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