinae attach to

Answer 16

T and M valves and papillary muscles

Question 17

where are elastic fibres on ELASTIC arteries

Answer 17

tunica intima AND adventitia

Question 18

How big are elastic arteries

Answer 18

> 10mm

Question 19

how big are muscular arteries

Answer 19

0.1-10mm

Question 20

describe the make-up of muscular arteries

Answer 20

fewer elastic arteries, more myocytes

Question 21

what do muscular arteries have a leading role in

Answer 21

vasoconstriction

Question 22

describe arterioles - size, constituents

Answer 22

<30um, 1-2 layers smooth muscle

Question 23

what are the 3 types of capillaries

Answer 23

continuous
fenestrated
discontinuous

Question 24

where are fenestrated capillaris

Answer 24

kidney, endocrine, synovial

Question 25

where are discontinuous capillaries

Answer 25

liver, spleen, bone marrow

Question 26

what are sinusoids

Answer 26

another name for discontinous capillaries

Question 27

what is the role of arterioles

Answer 27

resistance, slows blood down so doesn’t damage capillaries

Question 28

how do you recognise lymphatics

Answer 28

looks like a tear in the tisue; no red blood cells
have valves

Question 29

what is plasma

Answer 29

blood without cells

Question 30

what is serum

Answer 30

plasma without clotting factors or fibrin

Question 31

what is the cellular makeup of blood

Answer 31

99% RBC
1%platelets and WBC

Question 32

what is the makeup of plasma

Answer 32

90% water
7% albumin, IG and fibrinogen
3%solutes inc. gases

Question 33

What are the signs of tamponade

Answer 33

Beck’s triad: elevated JVP, muffled heart sounds, tachycardia

Question 34

What are the signs of tension pneumothorax

Answer 34

Tachycardia, elevated jvp, absent breath sounds