Test 2 Chapter 10 Peripheral Vasculature Flashcards
Chapter 10 …You’re Almost there!!
Vasculature
Function of blood vessels?
Responsible for moving blood throughout the body
Specific functions for different locations
What are the 3 layers (tunica) of blood vessels?
Adventitia
Media
Endothelial
(Intima)
What are the Blood Vessel Types?
Artery
Arterioles
Metarterioles
Capillary
Venules
Vein
External Layer?
External or Adventitia
Made of connective tissue
Middle Layer?
Media
Smooth muscle layer
Inner Most layer?
Endothelial Layer
made of Epithelial Tissue
What is the Intima
Endothelium and basement membrane
Where atherosclerosis (fatty deposits) occurs underneath blood vessel lining
What is an artery?
Characterized by?
Blood vessel leaving the heart
Smooth muscle-large media layer
Describe Arterioles
Small Artery
Less than 1/2 mm in diameter
Metarteriole
Contains what?
Branches off of the arteriole
Isolated sections of smooth muscle (Precapillary sphincters)
Pre-Capillary sphincters allow blood flow through capillary bed
Capillary
Layer of endothelium (intima) in basement membrane
1 endothelial cell thick
Exchange occurs here (short distance)
Venules
Small veins with limited or no smooth muscles
Vein
Less smooth muscle than arteries
Do capillaries contain smooth muscle?
NOPE
What are the 4 Physical Properties that define function?
- Ohm’s Law
- Poiseuille’s Law
- Capacitance (distensibility)
- Mean Arterial Pressure
Ohm’s law
PRESSURE=FLOW x RESISTANCE
How blood flows through blood vessel
(V=IR)
Mean Arterial Pressure
Average pressure in an artery & equal to flow through the arteries
Flow=Cardiac output X total peripheral resistance
F=CO x TPR or
BP=HR x SV x TPR
Poiseuille’s Law
Calculating resistance nL8/(pi)x r^4
manipulating resistance ->effects pressure
According to Poiseuille’s Law, what happens to pressure with change in resistance?
Increase resistance=increase pressure
Decrease resistance=decrease pressure
Small change in radius produces a profound change in resistance and blood flow
Capacitance/Distensibility
C= Change in volume/change in pressure
Compare veins and arteries in terms of capacitance and distensibility
Capacitance-ability of a vessel to accept volumes easily
Change in volume/change in pressure
Veins= high capacitance. Can easily distend and accept large volumes w. Little change in pressure
Artery=low capacitance. As volume increases pressure increases
Calculate Mean Arterial Pressure
MAP= Diastolic Pressure + 1/3 pulse pressure
So
80 + (1/3)40=93mmHg
Functional properties of Arteries?
Arteries are pressure reservoirs.
What sustains the pressure the heart creates?
Arteries
Doppler Sounds in an artery
1st surge
2nd surge
1st surge=heart beating
2nd surge due to artery recoiling
Dichroitic Notch
Located in the arterial pulse wave
Point when semilunar valves close
The little blip=arterioles recoiling=2nd surge of blood
Systolic Blood Pressure
Created by contraction of the heart
Diastole
Heart relaxes
BP gradually comes down (low point) pressure in the artery drops down to low point
Systolic blood pressure/diastolic pressure what is the typical blood pressure?
120/80
Pulse Pressure?
Difference between systolic blood pressure and diastolic pressure
The driving pulse
What is typical mean arterial pressure?
93mmHg
Function of Arterioles?
What kind of control do arterioles have?
Resistance vessels
Vasomotor control
What are the 2 types of vasomotor control that controls arteriole resistance?
Vasodilation
Vasoconstriction
Estimating MAP
Diastolic blood pressure + [1/3xpulse pressure]
Vasodilation of arterioles in terms of resistance and blood flow
Decreased resistance =increased local blood flow
Vasoconstriction
Increased resistance and decreased local blood flow
What are the small arteries that vasodilation and vasoconstrict?
Arterioles=resistance vessels
5 mechanisms that control vasomotor tone in ARTERIOLES?
Effecting unitary smooth muscle cells
Myogenic Autonomic Nervous System Hormones Paracrines Autoregulation
- MYOGENIC
Unitary smooth muscles around arterioles are…
Can stimulate themselves because they are myogenic
- Autonomic Nervous System
-involuntary control but have SYMPATHETIC CONTROL-1 side
Norepinephrine->smooth muscle surrounding arterioles->produces stronger contraction-> VASOCONSTRICTION->resistance increases->blood flow decreases
To vasodilate arterioles what needs to happen?
Decrease sympathetic control
- Hormones that cause vasocconstriction
Epineprhine
Norepinephrine
Angiotensin
Vasopressin
- Autoregulation of arterioles
Local control based on local metabolites which cause vasoconstriction or vasodilation
- Paracrines
Vasodilators
Vasoconstriction
Local in its effect-does not enter blood stream
- Vasodilators: Nitric oxide (endothelium)
- Histamine (immune response)
Vasoconstriction-Endothelin-produced in endothelium
Major causes of vasodilation via AUTOREGULATION
Decreased Oxygen and pH
Increased CO2, Temp, ADP, Potassium
Major causes of Vasoconstriction via AUTOREGULATION
Increased: Oxygen and pH
Decreased CO2, TEMP, ADP, Potassium
What are the Metarterioles
Function:
Similar to ____ except for_____
Resistance vessels
Similar to arterioles except not controlled by AUTONOMIC NERVOUS SYSTEM. Controlled by MYOGENIC PROPERTIES, HORMONES, PARACRINES & Autoregulation
Capillaries
Function
Description
Function: exchange vessel
Small, thin, 1 cell layer thick->ideal simple diffusion conditions
What are the key factors in diffusion?
Large surface area
Short distances
High concentration gradients
slow velocity
What exchange mechanisms do capillaries do capillaries participate in?
- Diffusion
2. Bulk Flow
What is Bulk Flow in the Capillaries
-fluid leaks out and is reabsorbed into the capillaries via OSMOSIS
Consists of ultrafiltration
& reabsorption
What are the 4 forces facilitating bulk flow in the capillaries?
- Capillary pressure
- Plasma colloid osmotic pressure
- Interstitial fluid hydrostatic pressure
- Interstitial fluid colloid osmotic pressure
What are the inward pressures pushing into the capillary
Plasma colloid osmotic pressure
(25mmHg)
Interstitial fluid hydrostatic pressure
1mmHg
What are the outward pressure forces?
- Capillary pressure (37mmHg)
2. Interstitial fluid colloid osmotic pressure (0mmHg)
Capillary pressure
Pressure from inside pushing out
37mmHg-arteriole end
17mmHg-Venules end
Plasma Colloid osmotic pressure?
Pressure pulling in
Constant 25mmHg
Interstitial fluid Hydrostatic Pressure
Due to fluid on outside pushing in 1mmHg
Interstitial fluid colloid osmotic pressure
Due to osmotic proteins.
Pulls fluid out of capillaries (0mmHg)
Net inward pressure on Venule end of capillary?
9mmHg
Net outward f\pressure on arteriole end of capillary
11mmHg
Ultrafiltration
Occurs on arterial end of capillary
3 L of Fluid leaks out into interstitial fluid the rest is reabsorbed
Reabsorption
Venous end of capillary. Reabsorption of fluid that has leaked out
Lymphatic system consists of what
Lymph=3L of fluid not reabsorbed by capillary
Lymph nodes: filters lymph before being returned into circulation
What are Venules?
Very little smooth muscle & Function as conduits (they are just a pass to veins)
Veins
Function
Function: volume reservoirs or high capacitance vessels
65-75% of blood located here
Veins allow to manipulate venous return