Blood Vessel Structure and Function Flashcards
What are the 4 general layers of every blood vessel?
- Lumen
- Tunica intima
- Tunica media
- Tunica adventitia
What is the tunica intima layer made up of
Internal elastic lamina
what is the tunica layer media made up of
External elastic lamina
- What is found in the tunica intima
- Endothelial cells
- Basement membrane that supports connective tissue
- What is found in the tunica media
Smooth muscle and elastin
- What is found in the tunica adventitia
Supporting connective tissue that contains fibres with some vessels & nerves
- Describe the differences in structure of the layers of arteries and veins
- Arteries: smaller lumen, large tunica media
- Veins: thin walls, larger lumen
- What is the importance of veins having thinner walls?
allows for stretch to occur which allows for additional blood volume into the vessel
- What are arterioles?
Small resistance vessels with muscular walls
What are venules?
smallest vessels in the venous circulation
- Describe what happens when blood flow is reduced.
Reduced blood flow leads to improper perfusion of tissues and lack of nutrients (ischaemia). this can lead to cell death
- What does too much flow to arterioles do?
Too much flow damages delicate tissue structure.
- How do arterioles control reduced/ too much blood flow?
Arterioles control this by varying their diameter
What is raynaud’s disease?
When smaller arteries that supply blood to the skin become limited, causing vasospasms
Name 4 components of capillaries
- Endothelial cells (1 cell thick)
- Basement membrane
- Some collagen fibrils
- Occasional pericytes
What are occasional pericytes
contractile cells that work with collagen fibrils to aid in the constriction and dilation of capillaries
- What is the diameter of capillaries
5-8 µm
- How are endothelial cells joined and what do they contain?
Joined together by tight junctions and contain many vesicles
- Name 6 functions of endothelial cells
- Permeability barrier
- Produces extracellular matrix
- Produces factors that modulate blood flow
- Produces anticoagulants and prothrombotics
- Regulates inflammation
- Cell growth
- Name 3 ways things inside the capillaries are transported across endothelial cells
- Diffusion
- Transcytosis via pinocytotic vesicles
- Via the intercellular space
How do gases and ions travel across the endothelial cells?
diffusion
How do proteins and lipids travel across the endothelial cells
Transcytosis via pinocytotic vesicles
- How do cells travel across the endothelial cells
Via the intercellular space
What do fenestrated capillaries have in their walls
Fenestrae and diaphragm
- What do sinusoidal capillaries have in their walls?
literal gaps
What type of system is the venous system
low pressure system
Explain how valves and muscle surrounding the vein facilitates blood flow against gravity
- muscle around the vessel relaxes, causing the valves to close
- Muscle contracts. The upper valve opens, blood forced upwards. The lower valve stays closed
- Muscle relaxes, upper valve closes and the lower valve opens due to muscle contraction elsewhere. Blood flows upwards through lower valve.
- What does incorrect functioning of valves lead to
leads to formation of varicose veins
- What is the texture of the endothelium
the endothelium is a smooth, non-stick surface texture
- What type of flow does the endothelium facilitate
facilitates Laminar flow
- When does turbulent flow occur
turbulent flow occurs where vessels branch and when blood pressure is raised
What can turbulent flow lead to?
This can eventually lead to damage to the endothelium
What does damage to the endothelium result in?
Results in exposure of the blood to collagen and other factors resulting in blood clotting
- What is a thrombus
Solid mass of blood constituents formed within the vascular system in life
- What is atherosclerosis
fatty deposits in the tunica intima that harden the walls and narrow the lumen of arteries
- What is arteriosclerosis
wall thickening and hardening affecting smaller arteries and arterioles
- What are the main factors resulting in arteriosclerosis
Main factors are:
- Hypertension
- Diabetes mellitus
- Why do thrombuses, atherosclerosis and arteriolosclerosis pose a threat?
They pose a threat because they narrow the lumen reducing blood flow to tissues which can lead to ischaemia.
