Lecture 1 Flashcards
Where is the right portion of the heart located in relation to the ribs?
3rd costal cartilage to 6th intercostal space
Where is the left portion of the heart located in relation to the ribs?
From the 2nd to the 5th intercostal cartilage
The viseral pericardium is also known as the….
Epicardium
4 Layers of the heart
Parietal Pericardium
Visceral Pericardium (epicardium)
Myocardium
Endocardium
What are the 2 parts of an intercalated disc and their functions?
Desmosomes- attach cells together
Connexins- spread electrical impulse
The right coronary artery supplies the AV node in __% of people
55%
The left coronary artery supplies the AV node in __% of people
45%
What coronary artery supplies the SA node?
right coronary artery
The SA node automatically paces the heart to beat ___bpm
100
The parasympathetic NS (via the vagus nerve) slows it down to 60-90
The SA node must set a pace of depolarization that is _____ than any other cell
Faster
The AV node can spontaneous discharge at a rate of…
40-60bpm
Why is the SA node suspectible to disease?
Proximity to epicardium (Pericarditis)
Coronary artery occulsion
What does the PR interval represent on an EKG
The conduction time between the atria and the ventricals
What does the QT interval represent
The time between the onset of ventricular depolarization and the end of ventricular repolarization
What does the red portion of the chart represent?
Rapid influx of ___ ions during depolarization
Calcium (Ca2+)
The green part of the chart represents what ion?
K+ Ions
Normal stroke volume is ____L and may increase ____ times during exercise
5-6L of blood
x4-7
How do you calculate mean arterial pressure?
Diastolic + 1/3(Systolic - Diastolic)
Normal MAP is about 93. At what MAP should we be cautious with getting a patient out of bed?
60 or below
What are the three factors that effect blood pressure?
Heart rate
Stroke volume
Periphreal Resistance
Resistance of a system to blood flow is determined by the diameter of _____
Arterioles
Where are baroreceptors located?
Carotid Sinus and Aortic arch
What is the primary determinant for increased cardiac output and blood pressure during exercise
Heart rate
Cardiac preload AKA End Diastolic volume is….
amount of left ventricular blood volume prior to contraction
What is cardiac afterload?
Amount of resistance (pressure) encountered by the left ventricle (aortic pressure)
Increased afterload leads to ______ stroke volume and ______End systolic volume (ESV)
Decreased SV
Increased End Systolic Volume (ESV)
What is ejection fraction and how do you calculate it?
Amount of ventricular blood volume pumped per heart beat
Stroke volume/ end diastolic volume
What is the normal ejection fraction at the left ventrical?
55-70%
The S1 Sound _____ the carotid pulse, whereas the S2 sound _____ the carotid pulse
S1 precedes whereas S2 follows
most of the blood in the body (64%) is found in the….
Veins
What is the percentage breakdown of blood composition? Plasma? WBC? RBC?
55% plasma
> 1% WBC/Platelet
45% RBC
True or false: Thrombocytes are a bloodcell
False
hematopoiesis is what and where does it happen
production of RBC
Bone Marrow
Low levels of hematocrit lead to…
Anemia, vitamin deficienies, nutrition deficienies
High levels of hematocrit lead to…
dehydration, polycythemia vera, lung/heart disease
What does the hematocrit mean
the concentration of RBC in blood
What is hemogloblin
Specialized protein in RBCs that binds to O2 for delivery to all bodily tissues
One HgB molecules can bind up to four O2 molecules
Each gram of HgB can combine with _____ ml of O2
1.34 ml
__% of oyxgen in blood is bound to Hgb
97%
whereas 2% is dissolved plasma
Amount of O2 that is bound to HgB is called __________
O2 saturation (SaO2):
Normal is 95-97%
What is PaO2?
Partial pressure of oxygen in blood
If PaO2 is over or equal to 50mmHg, what happens to SaO2 (amount of oxygen bound to hemagloblin)
SaO2 does not need to decrease to release the oxygen into the blood to increase the pressure (NO CHANGE IN SaO2)
If PaO2 drops below 50mmHg what happens to SaO2?
SaO2 decreases because oxygen is released back into the blood from the hemaglobulin
What is Capillary hydrostatic pressure?
Pressure originates from the blood pressure in the arterial system
Moves blood from capillary to interstitium
What is Capillary oncotic pressure?
osmotic pressure induced by the albumin in a blood vessel’s plasma that causes a pull on fluid back into the capillary.
Albumin causes fluid to re-enter the capillary from the interstitial fluid
What does Interstitial hydrostatic pressure do?
Moves fluid from interstitium into the capillaries
what is Interstitial oncotic pressure:
Draws fluid out of the microcirculation (capillaries) into the interstitium
What is the fick equation?
Determines VO2
VO2 = cardiac output x (arterial oxygen content - venous oxygen content)
What is the net fluid exchange from a capillary?
2mmHg outward from capillary
Muscles normally receive ____% of cardiac output
but under intense exercise they can receive ____ % of cardiac output
10-15%
80-85%
Exercising muscle will require increased blood flow while tissue beds of other organs (GI, Splenic, Kidneys) are reduced
Increased blood flow directed to the skin to promote cooling
Mesenteric, splenic and portal tissues receive _______% of cardiac output
Brain and myocardium receive ~ __% of cardiac output
20-30%
5%
What is the oxygen extraction ratio at rest?
23%
4 effects of VO2 falling below critical levels
Anaerobic metabolism will ensue
Serum lactate levels will increase
Multi-organ system failure may be present
Sedation may be necessary to reduce tissue metabolism
What happens to VO2 levels in the blood if DO2 decreases (DO2= global oxygen delivery)
The tissues will utilize the same relative amount of O2 that is present in the blood
Tissue metabolism will decrease to survive on a lesser absolute amount of O2
Therefore VO2 does not decrease
Diffusion of O2 and CO2 across the alveoli to the pulmonary arterial circulation dependent on four factors:
Area of capillary membrane
Diffusion capacity of alveolar capillary membrane:
Pulmonary capillary volume:
Ventilation to perfusion ratio (V/Q) - Blood flow to avleoli must match the amount of oxygen
What happens if the V/Q Ratio is too low? (not enough blood flowing to alveoli)
vasodilation occurs at the arterioles to allow for increased blood flow
*If ventilation volume is too small for relative blood flow:
vasoconstriction occurs at the arterioles to reduce blood flow through the capillaries
What is the normal V/Q ratio?
0.8
Decreased O2 or increased ___ , ____ , _____ can lead to vasodilation
H+ ion
CO2
Metabolites
Vasoconstriction and vasodilation controlled by extrinsic controls such as…
Endocrine system
Autonomic nervous system
What controls the endocrine system?
Hypothalamus
Which nervous system decreases heart rate,
which nervous system increases it?
Sympathetic or parasympathetic
Sympathetic- Increases HR
Parasympathetic- decreases (via the vagus nerve)
Systolic heart failure results in a low ejection fraction whereas diastolic heart failure results in…
No change to ejection fraction
What does the S1 sound represent?
Closure of the mitral and tricuspid valves
What does the S2 sound represent
Closure of the Aortic and pulmonary valves
What part of the stethoscope do you use to hear heart sounds?
Diaphram (not the drum)
Blood makes up what percent of bodyweight on average?
7-8%
