A&P chapter 17
inferior vena cava
A vein that is the largest vein in the human body and returns blood to the right atrium of the heart from bodily parts below the diaphragm.
other factors that regulate HR
excercise, age, gender, body temperature
fossa ovalis
Oval depression located in the septal wall of the right atrium, remainder of the foramen (opening) ovalis in the fetal heart that normally closes soon after birth.
heart rate
- number of heartbeats per minute
congestive heart failure
A condition resulting from the heart's inability to pump out all the blood that returns to it; blood backs up in the veins leading to the heart, causing an accumulation of fluid in various parts of the body
pericardial cavity
A fluid-filled space that surrounds the heart
functional synctium
A tissue in which the cytoplasms of the cells are connected by gap junctions, allowing the cells to function as a unit. Cardiac and smooth muscle tissues are examples of functional synctiums.
pulmonary valve
A valve at the base of the pulmonary artery in the right ventricle of the heart.
mitral valve
A valve in the heart that guards the opening between the left atrium and the left ventricle; prevents the blood in the ventricle from returning to the atrium. Alternative name is bicuspid valve.
tricuspid valve
A valve that is situated at the opening of the right atrium of the heart into the right ventricle and that resembles the mitral valve in structure but consists of three triangular membranous flaps.
superior vena cava
A vein that is the second largest vein in the human body and returns blood to the right atrium of the heart from the upper half of the body.
contractility
Ability to respond to an electrical impulse with pumping action.
hypertension
Abnormally high blood pressure
tachycardia
Abnormally rapid heartbeat
bradycardia
Abnormally slow heartbeat
cardiac tamponade
Acute compression of the heart caused by fluid accumulation in the pericardial cavity
preload
Amount of blood left in the left ventricle at the end of diastole (end diastolic volume).
cardiac output
Amt of blood discharged from ventricles/mi = HRxSV
right atrium
A chamber of the heart that receives oxygen depleted blood from the vena cava and pumps through the tricuspid valve into its ventricle.
insufficient valve
Valve that cannot completely close (scarred, i.e. rheumatic fever). Results from backward blood flow (swish).
left pulmonary veins
bring oxygen-rich blood from the left lung to the left atrium
microscopic anatomy cardiac muscle
striated and contracts by sliding filaments. short fat branched and interconnected. each fiber contains one or two large pale centrally located nuclei, intercellular spaces are filled with loose connective tissue matrix connected to fibrous cardiac skeleton which acts as a tendon and an insertion giving cells something to pull or exert their force against. independent of eachother have intercalcated discs
structure and function of atria
superior chambers, receiving chambers, thinner walled because they need to contract minimally to push out blood.
right pulmonary veins
takes blood from the right lung back to the left atrium of the heart
right pulmonary artery
takes blood from the right ventricle to the right lung
systemic circuit
the blood vessels that carry blood to and from body tissues; the left side of the heart pumps through this circuit.
pulmonary circuit
the blood vessels that carry blood to and from the lungs; the right side of the heart pumps blood through this circuit.
cardiac reserve
the difference between a person's maximum cardiac output and resting cardiac output
coronary circulation
the functional blood supply of the heart. Coronary arteries arise from the aorta and carry oxygenated blood to the myocardium.
intrinsic conduction system
1. SA node (pacemaker) generates impulses. 2. the impulses pause (0.1s) at the av node. 3. the av bundle connects the atria to the ventricles. 4. the bundle branches conduct the impulses through the interventricular septum 5. the subendocardial conducting network depolarizes the contractile cells of both ventricles.
similarites of skeletal and cardiac contraction
1. depolarization opens fast voltage gated NA+ channels in sacolemma allowing extracellular Na+ to enter. influx intitiates a positive feedback cycle that causes the rising phase of the AP and reversal of membrane potential. 2. transmission of depolarization wave down the T tubules causes the SR to release Ca2+ into the sarcoplasm. 3. E-C coupling occurs as Ca2+ provides the signal for cross bridge activation and couples the depolarization wave to the sliding microfilaments.
Differences of skeletal and cardiac contraction
1. means of stimulation, cardiac is self excitable 2. organ vs motor unit contraction skeletal muscle uses only some motor units all fibers in the heart contract as one. 3. length of absolute refractory period. skeletal muscle contraction lasts 15-100 ms with brief refractory period of 1-2 ms, cardiac contraction lasts almost 200 ms refractory period is 200 ms
cardiac cycle
1. ventricular filling, mid to late diastole. 2. ventricular systole (atria in diastole) 3. isovolumetric relaxation, early diastole.
resting cardiac output for nonathelete
20-25 L/min
left ventricle
A chamber of the heart that pumps oxygen rich blood through the aortic valve into the aorta.
aortic valve
Between left ventricle and aorta
dilated cardiomyopathy
Cardiac failure associated with dilation of one or both ventricular chambers. Slow progression of biventricular heart failure with low ejection fraction. Not generating enough pressure to push blood.
myocardium
Cardiac muscle tissue separated by connective tissues and including blood capillaries, lymph capillaries, and nerve fibers Contracts to pump blood from the heart chambers
aorta
Carries oxygenated blood from the heart to the body
left atrium
Chamber that receives oxygenated blood from the pulmonary veins and pumps it into systemic circulation.
papillary muscle
Cone-like projections on the ventricular walls, to which the chordae tendineae are attached. The contraction of the papillary muscles and the tightening of the chordae tendineae prevent the valve flaps of the AV valves from turning inside out into the atria.
cardioinhibitory center
Contains parasympathetic neurons; releasing acetylcholine onto cardiac cells; decreasing heart rate but NO change in heart's contractile strength; projects via vagus nerve, CNX to SA & AV nodes
right ventricle
Contracts to pump oxygen-poor blood along the pulmonary arteries to the lungs.
pulmonary trunk
Deoxygenated blood leaves the heart for the lungs. Divides into right & left arteries
hypocalcemia
Depressed contractility.
myocardial infarction
Disruption in or deficiency of coronary artery blood supply, resulting in necrosis of myocardial tissue
pericardium
Double-walled membranous sac that encloses the heart. Fibrous pericardium and serous pericardium
fibrous pericardium
Fibrous pericardium is composed of tough, white fibrous tissue that loosely fits around the heart to protect it. It also attaches to the great vessels, diaphragm, and sternum.
endocardium
Glistening white sheet of endothelium lining the heart
pericarditis
Inflamation of the pericardium from very little pericardial fluid. layers stick together. Which may result in cardiac tamponade (heart plug)or pericardial friction rib (Creaking sound)
pectinate muscles
Internal ridges of myocardium in right atrium and both auricles
arrythmias
Irregular heart beats and rhythms disorders
pulmonary congestion
Left side of the heart fails, fluid accumulates in the lungs
parietal layer
Outer layer, lines the internal surface of the fibrous pericardium.
interventricular septum
Partition that separates the right and left ventricles.
afterload
Pressure needed to eject blood out of heart into the aorta (blood viscosity, volume, and PVR effect afterload); higher afterload means harder to eject blood which decrease SV. end systolic volume
peripheral congestion
Right Side Fails. Swollen Ankles. Blood not discharged from the right ventricle therefore backs up into systemic circulation.
serous pericardium
Serous pericardium is thin and smooth and consists of 2 layers; the parietal layer and the visceral layer
cardioacceleratory center
Sympathetic nervous system stimulates this control center and speeds up HR.
intrinsic conduction
System of autorhythmic cells in the heart that generate impulses which stimulate the heart to contract.
stroke volume
The amount of blood ejected from the heart in one contraction. SV=EDV-ESV
chemical regulation of HR
The hormones epinephrine and thyroxine increase heart rate, normal heart function depends on having normal levels of intra and extracellular ions
visceral layer
The inner layer, which lines the surface of the heart. also called epicardium
atrioventricular valves
Valves located between the atrial and ventricular chambers on each side of the heart, prevent backflow into the atria when the ventricles are contracting.
ectopic focus
an abnormal pacemaker that may appear and take over the pacing of heart rate due to an defective SA node
fibrillation
an extremely rapid and incomplete contraction of the heart muscle.
heart block
an interference with the normal electrical conduction of the heart
P wave
atrial depolarization
AV valves open
atrial pressure greater than ventricular pressure.
av valves closed
atrial pressure less than ventricle pressure
left pulmonary artery
carries poor oxygenated blood from the right ventricle to the left lung.
angina pectoralis
chest pain caused by blood deficiencies to the myocardium temporary
cardiac skeleton
dense bands of tough elastic connective tissue that encircle the bases of the large blood vessels carrying blood away from the heart and each of the valves
coronary atherosclerosis
fatty deposits form in an artery and cause an obstruction and deterioration to arterial wall; causes heart failure
chordae tendinae
fibers attatched to the tricuspid valve which pull it closed when papillary muscles contract, preventing backwash of blood
extrinsic innervation of the heart
fibers of the ans modify the marchlike beat and introduce a subtle variability from one beat to the next. SNS increases both rate and force of heartbeat, PNS slows the heart
structure and function of ventricles
inferior chambers, discharging chambers, thicker walled because they pump blood farther, right is thinner than left because left pumps blood throughout the body
ANS regulation of HR
most important extrinsic controls, emotional or physical stressors cause the SNS nerve fibers to release norepinephrine, higher rate and force of contraction
trabeculae carneae
muscular ridges on the internal surface of the ventricles
important factors that effect stroke volume
preload, contractility, afterload
extrasystole
premature contraction
semilunar valves
pulmonary and aortic valves located between the right ventricle and the pulmonary artery and between the left ventricle and the aorta
intercalcated discs
transverse thickenings of plasma membrane which contain desmossomes and gap junctions, desmosomes prevent adjacent cells from separating during contraction and gap junctions allow ions to pass from cell to cell
Blood flow through the heart
vena cavas and coronary sinus carry deoxygenated blood to the right atrium through the tricuspid valve to the right ventricle through the pulmonary semilunar valve to the pulmonary arteries to the lungs oxygenated blood to the pulmonary veins into the left atrium through the mitral or bicuspid valve to the left ventricle through the aortic semilunar valve to the aorta to the rest of the body and back to heart
semilunar valves open
ventricles contract and intraventricular pressure rises blood is pused up against sl valves forcing them open
semilunar valves closed
ventricles relax and intraventricular pressure falls blood flows back from arteries filling the cusps of sl valves forcing them to close
QRS complex
ventricular depolarization
T wave
ventricular repolarization
