Module 3 - Heart

Question 1

Structure of Heart

Answer 1

Structure of Heart
In Thoracic cavity
Between lungs in mediastinum
2/3s of heart to left of midline
Size of fist
Board at top and tapers at base
Bottom – Apex

Question 2

Pericardium

Answer 2

Pericardium – encloses and holds in place
Outer fibrous pericardium – dense connective tissue
Inner serous pericardium – secrets fluid
Parietal layer
Pericardial cavity – pericardial fluid – reduces friction
Visceral layer – Epicardium – shared by membrane and heart wall

Question 3

Heart walls – superficial to deep

Answer 3

Heart walls – superficial to deep
Epicardium
Myocardium
Endocardium

Question 4

Epicardium

Answer 4

Epicardium – visceral layer of pericardium – mesothelium and connective tissue

Question 5

Myocardium

Answer 5

Myocardium – thick cardiac muscle – contracts to pump – collagenous fibers, blood vessels, and nerve fibers – make fibrous rings around valves – thickness varies
Superficial layer – continuous all around the heart – figure 8 pattern
Deep layer – longitudinal – make up inner muscle
Middle layer – circular fibers – surround ventricles – left ventricle is thicker, more force needed b/c pumps further with greater resistance

Question 6

Endocardium

Answer 6

Endocardium – lines chambers and forms cusps of valves – made of endothelium and connective – help regulate contract and growth – direct contact with blood – double layer for cusps valves

Question 7

Chambers

Answer 7

4 Chambers: divided upper & lower, and left & right
Two upper atria – blood in
Two lower ventricles – blood out

Question 8

Septum

Answer 8

Septum – divides atria into left and right – oval depression called fossa ovalis

Question 9

Auricles

Answer 9

Auricles – extension of an atrium visible on superior surface of heart – small pouches – slightly increase capacity of atria

Question 10

Valves

Answer 10

4 Valves – open and close w/ pressure changes at contraction and relaxation – prevent back flow
Atrioventricular valves:
Tricuspid valve
Bicuspid/mitral valve
Semilunar valves
Pulmonary semilunar valve
Aortic semilunar valve

Question 11

Atrioventricular valves

Answer 11

Atrioventricular valves – between atria and ventricles – open when pressure is great in atria – close when pressure is greater in ventricles
Tricuspid valve
Bicuspid/mitral valve

Question 12

Tricuspid valve

Answer 12

Tricuspid valve – right atrium to right ventricle

Question 13

Bicuspid/mitral valve

Answer 13

Bicuspid/mitral valve – left atrium to left ventricle

Question 14

Semilunar valves

Answer 14

Semilunar valves – eject blood from ventricles to body – open when pressure is greater than arteries
Pulmonary semilunar valve
Aortic semilunar valve

Question 15

Pulmonary semilunar valve

Answer 15

Pulmonary semilunar valve – right ventricle to pulmonary trunk

Question 16

Aortic semilunar valve

Answer 16

Aortic semilunar valve – left ventricle to aorta

Question 17

Papillary muscles & Chordae Tendineae

Answer 17

Papillary muscles & Chordae tendineae – support atrioventricular valves in preventing backflow of blood from vents to atria

Question 18

Pulmonary Circuit

Answer 18

Pulmonary Circuit – Deoxygenated blood – Right Side
From body into Right Atrium – superior and inferior vena cava, and coronary sinus (heart blood)
Right Atrium to Right ventricle – passes tricuspid valve
Right ventricle to lungs – passes pulmonary valve to pulmonary trunk
Trunk to left and right pulmonary arteries
To lungs for gas exchange in pulmonary capillaries

Question 19

Systemic Circuit

Answer 19

Systemic Circuit – Oxygenated blood – Left side
From lungs into Left Atrium – left and right pulmonary veins
Left atrium to left ventricle – passes bicuspid/mitral valve
Left ventricle to aorta – passed aortic semilunar valve
Aorta to body

Question 20

Coronary Circulation

Answer 20

Coronary Circulation
Heart needs nutrients and O2
Myocardium and epicardium need blood
Blood supply through coronary arteries
Feeds heart during relaxation (Diastole) – during contraction, heart pushes blood from left ventricle to aorta to body – during relaxation, blood pools at the valve and files arteries

Question 21

Two Major Arteries - Coronary Circulation

Answer 21

Two major Arteries – left & right – from trunk of Aorta
Left coronary artery:
Left Anterior Descending Artery
Circumflex Artery

Right coronary artery:
SA nodal artery
Right Marginal Artery
Posterior Descending Artery (PDA)

Question 22

Left Coronary Artery

Answer 22

Left coronary artery – branches at front to:
Left Anterior Descending Artery (LAD) – goes down interventricular septum to apex and goes behind – feeds most of left atrium and left vent
Circumflex Artery – around back – feeds back left of heart – branches to:
Left Marginal artery – down the left lateral heart – feeds left vent

Question 23

Right coronary artery

Answer 23

Right coronary artery – travels towards back of heart – branches at:
SA nodal artery – on top of right atrium – feeds SA node
Right Marginal Artery – feeds right
Posterior Descending Artery (PDA) – makes CRUX, cross at back of heart – can joins with LAD, Anastomosis

Question 24

Anastomosis

Answer 24

Anastomosis – two arteries connect – detour if area is blocked

Question 25

Cardiac Veins

Answer 25

Cardiac Veins – take deoxygenated blood from myocardium back to Right Atrium Coronary sinus Great Cardiac Vein Middle Cardiac Vein Small Cardiac Vein

Question 26

Coronary Sinus

Answer 26

Coronary sinus – connected to right atrium, drains all blood in – all three veins drain blood into Great Cardiac Vein – parallels LAD – starts at anterior apex of heart – Up septum – around to back Middle Cardiac Vein – starts posterior apex – up septum Small Cardiac Vein – right margin – around to posterior

Question 27

Conducting System

Answer 27

Conducting System Cardiac muscle cells – self-excitable autorhythmic cells – myocardial contractile cells – specialized muscles fibers acting as nerves 60-100/minute Repeated generating action potentials – trigger heart contractions Establishes its own fundamental rhythm ANS and hormones (epinephrine and norepinephrine) modify heartbeat (speed and strength)

Question 28

Conduction Components

Answer 28

Components SA Sino-atrial Node – pacemaker – Top of right Atrium AV Node – bottom of right atrium Atrioventricular Bundle (bundle of his) – top of septum – bundle of neurons Right & Left Bundle branches – splits to left and right ventricles Purkinje Fibers – left and right ventricles – little off shoots it the myocardium of ventricles

Question 29

Conduction Steps

Answer 29

SA at rest Initiates action potential – sweeping across atrium to AV Atria contract – atrial systole Received trigger Delay to allow atria complete pump Impulse travels down and branches Atrial diastole Spreads action potential to left and right ventricles Contraction – ventricle systole

Question 30

Electrocardiogram

Answer 30

Electrocardiogram Impulse conductions make electrical currents Detectable on surface with ECG – electrocardiogram – records action potentials P wave – atrial depol QRS complex – ventricular depol T wave – ventricles repol

Question 31

P wave

Answer 31

P wave – atrial depol – impulse from SA over atria to AV – atria contract a little after

Question 32

QRS complex

Answer 32

QRS complex – ventricular depol – impulse spread to ventricles – contraction begins at R

Question 33

T wave

Answer 33

T wave – ventricles repol

Question 34

P-Q (PR) interval

Answer 34

P-Q (PR) interval – conduction time from beginning of atrial excite to beginning of ventricle excite – see delay from SA to AV

Question 35

S-T

Answer 35

S-T – time when ventricles fibers fully depol – plateau phase of impulse – ventricles contract to pump blood

Question 36

Cardiac Cycle

Answer 36

Cardiac Cycle Systole – contraction Diastole – relaxation 1. Relaxation (quiescent) 2. Atrial systole – atrial contracts 3. Atrial diastole – tricuspid and mitral valves close – ventricle fills 4. Ventricular systole – ventricle contracts 5. Ventricular diastole – atria and ventricle fill – AV delay

Question 37

Heart Sounds

Answer 37

Lub – S1 – atrioventricular valves closing – after ventricular systole – ventricles fill with blood Dub – S2 – semilunar valves closing – end of ventricular systole – ejected blood Between each is ventricular systole After S2 till S1 – ventricular diastole

Question 38

Cardiac Output

Answer 38

Cardiac Output CO = SV X HR – normal 5L/m Cardiac Output (CO) – volume of blood ejected from each ventricle – separately – per minute Left into aorta Right into pulmonary trunk

Question 39

Heart Rate (HR)

Answer 39

Heart Rate (HR) – how fast – beats per minute – influenced by: ANS innervation Sympathetic – increases Parasympathetic – decreases Endocrine SV

Question 40

Stroke Volume (SV)

Answer 40

Stroke Volume (SV) – how strong – volume of blood ejected by the ventricle each contraction – influenced by age, gender, fitness, duration of contraction SV = EDV – ESV Preload Contractility Afterload

Question 41

EDV

Answer 41

EDV – end diastolic volume – end of rest – max fill of blood in the heart – 130ml

Question 42

ESV

Answer 42

ESV – end systolic volume – remaining blood after contraction – 60ml

Question 43

Preload

Answer 43

Preload – stretch of cardiac muscles at max filled w/ blood before contraction

Question 44

Contractility

Answer 44

Contractility – force of ventricle contraction – availability of Ca creates contraction force Positive Inotropic agents Negative Inotropic agents

Question 45

Positive Inotropic agents

Answer 45

Positive Inotropic agents – promote availability of Ca Thyroid hormone Norepinephrine

Question 46

Negative Inotropic agents

Answer 46

Negative Inotropic agents – decrease availability of Ca Electrolyte imbalance Ca+ blockers

Question 47

Afterload

Answer 47

Afterload – pressure to be exceeded to eject ventricular blood – measure of resistance against blood as it leaves heart

Question 48

Frank-Starling – law of the heart

Answer 48

Frank-Starling – law of the heart Greater preload = increase force of contraction during systole Heart equalizes output of R & L ventricles to keep same volume in systemic and pulmonary circulation

Question 49

Autonomic and Chemical Alteration of HR

Answer 49

Autonomic and Chemical Alteration of HR Body changes HR to get homeostasis Nervous control in Medulla Oblongata Sympathetic impulses increase HR and force contraction – epinephrine, norepinephrine, thyroid hormones Parasympathetic impulses decrease HR Proprioceptors Baroreceptors Chemoreceptors - Other factors: Ion balance – Na+, K+, & Ca+, Age, Gender, Fitness level, Temperature

Question 50

Proprioceptors

Answer 50

Proprioceptors – in heart and pericardium Give info about hearts position and movement Control cardiac dynamic Detect dilatation of heart – stretching

Question 51

Baroreceptors

Answer 51

Baroreceptors – in vessels Send signals to brain to adjust HR and dilate or constrict BV Monitor blood pressure Sense changes in stretch of blood vessel walls

Question 52

Chemoreceptors

Answer 52

Chemoreceptors – carotid and aorta Sense changes in blood chemistry – O2 levels, blood pH Send signals to brain to regulate HR and breathing

Question 53

Coronary artery disease

Answer 53

Coronary artery disease – build up in arteries – narrowing or blockage – fats, cholesterol, & etc

Question 54

Myocardial ischemia

Answer 54

Myocardial ischemia – lack of oxygen to tissue due to blocked or reduced coronary arteries

Question 55

Myocardial infarction

Answer 55

Myocardial infarction – Heart Attack – tissue lack oxygen and die – blood flow decreases or stops in coronary arteries

Question 56

Atrial septal defect

Answer 56

Atrial septal defect – hole in septum wall that divides atria of heart – incorrect flow of blood

Question 57

Tachycardia

Answer 57

Tachycardia – increase HR – above 100bpm

Question 58

Bradycardia

Answer 58

Bradycardia – decrease HR – below 60bpm