4 - Blood Vessels Flashcards
Describe layers of blood vessel wall
1) Tunica Externa: Connective tissue
2) Tunica Media: smooth muscle, allowing vasoconstiction and dilation
3) Tunica Intima: smooth muscle
What are the 5 types of capillary bases
1) Continuous
2) Fenestrated
3) Sinusoidal
4) Sinusoids
5) Venous Sinuses
Continuous Capillary (function and location)
1 – Continuous: No gaps between endothelial cells. No fenestrae. Less permeable to large molecules. E.g. muscle and nervous tissue.
Fenestrated - function + location
2 – Fenestrated. Have pores, numerous fenestrae. Highly permeable. E.g. intestinal villi, glomeruli of kidney.
Sinusoidal - function + location
3 – Sinusoidal: large in diameter with large fenestrae. Less basement membrane. E.g. endocrine glands (large molecules cross their walls)
Sinusoids - function + location
4 – Sinusoids: large diameter. Sinusoidal capillaries. Sparse basement membrane. E.g.. liver, bone marrow.
Venous Sinuses - function + location
5 – Venous sinuses: Similar structure to sinusoids but even larger. E.g. spleen
What is fenestrae?
- FENESTRAE: are areas where cytoplasm is absent and plasma membrane is made of thin, porous diaphragm.
▪ Define vasoconstriction and vasodilation
▪ Vasoconstriction: smooth muscles contract, decreasing blood flow.
▪ Vasodilation: smooth muscle cells relax and increase blood flow.
▪ Define the term vasa vasorum
Vasa Vasorum: blood vessels that supply the walls of the arteries and veins. Penetrate the vessel walls from the exterior, branches of the arteries.
▪ Define the term portal veins
Portal Veins: Veins that begin in a primary capillary network, extending some distance and end in a secondary capillary network without a pumping mechanism.
What type of nerve fibres are blood vessels innervated by?
Sympathetic fibres
Arterial changes that occur with age
Arteriosclerosis: degeneration changes in arteries, making them less elastic.
Atherosclerosis: depiction of plaque on walls
How does odema occur?
Odema occurs when capillary walls become permable and allow proteins to leak from the capillary into its instersitial fluid
What are the factors effecting blood flow
- Blood pressure
- Flow
Resitance
What is blood pressure
force exerted by blood against vessel wall
What is blood pressure measured by?
Korotkoff sounds
What is normal blood pressure
120/80
How do you calculate flow?
P1-P2 (P represents a specific point in a unit of time)
How is a Korotoff sound produced?
By TURBULANT flow
What is laminar flow?
Streamlined flow - outermost layer is the slowest and innermost is the fastest
What is turbulant flow
Interupted flow due to rpughened surface (e.g. from a pressure cuff)
What is Poiseluilles law?
Flow increases when resistance increases (e.g. when exercising)
How does viscosity effect bloodflow pressure
Viscosity increases blood flow pressure
