physio e3l5: cardiac function/electrical activity

1. 3 parts cardiovascular system

2. what is its function?

1. heart ,blood vessels, blood

2. transport of substances (O2, wastes, hormones, immune cells, clotting proteins)

heart structure:

1. 4 chambers

2. 4 valves

3. 2 septums

4. base and apex?

5. draw it

1. r atrium, l atrium, r ventricle, l ventricle

2. valves

   1. atrioventricular (AV) valves = r tricuspid, l bicuspid (mitral valve)

      1. middle level

   2. semilunar (SL) valves = r pulmonary and l aortic

      1. bottom level

3. base = inferior point of left ventricle, apex = broad superior/posterior surface

blood vessels:

1. closed system?

2. 5 vasculature levels in order/ what they are

3. why do arterioles have high resistance?

4. aorta = ?

1. starts and ends in heart

2. 5 blood vessels:

   1. heart → arteries = large branching vessels

   2. arterioles = small branching vessels

      1. high resistance

   3. capillaries = site of exchange

   4. venules = small converging vessels

   5. veins → heart = large converging vessels

3. high SA, low velocity

4. largest artery/first one out of heart

blood components:

1. erythrocytes RBCs

2. Leukocytes WBCs

3. thrombocytes Platelets

4. Plasma

5. which 3 are cellular components

1. transport

2. immunity

3. cell fragments that clot/hemostasis

4. fluid + solutes

5. first 3

path of blood through heart/vasculature:

1. 2 circuits = where start/end

   1. function?

2. where 2 main capillary beds

3. what kind of flow

1. circuits

   1. pulmonary = BVs from heart, through lungs, back to heart

      1. oxygenation of blood

   2. systemic = BVs from heart, through systemic tissues, back to heart + coronary circulation

      1. supply tissues w/ O2 and nutrients

2. lungs and tissue

series flow through cardiovascular system:

1. systemic circuit = start and end points? 5 steps?

2. pulmonary circuit = start and end points? 5 steps?

3. draw it

1. systemic = LV, aorta, tissue, vena cava, RA

2. pulmonary = RV, PA, alveoli, Pulmonary veins, LA

Oxygen exchange:

1. pulmonary capillaries = where?

   1. blood entering v. blood leaving

   2. what happened?

2. systemic capillaries

3. deoxygenated blood = ?

1. pulmonary capillary beds

   1. blood entering lungs = deoxygenated

   2. O2 diffuses alveoli → blood

   3. blood leaving lungs = oxygenated

2. systemic capillaries = pick up CO2 and release O2 in tissue

   1. Blood entering tissues = oxy

   2. O2 diffuses blood → tissues

   3. blood leaving tissues = deoxy

3. deoxygenated = less O2 not none

parallel flow in cardiovascular system:

1. what kind of flow/why important

2. which oxygenated/deoxygenated

   1. arteries

   2. arterioles

   3. capillaries

   4. venules

   5. veins

1. parallel flow allows independent regulation of blood flow to organs via dilation/constriction

2. which oxygenated/deoxygenated

   1. arteries = oxy

   2. arterioles = oxy

   3. capillaries = both

   4. venules = deoxy

   5. veins = deoxy

parallel flow in cardiovascular system:

1. portal circulation: what is it/3 locations?

   1. how unique?

2. coronary circulation

   1. coronary arteries = where

   2. blood path

   3. myocardia ischemia?

   4. myocardial infarction?

1. portal circulation = if 2 capillary beds

   1. hypothalamus/ant pit

   2. intestines/liver

   3. nephrons of kidney

2. portal circulation = series flow instead of just parallel

3. coronary circulation = heart’s independent blood supply

   1. coronary artery → arteriole → cap → venue → vein

   2. l and r coronary arteries arise from aorta

      1. doesn’t use what it pumps on inside

   3. myocardia ischemia = less blood in coronary art due to blockage… leads to

   4. myocardial infarction/heart attack = heart low O2 supply

pericardium:

1. what is it

2. 2 layers

3. pericardial cavity

4. pericardial fluid

5. pericarditis?

1. sac around heart

2. 2 layers w/ cavity in b/t

   1. visceral pericardium/epipericardium = on heart

   2. pericardial cavity = contains pericardial fluid

      1. decrease friction of heart movement in tight space

   3. parietal = away from heart

3. pericarditis = inflammation/infection of pericardium

3 layers of the heart wall:

1. epicardium

2. myocardium

   1. left v right

3. endothelium

1. epicardium= external membrane

2. myocardium = middle, cardiac muscle, action

   1. left is thicker/stronger

3. endothelium = inner layer of endothelial cells

heart valves:

1. what do they do

2. what determines if they open

3. 2 things heart chamber pressure dependent on

4. normal direction of flow

1. directional, prevent blood back flow

2. open/close based on pressure gradient: high → low

3. amount of blood in chamber/ if muscle contracting

4. clockwise = atria to ventricle, ventricle to arteries

atrioventrical AV valve:

1. chord tendinae/papillary muscle = what do they do and how

2. why unidirectional

SL valves:

1. why unidirectional?

1. keep AV valves from everting

   1. Contraction of papillary muscles tightens chord tendinae and prevent valve cusps from being pushed into atria

2. ventricle relaxed v contracted

   1. ventricle relaxed = AV valve open = blood flows

   2. ventricle contracted = pap muscle contracted = AV valve closed

1, unidirectional bc of valve curvature

1. electrical activity of the heart leads to

1. mechanical activity

conduction system of heart:

1. autorhythmic? how?

2. autorhytmic cells

3. myogenic

4. 2 parts conduction system

1. heart is autorhythmic = generates own rhythm

   1. pacemaker cells

2. spread excitation throughout heart

3. myogenic = heart muscle myocardia contracts w/o NS input

4. conduction system = pacemaker cells and conduction fibers

conduction system of the heart:

1. pace maker cells/pacemaker potentials

   1. what are they why important

2. 2 places they are located/what

1. pacemaker cells have pacemaker potentials that

   1. spontaneous APs

   2. provide heart rhythm

2. myocardium

   1. sinoatrial AV node = myocardium pacemaker cells = pacemaker of the heart, the source

   2. AV node = myocardium pacemaker = secondary, picks up what’s coming from AV node

conduction system of heart:

1. why is it important

2. 3 step process of conducting APs

3. auto rhythmic cells

   1. 2 types

4. conduction fibers

   1. speed compared to other muscle fibers

5. contractile cells/myocardium

   1. 2 types

1. electrical activity of the heart is what leads to mechanical activity

2. autorhythmic cells generate AP → conduction fibers pass on APs → contractile cells/myocardium

1. autorhythmic cells = have pacemaker cells/generate pacemaker potentials, pacemakers of the heart

   1. SA node (SAN) = source, main pacemaker

   2. AV node (AVN) = secondary

2. conduction fibers = conduct APs to contractile cells/myocardium

   1. much faster 4m/s v .4m/s

3. contractile cells/myocardium

   1. Ventricle

   2. atrium

conduction system of heart:

1. which auto rhythmic cells Firing rate at rest is fastest:

2. why is that important?

3. cardiac cells linked by

1. SA node 70-80 AP/min = pacemaker bc faster depolarizing than all the other auto rhythmic cells

   1. SA node = main node, reason why resting heart rate is 70-80 bpm**

2. gap junctions

conduction system of the heart:

1. how does excitation b/T cells spread

2. how is that coordinated

3. intercalated disks?

   1. 2 parts

1. atria contract → ventricle contract

2. contracting order coordinated by gap junctions and conduction pathways

3. intercalated disks = junctions that connect cardiac muscle

   1. desmosomes = resist mechanical stress breaking electrical connection

   2. gap junctions for electrical coupling

Cardiac System Flow 8 steps:

1. Blue

   1. deox blood from tissue → RA

      1. superior vena cava = blood from waist up

      2. inferior vena cava = waist down

   2. RA pumps deox blood → RV

      1. through tricuspid valve

   3. RV pumps deox blood → pulmonary artery

      1. through pulmonary valve

2. pulmonary artery (deoxy) → Lungs → pulmonary vein (oxy)

3. Red

1. oxy blood pulmonary vein → LA

2. LA pumps oxy blood → LV

   1. through bicuspid/mitral valve

3. LV pumps oxy blood → tissue

   1. through aortic valve into aorta

1. which side of heart stronger

2. pulmonary vein and pulmonary artery

3. atrium or ventricle stronger

4. function of the septum

5. ventricle and atrium opposite functions

6. passive filling vs active filling

1. left side = left bc pumping to tissue

2. opposite to normal. pulmonary artery = deox

3. ventricle bc pumping out

4. separate oxy from deox blood

5. when one contracts the other relaxes

6. passive filling = atrium → ventricle just bc valve opened, most blood

7. active filling = atrium → ventricle contraction gets remaining out

AP plot for auto rhythmic vs contractile cells of heart:

1. auto rhythmic cell

   1. what are they, resting membrane potential

   2. 4 phases of the plot/ why does it look like that?

2. contractile cells 6 phases

draw it

1. auto rhythmic cell = ASAN and AVN

   1. Phase 4 =RMP -60 not static, depol start Na+ enters in ‘funny channels’

      1. funny bc always open even at low voltage

   2. Phase 0 = Ca+ enters L-Ca (lung) channels open

      1. AP climbs

   3. apex of AP = L-Ca+ close

   4. phase 3 = K+ leaves via K+ channels

   5. phase 4 = back at RMP

AP plot for contractile cells:

1. 6 phases

1. contractile cell = ventricles and atriums

   1. Phase 4 = RMP -90

   2. Phase 0 = Na+ influx

   3. Phase 1 = apex, Na+ influx closes, K+ leaves

   4. phase 2/plateu phase = K+ leaves, but Ca+ enters

      1. plateau bc Ca+ enters

   5. end of phase 2 = Ca+ closes

   6. phase 3 = K+ leaves

   7. Phase 4 = RMP again

1. Path of electrical activity in the heart

2. mechanical action

3. EKG

1. SAN (on RA) fires AP → spreads to both atrium

   1. reaches LA via Bachman’s fibers

2. AVN receives AP from SAN → slow, pauses

   1. make sure blood reaches ventricle first

3. AVN fires → bundle of His → left and right bundle branches → purkinje fibers that go throughout muscle of ventricle

6 EKG regions? what’s missing/why?

1. P wave = atrial contraction/depol

2. P-R flat region = AVN pause

3. QRS = ventricular contraction/depol in front bottom back order

4. T wave = ventricular relaxation/repol

5. ST segment = phase 2/plateau of contractile muscles

6. sometimes U wave = remnants of t wave

1. wave for atrial relaxation not shown bc it has low voltage masked by high voltage QRS

   1. QRS represents ventricular contraction ONLY

heart leads (what they stick on your skin during EKG)

1. 3 leads

2. where are they

3. what part of heart do they look at

1. Lead 1= comes from right arm → left arm

   1. looks at LA

2. Lead 2 = comes from right arm → left leg

   1. looks at RV

3. Lead 3 = left arm → left leg

   1. looks at LV

cardiac arrhythmia:

1. what is it

2. sinus rhythm

3. tachycardia

4. bradycardia

5. how fix?

6. 
   

1. abnormal electrical activity

2. sinus rhythm = pace generated by SAN

3. tachycardia = fast rhythm >100bpm

4. bradycardia = slow rhythm <50bpm

5. shock the patient to reset SAN

cardiac arrythmia:

1. first degree heart block

1. what does it do to ekg

1. second degree heart block

   1. what does it do to ekg

2. third degree heart block

3. extra contraction, 2 types

1. slowed/diminished AVN conduction

   1. increases PR segment (PQ interval) = increases pause b/t atrial and vent contraction

2. sometimes lack AVN conduction

   1. lose 1-to-1 relationship b/t p wave and QRS bc QRS caused by AVN

   2. not a QRS after every p wave

3. loss of AVN conduction

   1. p wave independent of QRS, can be fatal

   2. SAN 70-80bpm, AVN 30-40bpm

4. extra contraction= normal

   1. premature atrial contraction PAC → extra vent contraction = extra systole

   2. PVC → independent of atrial contraction = extra systole

cardiac arrhythmia:

1. fibrilation

2. atrial fibrilation (A-FIB)

   1. how serious

3. ventricular fibrillation (V-FIB)

   1. how serious

4. how correct both?

1. fibrilation = loss of heart electrical coordination

2. atrial fibrilation (A-FIB) = A pumping too fast, inefficient pumping to ventricle

   1. increase stroke / HA risk

3. ventricular fibrillation (V-FIB) = tissue not getting O2

   1. death in minutes

4. AED shock