Test Three Flashcards
What is % hemoglobin saturation?
Fraction of all oxygenated hemoglobin in the sample
What kind of oxygen can cross the plasma membranes and enter cells?
Unbound oxygen
As PO2 rises in the blood, % hemoglobin saturation does what?
increases, because more oxygen in dissolved in the plasma
Which is true?
A. PO2 in arterial blood can decrease a lot from its normal max value with a lot of decrease in percent saturation.
B. PO2 in arterial blood can decrease a lot from its normal max value with very little decrease in percent saturation.
B
What are the four factors that shift an hemoglobin saturation curve to the right?
- More acidic solution
- Increase in CO2
- Increase in temp
- Increase inBPG
A shift to the right in a hemoglobin saturation curve means what?
Decreasing the affinity of Hb for O2 at any given PO2
Why do muscle tissues have an increase in oxygen during exercise?
There is an increase in cellular activity leading to an increase in hydrogen molecules. CO2 is a waste product of making ATP from glucose. This increase in hydrogen molecules will cause an increase in pH.
How does CO2 travel?
23% in hemoglobin as carbamino Hb
7% dissolved in plasma
70% as bicarbonate ion
How do the lungs play an important role in regulation of pH?
controlling the rate at which CO2 is eliminated
What increases firing of the periphreal chemoreceptors?
decreased inspired oxygen, decreased alveolar PO2, decreased arterial PO2
If you are poisoned by CO will your breathing rate increase?
No because PO2 does not change, the CO just binds with higher affinity to Hb and less oxygen reaches tissues
What do peripheral chemoreceptors respond to?
DIssolved oxygen not oxygen bound to hemoglobin
When you blow up a pool raft what is happening internally to cause dizziness?
As you are breathing out deep you are ridding your body of CO2 causing an increase in pH. Holding your breath can fix this issue.
T or F:
CO2 and H are more potent stimuli for breathing than O2.
True
What are the peripheral chemoreceptors stimulated by?
Increase in H levels, which is indirectly CO2 levels
What do central chemoreceptors do?
Cells in the medulla oblongata that monitor H concentration of brains ECF
H ions dont cross BBB but CO2 does
What is the normal blood volume in adults?
5 L
How does blood move through vessels?
Bulk flow
Does more blood pass through the systemic than the pulmonary circuit?
No input for one circuit is the same for the other
What happens when aortic pressure excedes that of the ventricle?
The aortic semilunar valve closes
When does the aortic semilunar valve open?
When left vent pressure exceeds aortic
What causes S1 and S2?
S1: closing of the AV valves
S2: closing of the SL valves
Which semilunar valve is most anterior?
Pulmonary valve
What causes mechanical events in the heart?
Electrical events- SA and AV node actionpotentials
Cardiac muscle fibers of a given chamber contract how?
Simultaneously
What is a syncytium?
Fibers of the ventricles and separately fibers of the atria are functionally connected to rapidly spread action potentials
How does deoplarization occur in the SA node?
Gradually, after an AP the membrane potential returns o resting and gradually starts to depolarize again
What is a pacemaker potential due to?
Leakiness of sodium and other ions
All cardiac muscle cells are excited at the rate of the ____.
fastest one
What is an ectopic pacemaker?
When the pacemaker is not located in the SA node, another part of the heart develops a rhythm faster than the SA node
T or F: The atria contract at different times?
False the atria contract at relatively the same time, the AP spreads via gap junctions
How does an AP travel down to ventricles?
The SA node signal reaches AV node and it spreads through the AV buncle (bundle of his), through the left and right bundle branches to purkinjie fibers. The AV node is responsible for the delay in contraction between atria and ventricle.
P wave?
depolarization of atria
QRS Complex?
Deoplarization of the ventricles
T wave?
Repolariztion of ventricles
EKG’s record what kind of potential difference?
Extracellular recordings of leaking currents through the ECF from cardiac cells depolarizing or repolarizing
PR interval?
Time during the atria are contracting and generating force
QT interval?
Time during ventricular contraction where they are generating force
Where is lead one placed in a bipolar limb lead?
Right and left arms
Where is lead II paced?
RIght arm left leg
What is second degree heart block?
Skipped ventricular depolarization, no QRS complex,
What is third degree heart block?
QRS and P waves are are off beat
What kind of action potential occur in the ventricular muscle cells?
long continued depolarization
What kind of action potential occur in the ventricular muscle cells?
long continued depolarization
What causes the initial rising phase of an AP
sodium ions
The initial deoplarization causes what kind of channels to open and where?
Slow voltage gated calcium channels in the t tubules which results in plateau of depolariztion
Does intracellular calcium or extracellular calcium bind to troponin?
Intracellular, extracellular calcium causes the release of calcium from the sarcoplasmic reticulum
What muscle has a longer refractory period, skeletal or cardiac?
cardiac
How does premature ventricular contraction occur?
If the ventricle fires before the SA node, but after the refractory period. This could cause the SA node to fire during the refractory period resulting in no contraction
Systole?
Contraction divided into isovolumetric ventricular and ventricular ejection
Diastole?
Relaxation divided into isovolumetric ventricular relaxation and ventricular filling
When does the bicuspid valve open?
when atrial pressure is greater than ventricle
What is the first stage of systole?
Period of isovolumetric ventricular contraction both valves are closed and pressure is building to open the pulmonary or aortic semi lunar valve.
Second stage of systole?
Ventricular ejection
What marks the end of of isovolumetric contraction and beginning of ejection?
Opening of the aortic valves for ejection
How does ejection occur?
For the first half of vent ejection the pressure is rising and volume is falling, this works because the walls are powerful enough to squeeze the rest of the blood in the ventricles. During the second half the vent contraction weakens and prssure falls due to the weaker contraction and less blood volume, blood is ejected at a slower rate
What happens to the aorta during ventricular ejection?
Pressure rises, but not enough to close the valve bc vent pressure is also rising. Half way through ejection the rate of blood leaving and entering aorta is the same. Near end of systole aortic pressure falls bc the amount of blood leaving is greater than amount pumped in.
When does the systemic system start and end?
Left side of the heart and ends in the right side
Ventricular pressure begins to ___ immediately after the production of the QRS wave because ___.
rise; the ventricular fibers have become excited and began to squeeze in on the blood within the ventricle
Frank starling law states that ___ ventricular filling leads to a direct increase in____.
Increased; stroke volume
During the period of isovolumetric contraction the volume of blood in the left ventricle is___.
not changing because both the AV valve and SL valve are closed
What is the first stage of diastole?
isovolumetric ventricular relaxation
What marks the end of systole and beginning of diastole?
aortic valve closing producing S2
What is the incisura?
A bump on the aortic pressure curve when blood rebounds against the semilunar valve, a brief surge of pressure increase
When would the incisura and S2 occur?
Nearly the same time because the semilunar valve closing causes both
What marks the end of isovolumetric ventricular relaxation?
Opening of the bicuspid valve
What is CO?
CO=HR x SV
Volume of blood pumped by each ventricle per unit time
What is stroke voulme?
volume of blood ejected by each ventricle during each contraction.
Avg SV is 70
EDV-ESV=SV
What does parasympathetic stimulation to the SA node done and what is released?
Ach and it slows the heart rate down
What occurs when epinephrine and norepinephrine stimulate the heart?
Speeds it up
How does the release of Epi, Norepi, or Ach work on the heart?
They change the permeability of SA node cells to ions changing the slope of gradual depolarization
What is one way congestive heart failure occurs?
dysfunction of the left ventricle- doesn’t pump enough out and blood backs up into the left atrium and then pulmonary veins and capillaries resulting in congested lungs
Where would edema occur in right sided heart failure?
Systemically
How can sympathetic nerves and circulating epi increase SV?
By acting on other areas in the heart that aren’t the SA node
An increase in contractility leads to ___.
more complete ejection of the EDV
What is ejection fraction?
ratio of stroke volume to EDV
EF=SV/EDV
What is afterload?
increased arterial BP that decreases SV because the arterial pressure is what the ventricle has to work against to eject blood.
What has a direct effect on CO?
SV and Heart rate
What has a direct effect on SV?
EDV
Plasma epi
Sympathetic activity
What has a direct effect on heart rate?
parasympathetic activity, sympathetic activity, and plasma epi
What pressures do the aorta and large arteries transport blood under?
90-100 mm Hg
What is the function of arterioles?
main control site for blood flow and major site of resistance to flow
What is the function of capillaries?
Major site of water and solute exchange between blood and tissues
Where can a pulse be found?
only in arteries and arterioles
Mean Arterial Pressure can be estimated how?
MAP=Diastolic pressure + (pulse pressure)(1/3)
pp= 120-80
Why is the MAP not the halfway value ?
because diastole lasts longer that systole
Describe laminar flow?
blood flow in streamlines with each layer of blood the same distance from the wall, also silent
What is turbulent flow?
When blood flows crosswise and causes murmurs
What happens if you decrease the diameter of a vein?
you increase flow
What happens if you decrease diameter of an artery?
you decrease flow
What serves as the site of attachment for extrinsic eye muscles?
sclera
What bends light rays for focusing?
Cornea and lens
What structure absorbs stray light rays, and has a rich supply of blood vessels and is dark brown?
Choroid
What connects choroid to iris and contains ciliary muscle for changing lens shape?
Ciliary body
What kind of photoreceptors are found in high density in the fovea centralis?
cones
What fluid prevents the retina from moving and is found between lens and retina?
vitreous humor
What muscles contract in response to parasympathetic stimulation to constrict the pupil?
Circular muscle fibers
What muscle fibers contract in response to the sympathetic stimulation to dilate the pupil?
Radial
What type of curve causes light rays to diverge?
concave surface
What occurs to the eye as an object gets closer?
light rays from a single point strike cornea at greater angles and are refracted more strongly to converge on the retina
Close objects require lens to ___.
bend and become spherical to bend light more
Far objects require lens to ___.
Flatten
What is accomodation?
focusing at different distances by changing lens shape
What occurs when the ciliary muslce reduces tension on suspensory ligaments?
the lens rounds up and bends light more strongly to bring near objects into focus
Emmetropia?
normal vision
Myopia?
nearsidedness cant see far caused by eye too long or lens that is too strong correct with concave lens
Hyperopia?
farsightedness, cant see near caused by eyeball that is too short or lens that is too weak. Fixed with convex lens
Astigmatism?
Lens or cornea is not smoothly spherical
Presbyopia?
with aging lens looses elasticity and ability to become spherical lose ability to see up close
What is retinal derived from and what is it?
vitamin A and is the light sensitive part of photopigments
Describe resting potential in an unstimulated rod?
cation channels for Na are open and a constant influx of Na occurs the potential is -40mV
When a rod or cone is stimulated they become depolarized? T or F
False they become hyperpolarized go from -40 to -60 ish
What closes the cation channels in rods and cones?
When retinal in rhodopsin absorbs energy of light it changes the conformation closing the gates. Involves G protein leading to enzyme that degrades cGMP.
What is the receptor potential in rods?
Hyperpolarization
Describe the G protein pathway
- light activates transducin (G protein)
- G protein activates cGMP phosphodiesterase to degrade cGMP
- cGMP decreases causing Na channels to close
- closing of Na causes photoreceptors to hyperpolarize
Do rods and cones make AP?
No, they communicate synaptically with bipolar cells but do not make an AP
In the absence of light, rods and cones release steady amount of ____ onto ___ cells.
Glutamate, bipolar
Lateral inhibition?
refining and sharpening information in sensory neurons and paths. An excited fiber can stimulate some neurons while also giving inhibitory signals at the same time to adjacent neurons.
What enhances contrast in our visual field?
Lateral inhibition, some bipolar cells are hyperpolarized and others are depolarized.
Do bipolar cells make AP?
No, but they communicate with retinal ganglion cells through the release of transmitter. Ganglion cells do make AP.
___ cells provide further lateral inhibition and contrast enhancement.
Retinal horizontal cells
___ cells respond to changes in strength of illumination or movement of a spot.
Retinal amacrine cells
What half of the optic nerve crosses over?
the nasal half crosses midline and temporal half do not cross.
What structure in the brain receives the larges number of optic nerve fibers?
Thalamus
Each peripheral view is seen by both eyes. T or F?
False peripheral views are only seen by one eye
The right visual cortex receives information from?
The right temporal and left nasal optic tracts
Left visual cortex receives information from?
nasal right half and temporal left half
Right primary visual cortex receives direct information about only the left half of visual field
Left primary visual cortex receives information from only the right half of the visual field.
