Phys Rewrite Notes PDF

Cardiovascular system 3 components of cardiovascular system 1. Heart - pump that creates pressure to move blood through rest of body 2. Vessels - tubes that’s blood flows through 3. Blood - fluid that carries important gases Interventricukar septum: wall b/w right and...

Cardiovascular system 3 components of cardiovascular system 1. Heart - pump that creates pressure to move blood through rest of body 2. Vessels - tubes that’s blood flows through 3. Blood - fluid that carries important gases Interventricukar septum: wall b/w right and left · ventricle to stop blood from mixing Apex of heart: contractions start here, spread upwards Left ventricular myocardium: sm thickets than other wall must be forceful to move blood issue iin ar Heart valves: prevent back-flow of blood that tries to head to wrong chamber Heart sounds: “lub” and “dub” Lub - AV valves closing (contraction) Dub - aortic and pulmonary valves closing Heart is made up of cardiac muscle cells called (relaxation) cardiomyocytes which allows for contraction and relaxation Backflow is prevented by CUSPS, the valves. When blood tries to flow backwards, cusps fill with 2 types: blood,causing them to expand and close 1. Contractile cells ACTION POTENTIAL striated cells (due to how thin and thick myofilament is formatted) AP moves through gap junctions Needs calcium (stored in SR/ECF) calcium from Intercalated discs help lock cells tg through ECF inhibits release from SR special proteins called desmosomes ATP required AP influx on Ca causes depolarization K leak channels repolarization 2. Nodal/conducting cells (behave similar to Reaches somewhat relax but doesn’t stay neurons) there Don’t contract, very little actin and myosin Every 0.8 seconds (70 beats/min) Take AP and take it through heart Self excitable (create own AP) AP created by SA node, moves through gap junctions to contractile cells in atrium AP enter so AV node (AP slows down to allow atrial cardiomyocytes to finish contracting) AP goes to atrioventricular bundle Max HR equation: 220 - your age in years before heading to bundle branches to spread AP to both ventricles PSNS releases Ach which binds to Subendocsrdial branches excite muscaranic receptors on SA node to keep ventricular cardiomyocytes to contract heart beats below 100 by decreasing Na and FROM BOTTOM TO UP, to bring blood Ca permeability, increases permeability of to arteries and veins k ECG SNS releases norepinephrine and binds to P WAVE - depolarization on atria adregenic receptors on SA node to increase QRS WAVE - depolarization on ventricles HR, increases permeability of Na and Ca, T WAVE - repolarization of ventricles decreases permeability of K Cardiac cycle Systole: cardiomyocytes contracting ESV - End Systolic Volume Diastole: cardiomyocytes relaxing Amount of blood remaining in the ventricles at the end of systole after ventricles contract Cardiac cycle refers to series of events that occurs w/ every heartbeat Indicates efficiency of hearts pumping ability Lower ESV typically means heart contracting 5 phases of cardiac cycle: effectively, higher may indicate heart dysfunction 1. Isovolumetric ventricular systole - ventricles contract but unable to EDV - End Diastolic Volume pump blood of of heart (volume of Amount of blood in ventricles before ventricular ventricles doesn’t change) contraction 2. Ventricular systole - ventricles Ventricles have max volume after ventricular contract and blood moves into aorta diastole (L) and pulmonary arteries (R) 3. Isovolumetric ventricular diastole - SV - Stroke Volume ventricles relax and unable to fill Amount of blood pumped out or ejected by the with blood ventricles w/ each heartbeat 4. Late ventricular diastole - ventricles relax and fill w/ blood If we know how full the ventricle was (EDV) and how 5. Atrial systole - atrial contract, much remained after it contracted (ESV), we can moving blood into ventricles easily determine how much blood left the ventricle in that heartbeat. It is calculated by subtracting the end atrial diastole), but similar to what we saw systolic volume (ESV) from the end diastolic with the ECG, this takes place when the volume (EDV). Therefore, an increase in EDV or a ventricles are contracting, so we don't refer to decrease in ESV can lead to a higher stroke volume. it as one of the cardiac cycle phases. Looking at this as an equation: SV = EDV - ESV Ventricular systole and diastole have two phases, the first phase no volume change, second phase blood refills ventricles  Blood Vessels Aorta is largest artery in body Total volume of blood= 4-6L Blood flows through arteries into arterioles > - pulmonary circuit -15 % Divides into capillaries (smallest vessel in arteries 10 % body) Blood enters venules > - - systemic circuit -851. F capillarres5 Go to veins protect vessel , make sure walls receive O2 2. allows vessels to stretch Celastic Fibres > - ELASTIN) 3. aka - Endothelial cells Blood pressure highest in our arteries and lowest in veins 1. Arteries: Blood away from heart (aka distribution vessels), large diameter (25% thick as diameter walls) contains lots of elastin higher pressure during systole Lower pressure during diastole - Arteries have pulsatile pressure (fluctuating) 2. Arterioles (walls are 50% as thick as diameter) 4. Venules aka resistance vessels (due to vast amount of blood flows from capillaries into these vessels smooth muscle) next Smooth muscle can contract and relax to Pressure is lower than capillaries to allow for various stimuli blood to flow 3. Capillaries (smallest blood vessels) 5. Veins composed of a single layer of endothelial cells allows blood back into heart from organs and Very thin walls tissues Function: act as exchange vessels (O2 will leave Aka capacitance vessels blood and enter cells of systemic circuit) Large diameter, but thin walled (10% of Hormones leave capillaries and bind to receptors diameter) on target cells Contains valves to allow blood to flow in ONE direction  Blood flow Arterioles have the perfect structure the control the amount of blood flow a tissue will receive Regulate blood flow - to increase bloody supply to active tissues and decrease it to inactive tissues Blood supply to vital organs Maintain blood pressure Decrease heat loss from the body by redistributing blood Blood flow equation Blood flown= pressure gradient (p2-p1)/resistance Factors affecting resistance 1. Viscosity of 2. Length of blood vessel (longer more friction) 3. Lumen radius Capillaries Capillary wall is a single cell thick Substances use trans cellular transport (enters and exits cell) (referred to as endothelial cells) simple diffusion (O2 and CO2) non charged molecule used for exchange and ,over Diffusion using channels (ions and H2O) down a substances across capillary wall [gradient] through protein channel Two plasma membranes in Facilitated diffusion, uses transport proteins that endothelial cells change its shape to move across 1. Luminal membrane (closest to Active transport, against [gradient], uses ATP capillary lumen) Endocytosis, and exocytosis, takes advantage of 2. Basolateral membrane (one flexibility of plasma membrane through use of vesicles closest to interstitial fluid) Small enough ions and substances will move in intercellular clefts (in between endothelial cells) Type of transport is called paracellular transport (bulk flow) Continuous capillaries: less permeable Fenestrated capillaries: has pores that go through endothelial (allows transport from If filtration was left unchecked, we would have edema capillary to interstitial fluid that surrounds due to excessive bulk flow out of capillary Brain has continuous capillaries, but almost STARLING FORCES PROMOTES RETURN OF no permeability, whereas skin is more FLUID BACK INTO CAPILLARY Permeability of intercellular clefts is related to proteins that hold endothelial cells tg. Proteins form tight junctions, tighter the junction the narrower the intercellular cleft. BULK FLOW: When fluid and other substances move OUT of a capillary through bulk flow, we refer to it as filtration. Filtration will increase the amount of interstitial fluid surrounding our tissue cells. Vasoconstriction and vasodilation Regulatory systems for controlling flow: 1. Local regulation - changes in the conditions of organ or tissue. (INTRINSIC MECHANISMS) Seinfeld stimulus to chnage blood flow comes denim w/in very tissue or organ that needs it Yor t 2. Humoral regulation - involve substances that are travelling in blood through blood vessels of tissue/organ. - ve substances ALPR T Sunstabces change radius of blood vessels often binding to receptors that recognize substance. Some cause vasoconstriction while others cause vasodilation. (EXTRINSIC MECHANISMS) since regulation or hormones is produced elsewhere in the body. 2httiepepmadbatbindraptorsrelaxessmoa 3. Neural regulation - neurons from the sympathetic nervous system innervate the smooth muscle cells found in tunica media of many blood vessels. sy,pathetic MAP = diastolic pressure + 1/3 releases norepinephrine which binds to adrenergic receptors (systolic pressure-diastolic causing vasoconstriction which reduce blood flow. pressure) (EXTRINSIC MECHANISMS) Neurons originate outside ??? the tissue/organ Local regulation: A. Myogenic theory Hypertension - high BP can cause damage to blood Rise in BP, vasoconstriction vessels leading to heart diseases and stroke Drop in BP, vasodilation Hypotension - low BP, can cause inadequate blood B. Metabolic theory flow to organs, causes dizziness, faint or shock Not enough vasodilator metabolites promotes vasoconstriction or arterioles Too many, increases metabolism, causes vasodilation Negative feedback loop used for maintaining homeostasis of blood pressure is baroreceptor reflex (aka stretch receptors) detect changes in BP and sens to the medulla oblongata of your brainstem. This initiated to negative feedback loop that I adjust heart rate stroke volume and vessel diameter stabilize MAP