Human Anatomy & Physiology: Cardiovascular System - the heart Flashcards

layer that encloses the heart

direction in which the heart points

layer also known as the epicardium

separated from the epicardium by the pericardial cavity

layer that protects the heart by reducing friction

thick middle layer of the wall of the heart; composed of smooth, cardiac muscle

inner layer of the heart wall consisting of epithelium and connective tissue as well as some specialized muscle tissue

receive blood from lungs and body

receive blood from atria and force into body

separates right and left sides of heart

between right atrium and ventricle

fibers attatched to the tricuspid valve which pull it closed when papillary muscles contract, preventing backwash of blood

responsible for pulling the atrioventricular valves closed by means of the chordae tendineae

link between right ventricle and artery extending from it

between left atrium and ventricle

largest artery in the body

between the left ventricle and the largest artery in the body

pulmonary valve and aortic valve

rings of dense connective tissure surrounding the pulmonary trunk and aorta

first two branches of the aorta; feed the heart

extreme chest pain caused by blockage (thrombus) of coronary arteries

blood clot completely blocking a coronary artery, causes a heart attack

another name for heart attack

enlarged vein from junctions of coronary veins which empty into the right atrium

contraction of heart muscle

relaxation of heart muscle

atrial systole/ventricular diastole, ventricular systole/atrial diastole, brief complete diastole

mass of merging cells that function as a unit

fibers of cardiac muscle tissue which distribute impulses over the entire heart

small, elongated mass of specialized cardiac muscle tissue just beneath the epicardium in the right atrium near the opening of the superior vena cava-starts impulses

common name for S-A node

only normal conduction pathway between the atrial and ventricular syncytia

group of fibers which receive impluse from the atrioventricular node; also known as the bundle of His

extend from branches of A-V bundle, stimulate muscle fibers in the ventricular walls

recording of the electrical changes that occur in the myocardium during a cardiac cycle

deflection in a ECG

in an ECG corresponds to depolarization of the atrial fibers (leads to contraction

in ECG corresponding to depolarization of ventrical membranes, much stronger!!

in ECG last wave of cardiac cycle corresponding to repolarization

decreases S-A and A-V nodal activity; leads to heart rate decrease

detect changes in blood pressure

expandable extension of the atruim

groove that marks border between atria and ventricles

separates the two atria

separates the two ventricles

prominent muscular ridges along the inner surface of the auricle and across the adjacent anterior atrial wall

penetrates interatrial septum from fifth week of embryonic development until birth

small depression of site of prior foramen ovale

muscular ridges on the internal surface of the ventricles

approximately the siz of a fist

in the mediastinum between the 2nd rib and the 5th intercostal space, on the superior surface of the diaphragm, two thirds to the left of the midsternal valve , anterior to the vertibral column, posterior to the sternum

inflamation of the pericardium

(peri - around cardi - heart)double walled sac the encloses the heart -

it protects, anchors, and prevents overfilling

parietal layer: lines the internal surface of the fibrous pericardium
visceral layer(epicardium): on external surface of the heart - seperated by a fluid filled pericardial cavity (decreases friction)

A. Fibrous pericardium
B. Parietal layer or serous pericardium
C. Pericardial cavity
D. Epicardium
E. Myocardium
F. Endocardium

visceral layer of the serous pericardium

(made of muscle) spiral bundles of cardiac muscle cells, fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

anchors cardiac muscle fibers, supports great vessels and valves , limits spread of action potentials to specific parts

(inside the heart)is continuous with endothelial lining of blood vessels

two atria - left and right
two ventricles - left and right

seperated internally by the interarterial septum, coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles , auricles increase atrial volume

seperated by hte interventricular septum, anterior and posterior interventricular sulci mark the position of the septum externally

A. brachiocephalic trunk
B. superior vena cava
C. right pulmonary artery
D. ascending aorta
E. pulmonary trunk

F. right pulmonary veins
G. right atrium
H. right coronary artery
I. anterior cardiac vein
J. right ventricle

K. right marginal artery
L. small cardiac vein
M. inferior vena cava
N. left common carotid artery
O. left subclavian artery

P. aortic arch
Q. ligamentum arteriosum
R. left pulmonary artery
S. left pulmonary veins
T. auricle of the left atrium

U. circumflex artery
V. left coronary artery
W. left ventricle
X. great cardiac vein
Y. anterior interventricular artery
Z. apex

atria

walls of the atria

superior vena cava
inferior vena cava
coronary sinus

right and left pulmonary arteries

ventricles

the ventricles of the heart

into the ventricular cavities

pulmonary trunk

aorta

A. superior vena cava
B. right pulmonary artery
C. pulmonary trunk
D. right atrium
E. right pulmonary veins
F. fossa ovalis

G. pecinate muscles
H. tricuspid valve
I. right ventricle
J. chordae tendineae
K. trabeculae carneae
L. inferior vena cava

M. aorta
N. left pulmonary artery
O. left atrium
P. left pulmonary veins
Q. mitral (bicuspid ) valves

R. aortic valve
S. pulmonary valve
T. left ventricle
U. papilary muscles

V. interventricular septum
W. epicardium
X. myocardium
Y. endocardium

the pulmonary circuit - vessels that carry blood to and from the lungs

the systemic circuit - vessels that carry the blood to and from all body tissues

Superior & Inferior Vena Cavas and coronary sinus Right atrium  Tricuspid valve  Right ventricle  Pulmonary semilunar valve  Pulmonary trunk  Pulmonary arteries  Lung capillaries  Pulmonary veins  Left atrium  Bicuspid (mitral) valve  Left ventricle  Aortic semilunar valve  Aorta  to the systemic arteries  systemic capillaries  systemic veins  superior & inferior vena cavas and coronary sinus

gas exchange

yes

short, low pressure circulation

blood encounters much resistance in the long pathways

the left ventricle is thicker than the right ventricle

the shortest circulation in the body
is the functional blood supply of the heart

junctions - collateral routes that provide additional routes for blood delievery

A. Anastomosis
B. Left coronary artery
C. Right coronary artery
D. Circumflex artery
E. Posterior interventricular artery
F. Anterior interventricular artery

1. right and left coronary arteries (in atrioventricular groove)
2. marginal arteries
3. circumflex arteries (wraps around the heart)
4. anterior and posterior interventricular arteries

1. small cardiac vein
2. anterior cardiac vein
3. middle cardiac vein
4. great cardiac veins

the blood pooling area into the right atrium

chest pain
thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium

heart attack
prolonged coronary blockage, areas of cell death are repaired with noncontractile scar tissue

ensure unidirectional blood flow through the heart

prevent backflow into the atria when ventricles contract
tricuspid valve - right side
mitral (bicuspid) valve - left side

they anchor AV valve cusps to papillary muscles

prevent backflow into the ventricles when the ventricles relax
aortic semilunar valve and the pulmonary semilunar valve

1. blood returning to the heart fills the atria, putting pressure against the atrioventricular valves; atrioventricular valves are then forced open
2. as ventricles fill, atrioventricular valve flaps hang limply into the ventricles
3. atria contract, forcing additional blood into ventricles

1. the ventricles contract forcing blood against atriventricular valve cusps
2. atriventricular valves close
3. papillary muscles contract and chordae tendinae tighten, preventing valve flaps from everting into atria

as ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them to open

as ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close

cells are striated, short, fat, branched, and interconnected, the connective tissue matrix(endomysium) conects to the fibrous skeleton, t tubules are wide but less numerous, SR is simpler than in skeletal muscle, contain numerous large mitochondria (25-35 % cell volume), intercalated discs - junctions between cells which anchor cardiac cells,

desmosomes - prevent cells from seperating during contraction
gap junctions- allow ions to pass; electrically couple adjacent cells

that is contracts all at once

depolarization of the heart is rhythmic and spontaneous
•About 1% of cardiac cells have automaticity—(are self-excitable)
•Gap junctions ensure the heart contracts as a unit
•Long absolute refractory period (250 ms)
•Depolarization opens voltage-gated fast Na+channels in the sarcolemma
•Reversal of membrane potential from –90 mV to +30 mV
•Depolarization wave in T tubules causes the SR to release Ca2+
•Depolarization wave also opens slow Ca2+channels in the sarcolemma
•Ca2+surge prolongs the depolarization phase (plateau)
•Ca2+influx triggers opening of Ca2+-sensitive channels in the SR, which liberates bursts of Ca2+
•E-C coupling occurs as Ca2+binds to troponin and sliding of the filaments begins
•Duration of the AP and the contractile phase is much greater in cardiac muscle than in skeletal muscle
•Repolarization results from inactivation of Ca2+channels and opening of voltage-gated K+channels

the right side

pacemaker

generates impulses about 75 times/minute (sinus rythm)
depolarizes faster than any other part of the myocardium (has to get the signal out)

1. the SA node generates impulses about 75 times a minute (depolarizes faster than any other part of the myocardium)
2. the impulses pause at the AV node (for about 0.1 second) smaller diameter fibers and fewr gap junctions, depolarizes 50 times per minute in the absence of SA node input
3. the atrioventricular bundle (bundle of His) connects the atria to the ventricles (only connection between the atria and the ventricles)
4. the bundle branches conduct the impulses through the interventricular (two pathways )septum (the right and the left bundle branches - carry the impulses toward the apex of the heart
5. the perkinje fibers depolarize the contractile cells of both ventricles (complete the pathway into the apex and ventricular walls)

the AV bundles and perkinje fibers depolarize only 30 times per minute in the absence of AV node imput

1. arrythmias- irregular heart rythms
2. uncoordinated atrial and ventricular contractions
3. fibrilation- rapid, irregular contractions, useless for pumping blood

ectopic focus - abnormal pacemaker takes over
if AV node takes over, there will be a junctional rythm (40-60 bpm)

partial or total heart block, few or no impulses from SA node reach the ventricles - wont pump blood

the ANS autonomic nervous system

in the medula oblongata

cardioaccelaratory center inervates SA and AV nodes, heart muscles, and coronary arteries through sympathetic neurons

cardioinhibitory canter inhibits SA and Av nodes through parasympathetic fibers in the vagus nerves

ECG or EKG - a composite of all the action potentials generated by nodal and contractile cells at a given time

P wave: depolarization of SA node
QRS wave: ventricular depoolarization
T wave: ventricular repolarization

1. atrial depolarization - initiated by the SA node carries the P wave
2. with atrial depolarization complete the impulse is delayed at the AV node
3. ventricular depolarization begins at apex, causing the QRS complex - atrial repolarization occurs
4. ventricular depolarization is complete
5. ventricular repolarization begins at apex, causing the T wave
6. ventricular repolarization is complete

lub dup

first sound occurs as AV valves close and signifies begining of systole

second sound occurs when semilunar valves close at the begining of ventricular diastole

abnormal heart sounds most often indicitive of valve problems

all events associated with blood flow through the heart during one complete heartbeat

contraction, higher pressure - ventricular contraction

relaxation - ventricles are relaxed because they are filling - lower pressure

mm HG (mercury)

ventricular filling - takes place in mid to late diastole
- AV valves are open
- 80% of blood passively flows into ventricles
-atrial systole occurs, delivering the remaining 20%
END DIASTOLIC VOLUME(EDV) volume of blood in each ventricle at the end of ventricular diastole

ventricular systole
-atria relax and ventricles begin to contract
-risinf ventricular pressure results in closing of AV valves
-isovolumetric contraction phase (all valves are closed - breif moment)
- in ejection phase, ventricular pressure exceeds pressure in the large arteries, forcing the Semilunar valves to open = stroke vilume

the amount of blood ejected from the heart per beat

isovolumetric relaxation occurs in early diastole
- ventricle relax
- backflow of blood in aorta and pulmonary trunk closes semilunar valves and causes breif rise in aortic pressure
-END SYSTOLIC VOLUME (ESV) volume in blood in each ventricle at the end of ventricular systole

EDV

CO: cardiac output - volume of blood pumped by each ventricle in one minute
HR: heart rate - number of beats per minute
SV: stroke volume - volume of blood pumped out by a ventricle with each beat

stroke volume = end diastolic volume - end systolic volume

preload
contractility
afterload

degree of stretch of cardiac muscle cells before they contract (Frank - Sterling law of the heart)
cardiac muscle exhibits a length- tension relationship, at rest, cardiac muscle cells are shorter than optimal length, slow heartbeat and exercise increase venous return, increased venous return distends (stretches) the ventricles and increases contraction force

contractile strength at a given muscle length, independent of muscle stretch and EDV

increase contractility,
- hormones (thyroxine, glucagon, and epinephrine)

acidosis
increased extracellular K+
calcium channel blockers

pressure tha must be overcome for ventricles to eject blood

hypertension
increased ESV and reduced SV

emotional or physical stressors
norepinephrin causes the pacemaker to fire more rapidly (and at the same time increases contractility)

acetylcholine hyperpolarizes pacemaker cells by opening K+ channels - the heart at rest exhibits vagal tone (parasympathetic)

a sympathetic reflex initiated by increased venous return
stretch of the atrial walls stimulates the Sa node
also stimulatse atrial stretch receptors activacting sympathetic reflexes

1. exercise - fright- anxiety
2. sympathetic activity increases, parasympathetic activity decreases, contractility increases and venous return increases
3. EDV (preload) increases ESV decreases
4. heart rate increases, stroke volume increases
5. cardiac output increases

epinephrine - from adrenal medula enhances heart rate and contractility
thyroxine- increases heart rate and enhances the effects of norepinephrine and epinephrine

Ca+ and K must be maintained for normal heart function - changes in ion concentration affect heart excitability

age
gender
exercise
body temperature

abnormally fast heart hear over 100 beats per minute
- if persistant, may lead to fibrillation

heart rate slower than 60 beats per minute
may result in grossly inadequate blood circulation
maybe desirable result if endurance training

progressive condition where the CO is so low that blood circulation in inadequate to meet tissue needs
caused by
*coronary artherosclerosis
*persistant high blood pressure (hypertension)
*multiple myocardial infarcts
*dialated cadiomyopathy DCM)

sclerosis and thickening of valve flaps
decline in cardiac reserve
fibrosis of cardiac muscle
atherosclerosis