chapter 17- exam 2 Flashcards
(34 cards)
what controls the blood flow of the tisseus
the tissue controls its own blood flow to the proportion it needs (locally)
what does the tissue need
- Delivery of oxygen to tissues
- Delivery of nutrients such as glucose, amino acids, etc.
- Removal of carbon dioxide hydrogen and other metabolites from the tissues
- Transport various hormones and other substances to different tissues
what is the flow of blood to the tissues related too
the metabolic rate of the tissue if related to the flow
what does the increased tissue metabolism causee
increase to blood flow
what does a decrease of oxygen availability cause
the tissues increases tissue blood flow
look at graph
on slide 4
what are Two major theories for local blood flow
1) The vasodilator theory
2) Oxygen demand theory
what does flow equal
flow (q)= change in P/ R
- change in p = is between the tow ends of the vessel
- R= resistance of the vessels
WHY does the increased tissue metabolism cause increased BF
vasodilators
increased tissue metabolism →
↑ released of vasodilators →
↓ arteriole resistance →
increased BF
what are some vasodilators
Adenosine, CO2, ADP compounds, Histamine, K+ ions, H+ ions
WHY does decreased oxygen lead to increased tissue BF
↓ oxygen delivery to tissue →
↓ tissue oxygen concentration →
↓ arteriole resistance →
↑ blood flow
what is autoregulation
Ability of a tissue to maintain blood flow relatively constant over a wide range of arterial pressures
** plus look at the graph
how does the blood flow through autoregulation
metabolic theory
myogenic theory
what is metabolic theory
When arterial pressure decreases oxygen or nutrient delivery is decreased resulting in release of a vasodilator
what is myogenic theory
When arterial pressure decreases arterioles dilate in response to decreases in wall tension
do other systems have different autoregulatory theories ?
yes
–Kidneys have a feedback system between the tubules and arterioles
–Brain blood flow is controlled by carbon dioxide and hydrogen ion conc.
what is wall tension
laplaces law
what is Laplaces law
the large the vessel radius, the larger the wall tension required to withstand a given internal fluid pressure
Look at slide 13
what does pressure =
p= force / unit area
what does tension =
tension= pressure x radius
what is pascals law
a pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs
** will be equal at equilibrium
what is wall tension is proportional to
the pressure and the radius
in the heart tension =
T= (Px R)/ h
p= pressure R= radius h= wall thickness
what regulatory mechanism controls the blood flow effectively
the long term is better than the acute
