Cardiac Physiology Flashcards
What is the metabolic-cardiovascular-ventilatory coupling?
Cellular activity in periphery: increased O2 demand and increased CO2 production in the peripheral circulation
This leads to dilation of vessels causing increased SV and increased HR
Then the heart recruits the pulmonary system and there is an increase in tidal volume and breathing frequency
What are the 2 antagonistic subdivisions of the cardiopulmonary system?
Parasympathetic and sympathetic NS
Afferent/Efferent nerves
What are parts of the parasympathetic NS?
Vagus nerve (CN X) Thorax and upper abdomen ~75% of nerve fibers
Where do preganglionic sympathetic fibers originate?
Preganglionic cardiac and pulmonary sympathetic fibers originate in the spinal cord at T1-T5
What do sympathetic postganglionic fibers do?
Reach viscera
Run along surface of great vessels
Bronchi and vascular muscle
What are 2 neurotransmitters?
Acetylcholine (cholinergic): postganglionic parasympathetic
Norepinephrine (adrenergic): postganglionic sympathetic, there are exceptions (few blood vessels, sweat glands, and piloerector muscles
what are the cholinergic receptors?
Muscarinic: post-synaptic and effector
Nicotinic: pre/post synaptic neurons in ANS
Found in smooth muscle of lungs, bronchioles, cardiac tissue
Pair up with parasympathetic system
What are the adrenergic receptors?
Alpha 1: vascular smooth muscle
Alpha 2: help decrease sympathetic activity
Beta 1: located in atria, SA node, ventricle; increase in HR, this is where beta blocker drugs come from
Beta 2: in bronchiole smooth muscle
Where are dopaminergic receptors found?
receptors in adrenal gland, blood vessels, heart
Found in sympathetic nervous system
What is the pacemaker of the heart?
SA node
What is important of pulmonary ventilation?
Exchange of O2 (actively)
Exchange of CO2 (passively)
Control blood acidity
Oral communication: vibration of vocal cords
What controls normal/autonomic breathing versus forced breathing?
Brain stem regulates normal breathing.
Corticospinal tract can override the brain stem to make us breathe deeper.
Neurons in medulla fire when breathing needs increased (activated by chemo receptors)
What happens to lung pressures during inspiration?
External intercostals (move ribs up), and diaphragm (move ribs out) contract
Increases lung volume
Chest cavity pressure lowers
AIR FLOWS IN
What happens to lung pressure during expiration?
AIR FLOWS OUT
Inspiratory muscles relax and chest cavity recoils
Chest cavity pressure is greater than atmospheric pressure
What about A-V O2 difference?
Difference between what’s in arterial system versus venous system.
In the lung: capillaries full of oxygen rich blood
After muscles: CO2 is higher than O2 because we have used it all up with the muscle
What is typical tidal volume, anatomic dead space, breathing frequency?
500 mL
Area where gas exchange doesn’t occur
12-15 breaths/minute
What is tidal volume?
Volume of air that is normally exhaled/inhaled per breath
What is IRV?
Inspiratory reserve volume
Additional volume taken in
What is ERV?
Expiratory reserve volume
Additional volume let out
What is RV?
Residual volume
Volume of air that remains in the lungs after a forceful expiratory effort
What is IC?
Inspiratory capacity
Sum of tidal and inspiratory reserve volumes
Maximum amount of air that can be inhaled after a normal tidal exhalation
T/F: IC is the sum of tidal and inspiratory reserve volumes?
True
What is FRC?
Sum of expiratory reserve and residual volume.
Amount of air remaining in lungs at the end of normal tidal exhalation.
What does FRC represent?
point at which the forces tending to collapse the lungs are balanced against forces tending to expand the chest wall
T/F: during COPD the FRC gets smaller?
False, it should get bigger
What is VC?
Vital capacity
Sum of inspiratory reserve tidal and expiratory reserve volumes.
Maximum amount of air that can be exhaled following a maximum inhalation.
What is TLC?
Total lung capacity.
Maximum volume to which the lungs can be expanded.
Sum of all pulmonary volumes
What is Ve?
Minute ventilation.
Product of tidal volume and respiratory rate
What is FVC?
Forced vital capacity
Maximum volume of air exhaled from a full inhalation.
What is FEV1?
How much air that is blown out in first second.
If 70% or below you have COPD
What happens to pulmonary measurements with obstructive and restrictive disease?
Obstructive: FEV/FVC will be less because you can’t get air out
Restrictive: FEV/FVC will be higher because you can’t get air in, no problems getting air out
What is normal range for the body’s pH?
7.35-7.45
If too high or too low chemical reactions may not occur.
What is the buffering system for the acid/base balance?
Carbonic Acid-Bicarbonate buffering: lungs blow off or hold CO2, kidneys absorb or regenerate bicarbonate
Body’s adjustment to pH changes: compensation
Values for bicarbonate and carbonic acid return to normal: correction
What are normal values for bicarb and CO2 in body?
Bicarbonate: 22-26
CO2: 35-45
What happens during respiratory acidosis?
Body has increased CO2.
Renal system compensates by increasing levels of bicarbonate.
What are conditions that may cause respiratory acidosis?
COPD, pulmonary edema
Can’t blow air out so there is build up of CO2
What happens during respiratory alkalosis?
Body has decreased CO2 (blowing off too much)
Kidneys compensate by decreasing amount of bicarbonate.
What are conditions that may cause respiratory alkalosis?
Asthma
hyperventilating
What is metabolic acidosis?
There is a decrease in bicarbonate.
Lungs compensate by blowing off more CO2 (increase respiratory rate)
What conditions may cause metabolic acidosis?
Vomiting
People who use anaerobic metabolism at rest= organ failure
People who use body tissue for energy (end stage HIV, starvation)
What is metabolic alkalosis?
There is increase in bicarbonate
Lungs compensate by increasing CO2 (decrease respiratory rate)
What conditions may cause metabolic alkalosis?
Eat too many tums
What controls pulmonary ventilation?
2 main regulatory centers: medullary inspiration center, medullary expiratory center
They establish rate and depth of breathing.
Cortex can override these centers: active respiration
What controls respiratory muscles?
Motor neurons which are regulated by respiratory center.
What happens when sensors in aveoli detect increased fluid in lung tissues?
Rapid, shallow breathing
What happens when sensors in brain, carotid, and aorta detect carbon dioxide or oxygen levels in your blood?
Increased/decreased rate of breathing
What happens when body sensors in your joints and muscles detect physical activity?
Increased breathing rate
What are other factors that control pulmonary ventilation?
Peripheral chemoreceptors: sensitive to changes in PO2, PCO2, H
Lung receptors: acute stretch of alveoli (safety mechanism- decrease duration of inspiration)
Mechanical receptors: sense movement in skeletal muscles
