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Heart > 1.2 Histology of the cardiovascular system > Flashcards

1.2 Histology of the cardiovascular system Flashcards

1
Q

What is the function of the serous fluid?

A

To prevent friction when the heart is contracting within the thoracic cavity - lubricate

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2
Q

What is the structure & function of the fibrous pericardium?

A

a tough layer of CT continuous with the central tendon of diaphragm, non-distensible, prevents rapid overfilling of the heart
serious consequence e.g. cardiac tamponade

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3
Q

Where is the Transverse pericardial sinus?

A

posterior to ASCENDING aorta & pulmonary trunk
anterior to superior vena cava
superior to left atrium

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4
Q

What is cardiac tamponade?

A

Pericardial effusion can occur when there is accumulation of fluid within the pericardial cavity
heart becomes subjected to increased pressure, chambers become compressed, compromising cardiac output

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5
Q

Function of arteries & how they are classified?

A

carry blood away from heart to rest of body
classified as elastic (conduction) or muscular (distributing)
elastic arteries stretch during systole
muscular arteries branch into arterioles - control amount of blood into an organ/tissue by regulating blood pressure (constrict/dilate) - controlled by ANS

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6
Q

Name the groups of arteries from largest to smallest

A

arteries > arterioles > metarterioles > capillaries (smallest vessels in body)

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7
Q

Why does blood flow around body?

A

due to systolic pressure

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8
Q

Describe the structure of capillary walls

A

1 cell thick, allows exchange of substances between blood & tissue
can be continuous (no opening) / fenestrated (small openings in structure) / sinusoidal (large openings in wall allowing whole cells to move
surrounded by pericyte

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9
Q

What are pericytes?

A

branching network on the outermost surface of capillaries (endothelium), capable of dividing into muscle cells / fibroblasts during angiogenesis, tumour growth & wound healing

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10
Q

What is contained within the endothelium?

A

pericyte > basement membrane > endothelial cells

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11
Q

Which arteries tended to be elastic and which are muscular?

A

large arteries - elastic e.g. aorta (spring back during diastole to smooth out pressure changes)
medium arteries - muscular as they distribute into arterioles

elastic arteries > muscular arteries > arterioles > metarterioles > capillaries

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12
Q

Describe continuous capillaries

A

no gaps
in nervous, muscle & CT, lungs & secretory glands (don’t want leakage!)
joined by occluding (closed up) junctions

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13
Q

Describe fenestrated capillaries

A

small gaps in capillaries
in gut, endocrine glands & renal glomerulus
little ‘windows’ interrupt the endothelium

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14
Q

Describe sinusoid capillaries

A

discontinuous capillaries, larges diameter, slowest flow
in liver, spleen & BM
whole cells can move between blood & tissues through gaps & incomplete basal lamina (of basement membrane)

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15
Q

What do capillaries merge into?

A

capillaries merge to large vessels - venules

venules merge to form larger vessels - veins

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16
Q

Describe veins

A

similar to arteries, thinner wall & wider lumen
has semi-lunar paired valves to allow 1D blood flow (towards heart)
narrower than 1mm (thoracic / abdominal cavities don’t have valves)

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17
Q

What happens to veins when blood pressure not maintained? What is it determined by?

A

veins collapse

determined by ‘muscle-pump’ action in the leg (venous return) & pressure factors in abdominal & thoracic cavity

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18
Q

Describe postcapillary venules

A

similar to capillary walls (endothelial lining with pericytes)
more permeable than capillaries, larger lumen, lower pressure, fluid drains in (down pressure gradient) apart from inflammatory response: fluid & leukocytes (WBC) emigrate (drain out)
receive blood from capillaries

19
Q

Describe venules

A

Larger lumen, smooth muscle fibres begin to associate with endothelium, tunica media being to appear (intermediate layer after tunica intima)
endothelium associated with pericytes / smooth muscle cells (thin wall)
valves present to prevent backflow

20
Q

Describe Veins

A

Larger diameter (lower BP), thinner wall, more CT & fewer elastic & muscle fibres than accompanying arteries

21
Q

Describe small & medium veins

A

developed adventitia (outermost), thin media & intima layers

22
Q

Describe large veins

A

thicker intima, thin media, thick adventitia APART FROM superficial veins of the legs (thick muscular walls to resist distension - enlargement by gravity)
valves act with surrounding muscle contraction to push blood towards heart (1D)

23
Q

What are venae comitantes? (vena comitans - singular)

A

deep paired veins, accompanying each side of a smaller artery
(3) vessels wrapped around artery, all contained within 1 sheath
pulsing of artery promotes venous return within adjacent, parallel & paired veins

blood vessel reach all parts of body apart form cartilage, epithelia & cornea

24
Q

Describe all the different vessels blood travel through from capillaries to the heart

A

capillaries

25
Q

are arteries & veins oxygenated or deoxygenated?

A 
arteries oxygenated (apart from pulmonary artery - deoxygenated to lungs)
veins deoxygenated (apart from pulmonary vein - oxygenated from lungs to heart)
26
Q

What are the sections that vessel walls are split into?

A

tunica adventitia > tunica media > tunica intima

27
Q

Describe the structure of tunica intima

A

endothelium, subendothelial layer, thick elastic lamina

28
Q

What are end arteries?

A

terminal artery supplying all or most of blood to a body part without significant collateral circulation
progressive branching without developing channels connecting to other arteries

29
Q

What are examples of end arteries?

A

coronary artery, splenic (spleen) artery, renal (kidneys) artery

30
Q

what happens if end arteries are occluded?

A

insufficient blood supply to dependent tissues

31
Q

What are examples of absolute end arteries?

A

central artery to retina, labyrinthine artery to internal ear

32
Q

What is bridging (coronary artery)

A

compression of a segment of coronary artery during systole, results in narrowing of artery, opens up again in diastole

33
Q

Describe the structure of arterioles

A

carries blood fro muscular arteries to metarterioles

34
Q

Describe structures of tunica intima, media & adventitia

A

TI: inner layer of endothelial cells, thin layer of subendothelial CT (outer)
TM: single smooth muscle cell layer, completely encircles TI
TA: barely sufficient layers of fibroblasts

35
Q

Describe metarterioles

A

supply blood to capillary beds
non-continous smooth muscle layer, individual muscle cells spaced apart
contains precapillary sphincter

36
Q

What are precapillary sphincters and where are they located?

A

precapillary sphincters are muscles at the neck of capillary
each muscle cell acts as a sphincter, contracting to control blood flow through capillary bed
when sphincters are contracted, blood flow to capillary beds significantly reduced (higher pressure?)

37
Q

How are capillary beds like when muscles are working hard?

A

capillary beds should be flooded to provide max oxygen & nutrients

38
Q

What happens to the vessels in strenous exercise?

A

arterioles dilate, precapillary sphincters relax, increase blood flow to skeletal muscles

reverse for digestion : divert blood to vital organs (brain & heart) - constriction of arterioles to intestine to decrease blood flow

39
Q

Describe the structure of capillaries

A

largest SA for gas & nutrients exchange
passing RBC nearly fills entire lumen - short diffusion distance
structure: single layer of endothelium & basement membrane

40
Q

Gaps in capillaries

A

controlling which molecules & structures can leave capillary

continuous: only water & certain ions can leave
sinusoidal: cells & proteins can leave (larger structures) e.g. liver (large gaps in basement membrane as well as endothelium)

41
Q

Describe the purpose of lymphatic capillaries

A

drains away any excess fluid which isn’t drained by the capillary bed
returns the extracellular fluid to the body at junctions of the internal jugular (right side of neck) & subclavian veins (left side of neck) - a pair

42
Q

Inflammation & postcapillary venules

A

surrounds interstitum - tissues
pressure in venules increase in inflammation, higher than surrounding tissues, allow fluid to leak to site of inflammation with inflammatory cytokines & WBC’s

43
Q

Name the layers of the heart muscle

A

endocardium –> myocardium –> visceral pericardium –> (serous fluid) –> parietal pericardium –> fibrous pericardium

visceral + parietal = serous pericardium

Heart (18 decks)

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