A&P 2 the heart

intercalated discs

(junctions between cardiac muscle cells); these contain small tubes that are collectively called gap junctions. The tubes connect the cytoplasm of adjoining cardiac muscle cells

inferior vena cava

Returns blood from body areas below the diaphragm.

mediastinum

medial cavity of the thorax beneath sternum

auricles

protruding appendages of atria

tricuspid valve

the right AV valve, three flexible cusps

foramen ovale

within 48 hours of birth, the opening seals off and becomes the fossa ovalis

coronary sulcus

...The atria of the heart are separated from the ventricles by the coronary sulcus

posterior interventricular sulcus

...one of the two grooves that separates the ventricles of the heart

anterior interventricular sulcus

...one of two grooves that separates the ventricles of the heart, the other being the posterior interventricular sulcus. The anterior interventricular sulcus is situated on the sternocostal surface of the heart, close to its left margin.

Circuit systems

2 circuit systems: Pulmonary, pumps to and from lungs to receive oxygen and dispel carbon dioxide. Systemic pumps oxygenated blood through the body to supply tissue with nutrients and oxygen. The left side of heart receives the oxygenated blood from the lungs. The right side receives oxygen-poor blood and pumps it to the lungs.

Heart

4 chambers: Right and left atria receive, right and left ventricles pump out.

Atrioventricular Node

An electrical "bridge" or coupling that connects the atria with the ventricles b. location: within the interatrial septum near the tricuspid valve

Heart Skeleton

Band of dense connective tissue meshwork of collagen and elastic fibers that separate the atria from the ventricles (they are not made of bone) and extend up into the septa

pericardial cavity

Between visceral and pericardial layers, contains serous fluid, provides lubrication between layers to allow heart to move friction free.

pectinate muscles

Bundles of muscles that form ridges in anterior portion of right atrium.

Vein

Carries blood from capillaries to the heart

coronary sinus

Collects blood draining from the myocardium.

Cardiovascular system

Consists of the heart, blood vessels, and blood

serous pericardium

Deep to the fibrous pericardium, its parietal layer lines the surface of the fibrous pericardium and at the superior point of the heart turns inwardly around the valves and forms a visceral layer, called the epicardium, which is an integral part of the heart wall.

AV node

Function: delay the spread of the cardiac impulse to the ventricles long enough (about 0.1 sec or 100 msec) for the atria to empty and the ventricles to fill

Heart definition 2

Muscular pump that is about the size of a fist; The heart weights 1/200th (0.5%) of total body weight, yet receives 1/20th of all of the blood

Cardiac Muscle Properties

Myogenic, Long refractory period, high density of mitochondria, Intercalated Discs

atrioventricular valves

One at each junction of atrium and ventricle, prevents back flow of blood.

Artery

Pumps blood away from heart through to capillaries

superior vena cava

Returns blood from body regions superior to the diaphragm

Path of Cardiac Impulse

SA node (pacemaker) → atrial myocardium (atrial systole) → AV node → AV Bundle and branches → Purkinje fibers of the ventricles → ventricular myocardium (ventricular systole)

Size, Location, Orientation of Heart

Size of a fist, 250-350 grams, within mediastinum, sits obliquely from fifth intercostal space to second rib

electrocardiograph

a device used to detect the electric currents across the heart and generate an EKG

Pericardium

a double-walled sac that encloses the heart

Cardiac Duty Cycle

describes the mechanical operation of the heart as it pumps blood (i.e., beats) a. the resting heart beats about 70-75 x/min b. each beat is a complete cardiac duty cycle lasting about 0.8 seconds (0.5 - diastole, 0.3 - systole)

cusps

each SLV consists of 3 cup-shaped cusps or flaps (similar to a shirt pocket) 1. the pocket-like cup portion faces away from the ventricles

3 layers of heart wall

epicardium, myocardium, endocardium

Layers of heart wall

epicardium: superficial layer myocardium: middle layer, composed of cardiac muscle, forms bulk of heart endocardium: third layer, deepest, consists of squamous epithelium, lines heart chambers, is located on inner surface of myocardium.

endothelial lining

extends from the inner lining of blood vessels (simple squamous) to line the cavities and cover the valves; the endocardium is a continuation of the endothelial lining of blood vessels

pericardial cavity

fluid-filled cavity between the two membranes; the pericardial fluid is exuded by the serous pericardium

Electrocardiogram (EKG or ECG)

graphical record of cardiac impulse spreading across the heart,

reason for high density of mitochondria

high rate of oxygen-requiring cellular respiration by cardiac muscle cells to meet their ATP demands for contraction; at rest cardiac muscle cells get most of their ATP from the catabolism of fatty acids (60%), glucose (35%), and other organic compounds such as amino acids c. cardiac muscle cells can use almost any fuel substrate: glucose, fatty acids, amino acids, glycerol d. all highly active cells have a lot of mitochondria (heart, neurons, liver, kidney, muscle)

anchoring desmosomes

hold cells together in heart

endocardium

inner lining of the heart

myogenic

means the heartbeat originates in the heart,

EKG

measures the electrical activity associated with the spread of the cardiac impulse across the heart

right ventricle

not as strong a pump as the LV, LV wall is 3x thicker than this

Foramen ovale

opening in the interatrial septum that shunts blood from the RA to the LA thus routing blood away from the pulmonary circuit

fibrous pericardium

outer layer of pericardium; tough sac of dense connective tissue; lined with the parietal layer of the serous pericardium

sinoatrial node

pacemaker of the heart, generates the cardiac impulse which is a series of self-propagating action potentials (same as nerve impulse)

Coverings of the Heart

pericardium, serous pericardium, fibrous pericardium, pericardial cavity

refractory period

period of time after each contraction that the cardiac (heart) muscle must rest before it will contract again

function of heart skeleton

provide rigid support for the heart

Main Function of the Heart

receive low pressure blood and pump it out at high pressure

diastole

relaxation phase; as a chamber relaxes it fills with blood

epicardium

same as the visceral pericardium (inner part of serous); contains blood vessels (e.g., coronary arteries) and fat

Interatrial Septum

separates atria

Interventricular Septum

separates ventricles

fibrous pericardium

superficial wall of pericardium that protects the heart, anchors to surrounding structures, and prevents the heart from overfilling with blood.

Conduction System

system made up of specialized cardiac muscle cells that do not contract

mitral valve

the left AV valve, two cusps, aka bicuspid valve

pericardium

the membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane.

coronary circulation

the path through which blood flows to and from tissues of the heart

myocardium

thickest layer made up mostly of a highly vascular cardiac muscle; also contains connective tissue, blood supply, and nerves

chordae tendineae

tiny white collagen cords anchoring the cusps to papillary muscles in ventricular walls to keep the valves from being sucked up into atria during contraction

T wave

ventricular diastole=repolarization

QRS

ventricular systole=depolarization

SA node

cells of the this are "leaky" to Na+ thus they do not have a stable resting membrane potential; they continually depolarize towards threshold potential at regular intervals throughout life

serous pericardium

consists of 2 layers; a visceral layer lies on top of the heart and is also called the epicardium; a parietal layer forms the inner lining of the fibrous pericardium. The pericardial cavity is between the 2 layers of the serous pericardium

SAN

consists of a mass of special myocardial cells embedded in the wall of the right atrium just beneath the opening of the superior vena cava

systole

contraction phase of a heart chamber (atrium or ventricle); as a chamber contracts it empties (atria empty to the ventricles, ventricles empty to the arterial outlets)

gap junctions

allow ions to pass between the cytoplasm of 2 adjacent cells. This is a type of electrical coupling

Semilunar valves

aortic and pulmonary valves

P wave

atrial systole=depolarization

hypertension

can weaken the walls of small arteries and cause aneurysms. It also promotes atherosclerosis which can lead to heart problems