Physio 3 Flashcards
what determines total amount O2 bound and carried by Hb?
% saturation Hb (amount O2 bound) and total [Hb] blood
Lower than normal blood [Hb] =
anemia
Describe relationship between PO2 and % Hb saturation
directly proportional
What’s shape/what variables determine (IV/DV) of O2-Hb dissociation (association) curve?
sigmoidal curve
% Hb saturation and PO2
B/c of cooperative binding of O2:
—0-40 mm Hg = large magnitude change in % saturation
—40-120 mm Hg = very small change in % saturation
normal systemic PO2 = 104 mm Hg (arterial) and 40 mm Hg (venous) –> thus, since arterial
Why will Hb never reach 100% saturation in systemic arterial blood?
due to chemical nature (kinetics) of molecules - constantly moving = constantly colliding (possibly forming bonds) and weak intermolecular interactions = constantly dissociating –> thus, all molecules are constantly forming bonds/dissociating
significance of “plateau at the right end” of O2-Hb dissociation curve and how does it act as safety factor?
Provide an example where safety factor would be useful.
Due to cooperative binding of O2 = large mag. change PO2 in arterial blood = small mag. change in % saturation
“plateau” = safety factor for supply O2 –> tissues if ever large decrease in PO2 of arterial blood (= decrease overall [O2] in blood)
example - regions HIGH ALTITUDE = LESS O2 = less O2 in alveoli = decrease net [O2] diffuses into arterial blood = decrease PO2 (O2 dissociated in blood plasma)
Describe how increase in altitude does not dramatically effect % saturation
high altitude –> O2 molecules in atmosphere farther apart (less dense, so inhale less O2 each breath) –> alveolar PO2 decreases –> systemic arterial PO2 decreases –> small decrease % saturation
due to “plateau at right end” dissociation curve - aka cooperative binding O2
If constant PO2, what 3 other variables effect % Hb saturation and why? What impact have on hemoglobin at molecular level?
Alter Hb affinity for O2 via altering bond strength
- changes in: [H+], [CO2], temperature, and [2,3-bisphosphoglycerate (2,3-BPG)
% Hb saturation =
( [HbO2] / total [Hb] ) X 100
Or
(# O2 molecules bound / total # O2 molecules total [Hb] capable of binding)
what determines % Hb saturation
affinity / bond strength between Hb & O2
List changes in variables that would cause O2-Hb dissociation curve to “shift to the right” (decrease % saturation):
- increase [H+]
- increase [CO2] (direct effect = increase [H+])
- increase temperature
- increase [2,3-bisphosphoglycerate]
How are metabolically active tissues able to “extract” more O2 from blood?
Increase [CO2] (carbohydrate metabolism / cell respiration product) –> increase [H+] –> decrease pH = local increase acidity –> local decrease Hb affinity O2 = local region causes increase HbO2 dissociation –> increased [O2] diffuse into metabolically active tissues
Increase temperature = decreased Hb affinity O2;
HEAT = product carbohydrate metabolism = metabolically active tissues = regions increase temperature
Metabolically active tissues create localized regions of increased [H+], increased [CO2], and increased temperature - all DECREASE Hb affinity to O2 = local increase HbO2 dissociation = increased [O2] diffusion into cells
How does increased [2,3-bisphosphoglycerate] effect O2 -Hb affinity? Give examples when elevated [2,3-BPG]
2,3-BPG binds to heme groups on Hb, decreases available binding sites on Hb –> decrease % Hb saturation
important for adaptation to poor blood flow certain regions/tissues or high altitude
How does carbohydrate metabolism increase [CO2] and subsequently [H+]?
C6H12O6 + O2 –> H2O + CO2 + ATP
Carbon dioxide reacts w/ H2O in blood create bicarbonate - equilibrium rxn = carbonic acid + H+
Blood circuit:
LEFT ventricle - aorta - systemic capillaries - superior and inferior venae cavae - RIGHT atrium
= Systemic blood circulation
Blood circuit:
RIGHT ventricle - pulmonary trunk - right and left pulmonary arteries - pulmonary capillaries - pulmonary veins (4) - LEFT atrium
= Pulmonary blood circulation
Total blood volume of adult?
5 liters
Hematocrit
List normal values (adult, male, female)
% total blood volume = RBCs
Average adult ~ 40%
Male ~ 43%
Female ~ 39%
Why is hematocrit different for males and females?
testosterone stimulates kidneys which produces more EPO = increase RBC production in bone marrow \
Only site of transport into or out of blood circulation:
crossing CAPILLARY WALLS
Does more blood pass through the systemic than pulmonary circuit in a given period of time?
NO - both pump same volume of blood/unit time
Rate = same
Portal circulatory pathway =
List examples
2 capillary beds in a series instead of 1 capillary bed.
heart - arteries - 1 capillary bed - blood vessel - 2nd capillary bed - veins - heart
ex. - Hypothalamus capillaries - blood vessel - anterior pituitary - 2nd capillaries; all digestive organ blood dumps into hepatic portal vessel - 2nd capillary bed
What is responsible for majority of ventricular filling?
gravity
why you can live with atrial fibrillation ~ weak primer pumps ~
List the formed elements of blood:
erythrocytes
leukocytes
platelets
all suspended in liquid called plasma
List structural components of pericardium.
SEROUS pericardium + Outer FIBROUS pericardium
Serous pericardium = 2 continuous layers (parietal + visceral) separated by pericardial cavity
What tissue = bulk of heart walls
myocardium - cardiac muscle
Muscular interventricular septum
divides the heart into right and left fxnal halves
Heart Valves
Prevent backflow = ensure unidirectional blood flow
Atrioventricular valves
Tricuspid valve - between RIGHT atrium and ventricle
Bicuspid or Mitral valve - between LEFT atrium and ventricle
Prolapsepushing of AV valve into atrium while closed + ventricle contracting - restricts the movement of valve
chordae tendineae + papillary muscles
prevent backflow into atria - unidirectional flow
Open = atrium higher pressure Closed = ventricle higher pressure
Semilunar valves
Pulmonary valve - between RIGHT ventricle + Pulmonary trunk
Aortic valve - between LEFT ventricle + aorta
prevents backflow from pulmonary or aortic arteries into ventricles
lack chordae tendineae + papillary muscles
Open - higher ventricular pressure
Closed - higher pulmonary or aortic pressure
Is the opening / closing of heart valves a passive process?
YES - driven via pressure gradient across valves caused by blood filling spaces on either side
bicuspid / mitral valve
left atrium/ventricle
chordae tendineae + papillary muscles (extension of myocardium from ventricular walls)
-prevent prolapse
tricuspid valve
right atrium/ventricle
chordae tendineae + papillary muscles (extension of myocardium from ventricular walls)
-prevent prolapse
Prolapse
= inappropriate pushing of AV valves into atrium while closed/ventricular contraction; restricts range of motion - papillary muscle contraction during ventricular contraction pulls cusps down toward ventricle
no role in opening/closing just prevents valve from being pushed into atrium
chordae tendineae + papillary muscles allow this
papillary muscles
attaches to AV valves to contract and prevent prolapse
extension of myocardium of the ventricles
chordae tendineae
fibrous tendons that link AV valves to papillary muscles
Coronary arteries
1st 2 branches of aorta
provide blood supply to heart muscle (myocardium)
All of the cardiac muscle fibers of the heart need to be coordinated, simultaneous contraction.
= all cardiac muscle fibers must be simultaneously depolarized
Volume of blood pumped by each ventricle per unit time (minutes)
Cardiac Output
2 factors directly determine the cardiac output
Heart Rate (HR) stroke volume (SV)
Volume of blood ejected by each ventricle during each contraction (mL)
Stroke Volume (SV)
Equation to calculate Cardiac Output
CO = HR x SV
Equation Stroke Volume:
SV = EDV - ESV
What’s average Cardiac Output if average SV & HR = 70?
5000 mL or 5L
~ equal average total blood volume adult ~
Average EDV & ESV
EDV ~ 120mL
ESV ~ 50 mL
Volume of blood in ventricle following ventricular filling
End-Diastolic Volume (EDV)
Average volume = 120 mL
Volume of blood remains in ventricle following ventricular ejection
End-Systolic Volume (ESV)
average volume = 50mL
Systole + 2 subdivisions
Ventricular CONTRACTION
2 parts:
- Isovolumetric ventricular contraction (brief)
- Ventricular EJECTION
Diastole + 2 subdivisions
Ventricular RELAXATION
2 Parts:
- Isovolumetric ventricular relaxation
- Ventricular FILLING
What determines direction of blood flow?
1) primarily volumetric pressure differences caused heart contractions
- blood flows from HIGH fluid pressure –> LOW fluid pressure
2) Valves helps ensure unidirectional movement of blood by preventing backflow
The actual heart sounds (“lub-dub”) created via:
Vibrations + turbulent blood flow caused closing of valves
vibrations spread along to neighboring tissues continue to travel to superficial tissues where they can be heard
Sound 1 (“lub”) =
Atrioventricular valves close
Sound 2 (‘dub’) =
Aortic + Pulmonary semilunar valves close
What determines aortic (arterial outflow) pressure?
Rate of blood pumped IN
Vs.
Rate of blood going OUT to tissues
Why does pressure fall quicker in ventricles than in aorta or pulmonary arteries?
Elastic, muscular walls of arteries = continuous squeezing / contraction on blood inside
Isovolumetric =
same volume
- Volume does not change in these two subdivisions of systole and diastole b/c BOTH valves are closed
contract in response to parasympathetic stimulation to constrict pupil
circular muscle fibers
contract in response to sympathetic stimulation to dilate pupil
radial muscle fibers
What kind of muscle tissue in iris
smooth muscle
which muscle of iris controls normal, day-to-day dilation pupil? what innervation?
circular muscle fibers and parasympathetic autonomic nervous system
vitreous humor
viscous, jelly-like fluid that fills main/largest cavity of eye (lens + retina)
Gives eyes spherical shape + volumetric pressure it creates helps fix retina to posterior surface (choroid) / holds retina in place
aqueous humor
clear fluid fills space between lens + cornea
tunica of eye = mostly neural tissue
retina
describe physiology of blind spot
region in posterior of eye where neural fibers from retina exit
2 blind spots - 1 in each eye
what region delivers highest visual acuity? why?
fovea centralis - small central region within retina = high density of cones
name 3 tunica layers eye
fibrous, vascular, retina
continuous parts fibrous tunica
sclera (white of eye) + cornea
continuous parts of vascular tunica
choroid, ciliary body, iris
part of eye contains pigment melanin
choroid
part of eye rich supply of blood vessels
choroid
part of eye NOT rich supply of blood vessels
cornea - no blood vessels so transparent
part(s) eye containing muscle
iris (circular + radial) and ciliary body (ciliary muscle - focuses lens)
part of eye responsible for change in lens shape allowing for change in focus at different distances
ciliary body - specifically muscles
what is responsible for pupil appearing black
choroid @ posterior of eye - pupil just hole in iris
why do humans have decreased color perception and visual acuity in dim lighting (@ dusk)
rods - black/white images, less E required excitation
cones - color images w/ high acuity, higher E required excitation
dim lighting - less light rays = less light E traveling into eye, not enough E create AP in cones but rods still able to.
how does color of choroid important to fxn
it absorbs stray light rays bouncing around at back of eye which decrease visual acuity
pigment melanin makes choroid dark brown color - dark colors absorb almost all light waves
part of eye serves as attachment for extrinsic eye muscles?
sclera - white eye
what dense / fibrous part eye helps maintain structure?
sclera
part eye that bends light waves
cornea
what is retinal?
= part photopigment sensitive to / absorbs light E
-Vitamin A derivative
Photopigment in rods
rhodopsin (visual purple)
Range light wavelengths that Rhodopsin/Visual Purple sensitive to/excited by?
380nm - 650 nm
(violet-orange)
almost all visible light wavelengths EXCEPT RED
monolayer of epithelial cells in retina
Pigment layer
refraction
“bending” light rays as passes through one medium to another medium of a different density @ an oblique angle
Degree of curvature of 2nd mediums surface can cause light rays converge or diverge (convex and concave)
focusing
diverging light rays radiating from a 1 point on an object pass from AIR (medium 1) through convex surfaces of cornea + lens and refracted to converge @ a single point on retina
diverging light rays from others single points on the same object are similarly refracted to converge together at a single point @ different site on retina than other points but in proportion to object —– image refracted = upside down + left-right reversed
objects in center of visual field
images focused directly onto fovea centralis
Objects moving toward eye
increase angle between diverging light rays from point on object
Accommodation
The process CHANGING/ADJUSTING focus via changing shape lens
How is greater refraction accomplished?
Ciliary muscle contraction = lens shape become more round = increased angle of refraction = decreased distance until rays converge at single point
describe significance of ability to change lens shape
b/c distance from lens + retina fixed w/o ability to alter degree of refraction objects in center of field of view only be focused @ fixed distance from eye
Emmetropia
normal vision + focusing
Hyperopia
Farsightedness – can’t focus close objects
–Angle refraction too small = the converging light rays from a point on object intersect BEHIND retina
the average pressure throughout cardiac cycle
mean arterial pressure (MAP)
MAP = diastolic pressure + 1/3 (pulse pressure)
Systolic pressure - Diastolic pressure =
Pulse Pressure
Pulse Pressure
= working pressure of heart; amount of pressure added by ventricular contraction
Measure of elasticity + recoil of arteries - aka health arteries
age or diseased = decreased elasticity = expand recoil less readily = more difficult pump blood = increase pressure
veins + venules
return blood under LOW pressures
reservoir of blood –> 64% systemic blood
Major site of H2O + solute exchange between blood and interstitial spaces
capillaries
arterioles
main control blood flow + major site resistance to blood flow
precapillary sphincters
smooth muscle fiber encircles vessel @ each capillary origin
regulates blood flow into capillary bed
transport blood to tissues under high pressure; pressure reservoir
large arteries
Greatest pressure drop occurs across what arteries
arterioles + capillaries
b/c high cross sectional areas
average force on arteries by blood pressure during cardiac cycle
mean arterial pressure
relative duration diastole»_space; systole sooo:
MAP = diastolic pressure + 1/3(systolic pressure-diastolic pressure)
Laminar flow
blood flow streamlined + silent (arteries + veins)
Turbulent flow
blood flow not silent, flows crosswise in vessel, tends to cause murmurs - used to diagnose septal defects, valvular stenosis (narrow - stenotic, systolic), or valvular insufficiency (leakiness - regurgitation, diastolic backflow)
3 factors cause turbulent blood flow
increased speed blood flow, decreased diameter vessel, increase blood viscosity or density
Basal tone
basal tone in arteries - always present, slight contraction of arterial smooth muscle
baseline arteriole diameter from which constriction or relaxation occurs
under resting conditions cardiac muscle normally consumes and derives E from what macromolecule?
FATTY ACIDS (70%) instead of carbohydrates
