Vascular pt 5

Question 1

How do arterioles regulate capillaries?

Answer 1

Regulate blood flow and which capillaries are perfused. (metarterioles branch from arterioles into capillaries; precapillary sphincters help control flow)

Question 2

What do capillaries exchange?

Answer 2

Gas and nutrients

Question 3

What is pinocytosis?

Answer 3

Non-specific fluid and small protein ingestion (preformed by all cells)
Pinocytotic vesicles transport fluid and protein the endothelial cells

Question 4

What is exocytosis?

Answer 4

Vesicles are released into surrounding tissue

Question 5

Describe continuous capillaries

Answer 5

Tight, intercellular clefts; contain tight junctions that form major pathway for water and small molecules in skin, muscles, lungs, CT

Question 6

Describe fenestrated capillaries

Answer 6

Pinocytotic vesicles and channels; thin diaphragms in walls permitting larger molecule passage
Fenestrations are endothelial membrane gaps filled in by a single membrane permitting large molecule passage

Question 7

Describe discontinuous capillaries

Answer 7

(sinusoid) Intercellular clefts between cells; larger fenestrations permit free passage of proteins and red blood cells
- spleen, liver, marrow

Question 8

What is capillary action?

Answer 8

Filtration: water and small molecules diffuse out of proximal capillary via hydrostatic pressure
Absorption: water and small molecules diffuse back into the distal side

Question 9

What are Starling Forces?

Answer 9

Determinations of water and molecular flow among capillaries

Dependent upon: filtration coefficient, capillary reflection, and capillary/interstitial hydrostatic/oncotic pressures

Question 10

What is the difference between osmotic and oncotic pressure?

Answer 10

Osmotic: pressure exerted by ions across cell membranes
Oncottic: pressure exerted by proteins across epithelium

Question 11

What is the Net Filtration Pressure (NFP)?

Answer 11

Flow directed out because capillary hydrostatic pressure exceed oncotic pressure

Question 12

What is Net Absorption Pressure (NAP)?

Answer 12

Flow directed into the capillary because oncotic pressure exceeds hydrostatic pressure

Question 13

Where do you see a drop in hydrostatic pressure?

Answer 13

Along the length of the capillary (drops below oncotic pressure)

Question 14

What is interstitial fluid?

What does it contain

Answer 14

• Fluid extravasated from capillaries filling interstitium

- Contains: collagen fiber bundles, proteoglycans, and rivulets of free fluid

Question 15

How is capillary growth stimulated?

Answer 15

Oxygen depletion–> activation of hypoxia-inducible factor 1 (HIF-1)–>stimulates transcription of VEGF–> diffuses to endothelial cells and activates angiogenesis

Question 16

What are the four steps of angiogenesis?

Answer 16

1. proteases digest local basement membrane
2. endothelial cells migrate thru basal lamina to signal source
3. endothelial cells proliferate
4. cells from tubes and differentiate

Question 17

What is lymph?

Answer 17

The excess interstitial fluid (10%), small molecules and proteins recovered by lymphatic capillaries

Question 18

Where are lymphatic capillaries located?
What do they do?
What are flap valves?
What are anchoring filaments?

Answer 18

• Located adjacent to vasc. capillaries
• Terminals absorb excess fluid via interstitial hydrostatic pressure through gaps in lymphatic endothelial cells
• Prevent back flow of lymph
• Prevent collapse in increased interstatial pressure

Question 19

How is lymph transported?

Where does lymph ultimately drain to?

Answer 19

• SM propels lymph thru valves (response to transmural pressure); sympathetic activity does propulsion; transported thru nodes
• drains into veinous system

Question 20

What is a lymph node?

Answer 20

• Bean-shaped gland surrounded by dense CT capsule (hilum)

Question 21

Within a lymph node, what is the purpose of:

• reticular cells
• macrophages
• dendritic cells
• follicular cells

Answer 21

• essentially fibroblasts
• endocytosis
• detect antigens and activate lymphocytes
• antigen-antibody complexes that do long term immune memory

Question 22

What are lymph nodules?

What are germinal centers?

Answer 22

localized lymphocytes in cortex that form primary and secondary nodules

activated lymphocytes within secondary nodules

Question 23

What are lymphocytes?
Where do they develop?
What do they do?

Answer 23

• chief constituents of lymph tissue
• bone marrow and lymph tissue
• respond to antigens presented by other cells and generate immune response (enter from HEV and exit thru veins or into sinuses)

Question 24

Where are the superficial lymphs distributed?

Answer 24

they follow veins and converge onto nodes (widespread); concentrated in the axillary, cervical and inguinal regions

Question 25

Where are the deep lymphatics distributed?

Answer 25

(thorax/abdomen) follow arteries (ex aorta)

Question 26

Where does the thoracic duct drain lymph from?

Answer 26

From the abdominal internal organs (GI), left upper limb, left side of body and the lower half of the body

Question 27

Where does the right lymph duct drain from?

Answer 27

Upper right limb, and right side of head and thorax

Question 28

Where do the left and right ducts drain into?

Answer 28

Junction of internal jugular and subclavian veins on both sides

Question 29

What is edema?

Answer 29

Accumulation of interstitial fluid in a tissue or organs

Question 30

What is venous edema?

Answer 30

increased capillary hydrostat. pressure in lower limbs (venous occlusion)

Question 31

What is hypoalbuminemic edema?

Answer 31

low capillary oncotic pressure (reduces reabsorption)

Question 32

What is inflammatory edema?

Answer 32

leakage of proteins form capillaries (increased interstitial oncotic pressure; reduces fluid reabsorption)

Question 33

What is lymphatic edema?

Answer 33

lymph blockage by removal or infection