Week 2 - Structure and function of blood vessels Flashcards
types of vessels
Arteries
Veins
Artery
carries O2 away from heart
Veins
Returns blood to heart
two distinct circuits
Systemic
Pulmonary
Systemic
Moves blood from right side of heart to lungs
Oxygenates blood
brings blood back to the heart
Pulmonary
Moves blood from left side of heart to head and body
returns deoxygenated blood to right side
Arterioles
Thicker walls
smaller lumens
Lumens
hollow passageway
blood flows through
vasa vasorum
small vessels within walls of large arteries and veins
provides nutrients to vessel walls
Layers of a blood vessel (Arteriole)
Tunica Intima
Tunica media
Tunica externa
Tunica Intima
Inner layer
Releases chemicals that can open and constrict arteries
Endothelium
damage to this layer can cause clots
Tunica media
Middle layer
smooth muscle
allows for vasodilation and vasoconstriction
Vasodilation
widening of blood vessels
result of relaxation of blood vessel’s muscular walls
Vasoconstriction
narrowing of blood vessels
small muscles in their walls
Tunica externa
adventitia
outer layer
connective and elastic tissue
connective tissue
transports nutrients and wastes
defends against pathogens
stores fat
repairs damaged tissue
supports organs and cells
elastic tissue
composed mainly of elastic fibers
provides elasticity and resilience of tissue
How capillary beds work
blood moves from arterial system into capillaries
diffusion of blood, gases & nutrients occur here
can widen and narrow arterioles so blood flow is regulated
Blood reservoir
Veins act as reservoirs
contains 64% of blood volume
high capacitance
High capacitance
ability to distend
When rediverting blood is needed
sympathetic stimulation causes venous walls to squeeze blood back to the heart
Systemic blood pressure
Systolic
Diastolic
Pulse pressure
Mean arterial pressure
Systolic
Top number
Diastolic
bottom number
Pulse pressure
difference between systolic & diastolic
Mean Arterial Pressure
MAP
average pressure in arteries
Factors affecting blood flow and blood pressure
cardiac output
compliance
volume of blood
viscosity of blood
blood vessel length and diameter
How does the blood get back to the heart
Skeletal muscle pump
respiratory pump
Skeletal Muscle pump
Contraction of skeletal muscles surrounding a vein
High-Low pressure relationship
One-way valves
Respiratory Pump
aids blood to move through veins of thorax and abdomen
Diaphragm drops, intercostals contract
Intercostals
Capillary exchange
Hydrostatic
Osmotic
Hydrostatic
Pressure at the start
The push (filtration
Osmotic
Pressure at end
The pull (reabsorption)
Regulation of the vascular system
Maintaining homeostasis
Neural regulation of P & Q
Maintaining homeostasis
Cardiovascular system
Greater the energy needed by tissues, the greater demand for blood flow
body makes a priority list
Neural Regulation of P & Q
Cardiovascular centers in brain
baroreceptor reflexes
Chemoreceptor reflexes
Cardiovascular centers in brain
Located in medulla
Vasomotor centers
Medulla
Responds to changes in oxygen, carbon dioxide, hydrogen
Vasomotor centers
Control tone of smooth muscles in vessels
Chemoreceptor reflexes
Found in aortic and carotid sinuses
Responds to levels of oxygen, carbon dioxide, hydrogen (pH)
Low oxygen, high carbon dioxide and hydrogen
Baroreceptorss
Stretch receptors in blood vessels and heart
More blood = More stretch and more signaling
Autoregulation of Perfusion: Chemical Signals
Self-regulatory mechanisms
Opening of precapillary sphincter
closing of precapillary sphincter
Epinephrine and norepinephrine
Increases HR, Force of contraction, reduced blood flow to non-essential organs
Endocrine Regulation
Epinephrine and norepinephrine
Autoregulation of perfusion: Chemical signals
Autoregulation of perfusion: Myogenic response
Erythropeoietin
EPO
Increases RBC production and vasoconstricts
Antidiuretic Hormone
ADH
Increases water reabsorption in the kidneys
Increase blood volume and BP
Self-regulatory mechanisms
Can adjust blood flow
Atrial Natriuretic Hormone
ANH
Released when there is too much blood volume (reduces BP
Opening of precapillary sphincter
Increased perfusion
Cell metabolism byproducts
Closing precapillary sphincter
Decreased perfusion
Chemicals from vessel walls
Platelets
Prostaglandins
Cell metabolism byproducts
Increase in CO2
decrease in O2
Prostaglandins
Group of lipids with hormone-like actions that your body makes primarily at sites of tissue damage or infection
Prostaglandins control processes
inflammation
blood flow
formation of blood clots
induction of labour
Autoregulation of perfusion: Myogenic resposnse
Stretching of smooth muscle in arteriole wall
Low stretch of smooth muscle in arteriole wall
Vessel dilates and increases BF
High stretch of smooth muscle in arteriole wall
vessel constricts and reduces BF
