Exam 1: Heart Flashcards
1
Q
Heart Location
A
- Mediastinum: the cavity in the thorax which contains the heart
- extends from the 2nd rib to the 5th intercostal space
- rests on the superior surface of the diaphragm
- about 2/3 of the heart lies to the left of the midsternal line
- flat base on the posterior surface
- apex that points inferiorly toward the left hip
2
Q
Heart Covering
A
From superficial to deep:
- Fibrous Pericardium
- Serous Pericardium
3
Q
Fibrous Pericardium
A
- dense connective tissue
- protects the heart
- anchors the heart to surrounding structures
4
Q
Serous Pericardium
A
- thin
- two-layers
- — parietal layer: lines the inside of the fibrous pericardium
- — visceral layer: attached to the external heart surface and is called the epicardium
- — between the layers: pericardial cavity containing serous fluid lubricating the outside of the heart
- — loss of fluid creates painful pericarditis
- — cardiac tamponade: too much fluid which restricts the heart’s activity
5
Q
Layers of the Heart
A
From Superficial to Deep:
- Epicardium (visceral pericardium)
- Myocardium
- Endocardium
6
Q
Myocardium
A
- forms the bulk of the heart
- consists mostly of cardiac muscle
7
Q
Endocardium
A
- thin layer of squamous epithelium and connective tissue that lines the chambers of the heart
8
Q
Chambers of the Heart
A
- Right Atria and Left Atria
- — relatively small and thin-walled because their function is only to collect blood and pass it to the ventricles
- — atria are separated by the interatrial septum
- — right and left auricles protrude from the atria like ears
- — pectinate muscle: raised bundles line interior surface
- — fossa ovalis
- Right Ventricle
- Left Ventricle
- — ventricles are separated by the interventricular septum
9
Q
Fossa Ovalis
A
- shallow depression within the interatrial septum
- in fetal life, this was the foramen ovale
- – blood passed directly from right to left atrium
- — this opening closes shortly after birth
10
Q
Blood enters the right atrium from
1, 2, and 3
A
- superior vena cava - drains the upper part of the body
- inferior vena cava - drains the lower part of the body
- coronary sinus - drains the myocardium
11
Q
Blood enters the left atrium from….
A
- the pulmonary veins
- — two from the right, and two from the left
- — transport oxygen rich blood from the lungs back to the heart
- left atrium makes up most of the heart’s base
12
Q
Ventricles
A
- make up most of the heart volume
- trabeculae carnae: irregular ridges of muscles on the interior surface
- papillary muscles: cone-like muscles which connect to the valves
- thickened walls because of the amount of work required to pump the blood greater distances
- when the ventricles contract, blood is forced into circulation
13
Q
- Right ventricle sends blood through….
2. Left ventricle sends blood through….
A
- the pulmonary trunk
- divides into the right and left pulmonary arteries
- blood goes to lungs - aorta
- largest artery of the body
- blood goes out to body tissues
14
Q
Pulmonary Circuit
A
- the right side of the heart collects O2-poor and CO2-rich blood from the body and pumps it to the lungs where CO2 is unloaded and O2 is picked up
15
Q
Systemic Circuit
A
- the left side of the heart collects O2-rich and-CO2 poor blood and pumps it to the arteries where it is transported to the body tissues
- in the body, O2 is dropped off and CO2 is picked up
16
Q
How the heart tissue gets nutrients
A
- the heart picks up almost no O2 or nutrients from the chambers of the heart, but has its own coronary circulation
- the right and left coronary arteries arise from the base of the aorta and encircle the heart in the atrioventricular groove
- — left –> anterior interventricular artery (LAD) and circumflex artery
- — right –> marginal artery and posterior interventricular artery
- considerable variation among people in the arterial blood supply of the heart
- many anastomoses among the arterial branches
- — a grid of arteries which allows for detours to be taken if an artery is blocked
17
Q
Cardiac Veins
A
- collect blood after it passes through the capillary beds of the myocardium
- Three large veins
- — great cardiac, middle cardiac, small cardiac
- — drain into the coronary sinus which empties into the right atrium
- several anterior cardiac veins also empty into the right atrium
18
Q
Myocardial Infarction
A
- heart attack
- — lack of blood flow to one area of the heart
- can be caused by an arterial blockage in the coronary circulation
- cell death due to oxygen deprivation results in tissue replacement with scar tissue
19
Q
Heart Valves
A
- two atrioventricular valves
- — tricuspid and mitral
- two semilunar valves
- — aortic and pulmonary
20
Q
Atrioventricular Valves
A
- regulate flow of blood between the atrium and the ventricle on the same side
- — tricuspid on the right
- — mitral/bicuspid on the left
- valve flaps are connected to papillary muscles by collagen cords called chordae tendinae
- when the ventricle contracts, the valve closes preventing backflow into the atrium
- — papillary muscles also contract preventing the flaps from going into the atrium
21
Q
Semilunar Valves
A
- prevent backflow of blood back into the ventricle
- — Aortic Valve: between the left ventricle and the aorta
- – Pulmonary Valve: between the right ventricle and pulmonary trunk
- when the ventricle contracts, the semilunar valve is forced open
- when the ventricle is relaxed, backpressure of the aorta/pulmonary trunk forces the semilunar valve closed
22
Q
Cardiac Muscle
A
- striated and contracts by sliding filaments
- — like skeletal muscle
- has only one or two centrally located nuclei
- a greater portion of the the cell is made up of mitochondria
- — heart relies almost exclusively on aerobic respiration
- — cardiac muscle cannot incur much oxygen debt
- intercalated discs
- gap junctions
23
Q
Intercalated discs
A
- found in the junctions of cardiac muscle cells
- contain anchoring desmosomes
- — prevent separation of cells during contraction
24
Q
Gap Junctions
A
- found in the junctions of cardiac muscle cells
- allow ions to pass from cell to cell
- — this electrical coupling allows the entire myocardium to act as a coordinated unit
25
Q
Intrinsic Caidiac Conduction System
A
- autorhythmic cells: non-contractile cardiac cells
- able to to initiate action potentials that spread throughout the heart
- note: the heart is well supplied with nerves which can alter the rhythm
26
Q
Sequence of Excitation
A
- Sinoatrial node
- Atrioventricular node
- Bundle of His
- Purkinje Fibers
- Ventricular Muscle Cells
27
Q
Sinoatrial Node
A
- located on the right atrial wall just inferior to the entrance of the superior vena cava
- heart’s pacemaker: determining the sinus rhythm
- — contain autorhythmic cells
- start the sequence of excitation
28
Q
Atrioventricular Node
A
- recieve impulse after the sinoatrial node
- — step 2 of excitation
- —a wave of depolarization spreads via gap junctions throughout the atrium to the AV node
- located on the inferior interatrial septum
- impulse is delayed, allowing the complete contraction of the atrium
29
Q
Bundle of His
A
- receive impulse after the atrioventricular node
- — step 3 of excitation
- located in the superior part of the interventricular septum
- this is the only electrical connection between the atria and the ventricles
- splits into right and left bundle branches that the impulse continues along
30
Q
Purkinje fibers
A
- receives the impulse from the branches of the Bundle of His
- — step 4 of excitation
- reach down to the apex and then into the ventricular walls
- —- walls: cell to cell transmission via gap junctions occurs between ventricular muscle cells
31
Q
Arrhythmias
A
- irregular atrial or ventricular contractions
32
Q
Fibrillation
A
- condition of rapid and irregular or out-of-phase contractions in which contractions are no longer controlled by the sinoatrial node
- an electrical shock to the heart may allow the sinoatrial node to regain control of rhythms
- — defibrillation
- — depolarizes the entire myocardium
33
Q
EKGs
A
- an electrocardiograph records electrical currents generated in the heart and spread through the heart and the body
- three distinguishable waves
- — small P wave
- — QRS complex
- — T wave
- the size, duration, and timing of the deflection waves tend to be consistent in a healthy heart so that changes in patterns may reveal disease or past damage
34
Q
P wave
A
- small
- depolarization wave from the sinoatrial node through the atria
35
Q
QRS complex
A
- results from ventricular depolarization and precedes ventricular contraction
- obscures a graphical recording on the EKG of atrial repolarization
- — bc atrial repolarization occurs at the same time as ventricular depolarization
36
Q
T wave
A
- caused by ventricular repolarization
37
Q
Normal Heart Sounds
A
- lub-dup sound is associated with closing of heart valves
- lub: when AV valves close
- — ventricles contract
- dup: when SL valves close
- — ventricles relax
38
Q
Murmur
A
- abnormal heart sounds
- one fairly common murmur occurs when the mitral valve fails to completely close
- — swishing sound as the the blood backflows into the left atrium
39
Q
Cardiac Cycle
A
- Ventricular Filling
- Ventricular Systole
- Isovolumetric Relaxation
- Quiescent Period
- — total heart relaxation
- — about half of the cardiac cycle
40
Q
Systole
A
contraction of chambers
41
Q
Diastole
A
relaxation of chambers
42
Q
Ventricular Filling
A
- step 1 of the cardiac cycle
- mid to late diastole
1. blood flows passively from the atria to the ventricles - — SL valves are closed
2. then, the atrial systole occurs - — P wave
- — forces the remaining atrial blood into the ventricles
3. atrial diastole occurs as the ventricles depolarize - — QRS complex
43
Q
Ventricular Systole
A
- step 2 of the cardiac cycle
1. ventricles contract - — AV valves are closed
- — SL valves are forced open
- — blood is forced into the aorta and pulmonary trunk
- — pressure in the aorta generally reaches 120mmHg
- atria are filling as the ventricles contract
44
Q
Isovolumetric Relaxation
A
- step 3 of the cardiac cycle
- early diastole
1. following ventricular repolarization, the ventricles relax
2. pressure in the aorta and pulmonary trunk causes a backflow resulting in the closure of the SL valves
3. atria started filling while the ventricles contracted - — when the blood pressure in the atria exceeds that in the ventricles ( the ventricles are relaxed and got rid of their blood), the AV valves are forced open
45
Q
Cardiac Output
A
- amount of blood pumped by each ventricle in one minute
- calculated by multiplying the heart rate (number of beats per minute) times the stroke volume (the volume of blood pumped out by one ventricle with each beat
- varies considerably in response to the oxygen demands of the body
46
Q
Extrinsic Factors which regulate heart rate
in addition to the intrinsic conduction system
A
- autonomic nervous system
- hormones
- — epinephrine and thyroxine
- — increase heart rate
- imbalance in ion concentrations
- age, body temp, gender, exercise
47
Q
Autonomic Nervous System Regulates Heart Rate
A
- parasympathetic: decrease heart rate
- sympathetic: increase heart rate
- — release norepinephrine
- — enhance Ca2+ entry into contractile cells
- under resting conditions, both division of the ANS send impulses to the SA node
- — this usually inhibits the heart rate
48
Q
Imbalance in Ion concentrations affect heart rate
A
- the relationship between intracellular and extracellular ions must be maintained in a certain balance
- hypocalcemia decreases heart rate
- hypercalcemia may result in too many contractions
- Too much Na+ and K+ may interfere with the transport of Ca2+ into the cardiac muscle cells
- the mode of action of many cardiac drugs involves the transport of calcium into cardiac cells
49
Q
Disorders:
- Tachycardia
- Bradycardia
A
- abnormally elevated heart rate
- — usually > 100 bpm - abnormally depressed heart rate
- — usually
50
Q
Congestive Heart Failure
A
- cardiac output is not enough to meet tissue needs
- damage to the myocardium may be done by coronary atherosclerosis, chronic hypertension, and multiple myocardial infarcts
51
Q
If the left side of heart fails…
A
- pulmonary congestion
- the right side continues to pump to the lungs –>
but the blood can’t properly enter and exit the left side on the way back from the lungs –>
so everything is backed up as it waits (congestion) –>
lung tissue may become engorged –>
forcing circulation fluid into the lung tissue –>
causing a pulmonary edema - diuretics are often given to treat edema
52
Q
If the right side of the heart fails…
A
- results in edema in the extremities
- blood cannot properly enter and exit the right side as it comes back from the body –> everything comes backed up as it waits (congestion) –> fluid is absorbed into the body tissue because it has to go somewhere –> edema of the extremities
- diuretics are often given to treat edema
