HEART ANAT 2

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Heart

Muscular pump that keeps blood flowing through vessels

Blood Vessels

Deliver blood to organs and return blood to the heart

Pulmonary Circuit

carries blood to and away from lungs; supplied by right side of the heart

Systemic Circuit

carries blood to and from all organs of the body; supplied by the left side of the heart

Heart

4

Sternum

anterior

Lungs

lateral

Thoracic vertebra

posterior

Diaphragm

inferior

Right and Left Atria

Superior chambers; Receive blood returning to the heart via great vessels; Have earlike extensions to increase volume known as auricles

Right and Left Ventricles

Inferior chambers; Pump blood into arteries

Anterior intraventricular sulcus

Separate the R and L ventricles anteriorly

Posterior intraventricular sulcus

Separate the R and L ventricles posteriorly

Coronary atrioventricular sulcus

Encircles heart and separates atria from ventricles

Fibrous Pericardium

tough fibrous layer of dense connective tissue

Serous Pericardium

Refers to the parietal and visceral layers of serous pericardium

Pericardial Cavity

Enclosed space between visceral and parietal layers filled with serous fluid

Myocardium

the thickest middle layer made of cardiac muscle, performs mechanical work; Branched cells; single nuclei; striated; w/ Intercalated Discs; Support synchronous contractions. Have desmosomes and gap junctions.

Pecinate

muscular ridges of myocardium in atria

Trabeculae Carneae

rounded columns of myocardium in ventricles

Endocardium

Smooth inner lining of the heart. Simple squamous epithelium and thin areolar tissue; Covers the valve surfaces and is continuous with endothelium of vessel

septum

singular)

foramen ovalis

hole that allows oxygenated blood (from umbilical vein via vena cava) to bypass pulmonary circulatio

fossa ovalis

remnant of foramen ovalis, closes at birth

Interventricular septum

separates ventricles

Atrioventricular septum

divides the atria and ventricles. (valves also divide these structures)

Valves

ensure one

Right AV Valve

(aka Tricuspid Valve

AV Valves

(aka atrioventricular valves

Left AV Valve

(aka Bicuspid Valve aka Mitral Valve)

Chordae Tendineae

connect AV valves to papillary muscles

Cusps

leaflets or flaps that make up the valves

Semilunar Valves

Pulmonary semilunar valve and Aortic semilunar valv

Superior Vena Cava

delivers deoxygenated blood from the head and upper trunk to the right atrium.

Inferior Vena Cava

delivers deoxygenated blood from the lower trunk and extremities to the right atrium.

Pulmonary Trunk and Arteries

delivers deoxygenated blood from the right ventricle to the lungs

ductus arteriosus

allows most of R vent. blood to bypass lungs; becomes ligamentum artiosum when closes 12

Pulmonary Veins

(two from each lung) deliver oxygenated blood from the lungs to the left atrium

Aorta

Delivers oxygenated blood from the left ventricle to all organs of the body

Left Coronary Artery

small opening in ascending aorta

anterior interventricular branch

travels in anterior interventricular sulcus

circumflex branch

travels in coronary sulcus

Right Coronary Artery

small opening in ascending aorta

right marginal branch

runs towards apex of the heart

posterior interventricular branch

travels in posterior interventricular sulcus

Coronary Sinus

(is fed by cardiac veins)

Contractile cells

make up 99% of all cardiac muscle cells; don’t initiate own electrical potential but rather wait for an impulse to reach them.

Autorhythmic cells

aka pacemaker cells; self

Sinoatrial Node

pacemaker, fires first and fastest

Internodal pathway

distributes the information from SA node to the atrial muscle

Atrioventricular node

gathers information from the internodal pathway, is the electrical gateway to the ventricles

Atrioventricular bundle

aka bundle of hiss

Purkinje fibers

arise from lower bundle branches, turn up and spread through ventricular myocardium

Heart Rate

is measured in number of beats per minute. This corresponds to how often the pacemaker cells are firing Action Potentials

Autonomic Nervous System

acts to adjust heart rate via cardiac centers located in the medulla oblongata

Cardioaccelerator regions

stimulate the Sympathetic Nervous System

Cardioinhibitory regions

stimulate the Parasympathetic Nervous System

Cardiac Cycle

= one complete contraction and relaxation of all four heart chambers.

Systole

period of contraction, when heart pumps blood

Diastole

period of relaxation, when chambers fill with blood

Electrocardiograph

aka EKG

P Wave

signal travels through and depolarizes atria; atrial contraction

QRS Complex

signal from AV node spreads to ventricular myocardium; ventricular contraction

T Wave

ventricular repolarization; ventricle relaxes

Ventricular and Atrial Diastole

everything is relaxed; no APs, muscles are repolarizing; Atria fill from the veins; AV valves are open, ventricles are passively filling; No change in pressure; SA node fires and atrial depolarization begins

Atrial systole

the P wave; atrial contraction is forcing blood into the ventricles; volume of the atria are decreasing; Volume of ventricles increasing; Pressure in ventricles increasing

Early ventricular systole

ventricles begin to contract; AV valve snaps shut “Lub”; No change in volume of the ventricles; (max amount of blood has entered = End diastolic volume); Pressure is increasing

Ventricular Systole

QRS wave; semilunar valves open; Pressure increases; Volume in ventricles decreases; (End systolic volume = amt of blood left over after complete ventricular contraction)

Ventricular diastole

T wave; Ventricles relax and repolarize; Semilunar Valves snap shut “Dub”. All valves are closed in this stage; Decrease in pressure as ventricles relax; Volume stays the same

Cardiac Output

tells you how much blood is pumping through your body in a set amount of time

factors affecting HR

age, fitness levels, hormones, autonomic innervation

factors affecting stroke volume

heart size , fitness level, gender, contractility, duration of contraction, preload(EDV) , afterload (resistance)

cardiac output

SV x HR

SV

= EDV

Stroke Volume

is the total volume of blood pumped by one ventricle in one cardiac cycle and can change based on nervous input.

Preload

is the amount of tension (stretch) in the ventricular myocardium immediately before it contracts.

Frank Starling Law

(SV is proportional to EDV), meaning more blood = more stretched = greater next contraction

Contractility

refers to how hard the myocardium contracts for a given preload.

positive ionotropic factors

increase contractility ex. sympathetic stimulation, high blood calcium, certain drugs: Beta Blockers

negative ionotropic factors

decrease contractility ex. Parasympathetic stimulation, hypoxia, certain drugs: Epinephrine

Afterload

is the sum of all forces that must be overcome before a ventricle can eject blood

Tachycardia

persistent, resting adult heart rate above 100 bpm. Factors that raise HR are called positive chronotropic factors ex. Sympathetic stimulation, epinephrine, caffeine

Bradycardia

persistent, resting adult heart rate below 60 bpm. Factors that lower HR are negative chronotropic factors ex. Parasympathetic stimulation, hypothermia