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Y1 - Cardiovascular > Histology of the Circulatory system > Flashcards

Histology of the Circulatory system Flashcards

1
Q

Name the 2 division of the circulatory system

A
  • Cardiovascular system

- Lymphatic system

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2
Q

List the roles of the cardiovascular system

A
  • Transporting nutrients and oxygen to tissues
  • Transporting CO2 and waste away from tissues
  • Temperature regulation
  • Distribution of hormones
    and immune cells
  • Reproductive function (penile erection)
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3
Q

List the 3 layers of a blood vessel and describe their layering

A
  • Tunica intima (innermost)
  • Tunic media (middle)
  • Tunica adventitia (outermost)
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4
Q

Describe the tunica intima

A

Innermost layer

Consists of:

  • Single layer of squamous epithelial cells (endothelial cells)
  • Supported by a basal lamina
  • Thin layer of connective tissue (internal elastic lamina)
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5
Q

Describe the tunica media

A

Middle layer

The layers thickness varies greatly in different vessel types

Consists of:

  • Mainly smooth muscle
  • Some elastic fibres (external elastic lamina)
  • Can have lots of elastic fibres (e.g. elastic arteries)
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6
Q

Describe the tunica adventitia

A

Outer layer

Consists of:
- supporting connective tissue

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7
Q

Describe the:

  • Internal elastic lamina (membrane)
  • External elastic lamina (membrane)
A

Internal elastic lamina (membrane):

  • outermost bit of the tunica intima
  • separates the intima from the media

External elastic lamina (membrane):

  • outermost bit of the tunica media
  • separates the media from the adventitia
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8
Q

Describe elastic arteries

A

The largest arteries (e.g. aorta)

  • Have many sheets of elastic fibres in their tunic media
  • These provide elastic recoil, maintaining MAP during diastole
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9
Q

Describe arterioles

A

Only have 1 or 2 layers of smooth muscle in their tunica media

Have almost no tunica adventitia

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10
Q

Describe capillaries

A

Consist of:

  • Endothelial cells
  • Basal lamina
  • Pericytes
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11
Q

Describe a pericyte

A
  • Connective tissue cells
  • Wrap around the outside of the basal lamina
  • Have contractile properties
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12
Q

List the 3 types of capillary

A
  • Continuous
  • Fenestrated
  • Discontinuous (sinusoidal)
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13
Q

Describe continuous capillaries

Where are they found?

A
  • No gaps in endothelium
  • Basal lamina complete
  • Found in muscle, skin, lung, nervous and connective tissues
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14
Q

Describe fenestrated capillaries

Where are they found?

A
  • Small pores in endothelium
  • Basal lamina complete
  • Found in gut mucosa, endocrine glands, and kidney glomeruli
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15
Q

Describe discontinuous (sinusoidal) capillaries

Where are they found?

A
  • Large gaps in epithelium that macromolecules (sometimes cells) can fit through
  • The basal lamina is discontinuous or absent
  • Found in liver, spleen, and bone marrow
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16
Q

Describe microvascular networks and their structure

A

Connect small arterioles with small venules

Made up of:

  • Metarterioles
  • Capillary bed
  • Thoroughfare channels
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17
Q

Describe metarterioles and their structure

A

Links arterioles with capillaries

  • Has no continuous tunica media
  • Has a precapillary sphincter
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18
Q

Describe a precapillary sphincter and its structure

A

Individual smooth muscle cells (close together)

Found in metarterioles

Controles blood entrance to the capillary bed

19
Q

Describe the thoroughfare channels found in microvascular networks

A

A direct channel that connects a metarteriole to a venule

  • has capillaries surrounding it
20
Q

Describe a postcapillary venule

A

Consist of:

  • Endothelial lining
  • Thin layer of connective tissue
  • Pericytes (sometimes)

Capillary networks drain into post-capillary venules

(important site for diapedesis)

21
Q

Describe venules and their structure

A

Consist of:

  • Endothelial lining
  • Thin layer of connective tissue
  • Pericytes (sometimes)
  • Tunica media that contains myocytes
22
Q

Describe veins and their structure

A

Consist of:

  • Tunica intima
  • Tunica media (much thinner that that in arterioles)
  • Tunica adventitia
23
Q

Describe the tunica adventitia found in the largest veins (e.g. vena cava)

A

Very thick

Bundles of longitudinal smooth muscle

24
Q

Describe the composition of venous valves

A
  • In most small to medium sized veins

- Are extensions of the tunic intima

25
Q

List the 3 layers of the heart

A

Endocardium (inner)

Myocardium (middle)

Epicardium (outer)

26
Q

Describe the structure of the endocardium

A 
Endothelium
-->
Basal lamina
-->
Thin layer of collagen fibres
-->
Denser layer of connective tissue
27
Q

Describe the subendocardium and its structure

A

In some areas there is also a subendocardium

Consists of loose connective tissue containing:

  • small blood vessels
  • nerves
  • branches of the impulse conducting system (e.g. Purkinje fibres)
28
Q

Describe the structure of the myocardium

A

Thick central layer of heart

  • Bundles and layers of contractile muscle fibres
  • Individual fibres are surrounded by a collagenous connective tissue with capillaries
29
Q

Describe the surroundings of individual muscle fibres

A

each fibre is surrounded with a delicate collagenous connective tissue

This supports a rich capillary network

30
Q

Describe the nuclei found in contractile cardiac myocytes

A

They have a small central nucleus (sometimes 2)

Unlike skeletal myocytes

31
Q

Describe the intercalated discs between cardiac myocytes

A

Boundary between cardiac myocytes

Have:
- Gap junctions (for transmitting impulses)

  • Desmosomes (for attaching cells together)
  • Zonula adherens (for attaching cells together)
32
Q

Describe the contractile cardiac myocytes found in the myocardium

A
  • Large cells
  • Uninucleate (sometimes 2 nuclei)
  • Some have branches
  • Attached via intercalated discs
33
Q

Describe the structure of the epicardium (serous visceral pericardium)

A 
A single layer of simple squamous epithelium (mesothelium)
-->
basal lamina
-->
Fibroelastic connective tissue
-->
adipose tissue (in some places)
34
Q

Describe the structure of the pericardium

A

Fibrous pericardium:
- Sac of fibrocollagenous connective tissue

Serous pericardium:

  • single layer of simple squamous epithelium (mesothelium)
  • ->
  • basal lamina
  • ->
  • connective tissue
35
Q

In what layer of the heart do the coronary arteries and veins flow?

A

Epicardium

In the adipose tissue deep to the mesothelium, basal lamina, and connective tissue

36
Q

Describe the fibrous skeleton of the heart

A
  • Made of bands of connective tissue
  • Supports the valves
  • Electrically insulates the atria and ventricles
  • Supports myocardium
37
Q

Describe the histology of the heart valves

A

A core lamina fibrosa:

  • dense irregular connective tissue
  • is continuous with the fibrous skeleton

The lamina fibrosa is covered on both sides by endothelium:

Endothelial layer
-->
Basal lamina
-->
Collagen and elastin fibres
38
Q

Is there a vascular supply to the heart valves?

A

No

39
Q

What do the chordae tendineae attach to?

A

on one side the papillary muscles

on the other they merge with the lamina fibrosa of the valve

40
Q

List the 3 types of cardiac myocyte

A
  • Contractile cardiac myocytes
  • Pacemaker cells
  • Conducting cells
41
Q

Describe pacemaker cells

A
  • Much smaller than contractile cardiac myocytes
  • appear paler
  • very few myofibrils
  • Found in AV and SA nodes
42
Q

Describe Purkinje fibres

A
  • Larger than contractile cardiac myocytes
  • In subendocardium
  • No intercalated discs
  • They are NOT nerves
43
Q

Describe lymph vessels

A
  • This walled
  • Walls a bit like those of a vein
  • drain some of the ECF and return it to circulation
  • transport lymphatic fluid
  • passes through lymph nodes
44
Q

Describe what makes lymphatic fluid move

A
  • Skeletal muscle movement

- pressure from incoming fluid

Y1 - Cardiovascular (19 decks)

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