Blood and Blood Vessels

Question 1

Describe the tunica intima

Answer 1

• single layer of squamous epithelial cells termed endothelial cells
• supported by basal lamina & thin layer of connective tissue

Question 2

Describe the tunica media

Answer 2

• predominantly smooth muscle

- thickness of it varies tremendously

Question 3

Describe the tunica adventitia

Answer 3

-made of supporting connective tissue

Question 4

What separates the 3 layers of a blood vessel?

Answer 4

• T.I separated from T.M by internal elastic membrane (a perforated sheet of elastic fibre)
• T.M separated from T.A by external elastic membrane (a layer of elastic tissue)

Question 5

Describe the tunica media of elastic arteries

Answer 5

Much of the smooth muscle is replaced by elastic fibres to provide recoil to combat huge increases & decreases in pressure that would occur otherwise

Question 6

How do large arteries obtain nutrients?

Answer 6

Have their own vascular supply- the vaso vasorum

Question 7

Describe structure of arterioles

Answer 7

• 1/2 layers of smooth muscle in T.M
• almost no adventitia
• typically 30-200 micrometres
• particularly important in controlling blood flow in a tissue

Question 8

Describe the structure of capillaries

Answer 8

• essentially endothelial cells & a basal lamina
• 1 layer of smooth muscle
• diameter 4-8 micrometres
• (compare it to RBC)

Question 9

Name & describe the 3 types of capillary

Answer 9

1. Continuous: muscle, nerve, lung, skin
2. Fenestrated: small pores (50nm) gut mucosa, endocrine glands, kidney
3. Discontinuous/ sinusoidal: have large gaps, liver, spleen, bone marrow

Question 10

How do venules form?

Answer 10

1. Capillary networks drain into p.c venules
   - endothelial cell-lined & contain thin layer of connective tissue
   - important sites for exchange e.g. cells moving into tissue in inflammation
2. Once vessel starts to aquire intermittent smooth muscle cells in T.M referred to as venules

Question 11

Describe the structure of veins

Answer 11

• tunica intima
• thin but continuous T.M ; a few layers of smooth muscle cells
• obvious tunica adentitia
• largest veins have thick tunica adventitia which incorporates bundles of longitudinally oriented smooth muscle
• many small veins have valves (inward extensions of T.I) to prevent backflow of blood

Question 12

What is the lymph vascular system and what is its role?

Answer 12

• system of relatively thin walled vessels that drain excess tissue fluid into the blood stream
• Transports lymph to lymph nodes for immunological surveillance

Question 13

Describe the structure of the lymph vascular system

Answer 13

-no central pump
-smooth muscle in walls
-hydrostatic pressure in tissue
-flow produced by:
- hydrostatic pressure in tissue
-compression of vessels by voluntary muscle
valves in the vessels

Question 14

Is the lymph vascular system circulatory?

Answer 14

No.

Question 15

What is blood made up of?

Answer 15

55% PLASMA
-Water (90%)
-Proteins (mostly albumin, immunoglobins, clotting factors)
-Nutrients, salts
45% FORMED ELEMENTS
-Red cells
-Platelets
-White Cells
a)Granulocytes
i) Basophils
ii) Eosinophils
iii) Neutrophils
b)Agranulocytes
i)Lymphocytes
ii)Monocytes