Anatomy II chapter 15

cardiac muscle fibers

Smaller, striated, involuntary muscle fibers (cells) in the heart that contract to pump blood. for a functional synctium

structure of the heart

-Located in mediastinum -Four chambers - left atrium and ventricle, right atrium and ventricle -Two atrioventricular valves, two semilunar valves -Three layers - epicardium, myocardium, endocardium -The two AV valves are located at the entrance into the ventricles. They are called the tricuspid valve and the bicuspid (mitral) valve. The tricuspid valve is located between the right atrium and the right ventricle; the bicuspid (mitral) valve is located between the left atrium and the left ventricle. -The semilunar valves are located at the exit of each ventricle at the beginning of the great vessels. They are known as the pulmonic valve and the aortic valve. The pulmonic valve is located at the entrance of the pulmonary artery as it exits the right ventricle. The aortic valve is located at the beginning of the ascending aorta as it exits the left ventricle.

during ventricular systole and atrial diastole

-The A-V valves close -The chordae tendineae prevent the cusps of the valves from bulging too far backward into the atria -The atria relax -Blood flows into atria from venae cavae and pulmonary veins -The ventricular pressure increases and opens the semilunar valves -Blood flows into the pulmonary trunk and aorta

left atrium

Receives blood from the pulmonary veins; pumps blood to left ventricle

right atrium

Receives deoxygenated blood from the body receives blood from the inferior vena cava, superior vena cava and coronary sinus

murmur

abnormal heart sound from the cusps not completely closing

central venous pressure

all veins, except those returning to the heart from the lungs, drain into the right atrium this is therefore pressure in the right atrium (central venous pressure) factors that influence it alter flow of blood into the right atrium it affects pressure within the peripheral veins a weakly treating heart increases central venous pressure an increase in central venous pressure causes blood back up into the peripheral veins this can lead to peripheral edema

P wave

atrial depolarization

atrial wall cardiac muscle fibres

atrial syncytium

ascending aorta

branch: right and left coronary arteries supplies blood to the heart

arteries

carry blood away from the ventricles of the heart thick strong wall (three layers of tunics) endothelial linging middle layer of smooth muscle and elastic tissue outer layer of connective tissue carries blood under relatively high pressure

veins

carry blood toward the atria of the heart thinner walls than arteries (3 layers or tunics) middle wall poorly developed many have flap-like valves carry blood under relatively low pressure function as blood reservoirs

cardiac conduction system

clumps or strands of specialized cardiac muscle tissue which initiate and distribute impulses throughout the myocardium coordinates the events of the cardiac cycle

systemic circuit

composed of vessels that lead from the heart to all body parts (except the lungs) and back to the heart includes the aorta and its branches includes the system of veins that return blood to the right atrium

abdominal aorta

continuation of the thoracic aorta that runs through the abdominal cavity

atrial systole

contraction of the atria

ventricular systole

contraction of ventricles

parasympathetic impulses via vagus nerve...

decrease heart action

control of blood pressure

determined by cardiac output and peripheral resistance

skeleton of the heart

fibrous rings, together with masses of dense connective tissue in the portion of the septum between the ventricle (inter ventricular septum), constitute the skeleton of the heart

aortic valve

location: entrance to the aorta function: prevents blood from moving from the aorta into the left ventricle during ventricular relaxation

pulmonary valve

location: entrance to the pulmonary trunk function: prevents blood from moving from the pulmonary trunk into the right ventricle during ventricular relaxation

mitral valve

location: left atrioventricular valve separating the left atrium and ventricle function: prevents blood from moving from the left ventricle into left atrium during ventricular contraction

tricuspid valves

location: right atrioventricular orofice function: prevents blood from moving from pulmonary trunk into right ventricle during ventricular relaxation

myocardium

middle layer of the heart cardiac muscle tissue separated by connective tissue including blood capillaries, lymph capillaries and nerve fibres

blood vessels

organs of the cardiovascular system form a closed circuit to and from the heart

epicardium

outer layer of the heart also called the visceral pericardium serous membrane of connective tissue covered with epithelium and including blood capillaries, lymph capillaries and nerve fibers

thoracic aorta

part of the aorta the descends from the aortic arch through the thorax to the diaphragm

additional factors that influence heart rate

physical exercise, body temperature, concentration of various ions (potassium and calcium)

the heart is...

posterior to the sternum medial to the lungs anterior to the vertebral column the base lies beneath the 2nd rib the apex at the 5th intercostal space it lays just above the diaphragm

arterioles

receive blood from the arteries and carry blood to the capillaries thinner wall than an artery (3 layers or tunics) some smooth muscle tissue small amount of connective tissue helps control blood flow into a capillary through action of precapillary sphincters

left ventricle

receives blood from the left atrium and pumps the blood into the aorta for transport to the body cells

right ventricle

receives blood from the right atrium and pumps it into the pulmonary artery

electrocardiogram (ECG)

recording of the electrical changes that occur in the myocardium during a cardiac cycle

cardiac center...

regulates autonomic impulses to the heart

atrial diastole

relaxation of the atria

ventricular diastole

relaxation of the ventricles

arterial blood pressure

rises when the ventricles contract falls when the ventricles relax systolic pressure is the maximum pressure during ventricular contraction diastolic pressure is the minimum pressure when the ventricles relax

capillaries

sites of exchange of substances between the blood and body cells smallest diameter of all blood vessels they connect the smallest article and smallest venue they are extensions of the inner lining of arterioles the walls are endothelium only they are semi-permeable

venules

small veins that receive blood from the capillaries microscopic vessels that continue from the capillaries and merge to form veins thinner walls than arterioles less smooth muscle and elastic tissue than arteriole

lubb

the first heart sound occurs during ventricular systole A-V valves are closing

blood pressure

the force the blood exerts against the inner walls of the blood vessels most commonly refers to pressure in systemic arteries

blood supply to the heart

the left and right coronary arteries supply blood to the tissues of the heart

dubb sound

the second heart sound it occurs during ventricular diastole the pulmonary and aortic semilunar valves are closing

QRS complex

ventricular depolarization

T wave

ventricular repolarization

ventricular walls cardiac muscle fibres

ventricular syncytium

characheterisitcs of venous pathways

vessels of the venous system originate with the merging of capillaries into venules, venules into small veins and small veins into larger ones difficult to follow due to irregular networks and unnamed tributaries

lifespan changes

- cholesterol deposition in blood vessels - heart enlargement - death of cardiac muscle cells - increase in fibrous connective tissue of the heart - increase in adipose tissue of the heart - increase in blood pressure - decrease in resting heart rate

during atrial systole and ventricular diastole

-Blood flows passiviely into the ventricles **The remaining 30% of blood is pushed into the ventricles** -The A-V valves open and the semilunar valves close -the ventricles relax -This causes an increase in ventriccular pressure

factors that influence arterial blood pressure

-blood volume increases -heart rate increases -stroke volume increases -blood viscosity increases -peripheral resistance increases

Path of blood through the heart

1.superior and inferior vena cava (from the body) 2.right atrium 3.tricuspid valve 4.right ventricle 5.pulmonary valve 6. Pulmonary arteries 7.pulmonary veins (from lungs) 8. Left atrium 9.mitral valve 10.left ventricle 11.aortic valve 12.descending aorta

venous blood flow

Blood pressure decreases as the blood moves through the arterial system and into the capillary network, so little pressure remains at the venular ends of the capillaries only partly a direct result of heart action dependent on: skeletal muscle contraction breathing movements venoconstriciton

arch of the aorta

Branches to the brachiocephalic artery supplies blood to the right upper limb and right side of the head

SA node controls

heart rate

sympathetic impulses via vagus nerve

increase heart action

endocardium

inner layer of the heart membrane of epithelium and underlying connective tissue, including blood vessels and specialized muscle fibres