Cardiovascular system

Cardiovascular system

Heart + blood vessels; transport blood throughout the body; exchange between capillary blood and body cells

Perfusion

Delivery of blood per time per gram of tissue mL/min/g

Adequate perfusion

Sufficient delivery to maintain cells health

Blood vessels

Arteries, veins and capillaries

Arteries

Carry blood away from the heart

Veins

Carry blood back to the heart

Capillaries

Sites of exchange (ex gases) between blood and body cells

Sits posterior to sternum left of body midline; between lungs in mediastinum; slightly rotated right side more anterior than left

Location and position of the heart

Pericardium; Thoracic cavity

Heart is enclosed in _____ within ______ ______

Pericardium; fibrous pericardium, serous pericardium, fluid filled pericardial cavity

Double walled sac around the heart; composed of what

Parietal layer and visceral layer

2 layers of serous pericardium

Protects and anchors the heart; prevents overfilling; relatively friction free environment

What does the pericardium do

Pericarditis

Inflammation of the pericardium; caused by viruses, bacteria, or fungi; increased capillary permeability; friction rub

Coronary sulcus

Separates atria from ventricles

Intraventricular sulci

Separate left from right ventricles (anterior and posterior)

Coronary vessels

What do grooves contain that supply blood to heart wall

Anterior view of heart

Right atrium and ventricle = prominent; right auricle; also visible are aorta and pulmonary trunk; small portion of left auricle of left atrium; anterior interventricular sulcus, part of coronary sulcus

Posterior view of heart

Left atrium and left ventricle prominent; also visible are pulmonary veins attached to left atrium, superior and inferior vena cava, pulmonary arteries, osteoarthritis interventricular sulcus, part of coronary sulcus housing coronary sinus

Epicardium

Serous pericardium; outermost layer of the heart

Myocardium

Left vs right; muscle layer; most important functionally

Fibrous Skeleton of the heart

Crisscrossing, interlacing layer of connective tissue

Endocardium

Endothelial layer of the inner myocardial surface; innermost layer of the heart

4; lateral separation (atria and ventricles); longitudinal (right/left sides)

How many chambers does the heart have and how is it separated

Atria

What is receiving and has auricles

Superior and inferior venae cavae and coronary sinus

Blood → right atria from what

Pulmonary veins

Blood → left atria from what

Ventricles

Discharging; papillary muscles mark ventricular walls; right ventricle blood to pulmonary trunk; left ventricle blood to aorta

Unidirectional blood flow ( doesn’t allow backflow)

What do eart valves ensure

Atrioventricular (AV) valves

What lies between the atria and the ventricles

Aortic semilunar (SL) valve

What is between left ventricle and aorta

Pulmonary SL valve

What is between right ventricle and pulmonary trunk

Closing of heart valves - first sound is AV valve close, second is SL valve close

Heart sounds (lub-dup) are associated with what

Quiescent period

Pause between the heart sounds is what

Heart mumur

Abnormal heart sound; result in turbulence of blood passing through heart; some medically important some not

Valvular insufficiency

Cardiac valves leaking because cusps not closing tightly; blood regurgitating back through valve; may get heart enlargement

Valvular stenosis

Valve cusps scarred and cannot open completely; presents resistance to blood flow; reduces chamber output; chamber may enlarge and dilate

Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary arteries → lungs → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → systemic circulation

What is the pathway of blood through heart and lungs

Coronary circulation

Blood supply to heart muscle; blood flows through the heart constantly

In coronary sulcus (first and only branches off of ascending aorta)

Where do left and ight coronary arteries sit

Right marginal artery (supplies right heart border) and posterior interventricular artery (supplies posterior left and right ventricle)

Right coronary artery branches into what

Circumflex artery (supplies left atrium and ventricle) and anterior interventricular artery (supplies anterior surface of both ventricles, supplies most in interventricular septum, “widowmaker” nickname refers to high risk of fatality if occluded)

Left coronary artery branches into what

Great cardiac vein

Sits in anterior interventricular sulcus

Middle cardiac vein

Wits in posterior interventricular sulcus

Small cardiac vein

Sits next to right marginal artery

Coronary sinus

Sits in posterior aspect of coronary sulcus; receives blood from cardiac veins and drains into right atrium

Atherosclerosis

Built up blockage of plaque in arteries

Coronary spasm

Vessels in heart spasm/constrict reducing blood flow

Angina pectoris

Pain usually on left side of chest, left arm, or jaw; usually referred pain when performing a strenuous activity; treatments induce vascular dilation

Myocardial infarction

Heart attack; complete occlusion of coronary arteries; myocardium deprived of oxygen, possible tissue death; excruciating check pain radiating down left arm; weakness, shortness of breath, nausea, anxiety and sweating

Myocardium

Cardiac muscle tissue; cardiac muscle cells short and branched; one or two central nuclei, sarcomeres present (striated) sarcolemma (plasma membrane), t-tubules, sarcoplasmic reticulum

Connections via intercalated discs; desmosomes (rivets), gap junctions

Intercellular structures of cardiac muscle

Conduction system

Initiates and conducts electrical events to ensure proper timing of contractions; specialized cardiac muscle cels that have action potentials but do not contract; activate influenced by ANS

Sinoatrial (SA) node

Initiates heartbeat (pacemaker); located high in posterior wall of right atrium

Atrioventricular (AV) node

Located in floor of right atrium (near right AV valve)

Atrioventricular (AV) bundle (bundle of His)

Extends from AV node through interventricular septum; divides into left and right bundles

Purkinje fibers

Extend from left and right bundles at hearts apex; couse through walls of ventricles

Cardiac center of medulla oblongata

Cardioacceleratory and cardioinhibitory centers; input from baroreceptors and chemoreceptors; sends signals via PNS and SNS

PNS

Decreases heart rate; starts at medullas cardioinhibitory center; relayed via vagus nerve (CN X)

SNS

Increases heart rate and force of contraction; starts at medullas cardioacceleratory center

Heart muscle

Automaticity (beats on its own); contracts as a unit; has a long (250 ms) absolute refractory period

Depolarization→ fast Na channels; depolarization down T tubules; excitation- contraction coupling

Cardiac muscle contraction steps

Autorythmic cells

Pacemaker cells; initiate action potentials; have unstable resting potentials called pacemaker potentials; use calcium influx for plateau of cation potential

CANNOT; refractory period

Cardiac muscle ______ exhibit tetany; unlike skeletal muscle, cardiac cells have long _____ ______

ECG

Electrical activity is recorded by ____; generated in and transmitted; clinically recorded by 12 separate leads

P wave

QRS complex

T wave

_____ = depolarization of SA node

_____= ventricular depolarization

_____= ventricular repolarization

The ECG recording

Two segments between waves correspond to plateau phases of cardiac action potentials

P-Q segment

S-T segment

Atrial cells plateau (atria are contracting)

Ventricular plateau (ventricles are contracting)

Arrhythmias

Uncoordinated atrial and ventricular contractions

Fibrillations

Rapid and irregular/out of phase contractions; heart rhythm is taken away from the SA node; rapid activity in other regions; defibrillation can “wipe the slate clean”

Heart blocks

Impaired conduction; may result in light headedness, fainting, irregular heartbeat, chest palpitations

First degree AV block

PR prolongations; slow conduction between atria and ventricles

Second degree AV block

Failure of some atrial action potentials to reach ventricles

Third degree AV block

Complete; failure of all action potentials to reach ventricles

Ectopic focus

Abnormal pacemaker

Abnormal SA node

AV node CN become pacemaker; slow must still sufficient

Abnormal pacemakers can occur even in the presence of normal SA node; other heart regions are hyperexcitable; cline, nicotine; extrasystole (premature contractions)

Cardiac cycle

Refers to all events associated with blood flow through the heart ; systole, diastole; ventricles are the driving force; action through pressure gradients

Systole

Diastole

Contraction of heart muscle

Relaxation of heart muscle

Ventricular balance

Equal vol, blood pumped by left and right sides; left heart pumps farther (thicker muscle); ejected blood volumes must = edema

Cardiac Output (CO)

____ = heart rate (HR) x stroke volume (SV)

Heart Rate (HR)

Beats per minute

Stroke Volume (SV)

Amt of blood pumped by a ventricle/beat

Cardiac reserve (max)

Athletes (7x) - Mere mortals (3-4x)

5.25

5

Normal output is _____ L/min

Average adult blood volume is ____ L

Edema

Swelling; systemic and pulmonary

Systemic edema

May occur if right ventricle impaired; more blood remaining in systemic circulation; additional fluid entering interstitial space

Pulmonary edema

May occur if left ventricle impaired; more blood remaining in pulmonary circulation; swelling and fluid accumulation in the lungs; breathing difficulties and impaired gas exchange

Chronotropic agents

Change heart rate; alter activity of nodal cells (SA and/or AV node)

Positive chronotropic agents

Increase heart rate; sympathetic nerve stimulation; thyroid hormone, caffeine, nicotine, cocaine

Negative chronotropic agents

Decrease heart rate; beta-blocker drugs; interfere with EPI and NE binding to beta receptors; used to treat high blood pressure

Autonomic reflexes

Baroreceptors and chemoreceptors send signals to cardiac center; cardiac center influences sympathetic and parasympathetic systems to alter cardiac output as needed

Atrial reflex (bainbridge reflex)

Protects heart from overfilling; baroreceptors in atrial walls stimulated by increased venous return; increased nerve signals to cardioecceleratory center; increased excitation of sympathetic axons to heart; heart rate increase t move blood through quickly

Venous return, inotropic agents, and; afterload

What is stroke volume influenced by

Venous return

Volume determines preload- pressure stretching heart wall before shortening

Frank starling law

EDV increases = increased stretch of heart wall; more optimal overlap; contractility increases

Intropic agents

Change stroke volume; alter contractil Ca2+ availability; Ca2+ levels → number of cross bridges formed

Positive inotropic agents

_____ increase available Ca2+; EPI and NE; thyroid hormone

Negative inotropic agents

_____ decrease available Ca2+; electrolyte imbalances; certain drugs (Ca2+ channel-blocking blood pressure drugs)

Afterload (back pressure)

Resistance in retries to ejection of blood by ventricles; pressure that must be exceeded before blood ejected; atherosclerosis (plaque in vessel linings) increases afterload

Bradycardia

Persistently low resting heart rate in adults; below 60 beats per minute; normal change in athletes; abnormal due to hypothyroidism, electrolyte imbalances, and congestive heart failure

Tachycardia

Persistently high resting heart rate; over 100 beats per minute; caused by heart disease, fever, anxiety