L13 Flashcards
What is the purpose of the elastic systemic Arteries?
These are a pressure reserve that maintains blood flow during ventricular relaxation
Arterioles are the site of variable resistance, what do they do to maintain this resistance/decrease it?
Arterioles adjust their diameter
What do systemic veins serve as?
These serve as an expendable volume reserve
What side of the heart allows for material exchange?
The right side of the heart
What two components do blood vessels have? What are their function?
Blood vessels contain smooth muscle and elastic fiberous connective tissue:
Smooth muscle: regulates pressure
Elastic tissues: returning to normal state after stretch
Wall thickness varies in different vessels, the more ____ the vessel is, the ____ exchange of materials take place.
The more thin the vessel is, the greater exchange of material takes place
What is the inner most layer of blood vessels made of? What are the five function?
The inner most layer is endothelium which:
- acts as a barrier
- secretes paracrine factors
- regulates blood pressure
- regulates vessel growth
- regulates absorption
What is muscle tone?
This is a state of partial contraction, there is always a contraction occurring in blood vessels.
Describe the characteristics of arteries
- these are a key component in elasticity
- act as a pressure reservoir
- has a thick layer of vascular smooth muscles
- lots of elastic and fiberous tissues
Describe the characteristics of arterioles
- site of variable resistance
- part of microcirculation
- less elastic and more muscular
- several layers of smooth muscle that act for constriction and relaxation
Describe the characteristics of metarterioles
- branches of arterioles
- partial smooth muscle layer
- controls if blood goes into capillaries, acts as a bypass mechanism
- precapillary sphincters open and close to direct blood flow
What occurs during ventricular contraction? What is the beginning phase?
- contraction of the ventricles pushes blood into elastic arteries causing a stretch
- beginnings phase is ventricular contraction
What occurs during ventricular relaxation? What’s the beginning phase?
- elastic recoil in the arteries maintain driving pressure during ventricular diastole
- beginning phase is isovolumetric relaxation
When precapillary sphincters _______, blood flows through the capillary into the blood
Relax/dilate
When precapillary sphincters _______, blood flow bypasses capillaries completely and flows to metarterioles
Constrict
What is the primary site of interstitial fluid and blood exchange?
The capillaries
Describe the characteristics of the capillary walls
- more thin, less area to cross means more efficient
- lacks smooth muscles
- flat layer of endothelium
- basal lamina
Describe the characteristics of pericytes
- highly branched contractile cells associated with capillaries
- contribute to capillary impermeability
- secrete paracrine factors that promote vascular growth and differentiation
- MORE PERICYTES for a more secure area so it doesnt leak.
What is angiogenesis?
This is the development of new blood vessels (can cause spreading of a disease)
- necessary for normal development
- enhances heart and skeletal muscle blood flow
What is angiogenesis controlled by? What’s it inhibited by?
It is controlled by cytokines and promoted by vascular endothelial factor and fibroblast growth factors.
- its inhibited by angiostatin and endostatin
What is pulse pressure?
Pulse pressure measures strength pressure wave produced by ventricular contraction
Systolic pressure- diastolic pressure
(This decreases over distance due to friction)
What is mean arterial pressure? What are the two types?
Diastolic pressure + 1/3 pulse pressure
This represents the driving force. There are two types:
Hypotension- lower than normal MAP
Hypertension- higher than normal MAP
Volume of blood in arteries is determined by _______ and flow out
Is determined by input (cardiac output)
As arterial volume increases ______ increases
Pressure increases. This applies both ways. As arterial volume decreases pressure decreases.
If flow exceeds flow ____ (of) aorta then blood volume ______ and MAP increases
Out, increases
Vice versa can occur
Blood volume is relatively constant, change in blood volume affects blood pressure in the following ways:
Blood volume ____, pressure ______, / Blood volume ____, pressure _____
Increases, increases / decreases, decreases
MAP is determined by 4 factors, list them.
- Blood volume
- Effectiveness of heart as pump
- Resistance of the system to blood flow
- Distribution of blood between arteries/veins
Blood pressure control includes _____ responses from cardiovascular system and _____ responses from the kidneys
Rapid, slower
Arterioles have a resistance that is influenced by what?
Local and systemic control mechanisms (local control, sympathetic control, reflexes, hormones)
What do myogenics autoregulation adjust?
These adjust the blood flow which allows for vascular smooth muscles to regulate its own state of contraction.
Paracrine signals influence vascular smooth muscles, list more of their characteristics
- these secrete NO, which is a major signal in hypertension (which blocks airway)
- kinins and histamines are a potential vasodilator
- metabolic influences causes active vs reactive hypermia
What is hypermia? What are the two types?
This is a locally mediated increase in blood flow.
Active hypermia- direct matching of blood flow to increased metabolism
Reactive hypermia- follows a period of decreased blood flow
Neural and hormonal signals have three types:
- atrial nativertic peptide (this occurs in contraction)
- angiotensin II
- vasopressin (ADH)
Characteristics of sympathetic control on vascular smooth muscle
- adrenal medially releases epinephrine into blood
- epinephrine binds to alpha and beta receptors
- binds alpha receptors with very low affinity—> vasoconstriction
Binds beta 2 receptors on vascular smooth muscles of heart, liver and sketch muscle arteries which causes—> vasodilation
What is arteriole diameter controlled by?
Tonic release of norepinephrine
Blood distribution ____ according to metabolic need of individuals tissues
Varies
Two factors that govern distribution of blood
Local control mechanism and homeostatic reflexes
The flow in aorta is equal to _____ in all arterioles due to branching
The flow
What do individual arterioles regulate on their own?
They regulate their own flow by compensation in remaining arteries
What is the importance of the Cardiovascular Control Centre?
It’s contains the baroreceptor reflex that controls blood pressure, these produce continuous tonic action potential
Wha triggers the baroreceptor flex? Explain how.
Orthostatic hypertension triggers this reflex, this decreases in blood pressure due to postural change. Failure to compensate may lead to lack of O2 delivery.
What is the intrinsic rate of the heartbeat modulated by?
This is modulated by sympathetic and parasympathetic neurons. The blood vessel diameter is under tonic control by the sympathetic division
Difference between continuous and fenstrated capillaries
Continuous= have a leaky junction Fenstrated= larger pores
Describe what happens with velocity of the blood flow in capillaries
- constant rate of flow, velocity of flow is higher in smaller diameter tubes
- velocity of blood flow is lowest in capillaries
- total cross sectional area of capillaries is primary determinate of velocity
___ flow in artery system, ___ flow in capillaries and venules
Fastest, slowest
Exchange between plasma and interstitial fluid occur by what?
Paracelluallar pathways and endothelial transport
Describe movement by diffusion
This is small dissolved solutes and gases that depend on lipid solubility and concentration gradients
Describe the vesicular transport method
This carries large solutes and proteins via transocytosis
Describe what occurs during filtration
- this is where fluid movement is out of capillaries
- this had pressure laterally or against gradients
- if hydrostatic pressure increases (or is greater) filtration occurs
- caused by hydrostatic pressure—> which decreases with distance
Describe what happens during absorption
- Fluid movement into capillaries
- caused by colloid pressure
- due to presence of proteins in fluid that attract back into system
Net filtration at atrial end occurs when _______
Net absorption at Venus end occurs when______
Hydrostatic pressure> osmotic colloid
Hydrostatic pressure
A net average of ___L per day of fluid is filtered out of the capillaries
3
An increase in hydrostatic pressure ______
A decrease in colloid osmotic pressure ______
Forces fluids out of capillary
Forces fluids into capillary
What is Edema?
This is an accumulation of fluid in the intestinal space. Inadequate drainage of Lymph or filtration greater than absorption.
