Biol 320 Exam 2 Seely

what is the basic function of the heart?

Functions as double-sided pump that generates blood pressure and routes blood

what does the heart separate?

pulmonary and systemic circulations

what does the heart use valves for?

to ensure one-way blood flow

how does the heart regulate blood supply?

by adjusting heart rate and contractions force based on tissue needs

What does the right side of the heart do?

pumps pulmonary circulation to lungs

what does the left side of the heart do?

pumps blood through systemic circulation to body tissues

the size of the heart

size of fist

where is the heart located?

mediastinum

what portion of the heart lies left of sternal midline?

2/3

how is the apex positioned?

downward and to the left

how is the base positioned?

superior portion of the heart

What are the two types of pericardium?

fibrous and serous

what is fibrous pericardium?

tough outer layer that prevents overdistention

what is the serous pericardium?

thinner, more delicate membrane, double layer (parietal layer fused to fibrous pericardium and visceral layer called epicardium)

pariteal pericardium

lines fibrous layer

visceral pericardium

covers heart surface

What does the pericardial cavity contain?

fluid between layers to reduce friction

What are the layers of the heart wall?

epicardium, myocardium, endocardium

epicardium

smooth outer surface of heart

myocardium

middle layer of cardiac muscle responsible for contractions

endocardium

inner lining of heart

what does the endocardium include?

pectinate muscles in auricles

trabeculae carneae in ventricles

What does the left coronary artery branch into?

anterior interventricular artery

left marginal artery

circumflex artery

what does the right coronary artery include?

right marginal artery

posterior interventricular artery

what is the characteristics of blood flow during contractions?

discontinuous and compressed

what veins drain the left side of the heart?

great cardiac vein

what vein drains the right side of the heart?

small cardiac vein

what collects venus blood?

coronary sinus

Where does the coronary sinus drain into?

right atrium

where does the right atrium receive deoxygenated blood from?

superior vena cava

inferior vena cava

coronary sinus

Where does the left atrium receive blood from?

Receives Oxygenated blood from the lungs via the four pulmonary veins.

what does the right ventricle connect to?

pulmonary trunk

what does the left ventricle connect to?

aorta

what separates ventricles?

interventricular septum

What are the atrioventricular valves (AV)?

tricuspid valve

bicuspid/mitral valves

tricuspid valve

right side

3 cusps

bicuspid valve

left side

2 cusps

what are atrioventricular valves connected by?

papillary muscles by chordae tendineae

Semilunar valves

pulmonary valve (right side)

Aortic Valve (left side)

when do semilunar valves close?

when cusps fill with blood

Deoxygenated blood enters where?

right atrium

deoxygenated blood passes through what?

tricuspid valve to right ventricle

deoxygenated blood is pumped where?

through pulmonary valve to lungs

what blood returns to the left atrium?

oxygenated

how does oxygenated blood get to the left ventricle?

through the mitral/bicuspid valve

how is oxygenated blood ejected into systemic circulation?

through the aortic valve

fossa ovalis

remnant of foramen ovale of fetal heart

anastomosis

direct connections between arteries

what does cardiac muscle rely on?

aerobic cellular respiration for ATP production

T/F Cardiac muscle has a longer refractory period than skeletal muscle

True

1 multiple choice option

how is rhythm controlled in cardiac muscle?

by self-excitable pacemaker cells

what does cardiac muscle contain?

striations and actin/myosin myofilaments

why is cardiac muscle rich in mitochondria?

to aid in aerobic respiration

T/F cardiac muscle contains an extensive capillary muscle

True

how do cardiac muscle contractions compare to skeletal muscle?

slower and less powerful

What does the sarcoplasmic reticulum store?

calcium but has less regular arrangement than skeletal muscle

why must calcium diffuse across the SR?

To get to actin and myosin

where does some calcium come from?

ECF and T Tubules

what do intercalated discs specialize in?

cell-to-cell contacts with interdigitation

why do intercalated disks contain desmosomes?

for cell adhesion

what do gap junctions allow?

action potential propegation

what do intercalated discs form?

functional syncytium

how does cardiac muscle behave?

as a single electrical unit

Sinoatrial node (SA)

pacemaker of the heart

Atrioventricular Node (AV)

conducts signals more slowly

What do bundle branches extend to?

ventricles

What do purkinje fibers do?

conduct APs to ventricular msucle

Conduction sequence of the heart

Chambers are at rest

SA node generates AP

Signal spreads through atrial walls

conduction through AV node (0.04s delay)

signals travel through bundle branches and Purkinje fibers

ventricles contract from apex to base

What do pacemaker cells generate?

spontaneous action potentials

what does depolarization involve?

sodium and calcium influx

what phase maintains contraction?

plateau phase

what does repolarization involve?

potassium influx

what prevents tetanic contractions?

long refractory periods

P wave

atrial depolarization (contraction)

QRS complex

ventricular depolarization and atrial repolarization

T wave

ventricular repolarization

PQ Interval

0.16s

atrial contraction/relaxation

QT intervall

0.36s

ventricular contraction/relaxation

Tachycardia

Abnormally rapid heartbeat

HR > 100 bpm

Bradycardia

slow heart rate

HR < 60 bpm

Atrial Flutter

irregular beating of the atria; often described as "a-flutter with 2 to 1 block or 3 to 1 block"

atrial fibrillation

rapid, random, ineffective contractions of the atrium

ventricular fibrilation

parts of the myocardium contract random, no blood is pumped, treated with direct-current shock

AV node blocks

1st, 2nd or 3rd degree

1st degree AV node block

goes from a 1/10 sec delay to 2/10 sec

- means the PR interval starts getting longer

-as long as the PR interval is between 0.12 and 0.2

- have a 1/10 sec delay -- normal

-longer than 0.2- more than 1/10 second

2nd degree AV block

wenckeback/Mobitz type I: usually no s/s if rate drops dramatically CO will decrease. More P waves than QRS, PR INTERVAL INCREASED until QRS is dropped.

3rd degree AV block

atria and ventricles beat independently of each other

(P waves have no relation to QRS waves)

Premature Atrial Contraction (PAC)

irregular heart rhythm characterized by atrial contractions occurring before the expected time

premature ventricular contraction (PVC)

a ventricular contraction preceding the normal impulse initiated by the SA node (pacemaker)

what are the common causes of cardiac arrhythmias?

excessive sympathetic stimulation

ischemia or inflammation

elevated body temperature

lifestyle factors

cardiac tissue damage

Excessive sympathetic stimulation would inhibit what ?

Digestive processes

Salivation

Immune system function

reproductive function

lifestyle factors that can lead to cardiac arrhythmias?

caffeine

smoking

lack of sleep

How does cardiac muscle conduct APs?

from cell to cell

Why does cardiac muscle have slower propagation?

gap junctions

T/F Cardiac muscle has a plateau phase in APs

true

what type of calcium source does cardiac muscle use?

internal and external

T/F Cardiac muscle does NOT have a long refractory period

False

Initial Relaxation and Passive Ventricular filling

- All chambers are initially relaxed (diastole)

-blood moves into chambers due to higher pressure than heart chamber pressure

-blood flows from atria to ventricles through open AV valves

-accounts for approx 70% of filling

Atrial systole (active ventricular filling)

-SA node generates AP

-Atrial Contraction actively forces additional blood into ventricles

-not essential at rest but crucial during exercises

-during exercise heart pumps 300-400% more blood than at rest

How is an SA node generating APs show on an ECG?

as a p wave