Unit 2 Flashcards
Arteries have: \_\_\_\_\_\_ pressure \_\_\_\_\_\_\_ velocity of blood flow \_\_\_\_\_\_\_ walled Lots of \_\_\_\_\_\_, \_\_\_\_\_ and \_\_\_\_\_ muscle Functions as a \_\_\_\_\_\_ (resistance to flow doesnt change much
High pressure High velocity of blood flow Thick walled Lots of elastin, collagen and smooth msucle Functions as a conduit
_______ control flow into capillaries and are the MOST important determinant of PERIPHERAL RESISTANCE
Arterioles
What is the most important determinant of peripheral resistance?
Arterioles
Arterioles contains much ____ muscle and can change ______
Smooth muscle
DIAMETER
_____ function to exchange fluid, nutrients, electrolytes, hormones, etc to tissue cells.
Thin walled and no muscle
Capillaries
Veins and venules have _____ pressure
Thin walls that are ________
Low; distensible
The total cords-sectional area is the sum of the individual ______ area of each ______ category
Cross sectional
Blood vessel
Even though capillaries have the ______ diameter individually, they have the _______ cross-sectional area
Smallest; largest combined
Most of the blood volume is in the _______ system
Venous
Veins and venules are considered to be the _________
Blood reservoir
As total cross-sectional area increases, blood flow velocity _______
Decreases
V=Q/A or V= F/A
What is total cross sectional area?
The sum of the individual cross sectional areas of each blood vessel category
Capillaries have the smallest ______ individually and the largest combined
Diameter; cross sectional area
Blood flow (_or _) is the same or different? For each section of the circulation
Q or F; is the same for each section of circulation
Pressure in arteries is ____
Pressure in the capillaries averages about _____ mmHg
Pressure in venous system is ____
High; 17; low
What is Ohm’s law?
I=V/R
**algebraic rearrangement of this equation also hold true:
Delta P= QxR
R= delta P/Q
Blood flow (Q)= (P1-P2)/R is what equation?
Basic flow equation
AKA ohm’s law
Blood flow (Q) means what?
The volume of blood that passes a given point per unit of time
Ex: Liters per min
Cardiac output (CO) is what? And that is the typical caridac output
Q for the entire systemic circulation and typically is about 5 L/min
Explain laminar flow
Flow in layers
Parabolic shape of velocities
Generally quiet
Explain turbulent flow
Layers are disrupted by some partial obstruction or excessive velocity
Noisy
What is a carotid bruit?
Atherosclerotic plaques partially occluded an artery causing turbulent flow
When measuring blood pressure, cuff pressure should be ________ when inflated. One slowly let air out of cuff, between 80 and 120, will revive b
When the cuff is inflated so that it sto[s arterial blood flow. No sound can be heard through a stethoscope placed over the brachial artery distal to the cuff
Korotkoff sounds are created by pulsatilla blood flow through the compressed artery
Blood flow is silent when the artery is no longer compressed
What can be used to determine turbulent flow?
Reynold’s number
When Reynolds number rises above ______, turbulence is likely
200- 400
Turbulence often occurs in the _______ due to pulse and changes in vessel diameter during ejection
Aorta
T/F: Turbulence normally occurs in smaller vessels
F: turbulence normally doesn’t occur in smaller vessels
What is used to relate radius, viscosity and length to blood flow?
Poiseuilles law
Q= delta P x pie x r^4 / 8 n l
The total resistance of vessels in series is equal to the ________
Sum of their individual resistances
Rtotal= R1+R2+R3
For blood vessels arranged in parallel, more vessels means ______________
More avenues for blood flow and reduces resistance
1/Rtotal= 1/R1 + 1/R2
What is the reciprocal of resistance?
Conductance
What is a hematocrit?
The amount of RBCs present
What is the normal levels of hematocrit for the male and female? Hematocrit is also known as packed red cell volume
45%
What occurs with ppl who have increased hematocrit?
Erythrocytosis (increased RBCs due to illness or repsonse to external situations)
Polycythemia Vera- bone marrow disorder
Severe dehydration
What occurs with decreased hematocrit?
Anemia
Renal disease (decreased erythropoietin)
Leukemia
Overhydration
How would hemorrhage affect hematocrit within minutes of bleeding? After a few hours of bleeding?
Within minutes of bleeding: hematocrit would be the same
After few hours of bleeding: hematocrit would be decreased bc it is easier to make the fluid than the cells
The higher the hematocrit/ the higher the viscosity
Higher
Describe autoregulation
Tissues supplied by vessels adjust their vascular resistance to maintain normal flow during changes in arterial pressure
What is vascular compliance?
The amount the volume of a vessel changes in response to pressure
What is distensibility?
Refers to the elasticity of a vessel without consideration of volume changes
How would one calculate compliance?
C= change in volume/ change in transmural pressure
Veins are about _____ times more compliant than arteries due to ______
20 times; greater elasticity
T/F? Vasoconstriction increases pressure at any given volume
True
Increasing volume in a vessel increases pressure but then the pressure somewhat decreases as the walls stretch to accommodate volume. What is the mechanism to which this occurs?
Stretch-relaxation response of smooth muscle cells
What two factors affect the pulse pressure?
Stroke volume
Compliance of the arterial tree
What are pulse pressure contours? 3 examples
Upstroke (due to systole)
Incisura (due to aortic valve closure)
Diastolic decline
What is damping?
Progressive loss of pulsation upon entering the small arteries -> arterioles -> capillaries
Damping is proportional to _______ and ______
Resistance and compliance
What is central venous pressure?
The pressure in the RA because al systemic veins flow into the RA
What are the 3 factors that increase venous return?
Increased blood volume
Increased large venous tone
Dilation of arterioles
What is Normal RA pressure?
Abnormally high RA pressure?
Abnormally low RA pressure?
Normal: 0 mmHg
Abnormally high: up to 20-30 mmHg
Abnormally low: -3 to -5 mmHg
In vigorously pumping heart or in severe hemorrhage, what would the RA pressure (central venous pressure) be?
-3 to -5 mmHg
Large veins have ______ resistance in general
Little
What is the effect of RA pressure on peripheral venous pressure?
Increase causes blood back up and an increase in peripheral venous pressure
Effect of gravitational pressure:
Venous pressure above the heart is ____ than 0 mmHg
Venous pressure below the heart is ____ than 0 mmHg
Less than; greater than
What ensures one-way movement of the venous system?
Venous valves
What mechanisms moves the blood in the venous system
Muscle pump (extremity muscle contraction moves blood up toward th heart Thoracic pump (breathing action also massages blood up to heart)
What does venous valve incompetence cause?
Varicose veins in the legs
What are the principle blood reservoirs?
Large abdominal veins Spleen Liver Subcutaneous venous plexus Heart
What is the funciton of blood reservoirs?
Compliant nature of veins allows these vessels the ability to store blood
Define microcirculation
The microscopic circulation that occurs at the level of the tissues (capillaries)
What is the strucutre of a capillary bed?
Arteriole Meta arterioles and precapillary sphincters True capillaries Preferential channels (bypass) Venules
True capillaries DO NOT have smooth muscle. T or F?
True
What is vasomotion?
Contraction and dilation of metaarterioles and precapillary sphincters
What is autoregulation?
Regualtion of vasomotion by local tissue conditions (mainly O2)
What are the three types of capillary walls?
Continuous
Fenestrated
Sinusoidal/discontinuous
_______ capillaries are located in muscle, nervous tissue, heart, lung and skin
Continuous
________ capillaries are highly permeable and located in intestinal villi, choriod plexus, glomeruli and endocrine.
Fenestrated
_______ capillaries have a large diameter and are located in liver, bone marrow and spleen
Discontinuous
What are the three ways movement can occur through capillary walls?
Intercellular clefts (slit-pores)
Transcytosis
Fenestrae
Name the organ that has continuous capillaries with tight junctions that only allow small molecules to pass (water, oxygen and CO2)
Brain
What organ has discontinuous capillaries with wide intercellular clefts that allow all dissolved substances including plasma proteins to pass through
Liver
Name the organ that has fenestrae that allow absorption through capillary wall
GI tract
What has numerous fenestrae to allow large amount of filtration?
Glomerulus
_______ soluble substances can diffuse directly through membrane
_______ soluble substances rely on clefts/fenestrae etc
Lipid
Water
capillary pores are about ______ nm in diameter which is too small for most plasma proteins or blood cells to pass through
6-7
How much of the body consists of spaces between cells?
1/6th
What are the 3 components of the interstitium?
Collagen fiber bundles
Proteoglycan filaments
Interstitial fluid
** together these components form a gel
Interstitial fluid is derived by _______ and _______ from the capillaries
Filtration and diffusion
What are the 4 force that determine movement of fluid between the capillary and the interstitium?
Capillary pressure (Pc)
Interstitial fluid pressure (Pif)
Plasma colloid osmotic pressure
Interstitial colloid osmotic pressure
What causes fluid movement across the capillary wall in a particular direction?
Each of the starling forces
In capillary dynamics,
Arterial end there is net _________
Venous end there is net _____
Filtration
Reabsorption
At the ARTERIAL end of the capillary, what are the outward forces that result in net filtration?
Capillary pressure
Negative interstitial free fluid pressure
Interstitial colloid osmotic pressure
At the ARTERIAL end of capillaries, what are the inward forces that result in net filtration?
Plasma colloid osmotic pressure
At the VENOUS end of the capillary, what are the outward forces that result in net reabsorption?
Capillary pressure
Negative interstitial free fluid pressure
Interstitial colloid osmotic pressure
What is the inward force at the Venous end of the capillary that result in net reabsorption back into the capillaries?
Plasma colloid osmotic pressure
________ is an accessory route for the return of fluid and protein from the interstitial space to the blood
Lymphatic system
How much of the fluid that leaves the blood capillaries enters the lymph capillaries?
1/10th
________ are blind ended, lined with endothelial cells that overlap to form simple valve-like structures, lymphatics channels and valves.
Lymph capillaries
increases in the ________ pressure increase lymph flow
Interstitial pressure
What sterling forces increase interstitial pressure?
Elevated capillary pressure
Decreased plasma colloid osmotic pressure
Increased interstitial fluid colloid osmotic pressure
Increased permeability of capillaries
What are the functions of the lymphatic system?
Overflow system for capillaries
Controls the concentraiton of protein in the interstitial fluid
Controls the volume of interstitial fluid
Controls interstitial pressure (keeps it negative in most tissues)
Role in immune function
What are the mechanisms of blood flow control?
Short term (acute metabolic) control / autoregulation
Long term control (slow changes over days, weeks, or months by changing the number of capillaries in tissue
What are the two mechanisms of short term control of local blood flow?
Vasodilator theory
Oxygen lack theory
Describe the vasodilator theory
The greater the metabolic rate of a tissue, or lack of oxygen, the more vasodilator substances are secreted
What 3 things do vasodilators affect?
Pre-capillary sphincters
Met arterioles
Arterioles
Describe oxygen lack theory in short term control of local blood flow
Since oxygen is necessary for smooth muscle contraction, its lack will cause smooth muscle to relax
What are 5 important LOCAL vasodilators?
ADENOSINE*** CO2 Histamine K+ ions H+ ions (from lactic acid)
*** repeated this in the review a lot
_______ is an increase in the quantity of blood flow to a tissue or body part
Hyperemia
___________ is normal autoregulation to increase blood flow due to metabolic need
Active hyperemia
_____________ is response to temporary interruption of blood flow to pay back oxygen debt
Reactive hyperemia
________ is response of smooth muscle to contract with excessive pressure; is generally over-ridden by metabolic control of blood flow
Myogenic response
_________ occurs in kidneys. Is the composition of fluid in the distal tubule is sensed by the macula densa, which then regulates the afferent arteriole
Tubuloglomerular feedback
In the brain, the concentraiton of ____ and ____ are as important as O2 to normal brain function. ________ are important in regulating cerebral blood flow
CO2 and H+
Astrocytes
In the skin, blood flow control is closely linked to ________ regulation and is controlled largely via _______ innervation
Temperature
Sympathetic
_______ is an endothelial derived relaxing factor
NO (nitric oxide)
When is NO released by endothelial cells?
In small arteries in responses to shear stress, when there is rapid blood flow into the capillary bed
NO causes vasodilation in __________ which reduces wall stress and improves flow in downstream capillary
Small arteries
Long term control of blood flow is due to changes in ________
Vascularity
What is the main determining factor in long term control of blood flow?
Oxygen
What are the main vascular growth (angiogenesis) factors?
Vascular endothelial growth factor
Fibroblast growth factor
Angiogenin
What are examples of vasoconstrictors?
Norepinephrine and epinephrine
Angiotensin II
Vasopressin
Endothelin
______ is formed by a cascade initiated by renin release from the ______
Angiotensin II
Kidneys
What does angiotensin II cause?
Arteriole constriction to increase total peripheral resistance and increase blood pressure
Where are norepinephrine and epinephrine from?
Sympathetic NS and adrenal medulla
What vessels respond to NE and epinephrine by vasodilation?
*** normally NE and epinephrine result in vasoconstriction
Coronary arteries
What is another name for vasopressin?
ADH
Where is vasopressin (ADH) released from?
The posterior pituitary
What is the function of vasopressin (ADH)?
Increases water resorption by the kidneys
In increased amounts causes arteriolar vasoconstriction
Increases peripheral resistance and blood pressure
What triggers the release of endothelin?
Endothelial damage
What is the function of endothelin?
Prevents excessive bleeding
What are examples of vasodilators?
Bradykinin
Histamine
NO
How is bradykinin formed?
By cascade initiated by tissue inflammaiton
_________ causes dilation and increased capillary permeability
Bradykinin
________ is derived primarily from mast cells and basophils
Histamine
_______ causes vasodilation of arterioles in inflammatory reactions
Histamine
What is an important mediator in allergic reactions?
Histamine
What is the vascular effect of Ca?
Causes vasoconstriction (stimulates smooth muscle)
What is the vascaulr effect of increased K+ and Mg2+?
Vasodilation (inhibits smooth muscle)
What is i the vascular effect of H+?
Increases dilation (lowers pH)
Control of blood flow in tissues is mainly the funciton of local control mechanisms (ex: ___________)
Autoregulation
The sympathetics innverate all vessels except _______, ______ and _____
Capillaries, pre-capillaries and metarterioles
_______ innverates the heart ( increases HR)
Sympathetic
Vasoconstrictor fibers highly innervates what structures?
Kidneys, gut, spleen, and skin
Vasoconstrictor sympathetic fibers lightly innervates
Skeletal muscle and brain
Norepinephrine release binds to ______ receptors
**vasoconstrictor fibers
Alpha receptors
_______ fibers innervates the heart principally, some in skeletal muscle
Vasodilator fibers
With vasodilator fibers, norepinephrine release binds to ______ receptors
Beta
_______ releases epinephrine and norepinephrine as hormones
Adrenal medulla
Which of the adrenal medulla hormones (epinephrine or norepinephrine is a more potent stimulator of beta receptors?
Epinephrine
Vasodilation
Which of the adrenal medulla hormones are more potent stimulator of alpha receptors?
Norepinephrine
Vasoconstriction
______ innervates the heart but not the peripheral circulation
Parasympathetic
What parasympathetic neurotransmitter causes decrease in heart rate and a decrease in force of contraction
Ach
Where is the vasomotion center located?
Reticular substance in medulla and pons
What are the vasomotor center areas? (3)
Vasoconstrictor area
Vasodilator area
Sensory area
The vasoconstrictor area of the vasomotor center excites the ______ neurons of the sympathetic NS
Vasoconstrictor
What inhibits the vasoconstrictor area in in vasomotor center?
Vasodilator area
________ recieves sensory input from baroreceptors (blood pressure receptors)
Sensory area
The vasomotor center is involved in what two actions?
Control of blood vessels
Regulating vasomotor tone
The aortic baroreceptors transmit signals via the _______ nerve
Vagus
The carotid sinus transmits signals via the ________ nerve
Glossopharyngeal nerve
Vasomotor center control of heart is in the _____ area and _____ area
Lateral area and medial area
The lateral area of the vasomotor center controls ______ activity to the heart
Sympathetic
The medial area of the vasomotor center controls _______ activity to the heart via the ______ nerve
Parasympathetic activity via the vagus nerve
What occurs to increase arterial pressure?
Almost all arterioles are constricted (increase peripheral resistance)
Veins are constricted (increase venous return)
Heart is stimulated to (increase rate and contractility)
What plays a central role in the control of blood pressure on a long term basis by controlling fluid and salt balance?
Kidneys
Renal function curve shows that as arterial pressure increases, urinary output _______
Increases
Water balance is determined by what 2 factors?
Renal output of water and salt
Dietary intake of water and salt
What is the infinite gain principle?
When blood pressure increases or decreases, kidney output changes to restore equillibrium
What is equillibrium point?
Water and salt intake matches water and salt output and blood pressure is normal
Changes in the equillibrium point change the level of water and salt intake which shifts the pressure level for the renal output curve to the ______
Left due to alteration of kidney function or pathology
Will an increase in peripheral resistance cause an increase in long term blood pressure?
Unless there is a decrease in blood flow to the kidney, blood pressure will return to normal within hours or days
If the vasculature of the kidney is ALSO affected, this will shift the renal function curve to the RIGHT and cause hypertension
Increased blood volume ______ cardiac output and blood pressure
Increases
Increased cardiac output causes ________ (via autoregulation), increased ________ and ________
Vasoconstriction
Increased total peripheral resistance
Arterial blood pressure
Increased blood pressure _______ urine output via pressure _______ and ______
Diuresis and natiuresis
Increased salt intake increases ___________ which stimulates the thirst center of the brain (hypothalamus
Blood osmolarity
Increased osmolarity also stimulates ______ secretion from the posterior pituitary gland which increases water resorption in the kidneys
ADH
______ is cleared more slowly than water from the body
Salt
What is renin secreted from?
Juxtaglomerular cells of the kidneys
Renin is secreted by the ________ cells of the kidney in response to __________
Juxtaglomerular cells (JG) Low blood pressure
Renin catalyzes what reaction?
Angiotensinogen -> angiotensin I
Angiotensin converting enzyme is located in the ____ and catalyzes what reaction?
Angiotensin I-> Angiotensin II
What are the effects of angiotensin II
Vasoconstriction-> increased peripheral resistance and BP
Increased Na retention by kidneys-> fluid retention
Stimulates release of aldosterone -> increase Na retention and K excretion by kidneys
Where is aldosterone released from?
Adrenal cortex
What is mean arterial pressure?
MAP= 1/3 pulse pressure + diastolic pressure
Pulse pressure = systolic pressure minus diastolic pressure
________ is a common problem that can damage the heart kidneys, brain and other organs
Hypertension
What are hypertensive patients at higher risk for?
Congestive heart failure Coronary artery disease Renal damage Strokes Aneurysms
What is normal systolic and diastolic blood pressure?
Systolic: less than 120
Diastolic: less than 80
Elevated BP is _______ systolic and _______ diastolic
120-129 and
Less than 80
stage 1 hypertension of blood pressure: ______ systolic and ______ diastolic
130-139 systolic or
Diastolic 80-89
stage 2 HT: systolic _____ or diastolic _______
Greater than 140
Greater than 90
What are 2 other names for primary hypertension?
Essential hypertension, idiopathic hypertension
What are the treatments of primary hypertension?
Life style
Antihypertensive drugs
T/F: there is no known cause of primary hypertension
True
Secondary hypertension is due to a known cause; most lead to HT because of what?
An increased ECF volume
What are 4 examples of disorders that have HT as a symptom?
Primary hyperaldosteronism
Renal failure
Phenochromocytoma (adrenal medulla tumor)
What are non-pharmacological interventions for HT?
Weight loss Healthy diet Avoid excess sodium Get enough K+ Physical activity Moderation of alcohol Chiropractic
** used to treat elevated BP or for stage 1 HT with patients with low cardiac risk
What are the antihypertensive drug classes? (5)
Diuretics ACE inhibitors Vasodilator drugs Beta blockers Ca2+ channel blockers
What are common substances that can elevate BP? (6)
Alcohol Amphetamines Some kinds of antidepressants Caffeine Some kinds of decongestants NSAIDS Cocaine
Which of the following contains endothelium, elastic tissues smooth muscle and fibrous tissue? (2)
Artery Arteriole Capillary Venule Vein
Artery
Vein
Which of the following contains endothelium and smooth muscle only?
Artery Arteriole Capillary Venule Vein
Arteriole
Which of the following is made up of only endothelium?
Artery Arteriole Capillary Venule Vein
Capillary
Which of the following is made up of endothelium and fibrous tissue only?
Artery Arteriole Capillary Venule Vein
Venule
Renal disease is associated with what risk?
Risk of high blood pressure
