Blood vessels and bloods

Question 1

Briefly describe the different layers of the average artery from lumen out. Remember there are variations in this general architecture.

Answer 1

Tunica intima (squamous endothelial cells supported by a basal lamina and a thin layer of connective tissue), internal elastic membrane, tunica media (predominately smooth muscle), external elastic membrane, tunica adventitia (supporting connective tissue).

Question 2

What is the term used to describe the blood vessels of large blood vessels.

Answer 2

Vasa Vasorum

Question 3

Name the three types of capillary and where they can be found.

Answer 3

Continuous: muscle, nerve, lung and skin.

Fenestrated: (have small pores) gut mucosa, endocrine glands, kidney.

Discontinuous: (have large gaps), liver, spleen, bone marrow.

Question 4

What is another name for inward extensions of the tunica intima.

Answer 4

A valve

Question 5

What is the average blood volume of an adult

Answer 5

4.5-6 litres

Question 6

Describe erthrocytes.

Answer 6

RBCs are are biconcave discs about 7µm in diameter. Mature RBC’s are not true cells as they have no nucleus or organelles. They are basically deformable bags with about 1/3 of their volume taken up by the iron-containing protein haemoglobin. They contain a network of flexible cytoskeletal elements that allow them to deform and slip through spaces smaller than themselves. Erythrocytes last approximately four months in the circulation. aged RBCs are removed by the spleen/liver.

Question 7

List some of the main leukocytes in order of most common to least common.

Answer 7

Neutrophils, lymphocytes, eosinophils, monocytes, basophils.

Question 8

Describe neutrophils.

Answer 8

Granulocytes. Stain poorly. Highly motile phagocytes. Very good at killing bacteria. Multilobed nucleus.

Question 9

Describe eosinophils

Answer 9

Granulocytes. Granules contain enzymes important in inducing and maintaining inflammation. They are also important in fighting parasitic infection. Most are found in the tissue rather than blood stream.

Question 10

Describe basophils

Answer 10

rarest of granulocytes. Acts as an effector cell in allergic reactions. Granules contain histamine, heparin, and other inflammatory mediators.

Question 11

Describe monocytes.

Answer 11

Serve as the precursor for tissue macrophages. Largest of of the cells circulating the blood.

Question 12

Describe lymphocytes.

Answer 12

There are two general classes of lymphocytes, B cells and T cells, however these cannot be distinguished in routine stained sections. Both types of lymphocyte arises in the bone marrow, but T cells differentiate in the thymus (in the neck). Both cell types participate in the specific immune response. B cells give rise to antibody secreting plasma cells while T cells form a complex set of cells that perform many defense functions (aiding other immune cells, killing defective cells, etc).

Question 13

What is the main role of platelets.

Answer 13

Platelets play a key role in hemostasis (the prevention of blood loss). They contain granules that themselves contain clotting factors.

Question 14

What is the term for blood production.

Answer 14

Hemopoiesis.

Question 15

Name the cell that makes platelets

Answer 15

Megakaryocytes.

Question 16

Describe the change of site of hemopoiesis over time.

Answer 16

During pregnancy, the site of hemopoiesis changes from outside the embryo (about 3 weeks) to the liver and the spleen (second trimester). By birth the bone marrow is the main site of blood formation and all bones participate. As bones enlarge there is excess capacity and so hempoiesis is shut down in most appendicular bones. The bone marrow in these bones are now called yellow marrow as it is now adipose cells. where as in blood producing marrow it is called red marrow.