Biomed Cardiovascular system ( PART 1)

First set of flashcards

What is the cardiovascular system?

What is the function of the cardiovascular system?

The cardiovascular system is a closed system of the heart and blood vessels.

heart to vessels - vessels circulate blood to all the body/cells

Functions: transport O2, Delivers Hormones & nutrients, Removes co2 - cells in body

Anatomy of the Heart

The location and layers of the Heart

Pericardium

Epicardium

Myocardium

Endocardium

Location b/t the lungs and behind the sternum

Pericardium - outer membraneous sac w/lubricating fluid (Pericardial Effusion=Cardiac tamponade)

Epicardium - outside layer of connective tissue on the surface of the heart

Myocardium - the heart muscle with tight interconnective cells of cardiac muscle tissue (muscle don’t want hypertrophy)

Endocardium - the inner epithelial and connective tissue lining of the heart and valves 

Layers of the heart

Pathway of the blood in the heart

Superior + Inferior Vena Cava → RA→ tricuspid→ RV→ left + right pulmonary artery→lungs→pulmonary vein→LA→bicuspid→LV→aortic valve→aorta→body

Aorta:

The first set of arteries off the aorta are the coronary arteries→ These arteries supply the heart itself 

The heart make up: 

4 chambers = 2 upper thin atria/ 2 lower thick ventricles

septum divides the right and left sides

Atrioventricular valves - b/t the atria and ventricles 

Tricuspid valve ( Right AV) & Bicuspid/mitral Valve (Left AV)

• valves are attached via chordae tendinae attached to muscular projections within ventricles

Semilunar valves are the aortic and pulmonic valves

View of the heart 

Chambers of the heart

Atria: receiving blood chambers (LA & RA)

Ventricles: Discharging chambers (RV& LV)

LV hypertrophy seen in people with chronic high BP - increasing work the heart to pump the blood out 

LV - is also the workhorse of the heart

Heart valves

allow blood in one direction - valves open as blood is pumped through 

valves close to prevent backflow

4 valves

Atrioventricular: b/w the atria and ventricles

• bicuspid valve (mitral) - LAV

• Tricuspid valve - RAV

Semilunar valves: Pulmonary & Aortic

Chordea tendinae = anchor + maintain valve stable and shut

Great vessels of the heart

Aorta - leaves the LV (largest)

Pulmonary arteries - leave the RV (carry deoxygentated blood to the lungs)

Pulmonary veins (4) - oxygenated from lungs

Vena Cava - Superior and Inferior - 

• SVC syndrome (tumor compression) - impedes lymphatic drainage (edema superior) - veins better at handling edema then arteries 

• IVC syndrome lower extremity edema

The blood vessels 3 types

Arteries (arterioles) - carry oxygenated blood away from the heart except the pulmonary and some fetal (have higher pressures inside *aorta*)

Capillaries - where nutrients and gas exchange happens

Veins (venules) - carry deoxygenated blood toward heart except pulmonary veins carry oxygen rich blood from lungs to heart

Arteries

Arteries (arterioles) - carry oxygenated blood away from the heart except the pulmonary and some fetal (have higher pressures inside *aorta*)

Smooth muscle → constricts/dilates→based on BP (response to fluid volume/BP)

middle layer of the artery wall is smooth muscle

• constricts to regulate blood flow and blood pressure 

Arterioles can constrict or dilate, changing blood pressure 

Capillaries

-walls are only one cell thick to allow exchange of gases and nutrients with tissue and fluid

-present in all body but capillary beds aren’t open at the same time

-Contraction of a sphincter muscle closes off the bed and blood flows through arteriovenous shunt that bypass the capillary bed 

What happens at the capillaries?

Starling forces govern fluid across a capillary membrane

fluid between the capillaries and interstitial space is balanced by:

• Capillary hydrostatic pressure - pushes fluid out (filtration)

• Capillary Colloid Osmotic Pressure(CCOP) - pull fluid in w/proteins (reabsorbs)

Also influenced by interstitial pressures: hydrostatic and colloid osmotic 

Net effect = the effect of the hydrostatic and the osmotic 

• @ venous reabsorption because Oncotic>Hydrostatic - why oxygen and nutrients are delivered to tissues from the blood 

• @arteria ends filtration because Hydrostatic>Oncotic -how waste products and CO2 return to blood stream

Blood flow in the capillaries 

Time?

1 cell thick allows for nutrients exchange

Bypassed via AV shunt

Blood moves slowly cuz more capillaries than arterioles

slow movement allows time for substances to be exchanged 

Capillary exchange

Renal and Hepatic Circulation are different 

What are Veins?

What are there blood flow?

Venules drain blood from capillaries & join to veins and take blood to heart 

• valves that prevent backward flow

• carry 70% of bodies blood and act as reservoir during hemorrhages 

Blood flow depends on: skeletal muscle contraction, valves, respiratory movements 

• compression of veins causes blood to move forward past a valve then prevents backflow

• Thoracic and abdominal pressure occur with changes in breathing assist return of blood 

  • inc. pressure = inc. venous function

Issues with Veins

Varicose veins- develop when the valves of veins become weak causing blood to settle out - espicially lower

Hemorrhoids because of varicose veins in the rectum 

Phlebitis inflammation of a vein and can lead to blood clots (phlebitis by itslef is okay but inflammation is what leads to clotting) - death if cloth is carried to a pulmonary vessel

• remove IV compress suction

Blood under pressure is sent out to the arteries 

• BP is greatest at the aorta - LV of the heart is thicker than the right because the left pumps blood to the entire body 

• BP decreases @ the cross-sectional area of the arteries and then arterioles increase

Passage of the blood through the heart *important for exam*

deoxygenated blood is returned from the body into the S&I Vena Cava →RA→tricuspid→RV→pulmonary semilunar valve→pulmonary trunk and arteries to lungs→(oxygenated) pulmonary veins leaving lungs→LA→bicuspid(mitral)→LV→aortic semilunar valve→aorta→body

tricuspid (RA-RV), pulmonary, mitral(LA-RV), aortic

The vascular pathway has 2 circuits maintain homeostasis 

• pulmonary circuit 

• systemic circuit

Pulmonary: circulates blood through the lungs 

• begins with the pulmonary trunk from RV branches into 2 pulmonary arteries (take oxygen-poor blood to the lungs)

• lungs oxygen diffuses into the blood and carbon dioxide diffuses out of blood to be expelled through the lungs

• 4 pulmonary veins return oxygen-rich blood to LA

• Adults

  • arteries carry blood that is high in co2 and low in o2

  • veins carry blood that is high in o2 and low in co2

  • why DVT ends up in pulmonary circuit

Systemic: circulates blood through the rest of the body 

• systemic circuit starts with the aorta carrying O2-rich blood from the LV

• aorta branches w/and artery going to each specific organ

• artery divides into arterioles and cappilarries which then lead to venule

• adults

  • artreies carry blood that is high in O2 and low in CO2

  • veins carry bklood that is low in O2 and high in CO@

  • Arterial embolisms will not end up in pulmonary but rather end up back into the Right heart

Coronary arteries

• serve the heart itself - first branch off the aorta

• can easily get clogged, leading to heart disease

  • CAD - plaque build up (atherosclerotic) - plaques can rupshure and occlude vessels and this leads to a heart attack

Hepatic portal system

Carries blood rich in nutrients from (digestion) the small intestine to the liver organ, monitors the composition of blood

Dual Blood supply

• receives O2-rich blood from hepatic artery

• receives nutrient-rich (no O2) from portal vein from GI Low O2 but high nutrients

Sinusoidal Capillaries (livers)

• highly permeable allow for nutrients (proteins, cells) to exchange and more between blood and hepatocytes

Key role in fluid imbalance

• liver makes albumin, which maintains oncotic pressure

• liver dysfunction= low albuinum = low oncotic pressure =edema

Venous Drainage into systemic circulation:

• blood exits hepatic veins to inferior vena cava and return to the heart

  • liver failure can cause an increase in portal system pressure → Varicose veins in esophagus - inc. build up of blood

  • heart failure can cause hematensia

heart creates blood pressure to propel blood into the arteries and arterioles

Arterioles lead the capillary to where the exchange with tissues takes place 

Blood Flow in the arerioles

Arteries: BP due to the pumping of the heart accounts foe the flow of the blood in the arteries 

Systalic pressure is high when the heart expels blood ( ventricular contrcation)

Dystolic pressure is when the heart ventricles relax (vetricular relaxatoion 

BP decreases as it gets farther from the LV - becasue blood enters more and more arteries 

• smaller diameters more smooth muscle - constrict and dilaetes

Blood flow in capillaries 

Slow flow = increase gas/nutrient exchange

-a slower movement because more capillaries →allows time for substances to be exchanged between the blood and tissue

Capillaries: DEC BP, DEC velocity, INC Surface Areas

 

Blood flow in Veins

Lower flow state - there is still pressure form the heart but it is much lower than the arteries 

Veins have larger diameters, valves, little smooth muscle

Venous blood flow is more dependent on

• skeletal muscle contraction

• presence of valves in veins and respiratory movement

Compression of veins causes the blood to move forward papss the valves, and the valves prevent the blood form moving backward - normally

changes in the thoracic and abdominal pressure that occur with breathing also assist in the return of blood

Coronary artery circulation 

serve the heart itself - they are the first branch off the aorta 

they are susceptible to build up - because of small diameters which can lead to heart diseases 

The heart beat - cardiac cycle

S1 and S2

2 atria contract simutanesouly and then 2 ventricles contract and then the heart relaxes 

Systole is the contraction

Diastole is their relaxation

S1= AV close 

S2= semilunar close

How heart Valves function

pressure builds up in Atria→AV open→blood flow to ventricle, AV close→ ventricles contract→ flow through semilunar valves → semilunar valves close 

What is Preload?

What is AfterLoad?

Preload- how full is the heart before it contracts

• the stretching of the ventricle as it fills with blood during diastole 

• degree to which the cardiac muscles are stretching during contraction- the volume in the blood in the ventricles at the end of diastole 

• the filling phase before its let out 

Afterload - pressure the ventricle must overcome to eject blood into the circulatory system during systole ( pumping phase)

• inc BP = inc afterload 

• the wall stress during the contraction and ejection 

• how hard the heart has to work

• resistance the heart must overcome to pump blood out of ventricle 

Control of the heartbeat

The SA node (pacemaker) initiates the heartbeat and causes the ATRIA to contract

AV node conveys the stimulus and initiates the contraction of the ventricles 

Signal for the ventricles to contract, tables from the AV node through the atrioventricular bundle to the smaller Purkinje fibers 

If the SA node fails the AV node will take over, but the contractions will be much slower

SA node →AV node→AV Bundle of His →purkinjee fibers

If there is and SA node dysfunction

Dizziness, fatigue, fainting, SOB, no longer circulates volume effectively - also a symptom of B-blockers (symptomatic Bradycardia)

Extrinsic control of the heart

Outside of the heart

a cardiac control center in the medulla oblongata speeds or slows down the heart rate via the Autonomic nervous system: PNS (slows HR) and the SNS (increases the heart rate) 

Hormones such as epinephrine and norepinephrine from the adrenal medulla also stimulate faster heart rate

What is and ECG?

a recording of the electrical change that occurs in the myocardium during a cardiac cycle 

Atrial depolarization creates the P-wave the ventricular depolarization creates QRS wave, and repolarization of the Ventricles produces the T-wave

graphical recording of hearts electrical activity - deteced via skin electrodes - shows depolarization and repolarization - used for detecting arrhythmias, ishcemias, infractions, electrolyte isues

What does an ECG show

ECG shows electrical activity

atrial depolarization = atrial systole 

ventricular depolarization = ventricular systople 

EKG/ECG what do each mean

P wave: impulse across atria, atrial depolarization

PR: atria to ventricle movement : 0.12- 0.20 sec

QRS complex: spread of impulse down the septum around ventricles in Purkinje; ventricular depolarization <0.12 sec

QT: <0.44 sec (varies with HR)

T: ventricular repolarization 

U-wave : late repolarization

Interpret ECG

Clinical red flags in EKG

Symptoms for brady: lightheadedness, dizziness, lethargy, SOB, 

Symptoms for tachy: normal or compensation for sometheling - with a decrease in blood pressure most likley sepsis - sweating

Hyperkalemia

Peaked T-waves and wide QRS (renal dysfunction)

tall peaked T waves - multiple leads 

severe hyperkalemia 

Hypokalemia

Flat T wave and U wave

Hypercalcemia and Hypocalcemia 

hyper: SHORT QT

hypo: LONG QT wave

Normal sinus in a ECG

reugular rythym 

rate: 60-100 bpm

p waves procede eachh QRS 

normal PR and QRS

SINUS brady

Rate: <60 bpm

everything else is normal - common in well conditioned poeple 

Can be nromal or systemic 

atrial fibrillation

Decreases Cardiac Output

Irregular rhythm no visbile P waves narrow QRS risk for thromboembolism

Usually wide but doenst have to be

Ventricular tachycardia (Vtach)

Wide QRS

regular rapid rhythm

life thretannig

originates from the right or left ventricle 

needs cpr immediatly

Cardiac Output and Stroke Volume

The amount of blood pumped by each side of the heart in one minute 

CO= (heart rate) x (stroke volume)

Normal CO= 5-6 L/min

Stroke volume: volume of blood pumped by each ventricle in one contraction - normal stroke volume is 60-100 mL of blood per beat

Examples of Low CO 

The heart is not pumping enough blood

CHF, MI, cardiomyopathy (pump)

severe blood loss(hemorrhage) (volume)

Septic shock (pump and volume and vasodilation)

Examples of high Cardiac output

body needs increase blood flow or there is increased vascular resistance

• intense exercise and pregnancy as well as conditions such as spesis( initial), severe anemia, hyperthyroidism 

Heart Rate Regulation

How its regulated 

Why HR would change 

Increased HR 

Decreased GR

SV usually remains constant 

Starling’s law of the heart: blood fill = stretch = contraction force 

• This helps the heart match its output to the blood returning to it, a crucial mechanism to maintain adequate blood flow

Changing the heart rate is the best way to change the cardiac output - NOT SV

Increased heart rate

• SNS (crisis or low BP)

• hormones (epinephrine or Thryoxine T3 or T4)

• Exercise

• Decreased blood volume

  • Hypotension or hypovolemia 

Decreased heart rate 

• parasymathetic nervous syten 

• high BP (hypertension) high blood volume (hypervolemia)

• decreased venous return - associated with hypovolemia 

• medication

Vital signs to messure

Pulse (arterial) - pulse pressure wave of blood 

• monitored at pressure points where pulse can be palpated 

• certain arteries are used for assessing PAD - femoral, polietal, tibial, dorsialias

Blood pressure: the pressure of larger arteries

Resipitory rate 

Body temperature 

all indicative of the efficiney of a system 

Blood pressure: on pressure of larger arteries

• systolic pressure at the peak of ventricular contraction 

• diastolic pressure when the ventricles relax

• pressure in blood vessels decreases as the distance away from the heart increases

• L. Brachial artery relaxed best levels of the heart

• Foremarm and ankle

Factors affect BP

Neural

• ANS (sympathtic) 

  • SNS inc SA node, Vasocuntsictioun = increase in contraction force

  • PNS= DEC HR + BP

renal 

• regulate by altering blood volume

• renin - hormonal control

temperature

• heat has a vasodilatation effect = decrease in BP

• Cold has a vasoconstriction effect increases BP

checmical and med 

Diets - High NA

Variations of BP

Normal: sys(110-140) and dys(60-80)

Hypotension: low systolic less than 110 and its usual illness- important to know patient’s baseline 

Hypertension, high systolic 140 above can be dangerous if chronic 

• hypertensive emegeyc above 180 and dys above 100

Blood basics what is blood?

Specialized CONNECTIVE TISSUE

Functions: transport regulation, protection

usually 5 liters in average adult 

Sustain life cardiovasculr system

Plasma

Makes up about 55% Blood volume

key proteins: albumin (oncotic pressure) + fibronogen (clotting)  + globulins (immune functions) 

Cellular compensate of blood

Cardiovascular blood health

RBC: contain hemoglobin and carry oxygen and most abundant in the blood

WBC: immune defense,

Platelets (thrombocytes: fragmented cells that initiate blood clotting 

CBC with differentiation helps identify  the kinds of WBC and 

Perfusion requires adequate BV + plasm proteins and platets and clotting factors

• disruptions impact CO and tissue oxygenation

Cardiac Labs 

Troponin: releases in response to herat damadge or high stress

• normal less .04

• if tested 12 -24 hours later after a heart attack, you will see heart damage and an increased level

• MI if elevated

BNP: <100

• CHF if elevated - disguising fluid bc of atrial stretch

CK-MB; creatain kinase myocardial bond = increases heart damage and injury loss

• <5

• cardiac damage marker if higher

Potassium: 3,5-5.5

• dysrhythmias if potassium is elevated

Magnesium 1.5-2.5 

• torsades if low 

• creates dysrhythmias

Tropinist & CKMB are intracellular- if they are found in blood it means that the heart has been damdged