Exam 3: Intro To Cardiorespiratory system

when depolarized, the insides of the cells become ______charged

The outsides of the cells become _______ charged

positively, negatively

K+

After depolarization ___ ions leave the cells repolarization heart muscle cell returns to starting electrical state

Afterload

The pressure the heart must pump against to eject blood; also referred to as average aortic blood pressure or mean arterial pressure.

Arteriovenous Difference (a-vO2)

The amount of O2 that is taken up from 100 ml of blood as it passes through tissues.

Increase during exercise

Cardiac Cycle

The repeating pattern of contraction (systole) and relaxation (diastole) of the heart.

Cardiac Output (Q)

The volume of blood pumped by the heart per minute. Calculated as Heart Rate (HR) × Stroke Volume (SV).

Cardiovascular Drift

A gradual increase in heart rate during prolonged exercise, which offsets a gradual decrease in stroke volume to maintain cardiac output.

Diastole

The relaxation phase of the cardiac cycle, during which the ventricles fill with blood.Systole

Double Product

An index of the work of the heart, calculated as Heart Rate × Systolic Blood Pressure.

increases linearly with intensity

End-Diastolic Volume (EDV)

The volume of blood in the ventricles at the end of diastole. Also known as "preload."

Fick Equation

The equation describing the relationship between cardiac output (Q), a-vO2 difference, and oxygen uptake (VO2): VO2 = Q × a-vO2 difference.

Frank-Starling Mechanism

A principle stating that a greater end-diastolic volume (EDV) results in a more forceful contraction of the ventricle and thus a greater stroke volume.

Hematocrit

The percentage of blood that is composed of cells (red blood cells, white blood cells, platelets).

Intercalated Discs

Specialized intercellular connections in cardiac muscle that allow for the rapid transmission of electrical impulses, enabling the heart to contract as a single unit.

Myocardium

The muscular middle layer of the heart wall, responsible for contracting and forcing blood out of the heart.

Preload

The volume of blood in the ventricles at the end of diastole. Synonymous with End-Diastolic Volume (EDV).

Pulmonary Circuit

The right side of the heart, which pumps deoxygenated blood to the lungs and returns oxygenated blood to the left side of the heart.

Sinoatrial (SA) Node

A cluster of cells located in the right atrium that serves as the natural pacemaker of the heart, initiating depolarization.

Stroke Volume (SV)

The volume of blood pumped by the heart per beat.

Systemic Circuit

The left side of the heart, which pumps oxygenated blood to the entire body and returns deoxygenated blood to the right side of the heart.

Systole

The contraction phase of the cardiac cycle, during which blood is ejected from the ventricles.

Total Vascular Resistance

The sum of the resistance to blood flow from all systemic blood vessels.

hemoglobin

Oxygen carrying pigment in red blood cells

75

what percentage of oxygen is used by the heart at rest

shorter

during exercise, heart systole and diastole are _____, but diastole is much more.

pulse pressure

difference between systolic and diastolic pressure

blood pressure

a measure of the amount of force that the blood places on the walls of blood vessels, particularly large arteries, as it is pumped through the body

Mean Arterial Pressure (MAP)

average pressure in arteries during a cardiac cycle, rate of blood flow through systemic circuit

diastolic pressure + 1/3 pulse pressure

upright exercise

what kind of exercise increases cardiac output due to increase in HR and SV

parasympathetic nervous system

Braking system, slows HR by inhibiting SA and AV nodes, releases acetylcholine, vagus nerve

sympathetic nervous system

increase HR by stimulating SA and AV node, norepinephrine

medulla oblongata

where is the control center to maintain balance btwn parasympathetic and sympathetic activity

heart rate variability

Variations in the time interval between heartbeats. reflects balance between SNS and PNS. Wide range is “healthy” and a low HRV shows imbalance between autonomic systems.

skeletal muscle pump

Rhythmic skeletal muscle contractions force blood in the extremities toward the heart

One-way valves in veins prevent backflow of blood

respiratory pump

pressure changes during breathing move blood toward heart by squeezing abdominal veins as thoracic veins expand

Afterload

stroke volume is inversely proportional to _________, which increases during exercise

blood flow

directly proportion to pressure difference between 2 ends of system, inversely proportional to resistance

resistance

Length x viscosity / radius ^4

arterioles

resistance vessels, largest blood pressure drop occurs here

40-60% VO2 max

SV increases than plateaus in untrained individuals when

upper body

what kind of exercise results in higher HR and BP

End Systolic Volume (ESV)

volume of blood remaining in each ventricle after systole

Systolic Increases, Diastolic stays the same

with incremental exercise, how does systolic and diastolic blood pressure respond

central command theory

initial signal to "drive" cardiovascular system comes from higher brain centers