Histology of circulatory system

Question 1

What two systems does the circulatory system involve?

Answer 1

The cardiovascular system The lymphatic vaacular system

Question 2

What is the cardiovascular system made up of?

Answer 2

Closed system consisting of heart, arteries, capillaries and veins

Question 3

Roles of the circulatory system?

Answer 3

-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

Question 4

Basic 3 layer structure to a blood vessel?

Answer 4

Tunica Intima - most inner Tunica Media Tunica adventitia

Question 5

Description of tunica intima?

Answer 5

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

Question 6

Description of tunica media?

Answer 6

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

Question 7

Description of tunica adventitia?

Answer 7

Made up of supporting connective tissue- outer most layer

Question 8

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

Answer 8

Layer of elastic tissue called the internal elastic membrane

Question 9

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

Answer 9

Layer of elastic tissue called th eexternal elastic membrane

Question 10

What colour do elastic fibres stain?

Answer 10

Black

Question 11

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

Answer 11

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

Question 12

Describe the make up of arterioles?

Answer 12

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.

Question 13

What are capillaries essentially composed of?

Answer 13

Endothelial cells and a basal lamina

Question 14

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

Answer 14

Pericytes - connective tissue cells that have contractile properties

Question 15

Wher are continuous capillaries found?

Answer 15

In muscle, connective tissue, lung, skin & nerves

Question 16

Where are fenestrated capillaries found?

Answer 16

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

Question 17

Where are discontinuous capillaries found?

Answer 17

Liver spleen and bone marrow

Question 18

Description of discontinuous capillaries?

Answer 18

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

Basal lamina is discontinuous or not present

Question 19

What is microvasculature?

Answer 19

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

Question 20

What helps control flood flow through microvasculature?

Answer 20

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

Question 21

What do capillary networks drain into?

Answer 21

Post capillary venules

Question 22

Describe post capillary venules?

Answer 22

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

Question 23

When is a post capillary venule described as a venule?

Answer 23

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

Question 24

Describe veins?

Answer 24

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

Question 26

Difference between large veins and small/medium veins?

Answer 26

Large veins (HPC/VC) have bundles of longitudnally orientated smooth muscle cells Small/medium veins have Valves- inwards extensions of the tunica intima

Question 27

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

Answer 27

A= small artery B = Small vein

Question 28

3 Layers of the heart?

Answer 28

Endocardium - inner layer Myocardium - Middle layer Epicardium- Outer layer

Question 29

Layers of e heart from the outside in?

Answer 29

Adipose tissue Fibrous pericardium } Pericardium Parietal layer of serous pericardium Pericardial cavity Visceral layer of serous pericardium Epicardium Myocardium Endocardium

Question 30

What does the endocardium do?

Answer 30

Lines the entire inner surface of the heart including the valves

Question 31

Structure of endocardium?

Answer 31

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

Question 32

What is the myocardium?

Answer 32

Thick Middle layer

Question 33

Structure of myocardium?

Answer 33

Bundles and layers of contractile cardiac muscle fibers Individual muscle fibers are surrounded by delicate, collagenous connective tissue with a rich network of capillaries

Question 34

Describe cardiac muscle cells?

Answer 34

Single central nucleus (sometimes 2) Intercalated discs passing across fibers at irregular intervals

Question 35

Role of intercalated discs in cardiac muscle cells?

Answer 35

Acts to attach cells but also allows spread of electrical activity

Question 36

What is the epicardium?

Answer 36

Outer layer of the heart

Question 37

Structure of epicardium?

Answer 37

Outer layer of heart= Single layer of flattened epithelium called mesothelium Basal lamina Fibroelastic connective tissue and in some places adipose tissue

Question 38

Structure of pericardium?

Answer 38

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

Question 39

What does the serous pericardium line?

Answer 39

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)

Question 40

What is the hearts fibrous skeleton formed from?

Answer 40

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

Question 41

Structure of heart valves?

Answer 41

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 -

Question 42

3 types of cardiac muscle cell?

Answer 42

Contractile cells (99%) Pacemaker cells Conducting cells

Question 43

Describe pacemaker cells?

Answer 43

Highly specialized muscle cells Considerably smaller than contractile cardiac myocytes Embedded in extensive matrix of connective tissue Appear pale Few myofibrils

Question 44

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

Answer 44

Electrically isolating atria from ventricles

Question 45

Structure of purkinje fibers?

Answer 45

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

Question 46

Role of purkinje fibers?

Answer 46

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

Question 47

What does the lymph vascular system consist of?

Answer 47

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

Question 48

Describe the role of lymph vascular system?

Answer 48

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

Question 49

What is in Lymph?

Answer 49

Ions Lipids Proteins Ocassional cells

Question 50

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

Answer 50

Smooth muscle iin walls Hydrostatic pressure in the tissue Compression of the vessels by voluntary muscle Combined with valves in the vessels