Histology of Blood Vessels and Blood film (Function of Blood cells)

Question 1

Order of Blood Vessels

Answer 1

1. Arteries
2. Elastic Arteries
3. Muscular arteries
4. Arterioles (Meta + Terminal)
5. Capillaries
6. Venules
7. Post Capillary venule
8. Veins

Question 2

Blood

What is Average adult blood volume?

Answer 2

4.5-6 litres

Question 3

What are the components and composition of blood?

Answer 3

Formed Elements (~45%)
* Platelets
* Red Cells
* White Cells:
-Neutrophils Eosinophils Basophils (Granulocytes)
-Lymphocytes Monocytes (Agranulocytes)

Plasma (~55%)
* Water (~90%)
* Proteins (mostly clotting factors)
* Nutrients, Salts

Question 4

What is serum?

Answer 4

Plasma with clotting factors removed

allow the blood to clot then remove the clot b4 spining blood.

Question 5

How can blood be separated by spinning in a centrifuge?

Answer 5

The red cells are densest - (bottom)

The white cells are next

Plasma (liquid portion) of blood - top.

Question 6

Describe the structure of Erythrocytes (RBCs)?

Red Blood Cells

Answer 6

• Biconcave discs around 7µm in diameter
• No nucleus or organelles (when mature)
• Network of flexible cytoskeletal elements for movement
• 1/3 of their volume taken up by the iron- containing protein haemoglobin
• last approx 4 months in the circulation.

Question 7

What is Hematocrit?

+ values for norm

Answer 7

The Proportion of Blood that is Red Blood Cells

Question 8

% Proportions of White Blood Cells

Answer 8

Neutrophils - 40-75%
Lymphocytes - 20-50%
Eosinophils- 5%
Monocytes - 1-5%
Basophils - 0.5%

Question 9

granulocytes

Describe Neutrophils…

Answer 9

• 40-75% of WBCs
• Granulocytes (cytoplasm contains many granules but these stain poorly with either acidic or basic dyes (hence the ‘neutro’))
• Single, multi-lobed nucleus
• Short-lived (high proportion of bone marrow is devoted to production)
• Highly Motile Phagocytes (when activated)

granules, mullti lobed nucleus, larger than RBC

Question 10

granulocytes

Describe Eosinophils…

Answer 10

• 5% of WBCs
• Acidic granules that stain red, and a bi-lobed nucleus
• Granules contain hydrolytic enzymes - inflammation
• Slightly larger than neutrophils

Question 11

granulocytes

Describe Basophils…

Answer 11

• 0.5% of WBCs
• Basic granules that stain purple/blue, and a bi-lobed nucleus
• Effector cells in allergic reactions (release its granules after binding to receptor (termed degranulation)).
  -This leads to hayfever, allergic asthma, allergic dermatitis etc.

Question 12

agranulocytes

Describe Monocytes…

Answer 12

• 1-5% of WBCs
• Precursors of tissue macrophages (phagocytes)
• Large, kidney bean-shaped nucleus
• small lysosomal granules in their cytoplasm.
• become macrophages when leave blood particularly found in loose connective tissue

Question 13

agranulocytes

Describe Lymphocytes…

Answer 13

• 20-50% of WBCs
• Small spherical nucleus and basophilic (blue) cytoplasm
• B + T cells arise in the bone marrow
• B cells: give rise to antibody secreting plasma cells
• T cells: differentiate in thymus, many defensive functions

Question 14

What are Platelets?

Answer 14

Cell fragments that have a key role in haemostasis (preventing bloodloss)
- 2µm in diameter
- clotting/coagulation factors
- mostly water (90%)

• organelles, but no nucleus

tiny purple stained dots (smaller than RBC)

Question 15

Describe the morphology of the white blood cells

Answer 15

Question 16

Describe the Structure of Arteries

(3 layers) (2 sub-layers)

Answer 16

• Tunica intima: single layer of squamous epithelial cells (endothelium) supported by a basal lamina and a thin layer of connective tissue
• internal elastic membrane.
• Tunica media: predominantly made up of smooth muscle
• external elastic membrane.
• Tunica adventitia: made up of supporting connective tissue

Question 17

What are the larger arteries called and why?

Answer 17

elastic arteries
-found closer to the heart
why?-sheets of elastic fibres in their tunica media to provide elastic recoil

elastic fibres stained black

Question 18

What is the vasa vasorum?

Answer 18

• in large arteries only the inner part of the wall can obtain nutrients from the lumen
• vessels will have their own vascular supply: the vasa vasorum

white circle

Question 19

Describe the Structure of Arteriole

Answer 19

-intima- endothelial cells on a basement membrane
-1 or 2 layers of smooth muscle in tunica media
-almost no adventitia
-30-200µm

Question 20

Describe the Structure of Capillaries

Answer 20

-Endothelial cells (1 cell thick) and a basal lamina
-4-8µm

Question 21

Describe the 3 Types of Capilaries

Answer 21

Continuous: muscle, nerve, lung, skin
Fenestrated: have small pores (50nm), gut mucosa, endocrine glands, kidney
Discontinuous or Sinusoidal: have large gaps, liver, spleen, bone marrow

Question 22

Describe the Structure of Venules

Answer 22

• Postcapillary venules: endothelium and thin layer of connective tissue
• Venules: intermittent smooth muscle in tunica media

Question 23

Describe the Structure of Veins

Answer 23

• Tunica intima
• a thin, continuous tunica media
• tunica adventitia
• small veins have valves to prevent backflow of blood