ANATOMY Blood Vessels

Question 1

Basic structure of capillary

4

Answer 1

1-smallest BV= short diffusion distance
2-endothelium / basement membrane = no smooth muscle / highly permeable
3-fenestrations ( in some )
4-MANY capillaries = Increases SA

Question 2

Types of capillary ?

3

Answer 2

1- Continuos capillary = no gaps =permeability is low found in nervous systems , fat and muscle tissue
2-Fenestrated capillary = M=( x<100nm) can fit through =exocrine and endocrine glands
3 -Discontinuos capillary= XL GAPS =Incomplete basement membrane =(600

Question 3

Describe the structure of microcirculation in a capillary ?
sphincters are open / closed !

What causes reaction of spincters ?

(6)

Answer 3

a) Pre capillary sphincters are made of smooth muscle , when they open/relaxed = blood flows through web = true capillaries
b) When the Spincters are closed =Blood goes straight through Metarteriole (like motor way) = straight channel =shunts blood away from true capillaries

FACTORS THAT EFFECT OPEN /CLOSING FACTORS:

• metabolites = relaxation of spincters = blood flows through capillary bed
• Most beds are closed = sphincters are contracted
• When Muscle is being used = they use oxygen =HYPOXIC( NEED MORE O2)=> capillary bed is used = spincters OPEN !

Question 4

regulation of capillary blood flow ?
(4)
what forces /pressure

Answer 4

starling forces : Hydrostatic pressure / oncotic pressure
1-Hydrostatic pressure is greatest at arteriolar end and decreases towards venule end =MAIN OUTWARD FORCE
2-Plasma Oncotic pressure is MAIN INWARD FORCE
Arteriolar end =positive pressure difference = ULTRAFILTRATION (more moved out)
venule end =hydrostatic pressure has decreased so REABSORBTION OCCURS ( more is moving in )

Question 5

Describe the causes & and consequences of oedema ?
(7)
-how can u get it , in what situation ?

Answer 5

1- Increased capillary pressure =vasodialation, expansion of ISF
2-increased venous failure =heart failure =blood backs up and cant pump properly = more fluids move out for a longer time across the capillary
3-Decreased Plasma Oncotic pressure = less fluid moves into capillary = too much ISF =Kwashiorkor Disease
4-Prolonged standing
5-Flights ( wear compression stockings to keep circulation moving )
6-Inflammation
7-ISF pressure increases , because it cant drain into the lymphatic system =blocks movement of fluid =accumulation of fluid =elephantiasis ! ( looks like elephant skin )

Question 6

Briefly describe vein structure ?

3

Answer 6

1- 3 layers :THIN
-Tunica intimia
-Tunica media= thinner than arteries
-Adventia =larger than arteries (prevents collapse )
2-Valves to prevent back flow
3-Wider lumen to carry blood back to heart (lower pressure)

Question 7

Main functions of veins ?

2

Answer 7

1- transport of blood back to the heart

2-storage of blood (pooling ) , and prevent back flow

Question 8

What factors effect venous return ?
(5)
requires explanation ,
think about what you need to do to increase venous return …

Answer 8

1-Valves ( should work !)

2-cardiac suction effect (when the ventricles contract , they create a negative pressure gradient which pulls blood into the atria via vena cava)

3-skeletal muscle pump ( milking )/ pressure of the blood after contraction in smooth muscle within veins due to :

• excersize , sympathetic stimulus
• activted venous stretch receptors
• Hormones : A, NA

4-RESPIRATORY PUMP contraction of diaphragm (goes down when u breathe in = increasing vertical diameter of thoracic cavity= V increases , hence Pressure DECREASES . This increases the pressure gradient towards the RA , so more blood is pulled towards RA

5-If blood volume increases the BP increases which increases the gradient ( so

Question 9

How are veins adapted to be good storage stores fro blood ?
(venous compliance )
- what tissue is reduces
-properties 
(3)

Answer 9

1-They can dilate and contract , allowing vascular compliance
2-They can accommodate changes in BV without changing pressure ( reduced amount of elastic tissue, so they don’t recoil !)
3-large storage capacity = Blood reservoir , due to the larger lumen

Question 10

Differences between veins and arteries ?

5

Answer 10

ARTERIEs/VEINS
Functions:
A-Involved in carrying pure, oxygenated blood and nutrient-rich blood.
V-Involved in carrying impure, deoxygenated blood

Walls/structure :
A-Consists of three distinct layers, which are rigid, thicker and highly muscular.(smaller Lumen )
V-Consists of three distinct layers, which are thin and collapsible. (Larger lumen & veins have valves)

Position
A-Located deep within the body.
V-Peripherally located closer to the skin.

Transports
A-Carry blood away from the heart to various parts of the body.
V-Carry blood towards the heart from the various parts of the body.

Rate of pressure
A-High pressure,
V-Low pressure,

Question 11

what is the equation for compliance ?

2

Answer 11

1-Compliance = Change in Volume/ change in pressure

Question 12

What is Venous tone ?

2

Answer 12

Venous tone = degree of constriction of vein
-An increased venous tone caused by venoconstriction leads to an increased net capillary filtration by increasing the venous resistance and venous pressure

Question 13

functions of the lymphatic system ?

3

Answer 13

1-fat absorption
2-defense against disease
3-Fluid balance ( collect ISF)