Histology of circulatory system Flashcards

1
Q

What two systems does the circulatory system involve?

A

The cardiovascular system The lymphatic vaacular system

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2
Q

What is the cardiovascular system made up of?

A

Closed system consisting of heart, arteries, capillaries and veins

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3
Q

Roles of the circulatory system?

A

-Transport of nutrients and oxygen to the tissues -Transport of CO2 and other metabolic waste from the tissues - Temperature regulation - Distribution of hormones and immune cells - Reproductive function in males- penile erection

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4
Q

Basic 3 layer structure to a blood vessel?

A

Tunica Intima - most inner Tunica Media Tunica adventitia

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5
Q

Description of tunica intima?

A

Single layer of squamous epithelial cells termed endothelial cells, supported by a basal lamina and a thin layer of connective tissue- It is the inner most layer

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6
Q

Description of tunica media?

A

Made up predominantly of smooth muscle Thickness of this layer varies tremendously

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7
Q

Description of tunica adventitia?

A

Made up of supporting connective tissue- outer most layer

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8
Q

What is the tunica intima separated from the tunica media by?

A

Layer of elastic tissue called the internal elastic membrane

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9
Q

What is the tunica adventitia separated from the tunica media by?

A

Layer of elastic tissue called th eexternal elastic membrane

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10
Q

What colour do elastic fibres stain?

A

Black

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11
Q

What are the very largest arteries called? And why are they termed this?

A

Elastic arteries. Because they have many sheets of elastic fibres in their tunica media to provide elastic recoil

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12
Q

Describe the make up of arterioles?

A

Have only one or 2 layers of smooth msucle in the tunica media and almost no adventitia. They are particularly important in controlling blood flow in tissue.

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13
Q

What are capillaries essentially composed of?

A

Endothelial cells and a basal lamina

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14
Q

What do capillaries have at intervals just outsude of the basal lamina?

A

Pericytes - connective tissue cells that have contractile properties

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15
Q

Wher are continuous capillaries found?

A

In muscle, connective tissue, lung, skin & nerves

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16
Q

Where are fenestrated capillaries found?

A

Mucosa of the gut, endocrine glands and glomeruli of the kidney

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17
Q

Where are discontinuous capillaries found?

A

Liver spleen and bone marrow

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18
Q

Description of discontinuous capillaries?

A

Large gaps through which macromolecules can fit , in some cases even cells can fit through aswell

Basal lamina is discontinuous or not present

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19
Q

What is microvasculature?

A

Small arterioles connecting to postcapillary venule through this network of metarterioles, thoroughfare channels and capillaries.

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20
Q

What helps control flood flow through microvasculature?

A

Pre-capillary sphinctors - composed of smooth muscle at the beginning of the capillary

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21
Q

What do capillary networks drain into?

A

Post capillary venules

22
Q

Describe post capillary venules?

A

Endothelial lined and contain a thiin layer of connective tissue and occasional pericytes - important sites for exchange

23
Q

When is a post capillary venule described as a venule?

A

When smooth muscle cells start to be acquired in the tunica media layer.

24
Q

Describe veins?

A

Thin tunica media- few layers of smooth muscle - markedly thinner than in an artery

Large veins have- thick tunica adventitia - with bundles of longitudnally orientated smooth muscle

Veins are flexible- can accommodate expansion

Have a tunica intima

25
Q
A
26
Q

Difference between large veins and small/medium veins?

A

Large veins (HPC/VC) have bundles of longitudnally orientated smooth muscle cells

Small/medium veins have Valves- inwards extensions of the tunica intima

27
Q

What of these is a small artery and which is a small vein?

A

A= small artery

B = Small vein

28
Q

3 Layers of the heart?

A

Endocardium - inner layer

Myocardium - Middle layer

Epicardium- Outer layer

29
Q

Layers of e heart from the outside in?

A

Adipose tissue

Fibrous pericardium

} Pericardium

Parietal layer of serous pericardium

Pericardial cavity

Visceral layer of serous pericardium

Epicardium

Myocardium

Endocardium

30
Q

What does the endocardium do?

A

Lines the entire inner surface of the heart including the valves

31
Q

Structure of endocardium?

A

Endothelium

Basal lamina

Thin layer of collagen fibers

Layer of denser connective tissue

In some areas there can also be a subendocardium of loose connective tissue containing small blood vessels and nerves and branches of impulse conducting system

32
Q

What is the myocardium?

A

Thick Middle layer

33
Q

Structure of myocardium?

A

Bundles and layers of contractile cardiac muscle fibers

Individual muscle fibers are surrounded by delicate, collagenous connective tissue with a rich network of capillaries

34
Q

Describe cardiac muscle cells?

A

Single central nucleus (sometimes 2)

Intercalated discs passing across fibers at irregular intervals

35
Q

Role of intercalated discs in cardiac muscle cells?

A

Acts to attach cells but also allows spread of electrical activity

36
Q

What is the epicardium?

A

Outer layer of the heart

37
Q

Structure of epicardium?

A

Outer layer of heart= Single layer of flattened epithelium called mesothelium

Basal lamina

Fibroelastic connective tissue and in some places adipose tissue

38
Q

Structure of pericardium?

A

2 parts

Fibrous pericardium - sac of tough fibrocollagenous connective tissue

Serous pericardium- Layer of simple squamous epithelium, backed by basal lamina and connective tissue

These layers are separated by a thin pericardial cavity containing small amount of pericardial fluid that provides lubrication for heart movement

39
Q

What does the serous pericardium line?

A

Inner surface of fibrous pericardium (where is is the parietal serous pericardium)

And also covers the surface of the heart (where it is known as visceral serous pericardium)

40
Q

What is the hearts fibrous skeleton formed from?

A

Thick bands of fibrous connective tissue around the heart valves, between atria and between ventricles

This CT supports the valves but also provdes attachmnet for cardiac muscle fibers

41
Q

Structure of heart valves?

A

They have

  • an outer endothelial layer
  • Layers of collagen and elastic fibers
  • Core of dense connective tissue (lamina fibrosa) in continuity with fibrous skeleton
  • Leaflets of valves separating atria from ventricles are anchored to papllary muscle in walls of ventricles by chordae tendonae
  • No blood vessels in valves

-

42
Q

3 types of cardiac muscle cell?

A

Contractile cells (99%)

Pacemaker cells

Conducting cells

43
Q

Describe pacemaker cells?

A

Highly specialized muscle cells

Considerably smaller than contractile cardiac myocytes

Embedded in extensive matrix of connective tissue

Appear pale

Few myofibrils

44
Q

Role of the non-conducting tssue of the fibrous skeleton of the heart?

A

Electrically isolating atria from ventricles

45
Q

Structure of purkinje fibers?

A

Larger than normal cardiac muscle cells

Found in subendocardial layer just deep into the endocardium

They have- abudant glycogen, no T-Tubules, no intercalated discs and no sparse actin and myosin filaments

Appear pale

46
Q

Role of purkinje fibers?

A

Distribute the excitatory activity such that ventricular contraction generally occurs from inferior to superior

47
Q

What does the lymph vascular system consist of?

A

Lymphatic vessels that drain tissue fluid eventually returning it o veins in the base of neck

48
Q

Describe the role of lymph vascular system?

A

System of relatively thin walled vessels that drain XS interstitial fluid into blood stream

Most of the XS interstitial fluid returns to capillaries and venous vessels but a portion returns to circulatory system by entering lymphatic vessels

49
Q

What is in Lymph?

A

Ions

Lipids

Proteins

Ocassional cells

50
Q

What makes up for lymoh vessels lack of a central pump?

A

Smooth muscle iin walls

Hydrostatic pressure in the tissue

Compression of the vessels by voluntary muscle

Combined with valves in the vessels

51
Q
A