vesseles Flashcards
Arteries
Elastic: low resistance, no constriction, elastic fibers, act as pressure reservoir
Muscular: deliver to organs,can constrict,smooth muscle,elastic fiber
Arterioles: maintain resistance
Capillaries
-supply all cells but cartilage, epithelial, cornea and lens of eye
- pericyte: spider shaped stem cells stabilize capillary wall, control permeability, role in BV repair
Three types of capillaries
continuous: Lungs, muscles, CNS, skin
Fenestrated: kidneys, Gut( intestines)
sinusoidal: Spleen, liver, adrenal medulla, bone marrow
Capillary beds
- when arterioles dilate, blood flows through cap. When constricted, no flow here
key terms: terminal arterial, post-capillary venule
Veins
- carry blood to the heart
- has all tunics, but thinner to form larger lumen
media thin, externa thick - venules form from merge of capillaries
- consist of endotherlium+few pericytes(similar to capillaries)
-allow WBCs inside
Veins have lower blood pressure + rate of flow
- large diameter lumen = lower resistance
-venouse valves ( mostly in limbs, orevent back flow) - skeletal+smooth muscle contract to help move blood through veins aswell
Vasa Vasorum
found within tunica externa and provide BV walls with blood( O2 =energy)
Blood vessel issues
-varicose veins
- dilated, painful veins->heredity+ conditions that inhibit venous return
- elevated Venous pressure
- varicosities in ones ass are callled hemorrhoids and are caused by constipation
- defective valves
Anastomosis
connection created between tubular structures such as blood vessels or loops of intestine
Anastomonsis Types
Vascular-> interconnections of BV
arterial->connections between arteries to ensure blood gets to wanted location even with a block
- common in joints, ab organ, brain, heart
- nine in kidney, retina, spleen
venous->hella abundant so occluded vein rarely have a problem
Blood flow
volume of blood flowing through vessel organ or entire circulation in a period of time
Blood pressure
force per unit area exerted on wall of BV by blood
Resistance
opposition of flow
Three Types of resistance impactors
Viscosity ↑, resistance ↑
Vessel length↑, resistance ↑
Vessel diameter ↑, resistance ↓
-small diameter arterioles are major contributors
power of 4 rule
- diameter /2
- resistance x 2^4=16
Blood flow calculations
F=blood flow
∆P= blood pressure
R= resistance
F=∆P/R
*R is more importent to local blood flow
systemic pressure
- Highest in aorta
- steepest drop in arterioles
BP reg. in arteries
- elasticity
- volume of blood forced inside
- BP near heart is pulsatile so it rises and falls with each beat
Mean arterial Pressure ( MAP )
- pressure that propels blood to tissues
MAP= diastolic pressure + 1/3 pulse pressure
pulse pressure= systolic-diastolic
blood pressure= systolic/ diastolic -> 120/80 is normal
what is a pulse
- Throbbing of artery during systolic ventricular contraction
Measuring Blood pressure
-stethoscope or other auscultatory methods using sphygmomanometer
- Examiner listens for sounds of Korotoff
Korotoff sounds
Korotkoff sounds are generated when a blood pressure cuff changes the flow of blood through the artery
ideal results blood pressure
systolic: less then 120mmHg
- sound first occurs when blood spurts through artery
diastolic: less than 80mmHg
- sounds disapper as artery no longer constricted
Capillary BP regulation
-beginning of bed 35mmHg
_End of bed 17mmHg
Low capillary pressure is desirable
- High BP can rupture capillary
-capillaries high permeable
Venouse BP regulation
promoted by
- skeletal muscle
- respiratory system
- smooth muscle
- Valves
BP and cardiac output
Three main factors of BP regulations
- cardiac output
- peripheral resistance
- blood volume
