session 5

Question 1

main types of blood vessels (5)

Answer 1

• arteries
• arterioles
• capillaries
• venules
• veins

Question 2

define blood vessels

Answer 2

closed system of tubes which carry blood from heart to regions of the body and back to heart

Question 3

what is angiogenesis

Answer 3

growth of new blood vessels

Question 4

where is most blood stored

Answer 4

in veins and venules

This is why they are called blood reservoirs

Question 5

arteries vs arterioles

Answer 5

• artery carry blood from heart to tissues
• arteriole small arteries that connect capillaries

Question 6

what occurs in capillaries

Answer 6

exchange of oxygen and other nutrients between blood and the body tissue

Question 7

veins vs venules

Answer 7

• veins blood from tissues back to heart
• venules connect capillaries to larger veins

Question 8

vaso vasorum

Answer 8

• Small blood vessels which supply the outer wall layers of arteries and veins

Question 10

Question 11

blood vessel wall layers

Answer 11

• tunica intima
  
  • ​has endothelium, basement membrane and internal elastic lamina
• tunica media
  
  • ​smooth muscle and elastic fibers
• tunica externa
  
  • ​elastic and collagen fibers

Question 12

elasticity of vessles

Answer 12

due to elastic tissue in tunica interna and media

Beneficial in arteries to receive high pressured blood flow

Question 13

contractility of vessels

Answer 13

Due to smooth muscle in tunica media

Allows for changed lumen size

Question 14

Vascular smooth is innvervated by

Answer 14

sympathetic nervous system

• increased stimulation = vasoconstriction
• decreased stim = vasodilation

Question 15

What chemicals also cause vasodilation

Answer 15

nitric oxide (NO), hydrogen and lactic acid

Question 16

Two artery types

Answer 16

• elastic arteries
  
  • ​largest type
  • tunica media has more elastic fibers and less smooth muscle
  • ​conduct blood into muscular arteries
• muscular arteries
  
  • ​medium sized
  • Tunica media with more smooth muscle
  • direct blood flow to tissue and can constrict/dilate

Question 17

anastomoses

Answer 17

• union of 2 or more arteries supplying the same body region
  
  • blockage of one pathway has no effect on circulation
• eg GIT, coronary circulation

Question 18

arterioles

1. structure
2. function as
3. define metarteriole
4. precapillary sphincters

Answer 18

1. very few layers
2. deliver blood to capillaries. Regulate blood flow and BP
3. terminal end of the arteriole before it becomes capillaries
4. between metarteriole and capillaries. Can contract and relax to control blood flow into capillary bed

Question 19

capillaries

1. structure
2. function

Answer 19

1. smallest blood vessel. Only have tunica interna with one single layer of endothelial cells
2. exchange of nutrients and waste between blood and tissue fluid

Question 20

types of capillaries

Answer 20

• continuous capillaries
  
  • ​continuous tube
  • located in CNS, lungs, muscle tissue and skin
• fenestrated capillaries
  
  • ​many holes in plasma membrane of endothelial cells
  • located in kidneys, endocrine glands
• sinsoidal capillaries
  
  • ​endothelial cells have large fenestrations
  • basemement membrane is incomplete or absent
  • allows even proteins or blood cells to pass
  • located in liver, bone marrow, spleen, pituitary

Question 21

Two types of venules

Answer 21

• Post capillary venule
  
  • change of nutrients and wastes
• Muscular venules
  
  • no exchange

Question 22

veins structure

Answer 22

• all vessel layers (intima, media and externa) are thinner than in the artery
• veins also have one way valves which prevent backflow

Question 23

what are varicrose veins

Answer 23

• twisted superficial veins
• Caused by leaky venous valves
  
  • ​can be congenital or from stress like pregnancy
• Backflow of blood = pooling of blood
  
  • ​particularly in lower limbs, oesophagus and anal canal (haemorrhoids)
• Treatment eg surgical stripping

Question 24

blood distribution in veins/venules and arteries/arterioles

Answer 24

• veins/venules
  
  • 64% of blood at rest
  • blood reservrois
• artery/arteriole
  
  • 13% of blood volume

Question 25

capillary exchange

Answer 25

* movement of substances between blood in capillaries and interstitial fluid * methods include * **diffusion** * **​**eg o2, co2, glucose, hormones * pass down concentration gradient through fenestrations, sinusoids * **transcytosis** * **​**in tiny vesicles by endo/exocytosis * eg proteins across placenta * **bulk flow** * **​**movement of large amount of material * movement in response to pressure

Question 26

blood brain barrier

Answer 26

* **block movement of certain materials into and out of brain** * formed by non fenestrated epithelial with tight junctions * **Materials tha can pass BBB are** * **​**g*lucose (by active transport)* * *creatinine, urea* * *lipid soluble substances like oxygen, CO2, alcohol* * Proteins and most antibiotic drugs wont pass

Question 27

starlings law of capillaries

Answer 27

volume of fluid and solutes reabsorbed is almost as large as the volume filtered

Question 28

oedema

Answer 28

* **abnormal increase in interstitial fluid** * filtration exceeds reabsorption meaning not enough blood going back into capillaries * Excess filtration can be caused by * *hypertension (high BP)* * *increased permeability of capillaries = proteins to escape* * Inadequate reabsorption * reabsorption is controlled by colloid osmotic pressure which is the result of protein concentration * low plasma proteins = low osmotic pressure = inadequate reabsorption