A&P 2 Heart

60,000

The heart is the pump that circulates the blood through an estimated ______ miles of blood vessels

1 million

Heart pumps over _ _______ gallons per year

mediastinum

The heart is situated between the lungs in the ___________ with about two-thirds of its mass to the left of the midline

cardiology

The study of the normal heart and diseases associated with it

pressure changes

Valves open and close in response to

heart contracts and relaxes

Causes of pressure changes

pressure

Blood filling up atrium/ventricle causes __________ to increase

Ventricle

Atrium →

Valve to ventricle to open

Pressure build up in atrium causes

Right atria

Blood returning to heart fills

tricuspid valve to open

Pressure in right atria causes

tricuspid valve

AV Valve

Opening of AV Valve

allows blood to flow into the right ventricle

Atria contracts

What forces additional blood into ventricles

Atrial, ventricular

When AV valves open; _________ pressure is greater then __________ pressure

pressure

Atria contracts → _________ increases

valves to open

Pressure increase in atria forces

Papillary

What muscles contract stopping valves from opening

AV Valve Cusps

Ventricles contract, forcing blood against

Chordae Tendineae

Papillary muscles contract and ___________ ____________ tighten

Papillary Muscle, Chordinae Tendineae

What contracts to prevent AV Valves from opening after blood goes to the ventricle

Atrial, Ventricular

Av valves closed; ____________ pressure is less then ______________ pressure

ventricular, atrial

AV valves open and allow blood to flow from atria into ventricles when ___________ pressure is LOWER than atrial pressure

AV valves

WHAT closes preventing backflow of blood into atria

ventricles

WHAT are contracted when AV Valves close

Closed

increased blood pressure in ventricles push valve cusps _______

AV Valves Close

papillary muscles contract to pull cords and prevent cusps from everting when

interventricular

ventricles contract and ____________ pressure rises

semilunar

ventricles contract and interventricular pressure rises, blood is pushed up against ___________ valves

falls

Ventricles relax and intraventricular pressure ______

close

blood flows back from arteries, filling up the cusps of semilunar valves forcing them to

Relaxation phase

Semilunar valves closed, AV Valve open

Contraction Phase

Semilunar open, AV Valve closed

ventricular contraction

Semilunar valves open with

pulmonary trunk and aorta

Semilunar valves open, allowing blood to flow into

ventricular relaxation

Semilunar valves close with

ventricles

Semilunar valves close prevents blood from returning to

SL valves

Semilunar valves close, blood fills valve cusps and tightly closes the

resting

Cardiac cells don’t have a __________ potential

Autorythmic cells

Cells that generate AP better then others

longer

AV Nodes take _______ to get to threshold

faster heart rate

Steeper Slope =

Pacemaker potential

Slow depolarization is due to both opening of Na+ channels and closing of K+ channels

depolarization

When threshold is reached

action

the ________ potential begins when the pacemaker potential reaches threshold

• depolarization

Depolarization

____________ is due to Ca+ influx through Ca+ Channels

flat line

Membrane potential is never a

depolarizes

Voltage gated Ca+ Channels _____________ cells

Repolarization

WHAT is due to Ca+ channels inactivating and K+ channels opening

negative

K+ Leaves → __________ value again

negative

influx of k+ brings membrane potential back to _________ voltage

autorhythmic

Cardiac muscle cells are _____________ cells

autorhythmic

self-excitable cells

Cardiac Cells

Repeatedly generate spontaneous action potentials that then trigger heart contractions

sodium

Pacemaker potential is due to influx of

calcium

Depolarization phase is due to influx of

Repolarization

______________ is due to calcium channels inactivating and potassium channels opening

heartbeat

The ANS and hormones, such as epinephrine, do modify ________

(in terms of rate and strength of contraction)

Epinephrine

Which hormone modifies heartbeats

ANS and hormones (Epinephrine)

do not establish the fundamental rhythm in heartbeat

increase

caffeine & nicotine _________ heartbeat activity

Heart rate, pacemaker

ANS influence speed of ____________ and ___________ potential

Pacemaker Potential

Makes slope higher

faster

Sympathetic NS makes HR go

Slower

Parasympathetic NS makes HR go

Vagus Nerve

The ______ _______ decreases HR

epinephrine

Heart Transplant makes HR increase because of _________ increase

impulses

The SA node generates

Primary HR

The SA Node sets

AV

The impulses pause at the ___ node

AV

The ___ Bundle connects the atria to the ventricles

Bundle Branches

The ________ __________ conduct the impulses through the interventricular septum

Subendocardial conducting network

The _________ ________ __________ depolarizes the contractile cells of both ventricles

SA Node

Autorhythmic cluster of cells in wall of right atrium

SA

__ node generates an Action potential spontaneously 90-100 times per minute 

SA Node

begins heart activity that spreads through the intercalated discs to all cardiac muscle cells in both atria

AV

Sa Node → __ node

AV

Node in in atrial septum

AV

__ node fires at 40-50 times per minute

AV Node

Node that transmits signal to atrioventricular bundle (bundle of His)

Atrioventricular (AV) bundle

the connection between atria and ventricles

Atrioventricular (AV) bundle

divides into bundle branches

Right and left bundle branches

large diameter fibers that conduct signals quickly in the interventricular septum

Purkinje fibers

in trabeculae carneae, papillary muscles and the myocardium

fastest

SA node sets pace since it is the

AV node

In 50 msec excitation spreads through both atria and down to

filling

100 msec delay at AV node due to smaller diameter fibers - allows atria to fully contract ______ ventricles before ventricles contract

ventricles

In 50 msec excitation spreads through both ___________ simultaneously

Plateau Phase

phase due to Ca+ influx through slow Ca+ channels

keeps cell depolarized because K+ channels are closed

excitation-contraction coupling

depolarized cell because K+ channels are closed starts

long

Absolute refractory period is very

rapid depolarization, plateau, and repolarization

An Action potential in a ventricular contractile fiber is characterized by

tetnus

tension relaxes before refractory period is over so cardiac muscles does not go into

Depolarization

Cardiac cell resting membrane potential is -90mv

intercalated discs

Depolarization; excitation spreads through gap junctions in the

depolarization

fast Na⁺ channels open for rapid

Plateau phase 

250 msec (only 1msec in neuron) 

Plateau phase 

Phase where slow Ca⁺² channels open, let Ca⁺² enter from outside cell and from storage in sarcoplasmic reticulum, while most K⁺ channels remain closed

Plateau phase 

Phase where Ca⁺² binds to troponin to allow for actin-myosin cross-bridge formation & tension development

Refractory period

the time interval when a second contraction cannot be triggered very long so heart can fill