Human Physiology Overview

What determines blood flow through vessels

Pressure gradient

What happens to blood flow if total peripheral resistance increases

Decreases

What two factors determine arterial blood pressure

Cardiac output and total peripheral resistance

What happens to resistance when vessel radius decreases

Increases dramatically (4th power rule)

What structure ensures one-way blood flow through the heart

Valves

What happens to blood pressure if cardiac output increases while resistance stays the same

Increases

What type of vessels primarily control resistance in circulation

Arterioles

What force pushes fluid out of capillaries

Hydrostatic pressure

What force pulls fluid back into capillaries

Oncotic pressure

What happens if filtration exceeds reabsorption

Edema

What system removes excess fluid from tissues

Lymphatic system

What happens to reabsorption if plasma protein levels drop

Decreases

What happens to edema risk if capillary permeability increases

Increases

What receptor causes vasoconstriction when activated?

Alpha receptors

What receptor increases heart rate and contractility?

Beta 1 receptors

What receptor causes vasodilation in skeletal muscle?

Beta 2 receptors

What neurotransmitter is released by sympathetic postganglionic neurons?

Norepinephrine

What hormone is released from the adrenal medulla during stress?

Epinephrine

What happens to blood vessels in hypoxic tissues?

Vasodilation

What structure initiates the heartbeat?

SA node

What structure delays conduction to allow ventricular filling?

AV node

What spreads electrical signals through the ventricles?

Purkinje fibers

What allows the heart to contract as one unit?

Syncytium

What happens to stroke volume if heart rate becomes too high?

Decreases

What molecule increases heart rate by affecting funny channels?

cAMP

What cells form the initial plug during vessel injury?

Platelets

What enzyme converts fibrinogen into fibrin?

Thrombin

What pathway is triggered by tissue damage outside the vessel?

Extrinsic pathway

What pathway is triggered by collagen exposure inside the vessel?

Intrinsic pathway

What is the main goal of clot formation?

Prevent blood loss and maintain blood pressure

What hormone increases blood pressure through vasoconstriction?

Angiotensin II

What cells release renin when blood pressure drops?

JG cells

What hormone increases water reabsorption in the kidneys?

ADH

What part of the nephron creates an osmotic gradient?

Loop of Henle

What happens to ventilation when CO₂ levels increase?

Increases

What substance prevents alveolar collapse?

Surfactant

What protein carries oxygen in the blood?

Hemoglobin

What happens to pH when CO₂ increases?

Decreases

What does bicarbonate do in the blood?

Buffers hydrogen ions

What enzyme converts CO₂ into bicarbonate?

Carbonic anhydrase

What happens to oxygen delivery when the dissociation curve shifts right?

Increases

What condition occurs when potassium levels are high?

Hyperkalemia

What hormone lowers potassium levels in the body?

Aldosterone

What happens to blood pressure when sympathetic activity increases through alpha receptors?

Increases

What happens to cardiac output when beta 1 receptors are activated?

Increases

What happens to edema risk when hydrostatic pressure increases and oncotic pressure decreases?

Increases

What happens to blood flow when hematocrit increases and vessel diameter decreases?

Decreases

What happens to heart rhythm when potassium increases and is not regulated by aldosterone?

Becomes irregular

What happens to oxygen delivery during exercise when CO₂ and temperature increase?

Increases

What happens to blood pressure when angiotensin II increases and ADH is released?

Increases