Lecture 7

Question 1

What are capillaries?

Answer 1

Sites of exchange between blood and tissues

Question 2

What are the functional demands of capillaries?

Answer 2

Very Thin walls
Large cross sectional area of capillary bed
Slow and smooth blood flow

Question 3

What allows for slower blood flow to occur?

Answer 3

Large total area of capillary bed compared to arterioles

Question 4

Structure of Capillaries?

Answer 4

Endothelial cells that lines cardiovascular system wrapped around to form a tube and bonding ti neighbours to form cellular pipe. Lumen is only the size of a red blood cell so that erythrocytes can only travel single file

Question 5

Why do red blood cells travel single file down the capillary?

Answer 5

Makes distance for gas exchange down the tube as small as possible and therefore more efficient

Question 6

What is the purpose of intercellular junctions in capillaries?

Answer 6

tight junctions fuses the capillary wall to itself to seal the tube

Question 7

What is the supply pathway to capillary beds?

Answer 7

Terminal arterioles

Question 8

What is the drainage network from capillary beds?

Answer 8

Postcapillary venule

Question 9

What are precapillary sphincters?

Answer 9

Rings (involuntary muscle) that branch off the arterioles running into the capillary beds

Question 10

What is the role of Precapillary sphincters

Answer 10

Constrict and stop blood from going into capillary beds

Question 11

What is a vascular shunt?

Answer 11

Pathway that allows blood to pass from the arterioles to the venules without going through the exchange surfaces

Question 12

What factors can cause capillary structure to vary?

Answer 12

The structure of capillaries varies according to the rate of

exchange needed, and how controlled the exchange must b

Question 13

What are the three types of capillaries?

Answer 13

Continuous capillaries (the most widespread)
Fenestrated capillaries (leaky).
Sinusoidal capillaries (very leaky).

Question 14

What structures make up a continuous capillary?

Answer 14

Basement membrane
Endothelial layer (tunica intima)
Intercellular cleft

Question 15

What feature does fenestrated capillaries have?

Answer 15

Fenestrations

Question 16

What features does Sinusoidal capillaries have?

Answer 16

Incomplete basement membrane

intercellular gap

Question 17

What is the lymph vascular system?

Answer 17

An open entry drainage system

Question 18

What are the functions of the lymph vascular system?

Answer 18

Drains excess tissue fluid & plasma proteins from tissues and returns them the blood..
Filters foreign material from lymph
Screens lymph for foreign antigens & responds by releasing antibodies & activated immune cells.
Absorbs fat from intestine and transports to blood.

Question 19

Describe the structure of the lymphatic system ?

Answer 19

Lymphatic vessels.
Commence as large, blind ending capillaries
From small intestine, a special group of lymphatic vessels called lacteals drain fat-laden lymph into a collecting vessel called the cisterna chyli
Larger (thin wall) collecting vessels have numerous valves to prevent backflow.

Question 20

List the regional lymph nodes?

Answer 20

Cervical nodes
Axillary nodes
Inguinal nodes

Question 21

What does the structure of lymph nodes consist of?

Answer 21

Afferent lymph vessel
Efferent lymph vessel
Valves control direction of flow

Question 22

What are the functions of continuous capillaries?

Answer 22

Diffusion through membrane of lipid soluble substances.
Movement through intercellular clefts of water soluble substances.
Transport of large substances via vesicles or caveolae

Question 23

What are the functions of fenestrated capillaries?

Answer 23

Same as continuous plus the option of movement through fenestrations

Question 24

What are the functions of sinusoidal capillaries?

Answer 24

Same as continuous and fenestrated but will find that when moving through physical openings, basement membrane may not be present.

Question 25

What are fenestrations?

Answer 25

Physical openings in the cytoplasm of endothelial cell

Question 26

Where does lymph from the left side of the face, body and below diaphragm drain into?

Answer 26

Drained vias Lymph collecting vessels, into the thoracic duct (large lymph capillary) which runs and drains into the left subclavian vein, going back into the blood vascular system.

Question 27

WHere does lymph from the right side of the face and body above diaphragm drain into?

Answer 27

Right lymphatic duct which then drains into the right subclavian vein, going back into the blood vascular system

Question 28

What does the portal vein do?

Answer 28

Drains blood from the GI tract where it has been gaining nutrients, to the liver where the blood will be filtered