Lecture 11/12

Question 1

what is the circulatory system?

Answer 1

consists of the heart whose function is to pump blood, and the vascualr system of afferent and effeerent blood vessels

Question 2

what are efferent vessels?

Answer 2

arteries which conduct oxygen and nutrients to the tissues that diffuse out through a capillary network

Question 3

what are afferent vessesl?

Answer 3

veins which convey to the heart CO2 and waste products of the metabolism of tissues

Question 4

what are the lymphatics?

Answer 4

anastomotic network of vessesl that start as blind capillaries which converge into large lymphatic vessels and drain into large veins.

Question 5

what do lymphatic vessels conduct?

Answer 5

lymph, which is plasma enrched with immunoglobulins and lymphocytes, which is produced by phymphatic organs

Question 6

general plan od blood vessels.

Answer 6

• intima: endothelium (squamous simple epithelium), sub-endothelil layer, IELM (internal elastic lamina)
• Media: elastic membrane and/or smooth muscle (with reticular fibers and proetoglycans between layers)
• adventitia: dense irr. CT, vasa vasorum

Question 7

special features of the muscular artery

what differentiates it

Answer 7

• 4 or more concentric layers of SM
• 1mm or more in diameter

Question 8

special features of a middle size vein

what differentiates it

Answer 8

• incomplete media of SM
• collapse lumen

Question 9

what stain is used to visualize elastic fibers?

Answer 9

verhoeff stain

Question 10

special features of elastic arteries

Answer 10

• media has concentric layers of SM and elastic membranes
• vasa vasorum

Question 11

special features of large veins

Answer 11

media contains few layers of SM (4-5 layers) with no elastic membranes

Question 12

what intermediate fibers are found in vessel SM cells instead of normal SM cells?

Answer 12

vimentin instead of desmin

Question 13

special featuresof arterioles

Answer 13

• media has 1-2 layers od SM
• diameter is 0.5 mm or less
• has elastic fibers but no ILEM

Question 14

special features of venule

Answer 14

• absent media
• collapse lumen
• has pericytes

Question 15

a capillary network is found betwen what?

Answer 15

metaarterioles and postcapillary venules

Question 16

what are anastomosis?

Answer 16

capillary like vessel between arteriole and venule

Question 17

role of capillaries

Answer 17

slow down circulation of blood, allowing metabolic exchange between the blood and surrounding tissue:
* exchange
* nutrition
* thermoregulation
* blood pressure regulation
* inflammation

Question 18

what are the different types of capillaries?

Answer 18

• impermeable/continuous
• permeable - fenestrated
• permeable - sinusoids

Question 19

where are periocytes often found?

Answer 19

post-capillary venules

Question 20

function of pericytes

Answer 20

• secrete cytokines
• support
• phagocytic

Question 21

how are nutrients transported in impermeable capillaries?

Answer 21

via trans-endothelial channels and pinocytic vesicles

Question 22

where are impermeable capillaries found?

Answer 22

• nervous tissue
• muscle (all)
• skin
• lung
• lymphatics

Question 23

how are nutrients transported in fenestrated capillaries?

Answer 23

via trans-endothelial channels, pinocytic vesicles, and fenestration/pores with diaphrams

Question 24

where are fenestrated capillaries found?

Answer 24

• intestinal muscoa
• pancrease
• salivary gland
• endocrine gland
• kidney

Question 25

how do lipid soluble substances go through capillaries?

Answer 25

diffuse freely

Question 26

how do small water soluble molecules (<10A) and ions go through capillaries?

Answer 26

through trans-endothelial channels

Question 27

how do molecules (up to 90A) go through capillaries?

Answer 27

vesicles

Question 28

how do molecules (more than 90A) go through capillaries?

Answer 28

through pores

Question 29

how do the hydrostaic pressure and osmotic pressue compare in the arterial end and venous end of the capillary network?

Answer 29

- arterial end: high hydrostatic and low osmotic - venous: low hydrostatic and high osmotic

Question 30

general characteristics of lymphatic vessels | how does it compare to blood vessels?

Answer 30

- channels in CT containing lymph (not RBCs) - very thin endothelial cells (no occluding and gap junctions) - no BM associated with endothelium - endothelial cells are anchored to the CT fibers (type I/III collagen, elastic fibers)

Question 31

what do small or large lymphatic vessels usually have (that small ones don't)?

Answer 31

valves (fold of the wall projecting into the lumen)

Question 32

what do large lymphatic vessels have (that smaller ones don't)

Answer 32

smooth muscle cells in the walls

Question 33

function of the endothelium

Answer 33

- permeability - metabolic function (convert angiotensin I into angiotensin II, and inactivate bradykinin, a potentiator of SM contraction, and of serotonin/prostaglandins, NE) - production of vasoactive substances (endothelin and NO) - anti-thrombogenic function

Question 34

endothelin pathway

Answer 34

endothelin binds endothelin receptor, which converts PIP into IP3, which increases Ca2+, which causes contraction

Question 35

Nitric Oxide pathway

Answer 35

NO synthase makes NO (via conversion of L-arginine to L-citrulline), this activates guanylyl cyclase, whcih makes cGMP, which causes the vasodilation. Phosphodiesterase inactives cGMP into GMP.

Question 36

when and how do platlets form?

Answer 36

- clotting normally occurs when there is damage to a blood vessel - it immediately begins to adhere to the cut edges of the vessel and release chemicals that attract even more platelets - a platelet plug is formed and external bleeding is stopped

Question 37

what is fibrin?

Answer 37

a fibrous, non-globular protein

Question 38

how is fibrin made?

Answer 38

protease (thrombin) on fibrinogen, hwihc causes it to plolymerize

Question 39

role of fibrin

Answer 39

combines with platelets to form a hemostatic plug or clot over the wound site