Lecture 16 & 17 Flashcards
Transport of oxygenated blood
Arteries
Act as valves for entry into capillaries
Arterioles
Gas and nutrient exchange
Capillaries
Collects blood from capillary
Venules
Carry deoxygenated blood back to heart
Veins
- Contains lining of simple squamous epithelium (endothelium), basement membrane, and layer of elastic tissue (internal elastic lamina)
- Endothelium lines entire cardiovascular system and is only tissue that contacts blood
Tunica interna (intima)
- Thickest layer, middle layer
- Consists of elastic fibers and smooth muscle that extend circularly around the lumen
Tunica media
- Outermost layer
- Composed mainly of elastic and collagen fibers
- In muscular arteries, an external elastic lamina composed of elastic tissue separates the tunica externa form the tunica media
Tunica externa
Type of artery with largest diameter - tunica media contains large amounts of elastic fibers
Elastic arteries
This type of artery has
- More smooth muscle in tunica media (which is innervated by SNS)
- Fewer elastic fibers
- Capable of greater vasoconstriction and vasodilation to adjust blood flow
Muscular arteries
Carry oxygenated blood and empties into capillaries
Arterioles
Control blood flow into capillary bed
Metarterioles and precapillary sphincters
Site of gas and fluid exchange with the tissues
Capillaries
The wall of this is very thin (good for gas exchange); consists of a layer of endothelium and underlying basement membrane. They do not contain smooth muscle thus they are not capable of vasoconstriction or vasodilation
Capillaries
Receive deoxygenated blood from capillaries
Venules
Have smooth muscle, and are capable of vasoconstriction and vasodilation
Arterioles and venules
Consist of same three tunics as arteries (tunica interna, tunica media, tunica externa)
Veins
Much more compliant than arteries - can hold more blood, so they act as a reservoir.
Veins
Contain valves that prevent backflow of blood
Veins
The force exerted on the walls of the blood vessels by the blood
Blood Pressure
Blood flows through the body due to _______
Pressure gradient
Mean Arterial Pressure (MAP) equation
MAP=DBP + 1/3 (SBP-DBP)
_____ Represents the pressure gradient in the systemic circulation and is the major driving force for blood flow through the systemic circulation.
MAP (Mean Arterial Pressure)
Is pressure gradient in pulmonary circulation high or low?
Low
Is pressure gradient in systemic circulation high or low?
High
Pulse pressure equation
SBP-DBP
Factors that affect pulse pressure
Stroke volume and Compliance
Greater _____ results in greater pressure rise with each heart beat
Stroke volume
Lower _______ of artery results in a greater pressure rise with every beat
Compliance
________ are dampened further down the vascular tree; arterioles and capillaries do not experience significant _______
Pulsations (both blanks)
Factors that affect MAP
MAP = CO x TPR
______ is the resistance to blood flow through all of the vasculature in the body.
TPR
TPR represents ______ resistance.
Arterial; because venous vasculature is very compliant.
TPR ______ as arterial vessels vasoconstrict.
Increases
TPR ______ as arterial vessels vasodilate.
Decreases
This increases venous return through rhythmic contration of skeletal muscle which helps to push blood in the veins towards the heart.
Venous pump
During inspiration, abdominal pressure increases and intrathoracic pressure decreases. This leads to increased venous return due to increased pressure gradient.
Respiratory pump
Renin-angiotensin-aldosteron system
RAAS
Activation of ____ increases blood pressure
RAAS
_____ converts renin substrate (angiotensin) to angiotensin I in RAAS
Renin and decreased arterial pressure
_____ converts angiotensin I to angiotensin II in RAAS
ACE (Angiotensin Converting Enzyme)
Renin substrate (also called angiotensin) is secreted from _____
The liver
_______ is important in regulation of blood pressure.
Angiotensin I
_______ does not influence blood pressure
Angiotensin II
Receptors are in brain, kidneys, myocardium, peripheral vasculature, and adrenal cortex
Angiotensin I
Receptors are in adrenal medullary tissue, uterus, and brain
Angiotensin II
______ causes the kidneys to reabsorb salt and water in two ways
Angiotensin Ii
- Acts directly on kidneys to cause salt and water reabsorption
- Stimulates adrenal glands (cortex) to secrete aldosterone
Angiotensin II
_____ causes an increase in salt and water reabsorption in kidneys.
Aldosterone
Causes vasoconstriction,
Stimulates: SNS, thirst centers, ADH release from posterior pituitary
Inhibits renin release from kidney
Angiotensin II
______ is most prominent in capillary wall of lung, but also in other tissues of the body
ACE
True or False? Angiotensin can also be produced by other systems that function without ACE.
True
ADH
Anti-diuretic hormone (also called vasopressin)
Released from posterior pituitary gland in response to decreased blood volume and/or an increase in osmolarity
ADH
Increases BP by causing vasoconstriction and acting on kidneys to promote reabsorption of water (not salt)
ADH
V1a receptors
ADH receptor that mediate vasoconstriction
V2 receptors
ADH receptor that mediates antidiuretic effect in kidney
V1b receptors
ADH receptor
ANP or ANF
Atrial Natriuretic Peptide (or Factor)
Released by cells of atria in response to increase stretch
ANP or ANF
Lowers BP by causing vasodilation and acting on kidneys to promote loss of salt and water in urine
ANP or ANF
Suppresses secretion of renin, aldosterone and ADH
ANP or ANF
Released from ventricles in response to pressure & volume overload – function is similar to ANP in that it functions to decrease BP.
BNP or BNF
Innervates most vessels, except capillaries, precapillary sphincters, and metarterioles
SNS
Causes constriction of most vessels of body via alpha-1 adrenergic receptors
SNS
Stimulation of this type of receptor causes vasodilation.
Beta-2
This receptor type stimulates increased heart rate and contractility
Beta-1
Innervates the heart and increases heart rate and contractility
SNS
Majority of blood vessels are not innervated by _____
PNS
Innervates the heart and decreases heart rate and decreases contractility
PNS
Regulates the ANS
Vasomotor center in the medulla
Stretch receptors located in the walls of large arteries (Carotid artery and aortic arch)
Baroreceptors
Arterial pressure ____, and causes stretching of baroreceptors send info to vasomotor control center which then results in decreased TPR and CO
increases
Arterial pressure _____, stretching of baroreceptors is reduced which results in increased TPR and CO.
decreases
Important for rapid changes in BP and reduces variation in BP throughout the day
Baroreceptors
These types of bodies sense a decrease in O2 content and an increase in CO2 and H+ content
Carotid bodies and aortic bodies
If blood pressure decreases, blood flow decreases through this type of receptors in the ANS
Chemoreceptors
Blood pressure decrease and blood flow decrease in chemoreceptors causes stimulation of the receptors and excitement of the vasomotor center. What does this result in?
Increased blood pressure
These types of receptors are also called low pressure receptors
Atrial and pulmonary stretch receptors
These are receptors that are in the atria and pulmonary artery
Atrial and pulmonary stretch receptors
Low pressure receptors are important in minimizing changes in pressure in response to ________ changes.
Volume changes
