Lecture 7 - Heart

Question 1

Where does the heart sit in the body?

Answer 1

Chest
NOT directly on the midline
slightly rotated
most obvious part=ventricles
Heart of Males and Immature Females is at Nipple level

Base=area where heart is attached to the rest of the body=”anchoring point”=where vessels enter/exit
Apex=pointy part of LV
=point INferiorly(down), ANTeriorly(forward), to the LEFT

2/3 of mass lies to the LEFT of the midline, slightly Rotated
1/3 of mass lies to right of midline

Question 2

How is the heart orientated relative to the midline?

Answer 2

2/3 of the heart is on the LEFT of the midline (sqewd to the left), and is SLIGHTLY ROTATED

1/3 of the heart is on the right if the midline

Question 3

How is the heart protected?

Answer 3

most of the heart is protected by the Sternum

the Left Ventricle (LV) ISNT protected by the sternum

Question 4

What are the borders of the heart?

Answer 4

RIGHT border is formed mainly by the R.Atrium

INFERIOR border is formed mainly by the R.Ventricle

LEFT border is formed mainly by the L.Ventricle

Question 5

What is the Base and Apex of the heart?

Answer 5

Base=TOP=area where the heart is attached to the rest of the body
=attachment/entry and exit point
=ANCHORING point

Apex=BOTTOM

Heart sits free to move/unattached other than at the base

Question 6

Why are the borders of the heart important?

Answer 6

Cadaver= brown skin with not alot of colour

Chest X-rays

when the shape changes, you can see what part of the heart is causing the problem

Question 7

What is the Diaphragm?

Answer 7

Boundary between the Abdomen and Thorax

Question 8

What is Cardiohypertrophy?

Answer 8

Enlarged
Boot shaped heart
(bulging out LV
Deformed RA)

x-ray shows Cardio-throacic ratio is LArger than normal (greater than 50% of rib-to-rib line)

aortic stenosis (narrowing due to rheumatic fever) causes cardiohypertrophy= LV becomes even thicker and ore muscular to compensate the decreased integrity of the valve opening (due to lumpy/vegetation/scar tissue formation) =pressure

LV wall significantly thicker but LUMEN TINY
=less space to fill

heart struggles to INFLATE=doesn’t pump as well
Decrease in Flexibility (LOSS of COMPLIANCE)=harder to fill
cardiac OUTPUT DROPS=(GREATER AFTERLOAD)
So large that they OUTSTRIP ability to SUPPLY OXYGEN to all the LV muscle cells= fail

Question 9

What do Radiographers look out for?

Answer 9

Cardiac Thoracic ratio

Line from Rib to Rib
Heart should be LESS than 50% between the two lines

too big=heart occupies and area greater than 50% of the Rib-to-Rib line

Question 10

What is composed of alot of collagen?

Answer 10

Valve leaflets

the mass of collagen in Valve Leaflets contributes to them being Tough but Flexible

Question 11

What is Aortic Stenosis?

Answer 11

Narrowing
Stiffer Outlet
often due to Rheumatic Fever=STREPTOCOCCUS infection
body produces antibodies(immune system) which attacks your own bodily CT tissue (endocardium,myocardium and pericardium)
tends to attack collagen heavy tissues especially=valve leaflets (e.g aortic valve)

Able to Rebuild, but doesn’t rebuild as well=
scar tissue + vegetation + lumps on valve flaps form
= different efficiency in function
=RUINS INTEGRITY of the valve flaps

Narrower and Stiffer outlet RESTRICTS blood flow, as the L.V. has to Squeeze/WORK HARDER and become MORE MUSCULAR, undergoing hypertrophy to compensate and get the blood UP through the NARROW HOLE
(muscle which works harder builds muscle)

LV wall significantly thicker but LUMEN TINY
=less space to fill

heart struggles to INFLATE=doesn’t pump as well
Decrease in Flexibility (LOSS of COMPLIANCE)=harder to fill
cardiac OUTPUT DROPS=(GREATER AFTERLOAD)
So large that they OUTSTRIP ability to SUPPLY OXYGEN to all the LV muscle cells= fail

Question 12

What is the Pericardium?

Answer 12

the Bag the Heart sits in
what you see when the rib cage is first opened

“a continuous layer of PARIETAL and VISCERAL Pericardium which SURROUNDS and PROTECTS the heart”

most of the Pericardium is serous membrane/mesothelial cells

Question 13

How fast does your heart beat?

Answer 13

50-80 times per minute

dependant on health status

Question 14

What are the surrounding structures of the heart?

Answer 14

Lungs either side
infront = Sternum
behind= Boney rod= Vertebral Column

Heart and lungs both move upon breath
Heart will rub up against its neighbours

Question 15

What is the universal method that the body uses to deal with friction?

Answer 15

2x Serous membranes with serous liquid between them

Thin, Transparent, really slippery when wet

Question 16

What is a serous membrane?

Answer 16

Thin= simple=single layer
flattened cells (squamos)
attached to each other
forms a continuous sheet
secretes serous fluid
"Mesothelial cells"

MESOthelial cells are similar to epithelial cells but are found INSIDE your body

ORGANS which are INSIDE your body (not gut lining as that is Epithelial cells) typically have mesothelium/serous membrane around them

= great at reducing friction

Question 17

What is the Visceral Pericardium?

Answer 17

the VISCERAL pericardium is the INNER walls of the serous membrane of the heart (pericardium) which ADHERES to the heart’s outer surface (EPIcardium)

“viscera”=organ=”belongs to the organ”

Question 18

What is the name of the heart’s Outer surface?

Answer 18

EPIcardium

Question 19

What is the Parietal Pericardium?

Answer 19

the PARIETAL pericardium is (away from organ) the OUTER wall of the heart’s serous membrane (pericardium) which LINES a TOUGH FIBROUS SAC called the FIBROUS PERICARDIUM -DENSE IRregular

Question 20

What is the Fibrous Pericardium?

Answer 20

the TOUGH fibrous SAC (on the outside of the heart)
LINED with PARIETAL Pericardium

“outer layer of collagenous tissue”
more of a PROTECTIVE layer, rather than a lubricating layer

FIBRES/COLLAGEN can RESIST TENSION
DENSE IRRegular CT

Question 21

What is the Pericardial Space?

Answer 21

capillary thin space
contains serous fluid
“pericardinal space is a very thin film of fluid”
=contains only fluid, not the heart=IMPORTANT

REDUCES friction
acts as a LUBRICANT to PREVENT HEAT from rubbing against the THORACIC CAVITY with friction, as the heart beats

surrounded by the inner and outer wall of the Pericardium/Serous membranes, which is comprised by a singe layer of squamous mesothelial cells which SECRETE serous fluid

Question 22

What is inside the Peritoneal cavity?

Answer 22

*Exam question

fluid
no organs inside the peritoneal cavity

Question 23

What is the distribution in the heart wall?

Answer 23

composed of 3x layers “fist against water filled balloon”

Thin Inner layer=Lumen=ENDOcardium

Thick Middle layer =MYOcardium(muscle)

Very Thin Outer layer =EPIcardium (epi=outside)=Visceral pericardium

Question 24

What types of layers are there in the heart?

Answer 24

PROTECTIVE layer and LUBRICATING layer(s)

PROTECTIVE layer=FIBROUS pericardial sac

LUBRICATING layer(s)=Visceral and Parietal Pericardium(s)

Question 25

What is the Fibrous Skeleton of the Heart?

Answer 25

DENSE CT rings Coarse fibres purpose: 1. STRENGTHEN HOLES/valves (inlet/outlets) 2. ELECTRICAL INSULATOR b/w atria/ventricles (nerve impulses cannot pass through) 3. PREVENT OVER-STRETCHING of valves inlet/outlet valves form a continuous line/plateau across the heart openings=weakened area = b/w Thin-walled Atria and Thick-walled Ventricle Want to be strong as valve leaflets are attached to here Stops the distortion of valve leaflets, which otherwise would compromise valve Mitral Inlet and Aortic Outlet valves are HIGH PRESSURE valves and have FULL SKELETAL RINGS to Prevent Stretching TRIcuspid Inlet has a PARTIAL ring and the PULMONARY valve has NO ring. instead the Tricuspid and Pulmonary valves have LOOSE Fibres and FATTY tissue (not a true fibrous ring)

Question 26

What is Cardiac Tamponade?

Answer 26

During a MYOCARDIAL INFARCTION "dying of the muscles of the heart" (heart attack) part of your heart muscle dies (tissue INFARKTs) (not enough blood supply/oxygen) Infections causes puss and fluid to enter the Pericardium = PERICARDITIS = inflammation Although macrophages clean up dead tissue and our line area becomes replaced with scar tissue, which makes it THIN and WEAKER the High PRESSURE of LEFT.V, blood can move out through weakened area and blood moves into the Pericardial Space as L.V. RUPTURES Every time the LV contracts, blood squirts into the Pericardial Space (affecting the hearts ability to fill every beat) FIBROUS Pericardium is quite RIGID, so instead of the bag (pericardium) EXPANDING (due to the COLLAGEN which RESISTS TENSION), the heart will be SQUEEZED SMALLER and smaller, due to the ACCUMULATION of blood in the pericardial space Causes: 1. COMPRESSING of the heart 2. Ventricular FILLING DECREASED 3. CARDIAC OUTPUT Decreased 4. VENOUS RETURN to heart Diminishes 5. Blood PRESSURE FALLS 6. BREATHING Difficulty

Question 27

What is a heart attack called?

Answer 27

Myocardial Infarction | "dying of the muscle of the heart"

Question 28

What does infarkt mean?

Answer 28

tissue dying

Question 29

What is an infection of the heart called?

Answer 29

Puss and fluid enter the Pericardial Space Pericarditis "inflammation of the heart"

Question 30

What is the Conduction System of the heart?

Answer 30

The method by which the HEART BEATS are INITIATED and he method by which the heart is ELECTRICALLY STIMULATED No in-built nerves within its muscle fibres ONLY INFLUENCED by nerves Instead has highly modified cardiac muscle fibres

Question 31

What is special about cardiac muscle fibres?

Answer 31

designed to conduct nerve impulses AUTO-rhythmic fibres SELF-Excitable = can repeatedly Generate ACTION POTENTIALS triggering heart contraction allows for a WAVE of EXCITATION -but still Weakly Contractile UNLIKE nerve fibres

Question 32

What is the function of a Pacemaker?

Answer 32

sets the RHYTHM of electrical excitation --> contraction in the SinoAtrial Node (SA)

Question 33

What is the function of the Cardiac Conduction System?

Answer 33

Cardiac Conduction System is a network of Specialised cardiac muscle fibres that PROVIDE PATH for each cycle of Cardiac Excitation to pass through the heart

Question 34

What are the differences between Myocytes and Purkinje Cells?

Answer 34

Myocytes in the Atria Purkinje Cells in the Ventricles Purkinje cells are LARGER and WIDER than cardiac myocytes (Larger=good WIRING for the heart) Purkinje cells DONT BRANCH and DONT CONDUCT action potentials well Purkinje cells are WEAKLY CONTRACTILE are the "WIRING of the heart"

Question 35

What is the overall pathway in the conduction system?

Answer 35

1. SA node/Atrial Muscle 2. AV Node 3. AV bundle/Purkinje cells

Question 36

What is the overall transitions in speed of conduction during the conduction pathway? What does each step result in?

Answer 36

``` 1. slow=0.5m/s Atrial contraction (Uniformly) ``` 2. very slow=0.05m/s 100m/s delay Smaller Diameter between junctions 3. fast=5m/s Even, Rapid Ventricular Contraction = SYSTOLE

Question 37

What is the First step in the Propagation of Cardiac Action Potentials?

Answer 37

A. Cardiac excitation BEGINS at the SA NODE (SLOW) 1. SA node (collection of specialised cardiac muscle fibres) depolarises to threshold spontaneously via the Pacemaker Potential 2. AP is fired 3. each AP from the SA Node PROPOGATES through BOTH of the ATRIAs via GAP JUNCTIONS in the INTERCALATED DISCS of atrial muscle fibres (MYOCYTES) 4. following the AP, the TWO ATRIAS CONTRACT at the SAME TIME

Question 38

What is the SA node?

Answer 38

Sino-Atrial Node a KNOT of cardiac muscle fibres which have an UNSTABLE RESTING POTENTIAL so it DEPOLARISES to threshold SPONTANEOUSLY (intrinsic ability to generate activity) via the Pacemaker Potential spontaneously depolarises and repolarises 60-100x per minute (own internal clock) SA node is the MOST RAPID

Question 39

What does Spontaneous Depolarisation?

Answer 39

INTRINSIC ability to generate activity

Question 40

What is the AV Node?

Answer 40

Atrio-Ventricular Node "CLUSTER of fibres with its own AUTO-Rhytmicity, located at the TOP of the inter-atrial septum which forms a HOLE through the FIBROUS SKELETON so most of the AP STOPS but the rest GOES THROUGH the hole" rapid contraction "Fast STIMULATING HIGHWAY" Only electrical link between the Atrium and Ventricle HOLE in the Fibrous skeleton VERY GOOD INSULATOR TOP of the INTRA-VENTRICULAR SEPTUM (wall between ventricles) Allows Excitation to pass through it

Question 41

What is the Wall between Ventricles called?

Answer 41

Intra-Ventricular Septum | Allows Electrical Stimuli to pass through it

Question 42

What is the Second step in the Propagation of Cardiac Action Potentials?

Answer 42

B. Action Potential reaches the AV Node (VERY SLOW) 1. AV Node Hole in the FIBROUS SKELETON causes most of the AP to STOP, with the Rest GOING THROUGH the hole (hits fibrous skeleton and mostly stops) 2. AP Considerably SLOWS, due to the DIFFERENCE in CELL STRUCTURE and results in a 100ms DELAY BETWEEN the ATRIA and VENTRICLES contracting 3. the delay provides time for the Atria to EMPTY BLOOD into the Ventricles

Question 43

What is the Third Step in the Propagation of Cardiac Action Potential?

Answer 43

C. From AV Node, AP reaches the BUNDLE of HIS (FAST) 1. electrical impulses pass through here as it provides ELECTRICAL LINK between the Atria and Ventricles 2. is the only site where AP ___propogate?____ without being insulated by the fibrous skeleton

Question 44

What is the Bundle of His?

Answer 44

Electrical Link between the Atria and Ventricles

Question 45

What is the Fourth Step in the Propagation of Cardiac Action Potential?

Answer 45

D. AP enters BOTH the Right and Left BUNDLE Branches 1. AP extends through the Inter-ventricular septum and towards the APEX of the Heart

Question 46

What is the Fifth step in the Propagation of Cardiac Action Potentials?

Answer 46

E. AP conducts through the Purkinje Fibres 1. the LARGE DIAMETER of Purkinje Fibres RAPIDLY CONDUCTS the AP from the APEX UPWARDS to the REMAINDER of the Ventricular Myocardium 2. VENTRICLES CONTRACT (both sides of the ventricular muscles SQUEEZE SIMULTANEOUSLY) "Main event!" 3. EVEN Ventricular CONTRACTION 4. Pushes blood towards the SEMI-LUNAR VALVES

Question 47

What would a typical cardiac muscle fibre look like?

Answer 47

Branching Fibres Intercalated Discs Contractile

Question 48

At what speed will the SA node initiate an AP?

Answer 48

90-100 times/min the SinoAtrial Node will initiate an ActionPotential

Question 49

What happens if the SinoAtrial Node becomes diseased or damaged?

Answer 49

the CONDUCTION is blocked AV Node can pick up the PACEMAKER TASK will have a different intrinsic rate (slower) 40-60 time/min via Spontaneous Depolarisation or a Pacemaker can be Installed

Question 50

How is the rate of spontaneous depolarisation and repolarisation of cardiac fibres Influenced?

Answer 50

by HORMONES and by NERVES (Vagus Nerve in particular)

Question 51

What does the Propagation of Cardiac Action Potentials result in?

Answer 51

EVEN contraction of ventricular walls (SYSTOLE)

Question 52

What is Systole? Why is it needed?

Answer 52

refers to when things are CONTRACTING e.g. the even contraction of the Ventricular Walls in isovolumetric ventricular contraction Ventricle will only fill up until 80% of its volume PASSIVELY so it requires the ATRIA to CONTRACT AHEAD of it, in order to squeeze in the las 20% of blood REMAINING in the atria BEFORE it CONTRACTS ITSELF

Question 53

What does the Ventricular Filling stage in the Cardiac Cycle consist of?

Answer 53

LONGEST phase (HALF the cycle) SHORTENS FASTEST than other phases during EXERCISE (Influenced the most) Resting --> diastole Little bit of reserve present if you have a healthy heart 1. RELAXED heart wall. PRESSURE of VENTRICLE drops BELOW pressure of the Atria 2. Mitral Valve OPENS quietly as blood travels from HP-->LP i.e. Atria(high/80mmHG) --> Ventricle(less than 5mmHG) (Needs a Pressure Gradient) 3. Ventricle PASSIVELY (from left over pressure) fills to 80% of total capacity

Question 54

What does the Atrial Contraction stage in the Cardiac Cycle consist of?

Answer 54

"topping up" 1. SA Node DEPOLARISES 2. Atria CONTRACTS and completes the LAST 20% FILLING of the atrium (pressure increase) 3. Lasts about 0.2 sec 4. AV node has a 0.1 sec DELAY Small rise in atrial pressure Atria is a poor pump as a. Atria has a THIN muscle wall b. NO INLET valves - some of the blood goes into the VEINS as there is NOTHING to Prevent Backflow of blood

Question 55

Is the Atria a good or bad pump? Why?

Answer 55

Poor pump only small rise in atrial pressure 1. THIN atrial wall 2. NO INLET Valves therefore some of the blood goes back into he veins as there is NOTHING TO PREVENT Backflow back into Veins

Question 56

What does the Isovolumentric Ventricular Contraction Stage in the Cardiac Cycle consist of?

Answer 56

Isovolumentric Ventricular Contraction = SYSTOLE 1. Ventricles Contract (INCREASE in PRESSURE) and a (Decrease in Volume) 2. will slowly start to EXCEEDS Atrial Pressure 3. Blood TRIES to flow back into the atria but this causes blood to ABRUPTLY STOP as the VALVES CLOSE 4. closing of valves causes TURBULENCE and therefore the FIRST HEART SOUND (LUB) deeper and at the BEGINNING 5. at this brief period (0.05sec), Ventricular pressure is STILL BELOW arterial pressure so the OV(Aortic valve) closes. Both valves are closed = ISOvolumentric = fluid volume cannot change Atrial.P.

Question 57

What are the differences between the Right and Left sides of the heart during the Cardiac Cycle?

Answer 57

Right side has LOWER PRESSURE but the Volume is the Same/Beat

Question 58

What is another name for systole?

Answer 58

ISOVolumentric VENTRICULAR Contraction systole refers to when things are Contracting

Question 59

What does the Ventricular Ejection stage in the Cardiac Cycle consist of?

Answer 59

systole continues 1. Ventricular Pressure EXCEEDS AORTIC pressure 2. Aortic Valves/outlet OPEN quietly 3. Blood LEAVES to the Ventricle (70ml into the aorta) 4. Aorta/Elastic Artery Expands 5. blood is EJECTED into the AORTA FASTER THAN is can RUN-OFF into Distributing Arteries 6. Pressure in Ventricles and Aorta RISE STEEPLY 7. Later in the phase rate of EJECTION FALLS BELOW rate of run-off 8. Aortic and ventricular pressures LEVEL OFF and Begin too DECREASE (runs out of strength)

Question 60

What does the Isovolumetric Ventricular Relaxation Stage in the Cardiac Cycle consist of?

Answer 60

Short --> 0.05s repolarisation/rest phase 1. Limit of contraction so VENTRICLE RELAXES, walls move outwards (INCREASE VOLUME) and a (Decrease in Pressure). inflation of outlet valves 2. HIGH Pressure blood just got EJECTED into the ARTERY 3. Flow tries to reverse but the AORTIC VALVE CLOSES (the Cusps of the Ventricular Valves come together) 4. Blood comes to an ABRUPT STOP. 5. TURBULENCE occurs due to stopped blood, and results in Second heart beat (DUB) 6. MITRAL Valve CLOSES due to Atrial.P.

Question 61

What are the names of the phases of the Cardiac Cycle?

Answer 61

5 phases to the Cardiac Cycle 1. Ventricular Filling 2. Atrial Contraction 3. Isovolumetric Ventricular Contraction 4. Ventricular Ejection 5. Isovolumetric Ventricular Relaxation Doesn't matter where you start as it is a Cycle

Question 62

How long does the Cardiac Cycle take to complete?

Answer 62

1 sec

Question 63

What does x symbolise in the cardiac cycle?

Answer 63

contraction

Question 64

What does . symbolise in the cardiac cycle?

Answer 64

pressure

Question 65

Which phase in the cardiac cycle is the longest?

Answer 65

Step 1. : Ventricular Filling Most affected by exercise (shortens the most) acts as a reserve if require to eat into its time in the cycle

Question 66

What is Atrial Fibrillation?

Answer 66

CAN live with this fine Chamber DOESNT UNIFORMLY contract Heart quivers/FLUTTERS(non-rhythmic/non-cyclic contraction) due to the effect of OVERWHELMING IMPULSES that s____ from and to other organs NOT a rhythmic contraction Atrium cant Squeeze Lots of people live with this, especially as they get older, live fine 1. extra 20% is Not Nescessary 2. Blood POOLS in the ATRIA 3. Blood Clot may form

Question 67

What is Ventricular Fibrillation?

Answer 67

CANNOT live with this fine INSUFFICIENT CO (Cardiac Output) 1. UNCONSCIOUS 2. can die Defibrillator = Stops Fibrillation 1. Zaps heart with a LARGE ELECTRICAL CHARGE 2. DEPOLARIZES EVERYTHING 3. chance for the first cells (SA NODE) which will REpolarise again to TAKE OVER normal Pacemaker Function of the Heart and restart the Heart Beat Purpose: QUIETEN down the RANDOM INTERFERING SIGNALS in the heart which are INTERFERING with its normal RHYTHM and to REBOOT the heart via letting the SA Node TAKE OVER the PACEMAKER function Sinus Rhythm

Question 68

What is Sinus Rhythm?

Answer 68

normal heart beat, referring to BOTH the heart RATE and heart RHYTHM

Question 69

What is the Defibrillator?

Answer 69

Zaps the Heart with a LARGE ELECTRICAL CHARGE DEPOLARISES the entire heart Purpose: to QUIETEN down the heart's RANDOM SIGNALS which INTERFERE with RHYTHM. It REBOOTS the heart, and lets the SA NODE take over the role of the PACEMAKER

Question 70

Which heart beat is the deeper one?

Answer 70

LUB | the first heart beat

Question 71

What does Isovolumetric mean?

Answer 71

Same volume due to both the inlet and outlet valve being closed therefore total volume cannot change DUE to the PRESSURE of the VENTRICLE being INBETWEEN atrial and arterial pressures is WHILE the Ventricle is Contracting word which follows (contraction/relaxation) describes pressure change

Question 72

What is the duration of systole?

Answer 72

Atrial systole + ventricular systole | Atrial Contraction + Isovolumetric Ventricular Contraction + Ventricular Contraction

Question 73

What is the change in pressure on the left side of the heart?

Answer 73

120mmHg - 0mmHg

Question 74

What is the change in pressure on the right side of the heart?

Answer 74

25mmHg - 0mmHg

Question 75

What is the maximum volume of blood in one side of the heart?

Answer 75

120 mL

Question 76

What is the minimum volume of blood in one side of the heart?

Answer 76

60 mL (can only squeeze out about half of total volume) can change, depending on your demand

Question 77

When does Diastole occur?

Answer 77

1. Ventricular Filling | 5. Isovolumetric Ventricular Relaxation

Question 78

Why does the aortic pressure drop during ventricular filling and atrial contraction?

Answer 78

As blood is being drained out to vascular tree into the systemic circuit

Question 79

What is responsible for initiating contraction?

Answer 79

SA Node

Question 80

What happens to atrial pressure during atrial contraction?

Answer 80

A small increase in pressure is quite pathetic, this shows that the atrial muscular wall isn't strong enough to generate significant movement this is only "topping up" however don't need it to survive, many people live without functioning atria

Question 81

What changes almost instantaneously with ventricular contraction?

Answer 81

Increase in ventricular pressure closes inlet valve =SIMULTANEOUS increase in Ventricular PRESSURE = first HeartBeat= LUB step increase but remains "middle" pressure throughout isovolumetric ventricular contraction ventricular volume only starts decreasing during ventricular ejection. v.VOL remains SAME as is during ISOvolumetric ventricular contraction

Question 82

What occurs to pressures during ventricular ejection?

Answer 82

both the pressure of the Aorta and Ventricle increase simultaneously "in communication" Ventricular pressure still remains higher than Aortic Pressure. whilst Left Atrium remains very low

Question 83

What is special about the rate blood is squeezed out of the Ventricle during Ventricular Ejection?

Answer 83

rate CHANGES THROUGHOUT this phase starts rapid rate slows down Ventricles run out of their ability to SHORTEN FIBRES blood is still flowing from ventricle-->artery throughout the whole phase still reflects in pressure

Question 84

What happens almost immediately when the heart relaxes/stops contracting?

Answer 84

decrease in pressure (most significantly the ventricular pressure)

Question 85

What physically makes the heart beat sound?

Answer 85

NOT the leaflets the leaflets are SOFT and PLIABLE is actually the ABRUPT STOPPING of blood blood TRIES to come BACK down, the valve LEAFLETS CLOSE causing the blood comes to a SHUDDERING stop and causes the WALLS of the heart to VIBRATE (TURBULENCE) creating the HEART BEAT SOUND

Question 86

What does the pressure spike represent?

Answer 86

The blood BOUNCING as it comes to a SHUDDERING HALT | SECOND H.B.

Question 87

Why are heart sounds LUB DUB?

Answer 87

1st heart sound is meant to be LOW FREQ. as the IN-let valve is a BIG HOLE with BIG FLAPS has a DEEPER, more RESONANT sound 2nd heart sound is meant to be HIGH FREQ. as the OUT-let valve is a SMALL HOLE/AREA with SMALL LEAFLETS resulting in a HIGHER PITCH sound slightly SPLIT

Question 88

What is special about one of the heart sounds?

Answer 88

The SECOND heart beat is SLIGHTLY SPLIT 1. aortic 2. pulmonary the AORTIC valve is CLOSING just BEFORE the Pulmonary Valve these two ventricles are squeezing side by side, but the AORTIC ARTERY has a Higher PRESSURE (120mmHg : 25mmHg) The elastic recoil of the aorta pushes the blood down faster as it higher pressure, and therefore closes the aortic valve just marginally before the pulmonary valve

Question 89

Why is there an increase in atrial pressure during isovolumetric ventricular relaxation?

Answer 89

Blood POOLING in the atrium while it CANT get into the ventricle = doing its job and acting as a RESERVOIR

Question 90

When a doctor takes your blood pressure, what are they actually measuring?

Answer 90

The Pressure RANGE in your BRACHIAL ARTERY in your arm previously: stethoscope and sphygmomanometer measure PEAK PRESSURE 120/80 P.P/Minimal Pressure Minimal pressure= how low the pressure in the artery is allowed to drop down to (healthy is about 80) Females are a little lower 115/75 stays around about that