exam 1 review from 102

cardiovascular system

• the system that allows our cells/organisms to have exchange between blood and the outside environment

• blood vessels facilitate the exchange

• occurs in multiple areas (lungs, kidneys, GI tract)

main purpose of the CV system

facilitate exchange of gases, fluids, electrolytes, large molecules, and heat

2 primary parts of the CV system

pulmonary circulation and systemic circulation

pulmonary circulation

blood flow within the lungs that is involved in the exchange of gases between the blood and alveoli

systemic circulation

all the blood vessels within and outside of organs excluding the lungs

heart rate BPM terms

average: 60-100 bpm

tachycardia: >100 bpm

bradycardia: < 60 bpm

pericardium

double walled sac including the fibrous pericardium (outer) and the serous pericardium (inner)

fibrous pericardium

the outer layer of the pericardium that anchors the heart within the thoracic cavity and serves as a dense outer layer that protects the heart from infections

serous pericardium

inner layer of the pericardium that contains the parietal pericardium and the visceral pericardium (epicardium)

pericardial space

filled with an average of 15-50 cc of pericardial fluid, purpose is to reduce friction

3 layers of the heart wall

epicardium: visceral pericardium

myocardium: heart muscle

endocardium: inner surface of veins, arteries, and capillaries

epicardium

aka the visceral pericardium, it’s the layer that connects the heart to the pericardum

myocardium

the thickest of the 3 layers; composed of specialized heart muscle cells called cardiomyocytes and pacemaker cells

cardiomyocytes

striated muscle cells that produce ATP

• the ability to increase ATP production and maintain energy levels makes cardiomyocytes more resistant to fatigue than any other muscle cells in the body

pacemaker cells

aka autorhythmic cells, carry the impulses responsible for the beating of the heart

• spontaneously generates, sends, and receives electrical signals that are transmitted throughout the heart

intercalated discs

cellular bridges between the cardiomyocytes and the pacemaker cells

• forms junctional complexes which allows for movement of sodium, potassium, and calcium from cell to cell

syncytium

the heart functioning as a single cohesive muscle because of the rapid ability of impulses to move through the intercaladed discs

properties of myocardium

• excitability

• contractibility

• conductivity

excitability

the ability to respond to an electrical impulse or stimulus

contractibility

unique ability to contract in response to an electrical stimulus (generated by the SA node)

conductivity

the ability to transmit an impulse

endocardium

the innermost layer of the heart

• lines the inner heart chambers and heart valves

• primarily made up of endothelial cells

systole

contraction of the heart

• mitral and bicuspid valves are SHUT

• aortic and pulmonary valves are OPEN

diastole

relaxation of the heart

• aortic and pulmonary valves are SHUT

• mitral and bicuspid valves are OPEN

chordae tendineae

tendon-like chords that attach papillary muscle to cusps or flaps of valves; holds the valves closed and help prevent backflow

circulatory path

artery → arteriole → capillaries → venules → veins

electrical conduction order

1. sinoatrial node

2. internodal pathways

3. atrioventricular node

4. bundle of his (AV bundle)

5. right and left bundle brances (depolarizes)

6. purkinje fibers (causes contraction)

sinoatrial node

primary pacemaker in the heart, has automaticity (ability for cells to generate stimulus)

atrioventricular node

serves as an electrical relay from SA node before reaching the ventricles

heart sounds

caused by the closure of valves: S1, S2, S3, S4

S1

the first heart sound, heard when the atrioventricular (mitral and tricuspid) valves close; loudest of the 4 sounds

S2

second heart sound, heard from the closure of the semilunar valves

S3

third heart sound from the vibrations of ventricle filling, normally only heard in children

S4

fourth heart sound from the contraction of atria pushing blood into a stiff or hypertrophic ventricle (abnormal if heard)

cardiac cycle

rhythmic contractions and movement of blood through the heart

step 1: atrial contraction

• sinoatrial node fires

• atrial depolarization (contraction)

• S4 (abnormal if heard)

• “atrial kick”

• P wave

step 2: isovolumetric ventricular contraction

• ventricular depolarization (contraction)

• atrioventricular valves are closed, all valves are closed temporarily while pressure rises

• S1 heard here

• QRS complex

step 3: rapid ventricular ejection

• left ventricle contracts fully

• aortic and pulmonic valves open

• ST segment shows phase between ventricular depolarization and repolarization

step 4: reduced ventricular ejection

• ventricular repolarization

• T wave

step 5: isovolumetric ventricular relaxation

• ALL VALVES CLOSED; no blood entering or leaving the ventricles

• S2 heard here (aortic valve shutting)

• end of T wave

• V wave (atria filling w blood)

• Diacrotic notch

step 6: rapid ventricular filling

• AV valves are open

• S3 heard here (children only)

• y descent is here

step 7: reduced ventricular filling (diastasis)

• ventricles are 90% filled; other 10% is from atrial kick

• passive ventricle filling

systole vs diastole in cardiac cycle

steps 2-4 = systole

steps 5-7 = diastole

diacrotic notch

happens from aortic pressure being higher than left ventricle, causing backflow

preload

volume of blood in left ventricle at the end of diastole

• measured by LVEDP or PCWP

cardiac output

CO = Heart Rate x Stroke Volume

• volume of blood ejected from left ventricle into aorta

• measured in L/min

• normal range is 4-8 L/min

cardiac index

CI = Cardiac Output x Body Surface Area

• the cardiac output corrected for the individual’s body size

• normal range is 2.5-4.0 L/min/m^2

contractility (and influences)

the ability of myocardial sarcomeres to shorten

influenced by:

• preload

• sympathetic nervous system

• metabolic abnormalities

• pharmacologic agents

afterload (and influences)

the pressure that the chamber must generate to eject blood; represents impedance to ventricular ejection influenced by:

• radius of blood vessels

• blood viscosity

• mean arterial pressure

systemic vascular resistance (SVR)

the pressure in the peripheral blood vessels that the heart must overcome to pump blood into the system

SVR = ((MAP - CVP)/CO) x 80

pulmonary vascular resistance (PVR)

opposition encountered by the right ventricle

Ohm’s law

Pressure = flow x resistance

Resistance = Pressure/Flow

PVR = (mean PA - mean PCW)/CO

dynes and wood

vascular resistance originally results in millimeters per liter per min (mm/Hg/L/min), called Wood or Hybrid Units. To convert to SI units, multiply by 80. In SI Unites for vascular resistance it is expressed in dynes per second per centimeter ^ -5 (dynes/sec/cm^-5)

frank-starling mechanism

relationship between preload and contraction

• increase in preload = increase in contractility = increase in stroke volume = increase cardiac output

• after a critical point, any further preload results in decreased contracility (stretching a band)

cardiac insufficiency

when CO is decreased, so is systemic perfusion

symptoms: weakness, fatigue, mental confusion

normal cardiac pressures

RA = 2-8

RV = 25/4

PA = 25/10

LA = 2-12

LV = 120/10

Aorta = 120/80

normal cardiac oxygen saturations

RA, RV, PA = 75%

LA, LV, Aorta = 95%

patent formane ovale (PFO)

foramen ovale didn’t close all the way it should after birth, can permit paradoxical embolus to flow into arterial system causing stroke

atrial septal defect (ASD)

hole(s) in the atrial septum which permits blood flow between the two, leads to continuous left to right shunt and can permit paradoxical embolus to flow into arterial system causing stroke

ventricular septal defect (VSD)

when neonatal tissue fail to fuse the interventricular septum, causing a shunt

patent ductus arteriosus (PDA)

passageway between the aorta and the pulmonary artery remains open after birth instead of turning into a ligament. Can cause pulmonary congestion from blood flowing from aorta into lungs

tetralogy of fallot (TOF)

set of 4 congenital heart defects occurring together

• pulmonary stenosis

• right ventricular hypertrophy

• VSD

• overriding aorta (recieves blood from R+L ventricles)

transposition of the great vessels (TGV)

aorta connected to the right ventricle instead of the left; pulmonary artery connected to the left ventricle instead of the right; creates 2 separate circulatory circuits allowing mixture of blood. Opens 2 fetal shunts (foramen ovale and ductus arteriosus)

2 basic functions of the vascular system

distribution and exchange

distribution

transporting blood to and away from organs

exchange

movement of gases, nutrients, and fluid between blood and tissues

vascular network

• capillaries are primary exchange in the body

• together, veins and venules are primary capacitance (hold the most blood) vessels in body!!

pressure in aorta

pressure is at its HIGHEST in the aorta (95 mmHg) and progressively decreases as blood goes farther from heart due to energy being lost and heat lost because of friction

pressure in thoracic vena cavas

near right atrium, pressure is very close to 0 mmHg but can fluctuate during cardiac cycle

capacitance vessels

60-80% of blood within circulation resides within venous vascular!!

aortic pulse pressure

ejection of blood into the aorta by left ventricle; difference between systolic and diastolic pressure

systolic pressure

peak pressure of aortic pulse

diastolic pressure

after peak systolic pressure, theres the diacrotic notch followed by a diacrotic wave prior to the pressure falling to its minimal value

mean arterial pressure (MAP)

average pressure over time

MAP = ((2 x DP) + SP)/3

blood function

delivers necessary substances (oxygen and nutrients) to body's cells and transports metabolic waste products away from them

blood cell types

Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Hemostasis

to stop or control bleeding through vasoconstriction, platelet plug, and fibrin clot

vasoconstriction

aka vasospasm, occurs when a vessel's endothelium is compromised; this process buys time for platelet plug to form

platelet plug

a collection of platelets at the site of a damaged blood vessel that helps slow or stop blood loss; aka thrombus or blood clot

fibrin clot

coagulation cascade leads to formation of fibrin from inactive fibrinogen plasma protein, fibrin mesh is formed around the platelet plug to keep it in place

coagulation cascade

main elements are delineated by a series of roman numerals; coagulation proteins form an enzymatic cascade that eventually forms a fibrin clot

extrinsic pathway

cascade of clotting factors in blood that has escaped the vascular system to form a clot on the outside of the injured vessel; damaged tissues release tissue thromboplastin

intrinsic pathway

cascade of clotting factors leading to the formation of a clot within an injured vessel

tunica intima

intimal layer of vessel wall composed of endothelial cells that secrete nitric oxide (vasodialation), endothelin I (vasoconstriction), and chemicals that affect platelet aggregation and ones that affect smooth muscle cell proliferation

tunica media

medial layer of vessel wall composed of smooth muscle cells that constrict or relax causing vasodilation or constriction

tunica adventitia

adventitial layer composed of tough connective tissue

ejection fraction

stroke volume/end diastolic volume

Wigger's Diagram

shows left ventricular function or performance

What is the Auricle of the Left atrium also called?

left atrial appendage

What is the deep femoral artery also called?

profunda femoris

What is the femoral artery also called?

superficial femoral artery

What is the Right brachiocephalic artery also called?

the brachiocephalic trunk or the innominate artery