Blood Vessels and Connective Tissue

Question 1

Blood Vessels

Answer 1

Carry blood throughout the body
Made of tissue layers

Question 2

Types of Blood Vessels

Answer 2

Arteries - away from heart
Arterioles - smallest branches of arteries
Capillaries - where nutrient and waste exchange takes place
Venules - carry blood to veins
Veins - towards the heart

Question 3

What are the walls of blood vessels?

Answer 3

Tunica externa
Tunica media
Tunica intima

Question 4

Tunica Externa

Answer 4

Blends with surrounding connective tissue to hold vessel in place
Collagenous connective tissue
Elastic fibres
Thickest layer in veins

Question 5

Tunica Media

Answer 5

Smooth muscle fibres arranged in circular sheets
Circular muscles change diameter of lumen
SM supported by connective tissue containing elastic and collagenous fibres
Connective tissue binds layer to internal and external layer
Thickest layer in arteries

Question 6

Tunica Intima

Answer 6

Epithelial and connective tissue layers
- simple squamous epithelium
- areolar connective tissue containing elastic and collagenous fibres
Basement membrane around outside

Question 7

Connective Tissue

Answer 7

Most abundant primary tissue
Classified as loose, dense or specialised
Support and bind structures in the body
Can also insulate, store reserve fuel and transport substances in the body
Specialised connective tissue may have other functions

Question 8

Connective Tissue Structure

Answer 8

Cells far apart and surrounding extracellular matrix
Cell type and ECM components depend on type of CT

Question 9

Loose CT

Answer 9

Large amounts of ground substance and fewer fibres
Adipose
- made of adipocytes which store lipids
- insulates body
- protects internal organs

Question 10

Dense CT

Answer 10

Large amounts of fibres and less ground substance
Dense regular
- parallel fibres to increase tensile strength
- ligaments and tendons
Dense irregular
- random direction fibres
- stronger in all directions but weaker in one particular direction
Elastic
- strong but can also stretch

Question 11

Specialised CT

Answer 11

Cartilage
- chondrocytes
Bone
- strongest CT
- osteocytes
Blood
- no protein fibres
- transports things around the body

Question 12

How and why does blood pressure change as blood flows through the circulatory system?

Answer 12

As blood flows along the circulatory system, the pressure drops
The heart generates high pressure (energy) which is the driving force to move blood into the arteries
Pressure is lost to the walls of arteries (friction) as blood moves along the circulatory system

Question 13

How does blood pressure affect flow?

Answer 13

Blood flow (Q) is proportional to pressure gradient (ΔP)

Question 14

How can resistance affect blood pressure and flow?

Answer 14

Blood flow is inversely proportional to resistance
Therefore, Q is proportional to P/R
So if pressure stays the same, as resistance increases, blood flow decreases

Question 15

What determines resistance to blood flow?

Answer 15

Blood vessels with a great radius offer less resistance to blood flow
R is inversely proportional to r^4

Question 16

Factors which control vascular tone

Answer 16

Local
- myogenic response –> vasoconstriction
- metabolites –> vasodilation
External
- nerves (autonomic nervous system)
- hormones –> circulating and local

Question 17

Hydrostatic and Oncotic Pressure

Answer 17

Hydrostatic pressure pushes fluid out of capillaries
Oncotic pressure sucks fluid back into capillaries
These forces should be roughly in balance
Usually, you’ll push out more than suck back in but lymphatics pick up spare fluid and get it back to cardiovascular system