Heart <3

cardiology definition

cardiology definition

scientific study of the heart and associated diseases

heart descriptionn

• composed of cardiac muscle

• 4 chambers (2 atria & 2 ventricles)

• size of adult fist

heart location

• within the pericardial activity in a region called the mediastinum

• intermediate to L & R lung

• 2/3 of its mass is left of the body’s midline

apex

pointed end formed by tip of left ventricle

base

upper end where blood vessels attach

pericardium

• membrane surrounding the heart; anchors it in place and prevents overextension while beating

• contains pericardial fluid that allows contraction of tissue without friction

layers of the heart

• epicardium (superficial layer): provides external protection

• myocardium (intermediate layer; contains cardiac muscle: helps with contraction (pumping)

• endocardium (deep layer): provides internal protection

Artery

structure: 3 layers, more smooth muscle, higher BP

function: carries oxygenated blood away from the heart to the body tissues, maintains BP

Arteriole

structure: small arteries

function: same as artery

capillary

structure: 1 cell thick, formes “mesh” that connects arterioles and venules

function: allows materials to diffuse between vessels and body tissues

venule

structure: small veins

function: same as veins

veins

structure: 3 layers, less smooth muscle, contains valves to keep blood moving

function: carries deoxygenated blood back to heart/lungs

vasoconstriction

• increase contraction of muscle

leads to:

• decrease in vessel diameter

• decrease in blood flow

• increase in resistance

• increase in pressure

caused by:

• increase in oxygen

• decrease in carbon dioxide

• increase in sympathetic NS activity

• cold

vasodilation

• decrease in contraction of muscle

leads to:

• increase in vessel diameter

• increase of blood flow

• decrease in pressure

• decrease in resistance

caused by:

• decrease in oxygen

• increase in carbon dioxide

• decrease in sympathetic NS activity

• heat

superior & inferior vena cava

• vein

• function: transports from body to heart

Right & Left pulmonary artery

• artery but acts as a vein

• function: transports from heart to lungs

Ascending & Descending aorta

• artery

• function: transports from heart to body tissues

Right & Left pulmonary veins

• vein but acts as artery

• function: transports from lungs to heart

Coronary arteries

• artery

• function: transports to heart tissues (from blood flow)

coronary sinus

• vein

• function: transports from heart to lung (takes it to be oxygenated)

Right & Left Atria

• collect blood & moves it to ventricles

• thin walls

interatrial septum

tissue separating atria

auricle

• wrinkled pouch on anterior side of atria

• allows atria to hold more blood

Right & Left ventricle

• pumps blood

• thick walls (left is the thickest)

• right: pulmonary circulation (takes deoxygenated blood to lungs)

• left: systemic (lungs) circulation (takes oxygenated blood to body tissues

Interventricular septum

tissue separating ventricles

valves

• made of dense connective tissue

• open and close in response to pressure changes as heart contracts and releases’

• prevents blood from flowing backward

Bicuspid (Mitral)(L AV) valve

local: between L atrium & L ventricle

prevents: back flow of blood from ventricle to atria

Tricuspid (R AV) valve

local: between R atrium & R ventricle

prevents: backflow of blood from ventricle to atria

Pulmonary SL valve

local: between pulmonary artery & R ventricle

prevents: backflow of blood from artery to ventricle

Aortic SL valve

local: at entrance of aorta

prevents: backflow of blood form aorta to ventricle

stenosis

abnormal narrowing of a heart valve or blood vessel; restricts blood flow

mitral valve prolapse

• one or both cusps of mitral valve don’t close properly allowing blood to move backwards from ventricles to atrium

• affects 2-3% of population

Aneurysm

• weakening of blood vessel wall; bulges as blood flows past it

caused by:

• weakens in vessel (from birth)

• high BP

• plaque build up on vessel wall

in extreme cases, it can rupture leading to hemorrhaging

atherosclerosis

• hardening of the arteries due to buildup of plaque (cholesterol and lipids)

• decreases blood flow and can lead to heart attack and/or stroke

hypertension

high blood pressure (>150/90 mmHg)

blood flow of the heart

Superior & inferior vena cava > right atrium > tricuspid valve > right ventricle > pulmonary valve > pulmonary arteries > lungs > pulmonary veins > left atrium > bicuspid valve > left ventricle > aortic valve > aorta > body tissues

intrinsic rythmicity

• ability of the heart to beat without external stimulation

• 1% of cardiac muscle fibers can generate an AP

these fibers:

• acts as the heart’s pacemaker by setting the heart’s rhythm

• form the conduction system (route for AP)

sinoatrial (SA) Node

• pacemaker

• local: right atrial walls

• AP passes through atrial tissue in the intercalated discs

• causes: atrial contraction (sinus rhythm)

atrioventricular (AV) Node

• local: interatrial septum

• AP slows down (allows time for atria to empty blood)

• causes: atria to empty blood into ventricles

Bundle of His

• local: interventricular septum

• causes: AP to travel to ventricles

R & L Bundle branches

• local: interventricular septum

• causes: AP to travel to R & L ventricles

Purkinje Fibers

• local: ventricular walls

• causes: ventricular contraction (milliseconds after atrial contraction)

Arrhythmia

abnormal heart rate due to malfunctioning SA node

Bradycardia

HR <60 bpm

Tachycardia

HR >100 bpm

Fibrilatiion

uncoordinated contraction leading to lack of blood movement (V fib & A fib)

Artificial pacemaker

• treatment for arrhythmia’s

  • attached to heart via wires; regulates HR

cardiac cycle

• all events associated with one heartbeat

• contraction of atria followed by contraction of ventricles

Systole

• phase of contraction

• increase in pressure (due to decrease internal volume of chamber)(less space for blood)

• forces blood out of heart

Diastole

• phase of relaxation

• decrease in pressure (due to increase internal volume of chamber)(more space for blood)

• draws blood into heart

atrial/ventricular diastole

• repolarization (T wave)

• decrease pressure (falls below atrial pressure)

• AV valve opens (allowing blood into ventricles)

• SL valve opens

• cycles into atrial/ventricular systole next

Atrial systole

• depolarization (P wave)

• increase pressure

• AV valves open (to allow blood into ventricles)

• SL valves close

• cycles into atrial diastole next

ventricular systole

• depolarization (QRS complex)

• increase pressure

• AV valves close (to force blood out of ventricles)

• SL valves open

• cycles into ventricular diastole next

lubb

long, loud sound due to AV valves closing after ventricular systole begins (first sound)

dupp

short, sharp sound sue to semilunar valves closing at the end of the ventricular systole (last sound)

murmur

abnormal sound (clicking, rushing or gurgling) that may indicate a heart valve disorder

cardiac output (CO)

• volume of blood ejected per minute from L ventricle into aorta (same amount is moving from R ventricle to pulmonary trunk)

• CO=SV x HR

factors that influence cardiac output

1. stroke volume (SV) - amount of blood ejected by the L ventricle during contraction

2. Heart rate (HR) - number of heartbeats per minute (resting adult: 70 mL (SV), 75 bpm(HR))

factors that influence regulation of HR

1. chemicals (Ach, NE)

2. exercise

factors that influence regulation of SV

1. degree of stretch in heart before contraction

   1. increase space in chamber = increase force of contraction (Frank- starling law of heart)

2. Chemicals that change contraction strength

   1. epinephrine, NE Ca+, etc.

3. Pressure changes

Congestive heart failure (CHF)

• failure of the heart to pump

• results in: fluid accumulation in the lungs (pulmonary edema) that can cause suffocation

causes:

1. coronary artery disease

2. long-term high BP

3. MI (myocardial infarction)

4. valve disorders

Electrocardiogram (ECG or EKG)

• detects electrical currents in heart

P wave

• depolarization of atria before contraction (loss of charge- starts AP)

• missing= indicates dysfunction of SA node

QRS wave

• depolarization of ventricles before contraction

• repolarization of atria

• abnormal= indicates ventricle problem

T wave

• repolarization of ventricles

• repolarization of normal state

• abnormal= indicates a possible MI (myocardial infarction)

Blood Pressure (BP)

• force that pushes blood through arteries and arterioles

• BP is not measured through veins

BP Gradient

• difference in pressure between two regions; blood moves from a increase in pressure to a decrease in pressure

• the closer to the pump (heart), the greater the BP

korotkoff sound

• sound of blood squeezing through artery

• 1st sound= ventricular systolic pressure

• 2nd sound= ventricular diastolic pressure (almost inaudible)

• BP reading= ventricular systole / ventricular diastole

factors influencing BP

1. cardiac output: amount of blood pushed from heart to vessels per min

2. Peripheral resistance: friction as the blood passes through vessels which slightly slows blood flow

   1. determined by diameter of vessel

   2. determined by viscosity (resistance to flow)

3. Blood Volume: amount of blood; regulated by the kidneys

4. Venous Return: blood returned to the heart/lungs

5. Temperature: cold=vasoconstriction, heat= vasodilation

6. Chemicals

pulse

• expansion/recoil of an artery with each beat of the left ventricle

• pulse rate = HR

• influenced by:

  • activity

  • posture changes

  • emotions

• monitored in superficial artery such as carotid (neck) or radial (wrist)