cardiorespiratory sys. and gas exchange Flashcards
2 systems function..
1) provide oxygen and nutrients to the body under various changes
2) clearing metabolic by-product from muscle
blood structure
plasma 55%, leukocytes & platelets 1%, erythrocytes 45%;
Ph 7.4
reason for blood PH changes
exercise, stress, deases
physiological tolerance for changes in PH of arterial blood and muscle
- 9 - 7.5;
6. 63 - 7.1
ph is regulated by
bicarbonate, ventilation and kidney function
oxygen presents in the blood in 2 forms
dissolved in blood (0.3ml/100ml) and carried via hemoglobin
hemoglobin
iron-containing protein within the red blood cells that can bind 1-4 oxygen molecules.
1 gr hemoglobin can carry …ml of oxygen
1.39ml
healthy blood hemoglobin capacity
15gr per 100 ml = 20.8ml oxygen/ 100ml
healthy (non-anemic) adult blood volume
5L or 7% of the body weight
oxygen-hemoglobin dissociation curve
the curve is S-shaped/ sigmoidal.
As O2 partial pressure increases hemoglobin affinity for Os increases and plateaus at O2 pressure 60mmHg and 90% hemoglobin saturation. O2 of 100mmHg = 98% hemoglobin saturation
the partial pressure is
pressure exerted by one gas in a mixture of gasses and calculated as the product of total pressure of a gas mixture and % of concentration of the specific gas.
example: atmospheric pressure=760 mmHg; O2 concentration=20.93%; O2 partial pressure= 760 x 20.93/100=159mmHg
factors influencing O2-hemoglobin curve
1) decrease in body t shifts the curve to the left
2) increase - to the right
arterial blood acidity: acidic or low pH - to the right;high pH (alkalosis) - to the left.
3) exercise - higher body t - O2 is released at a higher partial pressure so to be used by muscles
cardiac morphology
- mononucleated cardiac muscle
- 4 chambers (right/left atrium and ventricle)
- is under involuntary neural control
- SA= sinoatrial node or pacemaker of the heart
SA function
generates the electrical impulse (at speed 0.08m/s) - to the both atrium - to the AV node (atrioventricular) impulse slows down; - to the left and right bundle branches into the Purkinje system - ventricular contraction. The total impulse time - 0.2 s
the Purkinje system is
a series of fibers that surround ventricles which then stimulate ventricular contraction.
venous blood route
right atrium (superior &inferior vena cava) - right ventricle - lung (via pulmonary artery) - gas exchange (load with O2 and remove metabolic by-products).
superior/ inferior vena cava fuction
superior returns blood from head and upper extremities
inferior - trunk, lower extremities
arterial blood route
left atrium (via pulmonary vein) - left ventricle - through the body via aorta - organs, tissues via vasculature
central and peripheral circulation
heart and lungs = arterial system; the rest of the body = venous system.
ECG (electrocardiogram)
detects electrical impulses of the heart by the surface electrodes (10-12 places on the chest) and presented as distinct pattern.
Is taken in a clinical setting to examine the heart under stress.
ECG components
1) P-wave (represents atrial depolarization on SA-AV way)
2) QRS (ventricular depolarization on AV-Purkinje way)
3) T-way (electrical recovery/repolarization of the ventricles)
Note: atrial repolization can’t be seen as it takes place during QRS complex.
blood circulation system is composed of
- arteries (carry blood from heart to the tissues and organs)
- veins (carry blood from the tissues and organs back to the heart)
- the pulmonary veins (carry oxygenated blood from the lungs to the heart)
artery and vein blood pressure
arteries: for the systematic circulation it’s high (100mmHg in the aorta and 60mmHg in the arterioles)
veins; very low; due to this veins have one-way valves and smooth muscle bands that continue moving venous blood toward the heart as we move and contract muscles in our extremities.
total peripheral resistance
the resistance of the entire systemic circulation.
relation b/n the vessel dilation and constriction and peripheral resistacne
dilation - decrease; constriction - increase
factors influencing the vessel dilation and constriction
type of exercise;
sympathetic nervous system stimulation;
local muscle tissue metabolism;
environmental stressors (heat,cold..)
influence of the exercise on the blood circulation
sympathetic nervous system stimulates arteries vasodilation, therefore increases blood floor to the working muscles. Blood is redistributed from other organs to the muscles used for the particular exercise.
cardiac cycle
events that occur from the one heartbeat to the start of another
cardiac cycle is composed of ..
1) diastole - period of relaxation
2) systole - period of contraction
diastole phase allows for the heart to
fill with blood
SBP (systolic blood pressure) is
pressure exerted against the arterial walls as blood is forcefully ejected during ventricular contraction (systole)
BP and HR measurements are used for..
describing the work of the heart and can provide and indirect estimation of the myocardial oxygen uptake
rate-pressure product (RPP) or double product is
estimate of the heart work
RPP=SBPxHR
DBP (diastolic blood pressure) is
pressure exerted against the arterial walls when no blood is being forcefully ejected through the vessels (diastole)
DBP indicates
peripheral resistance or vascular stiffness; tend to decrease with vasodilation and increase with vasoconstriction.
mean arterial pressure (MAP) is
the mean/average arterial pressure during a single cardiac cycle:
MAP = DBP + (0.333 x (SBP-DBP))
MAP norma
greater than 60 mmHg is enough to sustain the organs of the average person. MAP is NORMALLY between 70 to 110 mmHg[7]
If the MAP falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become hypoxic, a condition CALLED ischemia.
cardiac output (Q) is
the amount of blood pumped by the heart in 1 minute an dis represented by the formula: Q=SV x HR = (EDV-ESV) x HR
SV (stroke volume) is
amount of blood ejected per heartbeat
SV=EDV - ESV
EDV
ESV
end-diastolic volume - volume of blood in ventricles following filling.
end-systolic volume- volume of the blood in ventricles after contraction
The Frank-Starling principle suggests … based on…
…the more the left ventricle stretched the more forceful the contraction and thus the greater volume of blood leaving the ventricle.
…length-tension relationship
EDV factors
heart volume ; venous return of blood
blood distribution at rest…
at exercise…
….internal organs 20-25%; muscles - 15-20%; kidneys 20%; brain 15%; heart 4-5%; skin 4-5%; bone 3-5%
… muscle 70-80%; skin 5-20%; heart 4-5%; internal organs 3-5%; brain 3-4%; kidneys 2-4%; bone 0.5 -1%
