The Heart

Regulation of heart rate

stroke volume usually remains constant starlings law of the heart - the more that the cardiac muscle is stretched, the stronger the contraction changing heart rate is the most common way to change cardiac output

Blood pressure

systolic - pressure at the peak of ventricular contraction diastolic - pressure when ventricles relax pressure in blood vessels decreases as the distance away from the heart increases

Describe the effect stimulation by the vagus nerve has on heart rate

The vagus never innervates the heart and affects the SA node. Otto Loewi discovered that the vagus nerve through the action of Ach (a

murmur

an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves

heart for diagram

aorta leaves left ventricle pulmonary arteries leave right ventricle vena cava enters right atrium pulmonary veins (4) enter left atrium

Trace the pathway of blood through the heart

1) Superior and Inferior vena cava 2) Right Atrium 3) tricuspid valves 4) right ventricle 5)pulmonary semiluner 6) Pulmonary ateries 7) lungs 8pulmonary veins 9) left atrium 10) Bicuspid valves 11) left venticle 12)Aorta back to the body

The heart wall

3 layers Epicardium - outside layer Myocardium- middle layer Endocardium- inner layer

facts about the heart

A liquid, blood, to transport nutrients wastes oxygen and carbon dioxide hormones Two pumps (in a single heart) one to pump deoxygenated blood to the lungs; the other to pump oxygenated blood to all the other organs and tissues of the body. A system of blood vessels to distribute blood throughout the body Specialized organs for exchange of materials between the blood and the external environment; for example organs like the lungs and intestine that add materials to the blood and organs like the lungs and kidneys that remove materials from the blood and deposit them back in the external environment.

Heart sounds (on NC)

First Heart Sound S1, Second heart sound S2, Third heart sound, S3, Fourth heart sound.. S4, lub- closing of atrioventricular valves when ventricles contract, dup- closing of semilunar valves when ventricles relax

body's major arteries

Carotid artery: runs up both sides of the neck and is the artery felt when taking a pulse from the neck, delivers blood to the brain. Femoral: runs through the middle of the thigh on both legs, delivers blood to the lower extremities above the elbow. Brachial: runs from the anterior of the shoulder to the elbow, delivers blood to the upper extremities. Radial and Ulnar: stems off of the brachial and goes around the radius and ulna respectively, feeds blood to the flangies and lower extremites below the elbow.

pulmonary system

Deoxygenated blood from the body enters the right atrium. It flows through the tricuspid valve into the right ventricle. The term tricuspid refers to the three flaps of tissue that make up the valve. Contraction of the ventricle then closes the tricuspid valve and forces open the pulmonary valve. Blood flows into the pulmonary artery. This branches immediately, carrying blood to the right and left lungs. Here the blood gives up carbon dioxide and takes on a fresh supply of oxygen [More]. The capillary beds of the lungs are drained by venules that are the tributaries of the pulmonary veins. Four pulmonary veins, two draining each lung, carry oxygenated blood to the left atrium of the heart

coranary system

From the left atrium, Blood flows through the mitral valve (also known as the bicuspid valve) into the left ventricle. Contraction of the ventricle closes the mitral valve and opens the aortic valve at the entrance to the aorta. The first branches from the aorta occur just beyond the aortic valve still within the heart. Two openings lead to the right and left coronary arteries, which supply blood to the heart itself. Although the coronary arteries arise within the heart, they pass directly out to the surface of the heart and extend down across it. They supply blood to the network of capillaries that penetrate every portion of the heart. The capillaries drain into two coronary veins that empty into the right atrium.

Compare the pulmonary and systemic circuits

Pulmonary Circulation carries deoxygenated blood to the lungs to receive oxygen, while the Systemic Circulation carries the oxygenated blood throughout the body so the oxygen can be used, returning to the Pulmonary Circulation as deoxygenated blood.

atherosclerosis

condition in which fatty deposits called plaque build up on the inner walls of the arteries

Atria

receiving chambers right and left

Explain what information can be gained from an electrocardiogram (EKG)

The underlying rate and rhythm mechanism of the heart. The orientation of the heart (how it is placed) in the chest cavity. Evidence of increased thickness (hypertrophy) of the heart muscle. Evidence of damage to the various parts of the heart muscle. Evidence of acutely impaired blood flow to the heart muscle. Patterns of abnormal electric activity that may predispose the patient to abnormal cardiac rhythm disturbances.

Explain the operation of the heart vavles

The upper two are the right and left atria. The lower two are the right and left ventricles. Blood is pumped through the chambers, aided by four heart valves. The valves open and close to let the blood flow in only one direction.

capillary walls

There are three basic ways for things to cross the capillary wall:filtration diffusion diapedesis, exchanges between the tissue cells and blood occur here, semi permeable membranes contains pores that let small substances pass through but keep in blood cells and larger molecules like proteins.

Location of Heart

Thorax between the lungs pointed apex directed toward left hip about the size of your fist

function of veins

Veins bring deoxygenated blood into the heart from the rest of the body, except for the pulmonary vein, which brings oxygenated blood from the lungs to the heart. The vein has small one way valves, it carries the blood to heart. These are wide lumen, thin wall, superficial. Deoxygenated blood should not miconcepted with completely impure blood. Veins do not carry nitrogenous wastes and other wastes of body other than CO2

Describe the effect of epinephrine on heart rate

When epinephrine ( ner. trans. secreted by adrenal glands) is released, one of its effects is increased heart rate. This is because in a 'fight or flight' situation, the person decides if he should stay and fight the problem or run for his life. Both these activities need extra energy and oxygen. The brain senses this and sends signals to the adrenal glands (in the kidney), which secrete adrenaline into the bloodstream. The heart rate increases as the body girds itself for what it is about to do: fight or run. The blood vessels and air passages dilate, allowing more blood to the muscles and oxygen to the lungs.

Describe the effect exercise has on heart rate

Your heart rate increases directly as you increase your exercise intensity, until you are near the point of exhaustion as in Olympic cross-country skiing. As that point is approached, your heart rate begins to level off. This indicates that you are approaching your maximum value. The maximum heart is the highest heart rate value you achieve in an all-out effort to the point of exhaustion. This is a highly reliable value that remains constant from day to day and changes only slightly from year to year.

The cardiovascular system

a closed system of the heart and blood vessels the heart pumps blood blood vessels allow blood to circulate to all parts of the body the function is to deliver oxygen and nutrients and to remove co2 and other waste products

Pericardium

a double serous membrane, outside covering/skin of the heart

heart beats

bradycardia - 46 beats per minute tachycardia - 136 beats per minute ventricular - fibrillation

Valves

allows blood to flow in one direction, valves open as blood is pumped through, held in place by chordae tendiceae (heart strings), close to prevent backflow 4 valves Atrioventricular valves - between atria and ventricles bicuspid valve (left) tricuspid valve (right) semilunar valves - between ventricle and artery pulmonary semilunar valve aortic semilunar valve

cardiac output

amount of blood pumped by each side of the heart in one minute (CO = heart rate x stroke volume) stroke volume - volume of blood pumped by each ventricle in one contraction

Arteries

blood vessels that carry blood away from the heart

Veins

blood vessels that carry waste containing blood from the tissues back to the heart

coronary circulation

circulation of blood through the coronary blood vessels to deliver oxygen and nutrients to the heart muscle tissue

Ventricles

discharging chambers right and left

describe the effect of various ions on heart rate

epinephrine and thyroxine increase heart rate. electrolyte imbalances pose threat to heart. reduced levels of ionic calcium in the blood depress the heart, excessive blood calcium causes prolonged contractions that heart can stop entirely. excesses or a lack of needed ions such as sodium and potassium modify heart activity. a deficit of potassium ions in the blood cause heart beat feebly, and abnormal heart rhythms appear.

Cardiac cycle

events of one complete heart beat mid to late diastole - blood flows into ventricles ventricular systole- blood pressure builds before ventricle contracts, pushing out blood early diastole - atria finish re-filling ventricular pressure is low atria contract simultaneously atria relax then ventricles contract

heart contractions

intrinsic conduction system (nodal system) heart muscle cells contract without nerve impulses, in a regular, continuous way special tissue sets the pace sinoatrial node pacemaker atrioventricular node antrvent. bundle bundle branches purkinje fibers contraction is initiated by the sinoatrial node sequential stimulation occurs at other autorhythmic cells

variations in blood pressure

normal 140-110 mm Hg systolic 80-75 mm Hg diastolic Hypotension low systolic below 110 mm Hg often associated with illness Hypertension high systolic above 140 mm Hg can be dangerous if it is chronic (high blood pressure)

Pulse

pressure wave of blood on temporal artery, facical artery, carotid artery, brachial, radial artery, femoral artery, popliteal artery, posterior tibial artery, Dorsalis pedis artery

Cardiac cycle

the complete cycle of events in the heart from the beginning of one heart beat to the beginning of the next; an electrical impulse conducted through the heart muscle that constricts the atria which is followed by constriction of the ventricles) "the cardiac cycle can be shown on an electrocardiogram"

Systole

the contraction of the chambers of the heart (especially the ventricles) to drive blood into the aorta and pulmonary artery CONTRACTION

Capillaries

the smallest blood vessels which connect the smallest arteries with the smallest veins. Nourishment and fluid noramlly trapped in thick walled arteries and veins can easily pass through the delicate walls of the capillaries

major veins

the superior vena cava (a large vein to collect oxygen poor blood from chest and above) the inferior vena cava (a large vein to collect oxygen poor blood from all parts of body below the chest) pulmonary vein - one of two pairs of vessels carrying oxygenated blood from the lungs to the left atrium of the heart

Stroke volume

the volume of blood pumped out by a ventricle with each heartbeat

Diastole

the widening of the chambers of the heart between two contractions when the chambers fill with blood RELAXATION