Physiology Practice Flashcards

Comprehensive vocabulary flashcards covering cardiovascular physiology, blood pressure regulation, shock, and respiratory gas transport based on technical lecture notes.

Cardiac Output (COP)

The amount of blood pumped by each ventricle in one minute.

Heterometric autoregulation (Starling's law)

$\uparrow$ in preload leading to more stretch of cardiac muscle, which results in an $\uparrow$ in force of contraction and an $\uparrow$ in SV & COP.

Homeometric autoregulation

An $\uparrow$ in the force of contraction of cardiac muscle without an increase in EDV; it starts about $30\,s$ after an increase in VR and is lost in HF.

Afterload

The pressure exerted by the LV to overcome resistance facing blood to be ejected into the aorta; it is inversely proportional to SV.

MSFP

Mean systemic filling pressure; an $\uparrow$ in MSFP leads to an $\uparrow$ in VR and COP, often caused by muscular activity or increased blood volume.

RVR

Resistance to venous return; the resistance which blood meets during flow from the systemic venous network to the right heart.

Stress and reverse-stress relaxation

A phenomenon where a pressure change causes blood vessels to gradually adapt to a new size; includes circulation relaxation after massive transfusion and reverse relaxation after blood loss.

Renin-angiotensin system

A mechanism where $\downarrow$ renal blood flow causes the JGA to secrete renin, leading to the formation of angiotensin II, which causes arteriolar VC and salt and water retention.

Arterial Baroreceptors

High-pressure receptors located in the aortic arch and carotid sinus that are stimulated by stretching of the arterial wall between $60\text{--}180\,mmHg$.

Atrial Receptors

Low-pressure receptors (Type A & Type B) in the walls of the atria near venous openings that help regulate CVP.

Peripheral chemoreceptors

O2 lack receptors located in the aortic and carotid bodies stimulated by hypoxia to stimulate the pressor area and increase respiration.

Bezold-Jarish reflex

A coronary chemoreflex where chemicals released during MI stimulate ventricular chemoreceptors, causing reflex hypotension, bradycardia, and apnea.

Shock

Inadequate tissue perfusion with blood due to a progressive decrease in COP and ABP.

Anaphylactic shock

A type of normovolemic shock where an exaggerated antigen-antibody reaction releases histamine, causing VD and a drop in ABP.

Septic shock

A normovolemic shock caused by severe infection where bacterial endotoxins depress the vasomotor center.

Lung Surfactant

A surface tension lowering lipoprotein secreted by Type II pneumocytes that helps stabilize alveoli and prevents pulmonary edema.

Infantile respiratory distress syndrome (IRDS)

Respiratory failure in newborns due to decreased surfactant formation, occurring when the L/S ratio is less than one.

Central chemoreceptors

Receptors in the ventrolateral medulla stimulated indirectly by $\uparrow CO_2$ tension in arterial blood which penetrates the blood-brain barrier.

Herring-Breuer reflex

The vagal inhibition of inspiration resulting from the stimulation of stretch receptors in the smooth muscle of bronchioles.

Inspiratory ramp signals

Signals from the inspiratory center that begin weak and gradually increase for about $2\,S$ before stopping for expiration.

Apneustic center

A pontine center that sends excitatory impulses to the DRG to prevent the switch-off of ramp signals, resulting in long inspiration.

Pneumotaxic center

A pontine center that sends impulses to switch off the ramp signal, leading to short inspiration and an $\uparrow$ in respiratory rate.

Bohr effect

The decrease in blood pH causes a decrease in hemoglobin's affinity for $O_2$.

O2 capacity of Hb

The maximal volume of $O_2$ carried by $Hb/100\,ml$ blood at full saturation, which is $20\,ml\,O_2 / 100\,ml$ blood.

Chloride shift (Hamburger phenomenon)

The process at the tissue side where $\text{Cl}^-$ ions pass INTO RBCs from plasma to maintain electrical neutrality as $\text{HCO}_3^-$ accumulates and diffuses OUT.

Hypoxia

$O_2$ deficiency at the tissue level.

Histotoxic Hypoxia

A type of hypoxia caused by inhibition of tissue oxidative processes (e.g., cyanide poisoning) where tissue cannot uptake $O_2$.

Cyanosis

Bluish coloration of the skin and mucous membranes caused by an amount of reduced hemoglobin exceeding $5\,g\,Hb/100\,ml$.

Stagnant Hypoxia

Hypoxia resulting from decreased blood flow through tissues, often caused by CHF, hemorrhagic shock, or localized spasm.