Exam 3 Quiz 3 Flashcards
Describe the function Circulatory system
-contributes to homeostasis by transporting O2, Co2, wastes, electrolytes and hormones from one part of the body to another
What do cells need a constant supply of
-oxygen that is delivered by the circulatory system
what is removed by the cells via the circulatory system
-CO2 and other wastes are removed
What are the 3 basic components of the circulatory system and what do they do/ what are they are
Heart: dual pump that provides pressure to blood to establish pressure gradients needed for blood to flow to the tissues/ cells
Blood vessels: roadways/passageway through which blood is directed and distributed from heart to rest of the body returns the blood back to the heart
-they control the blood flow, they constrict or dilate the blood vessels
Blood: transport medium
what directions do fluid and air travel to
-all things fluid and air in the body move from areas of high pressure to low pressure
Name, in order, the valves of the heart as blood would normally circulate through them:
-tricuspid
-Pulmonary Semilunar Valve
-Mitral Valve
-Aortic Semilunar Valve
How is the heart a dual pump (hint: systemic circuit and pulmonary circuit)
-the pulmonary circuit is the right side of the heart and it pumps oxygen poor blood to the lungs
-the Systemic Circuit is the left side of the heart and it pumps oxygen rich blood to the body
List the flow of blood through the heart
-Deoxygenated blood enters through the superior and inferior vena cava
-blood enters the right atrium
-blood passes the tricuspid value into the right ventricle
-blood passes through the Pulmonary Semilunar Valve and goes into the pulmonary trunk
-the blood goes into the left pulmonary artery, gas exchange happens in the lung capillaries
-the now oxygen rich blood goes into the left atrium via the pulmonary veins
-the blood passes the Mitral(bicuspid) valve and enters the left ventricle
-the blood passes through the aortic valve, goes into the Aorta and goes to the rest of the body
Describe the pulmonary circuit’s pressure
-short, low, pressure circulation
is the volume of blood equal in both of the pulmonary circuit and the systemic circuit
-yes there are equal volumes of blood that are pumped to the pulmonary and systemic circuits
Describe the pressure of the systemic circuit
-the blood encounters much resistance in the long pathways
Compare the anatomy of ventricles that reflects the differences in pressure
-the left ventricle has the most pressure, and the ventricle walls are thicker bc it pumps harder
-the right ventricle walls are thin
Describe the electrical activity of the heart and how it is similar and different to that of skeletal muscle
-similar to skeletal muscle, contraction of cardiac muscle/ contractile cells (myocytes) to eject blood is trigged by Ap sweeping across muscle cell membrane
-electrical stimulus to myocytes come from pace maker cells
-unlike skeletal muscle, the heart generates it’s own Action potentials this is called autorhymicity through special pacemaker cells that make the intrinsic conduction system
what is the intrinsic cardiac conduction system
network of non contractile (autorhythmic) cells that initiate and distribute impulses to coordinate depolarization of heart
Describe the sinoatrial node
-The sinoatrial (SA) node: these are pacemaker cells
-generates the impulses about 75-100 per minute (this is the sinus rhythm)
-depolarizes faster than any other part of myocardium (therefore it drives the other cells)
-the depolarization starts here
What can change heart rate
-the external factors (ANS)
Describe the Atrioventricular (AV) node
-smaller diameter fibers; fewer gap junctions
-delays the impulses approximately o.1 seconds (this is bc of the small diameter and bc there is less distance to travel and also because of the amount of gap junctions)
-depolarizes 50 times per minute in absence of SA node input
-the AV node is the backup for the pacemaker of the heart
Describe the atrioventricular bundle and the right and left bundle branches (remember the bundle of His)
-also known as the bundle of His
-only electrical connection between atria and ventricles
-two pathways in interventricular septum that carry impulses toward the apex of the heart
Describe the Purkinje fibers
-complete pathway into apex and ventricular walls
-AV bundle and Purkinje fibers depolarize only 30 times per minute in absence of AV node input
-the second backup of the SA node
-only buys you time before you die
Describe the sequence of excitation in the heart
-depolarization starts in the Sinoatrial (SA) node
-The Atrioventricular (AV) node)
The Atrioventricular (AV) bundle (bundle of His)
-Right and left bundle branches
Purkinje fibers
What can defects in the intrinsic conduction system cause
-arrhythmias
-uncoordinated atrial and ventricular contraction
-fibrillation
what are arrhythmias
-irregularity in heart’s beating pattern
-irregular heart rhythms
-mechanical inefficiency; interrupt normal pattern of chamber filling and emptying
what is fibrillation
-rapid, irregular contractions; useless for pumping blood
Describe A-fib
-quivering of the atrium
-atrial fibrillation
V-fib
death, this is when they shock you
-ventricular fibrillation
What can a defective SA node result in (hint: ectopic focus)
Ectopic focus: abnormal pacemakers
-if the AV node takes over there will be a “junction rhythm” (40-60 bpm)
what can a defective AV node result in
-partial or total heart block
-few or no impulses from SA node reach ventricles
-ventricles contract slowly
Describe bradycardia
-low heart rate
-less than 60 bpm
-this is not always disease driven or bad, this could happen when you are sleeping
describe tachycardia, is it always disease driven or bad?
-abnormally high heart rate
-more than 100 bpm
-not always disease driven or bad
describe pacemakers
-some pace makers shock the heart
-small devices placed in the chest to help control abnormal heart rhythms
-uses electrical impulses to prompt heart to beat at a normal rate
-speed up, slow down, allow ventricles to contract normally if atria are quivering (atrial fibrillation)
-some are both pacemakers and defibrillators
-defibrillators send large waves of electricity to shock heart back into normal rhythm
what role does the ANS have in heart beat and what is it
heart beat is modified by the ANS
-this is an extrinsic innervation of the heart
where are the cardiac centers located and what is it
-in the medulla for both subdivisions of the ANS
-this is an extrinsic innervation of the heart
what does the cardioacceleratory center innervate and what is it
-innervates the Sa and AV nodes, heart muscle and coronary arteries through SNS neurons (innervates more parts of the heart)
-this is an extrinsic innervation of the heart
what does the cardioinhibatory center do and what is it
-inhibits SA and AV nodes through PNS fibers in vagus nerves to slow the pace of the heart
-this is an extrinsic innervation of the heart
Describe electrocardiogram
can be called ECG or EKG
-composite of AP’s generated by nodal and contractile cells at a given time
-ECG looks at all the Ap’s that are happening in the heart
What are the 3 waves of an EKG?
P wave, QRS complex, T wave
What does the p wave mean mechanically and electrically
Electrically: atrial depolarization
Mechanically: Atrial contraction
What does the QRS complex represent at a mechanical and electrical level?
ventricular depolarization and atrial repolarization (electrical level)
Ventricular contraction and atrial rest(mechanical level)
What does the T wave represent?
ventricular repolarization
what is normal sinus rhythm
60-100 bpm
describe junctional rhythm
-the Sa node is non functional
-p waves are absent and heart is paced by the AV node at 40-60 beats/min
describe second degree heart block
some waves are not conducted through the AV node; hence more P than QRS waves are seen
-in this tracing the ratio of P-waves to QRS waves is mostly 2:1
describe ventricular fibrillation
-these chaotic grossly irregular ECG deflections are seen in acute heart attach and electrical shock
Describe the Myocardium structure
-bundles of cardiac muscles are arranged spirally around atria and ventricles
-during contraction, the “wring” blood and propulsion occurs
-wringing starts in the apex and pushes blood towards the top
Describe the Microscopic Anatomy of Cardiac Muscle
-individual cardiac muscles cells are short, fat, branches and interconnected, while skeletal muscles are long and cylindrical
- the contractile cells of the heart are packed with the mitochondria
-there are numerous large mitochondria (they make up about 25-35% of the cell volume)
-there are adjacent cells joined by intercalated discs with 2 membrane junctions
-there are desmosomes and gap junctions
-cardiac muscle cells are very aerobic bc they have a lot of mitochondria
what are intercalated discs
-a junction between branches of the different cells
what is the role of gap junctions and desmosomes in the microscopic anatomy of cardiac muscle
-desmosomes: prevent cells from separating during contracting (they anchor)
-Gap junction allows ions to pass; allow AP to spread from one cell to the next (these are for communication)
Pacemaker cells can generate AP’s without any nervous stimulation, but how do they stimulate contractile cells?
-Action potentials spread to cardiac muscle cells via gap junctions allows a functional syncytium
Why do the atria and ventricles each form a functional syncytium and contract as separate units
-this is important because if they don’t contract as separate units the blood wont follow the normal pathway
what does synchronous contraction of the chambers produce
-produces the force needed to eject blood
Are atrial and ventricular contractile cells connected via gap junctions
No, if this was the case the atria and the ventricles would contract at the same time
-instead atrial contractile cells are connected to the same cells via gap junctions, and this is the same case for the ventricles
how is skeletal muscle contraction different from cardiac muscle contractions ( hint motor units)
-skeletal muscle contractions are generated by motor units and motor unit requirement
-cardiac muscle does not have motor units or motor unit requirement
Describe the types of cardiac cells and their electrical activity (dont forget functional syncytium and AP’s)
- Autorhythmic (pacemaker) cells: initiate and conduct Action potential that stimulate…
- Contractile cells (cardiac myocytes): which generate action potentials in response that produce mechanical work (contraction)
-they contract via functional syncytium
-they make up the 99% of heart cells
-both types of cells exhibit action potentials but they look different
Describe the action potentials autorhythmic (pacemaker) cells
-unstable (not a flat line) resting potentials (aka pacemaker potentials) due to open slow Na+ channels
-the Na+ channels are also called funny channels and the flow of Na+ current is called the funny current
-the pacemaker cells are always depolarizing because of the pacemaker potentials
-at the threshold the Ca2+ channels open
-explosive Ca2+ influx produces rising phase of AP
-repolarization results from inactivation of Ca2+ channels and opening of voltage- gated K+ channels
what is different in the action potentials in neurons and skeletal muscles and the autorhythmic (pacemaker)cells
-in neurons and skeletal muscles Na+ voltage gated channels open at threshold which causes the action potentials
-in autorhythmic (pacemaker) cells, the Calcium channels open at threshold, calcium enters which causes the rise in action potentials
-when repolarization happens, its because the Ca+ voltage gated channels inactivate and the K+ voltage gated channels activate
-the membrane potential is -60 mV and the threshold is -40
-the action potential reaches about 5 mV
list the steps of an action potential in autorhythmic cells
- Pacemaker potential: this slow depolarization is due to both opening of Na+ channels and closing of K+ channels. The membrane potential is never a flat line
- Depolarization: the action potentials begins when the pacemaker potential reaches threshold. depolarization is due to Ca2+ influx through Ca2+ channels
- Repolarization: is due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its most negative voltage
Describe the action potentials of cardiac muscle contraction
-this is for contractile cells
-depolarization opens voltage- gated fast Na+ channels in sarcolemma
-the depolarization wave also opens slow Ca2_ channels in sarcolemma allowing extracellular Ca2+ to enter the cell
-Ca2+ surge prolongs depolarization phase (the plateau)
-Reversal of membrane potential from -90mV to +30 mV (this sis similar to skeletal muscle)
-depolarization wave in T-tubules causes the sarcoplasmic reticulum is to release Ca2+
Describe the role of calcium in the action potentials of contractile cells (what does it do, what does it bind to etc)
-the influx of Ca2+ triggers opening of Ca2+ sensitive channels in the sarcoplasmic Reticulum which liberates bursts of Ca2+
-Excitation Contraction Coupling occurs as Ca2+ binds to troponin and sliding of filaments begins
- duration of AP and longer contractile phase is much greater in cardiac muscle than in skeletal muscle
-repolarization results from inactivation of Ca2+ channels and opening of voltage gated K+ channels
why is a longer contractile phase needed in the AP in the contractile cells
-these are needed to allow full contraction of atrial and ventricular cells
Describe the steps of Action Potentials in Contractile Cells
1: Depolarization: is due to Na+ influx through fast voltage gated Na+ channels. positive feedback cycle rapidly opens many Na+ channels, reversing the membrane potential. Channel inactivation ends this phase
2: Plateau phase: is due to Ca2+ influx through slow Ca2+ channels. This keeps the cell depolarized because few K+ channels are open
3: Repolarization: is due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potentials back to it’s resting voltage
Can the blood of the heart nourish the heart, why or why not
-no, although the heart is more or less continuously filled with blood, this blood provided little nourishment to heart tissue
-the myocardium is too thick for diffusion to occur
What is coronary circulation
-functional blood supply to heart muscle itself
what is the arterial supply of the coronary circulation provided by
- the left and right coronary arteries which both arise from the aorta
what do coronary veins do
-they return deoxygenated blood from heart tissue to the right atrium
what can bloakcage of coronary arterial circulation cause
-this can be serious and and it can be sometimes fatal
Describe Angina Pectoris
-choked chest
-thoracic pain caused by deficiency in bloody delivery to myocardium
what can Prolonged Coronary Blockage lead to
-it can lead to myocardial infarction (heart attack)
why is your heart weaker after a heart attack
-after a heart attack your heart is weaker because of all of the scars that are left behind
-most adult cardiac tissue is amitotic; most areas of cell death result in non functional scar tissue
Describe Bypass Surgery (hint: also answer the veins and arteries used)
-formally known as Coronary Artery Bypass Graft (CABG) surgery AKA heart bypass or bypass surgery
-take and use a segment of healthy blood vessel from another part of body
-internal mammary (thoracic) arteries, great saphenous veins or radial artery are primarily used
how does the number of the arteries bypassed influence the name
Single, double, tiple, quadruple and quintuple bypass
What does Propofol do when it is given to a patient, also when is it given to a patient
-it is a general anesthetic throughout the bypass surgery
-it is a sodium channel blocker therefore it blocks action potentials
What is Angioplasty and what is it used for (also list the other names it goes by)
-Percutaneous coronary intervention (PCI) percutaneous transluminal coronary angioplasty (PTCA), or coronary angioplasty is a procedure used to treat stenotic (narrowed) coronary arteries
Describe the steps of an Angioplasty
- catheter in the radial or femoral artery, traced into coronary arteries
- balloon inflated compressing plaque and stretching artery wall
- oftentimes, expandable wire mesh tube (stent) will be implanted to support new stretched open position of artery
what does the stent do in an angioplasty
-anchors vessels open
Describe the process of the AV values opening and compare the pressure of the ventricles and the atria
-when the AV values open; atrial pressure is greater than ventricular pressure
1. blood returning to the heart fills atria, putting pressure against atrioventricular valves are forced to open
2. as the ventricles fill, atrioventricular value flaps hang limply into ventricles
Describe the process of the AV valves closing and compare the pressure of the ventricles and the atria
- ventricles contract, forcing blood against atrioventricular valve cusps
- atrioventricular valves close
- papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into the atria
Describe the process of the semilunar valve opening
-as ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open
Describe the process of semilunar valves closing
-as ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing hem to close
Describe the heart sounds (how many are there and what are they associated with)
-there are two heart sounds (lub-dup) and they are both associated with the closing of heart valves
where does the first sound of the heart happen and what does it mean
-the first sound (lub) occurs as the AV values close and signifies the beginning of systole
where does the second sound of the heart happen and what does it mean
-second sound occurs where SA valves close at beginning of ventricular diastole
Describe heart murmurs, what are they and what do they indicate
-abnormal heart sounds most often indicative of valve problems
where can sounds of the aortic valve be heard, what sound is heard and what does that sound signify
-these sounds are heard in the 2nd intercostal space at the right sternal margin
-the aortic valve closes
-sounds like Dub
-means the end of systole and the beginning of diastole
where can sounds of the pulmonary valve be heard, what sound is heard and what does that sound signify
-these sounds heard in the 2nd intercostal space at the left sternal margin
-it sounds like Dub
-means the end of systole and the beginning of diastole
-it also means that the semilunar valves are closing
where can the sounds of the mitral value be heard what sound is heard and what does that sound signify
-these sounds are heard over the apex of the heart (in the 5th intercostal space) in line with middle clavicle
-gives the sound of lub
-begins at systole
-mitral valve closes
where can the the sounds of the tricuspid valve be heard, what sound is heard and what does that sound signify
-the sounds are heard in the right sternal margin of 5th intercostal space
-it gives the sound of lub
-begins in systole
-Av valves close
Define the cardiac cycle
-all events associated with blood flow through heart during one complete heartbeat
-these events are contraction and relaxation
Define systole and Diastole
Systole: is contraction
Diastole: relaxation (this is usually talking about ventricles, unless it is stated otherwise)
What are the phases of the cardiac cycle
- ventricular filling
- Isovolumetric contraction (ventricular systole)
- Ejection phase
- Isovolumetric relaxation
Describe Ventricular Filling
-this is the first phase of the cardiac cycle
-Mid to late diastole (relaxation of the ventricles)
-AV valves open and fill with blood
-80% of blood passively flows into ventricles
-atrial systole occurs delivering reaming 20%
-end diastolic volume happen at the end
what is end diastolic volume and in what phase is it seen
-volume of blood in each ventricle at end of ventricular diastole (relaxation)
-in other words volume of blood in the ventricles before contraction
-you see it in the ventricular filling phase
describe isovolumetric contraction (ventricular systole)
-the second phase of the cardiac cycle
-atria relax, ventricles begin to contract
-rising ventricular pressure result in closing of AV valves
-all valves are closed
Describe the ejection phase and what happens at the end
-this is the third phase of the cardiac cycle
-in this phase the ventricular pressure exceeds pressure in large arteries, forcing semilunar valves to open
-end systolic volume happens at the end
what is the end systolic volume and when do we see it
-volume of blood remaining in each ventricle after contraction
-aka ESV
-happens in the ejection phase of the cardiac cycle
Describe the Isovolumetric relaxation and what would we see on the graph
-the fourth and last phase of the cardiac cycle
-early diastole: all valves are closed
-ventricles relax
-backflow of blood in aorta and pulmonary truck closes semilunar valves and causes dicrotic notch (brief rise in aortic pressure)
Define Cardiac Output, what is it affected by and what is the calculation
-also known as CO
-volume of blood pumped by each ventricle in one minute (how much blood leaves the heart x minute
-CO= heart rate*stroke volume
-heart rate: HR
-number of beats per minute
-stroke volume: SV
-volume of blood pumped out by a ventricle with each beat
Describe the Maximal Cardiac Output in non athletes
-the maximal cardiac output is 4-5 times greater than resting cardiac output in nonathletic people
-this is the maximal stress of physical activity
describe the maximal cardiac output in trained athletes
-Maximal cardiac output may reach 35-40 L/min in trained athletes
-this doubles because of aerobic training
Define the cardiac reserve, what happens to the SV and HR, and who as a greater reserve
-difference between resting and maximal cardiac output
-someone with greater reserve has an easier time with aerobic exercises
-both the heart rate and stroke volume are affected the SV increases a lot
what are the 3 factors that affect stroke volume
-preload (stretch)
-contractility (how well it contracts)
-afterload (blood pressure)
what is the equation for regulation of stroke volume
stroke volume= EDV(end diastolic volume)-ESV(End systolic volume)
-EDV is the amount left in the heart before contraction
-ESV amount of blood left in heart after contraction
Define pre load
-the first factor that affects regulation of stroke volume
-the degree of stretch of cardiac muscle cells before they contract (frank starling law of the heart)
what increases the venous return
-slow heartbeat (more time in diastole) and exercise (venous muscle pump) increase venous return
-this allows for more time for blood to come back
-this is apart of the preload
what does increased venous return cause
-increased venous return distends (stretch ) the ventricles and increases contraction force
-this is apart of the preload
what is the length of the cardiac muscle at rest
-it is shorter than optimal length
-this is apart of the pre load
what does cardiac muscle exhibit (think of preload)
-this is apart of the pre load
-cardiac muscle exhibits a length tension relationship
what is contractility, what is the relationship that it has with calcium
-one of the factors that regulates stroke volume
-contractile strength at a given muscle length, independent of muscle stretch and EDV (end diastolic volume)
-has to do with presence of calcium
what are the positive inotropic agents that increase contractility (think about what would cause greater contraction)
-positive inotropic agents increase contractility at any given length
-increased Calcium influx due to sympathetic nervous system stimulation (this increases contractility because calcium causes contractions)
-Calcium influx will also be stimulated by hormones like thyroxine, glucagon and epinephrine
-this is apart of the contractility section in the regulation of stroke volume
what are the negative inotropic agents that decrease contractility
Acidosis- buildup of hydrogen ions at any given length
Increased extracellular K+: these are believed to mess with Na exchange
-calcium channel blockers: these prevent contraction, and it is common in BP meds
-this is apart of the contractility section in the regulation of stroke volume
what is afterload and what is the relationship that it has with hypertension
-pressure that must be overcome for ventricles to eject blood
-hypertension: increases afterload, resulting in reduced SV and increased ESV if accommodation doesn’t happen
-the last factor in the regulation of stroke volume
how do positive and negative chronotropic factors affect heart rate
Positive Chronotropic factors: increase heart rate (e.g. stress stimulates SNS)
Negative chronotropic factors: decrease heart rate
how do the sympathetic nervous system and norepinephrine affect the heart
-SNS is activated by emotional pr physical stressors
-Norepinephrine cause pacemaker to fire more rapidly (and increases contractility)
Describe the effects that Acetylcholine has on pace maker cells
-ACH hyperolarizes pacemaker cells by opening K+ channels
what do the muscarinic/ cholinergic receptors to with ACh
-they bind ACh released from postganglionic PNS fiber)
what tone does the heart exhibit at rest and what bpm does it cause (also what is it caused by)
-the heart at rest exhibits a vagal tone which causes to heart to beat at about 10-75 bpm
this is bc of the parasympathetic nervous system
what relationship does the parasympathetic nervous system have with the sympathetic nervous system
-PNS opposes the SNS
Describe the pressure and volume of the ventricles and the pressure of the aorta during ventricular filling
Ventricular pressure increases
Ventricular Volume: increases
Aortic Pressure decreases
Describe the pressure and volume of the ventricles and the pressure of the aorta during isovolumetric contraction
Ventricular volume: no change (bc the semi lunar valves are closed and the ventricles are filled at this time and the blood has not been ejected yet)
Ventricular pressure: increases because the ventricles are filled
Aortic Pressure: decreases because no blood is going there right now
Describe the pressure and volume of the ventricles and the pressure of the aorta during ventricular ejection
Ventricular volume: decreases because the blood is being pushed out
ventricular pressure: first increases and hen decreases because at first the pressure of the ventricles is so big that it exceeds the pressure of the large arteries and then it decreases because after the ejection the pressure is relived
Aortic pressure: first increases because of the contraction then decreases because of the relaxation
Describe the pressure and volume of the ventricles and the pressure of the aorta during during isovolumetric relaxation
Ventricular volume: no change
ventricular pressure: decrease
aortic pressure: first increases then decreases
what is venous return
-the rate that blood enters the heart
what is preload affected by
venous return and ventricular filling time
what is the only factor that decreases stroke volume
afterload
what does increased afterload do to the cardiac output
it decreases cardiac output
Describe the frank starling law of the heart
-the myosin and actin are too overlapped (this means that they are at a shorter than optimal length)
-the stretching of the ventricular walls bc of the blood that has filled the ventricles before contraction (EDV) causes the myosin and actin to separate and stretch to an optimal length of contraction
what causes a more forceful contraction
-more end diastolic volume= more preload= more SV= more forceful contraction
what are the three types of arteries
-elastic arteries (these are the conducting vessels)
-muscular arteries (distributing vessels)
-Arterioles (resistance vessels)
Compare and contrast the structure and function of the three types of arteries (Elastic arteries) (dont forget about the thick walled arteries)
Elastic arteries: these are conducting vessels because they are low-resistance pathways that conduct blood from the heart to medium-sized arteries
-they have high pressure and they receive the bolus of blood
-they have a lot of elastin to accommodate for the income of blood
thick-walled arteries near the heart—the aorta and its major branches
-they are relatively inactive in vasoconstriction
Compare and contrast the structure and function of the three types of arteries (muscular arteries)
-these are the distributing vessels because they deliver blood to specific body organs
-they progress and they get smaller
-they divert blood
-they have smooth muscle, which is why they are called muscular arteries
-more active in vasoconstriction bc they have more smooth muscle than elastin
Compare and contrast the structure and function of the three types of arteries (Arterioles and their relationship to the capillaries)
-these are the resistance vessels because changing diameter changes resistance to blood flow
-tiny arteries
- blood flow into the capillary beds is determined by arteriolar diameter
-When arterioles constrict, the tissues served are largely bypassed
-When arterioles dilate, blood flow into the local capillaries increases dramatically
-they add resistance to peripheral blood resistance
Define vasoconstriction and vasodilation
-Depending on the body’s needs at any given moment, regulation causes either vasoconstriction (lumen diameter decreases as the smooth muscle contracts)
-vasodilation (lumen diameter increases as the smooth muscle relaxes)
function of veins, and explain how veins differ from arteries
Veins carry blood from the capillary beds toward the heart
-these are low pressure
what are capillaries
-these are the exchange vessels, which which gas exchange happens
-contact tissue cells and directly serve cellular needs
what are the veins that we talked about in class
-postcapillary venule (tiny venule)
-small veins (capacitance vessels)
-Large veins (capacitance vessels, the superior and inferior vena cava are apart of the large veins)
list the order of the arteries, capillaries and the veins that blood travels through
-the heart
-elastic arteries
-muscular arteries
-arterioles
-capillaries
-postcapillary venule
-small veins
-large veins
what needs to be transported in between cells
-chemical messengers (hormones)
what exchanged in the cells
-picking up O2 and nutrients
-eliminated CO2 and other wastes
how are cells linked together to achieve transportation of hormones and the exchange between CO2 and O2 and other nutrients
-cells are linked together and with environment by blood vessels
Define and describe the components of blood flow
-volume of blood flowing through a vessel, an organ or entire circulation in a given period (remember you have to be specific about where it is flowing to)
-ml/min is the unite for blood flow
-equivalent to cardiac output for entire vascular system (the unit for this is L/min)
-relatively constant at rest
-varies widely through individual organs, based on needs
define and describe blood pressure and the role of the pressure gradient (how is it measured)
-force per unit area exerted on wall of a blood vessel by blood
-this can be for capillaries, arteries and veins
-unit is mm Hg
-measured as systemic arterial BP in large arteries near heart (mostly the brachial artery bc we put the cuff here to take BP
-pressure gradient provides driving force that keep blood moving from higher to lower pressure areas
Describe and define resistance (remember the last 3 bullet points)
- aka total peripheral resistance
-amount of friction blood encounters (the more blood that comes in contact with the ventricular walls= more friction therefore there is more resistance
-this is the biggest influence on the ability to have blood flow
-opposition to flow
-arterioles contribute to the resistance
-generally encountered in peripheral systemic circulation
what are the three important sources of resistance (TPR)
-blood viscosity (thickness of the blood)
-total blood vessel length (thicker blood= thicker/ wider vessel)
-blood vessel diameter (this is the most important)
what are 2 of the 3 factors that remain relatively constant in resistance
Blood viscosity: the stickiness of the blood due to formed elements and plasma proteins (how concentrated the molecule are in the blood)
-an example of this is when you are at a higher altitude and the plasma volume decreases.
-there is more hematocrit, bc you need to get more O2 since there isn’t a lot in the air
dehydration also increases blood viscosity
Blood vessel length: doesn’t really change, it only changed when you get taller
-longer vessels= greater resistance
describe vessel diameter
-this is the most important source of resistance
-frequently changes and alters total peripheral resistance
-it changes because of the ANS and local chemicals
-resistance varies inversely with the size of the vessel radius (to the 4th power)
-the inverse relationship means that when resistance decreases, blood flow increases and when the resistance increases, blood flow decreases
What is the major determinant of peripheral resistance and how does this affect resistance Hint: plaque and what does it distrupt
-small diameter arterioles
-abrupt changes in diameter or presence of fatty plaques from atherosclerosis dramatically increase resistance
-we all have atherosclerosis and as we get older it progresses and we can prevent it by healthy diet
-this disrupts laminar flow and cause turbulence
describe the relationship of blood flow, the pressure gradient and vascular resistance. What is the equation and what does each part of the equation represent
-the blood flow through a vessel depends on pressure gradient and vascular resistance
-F= total pressure/ R
F= flow rate of blood through a vessel
Total pressure= pressure gradient
R= resistance of blood vessel
describe the relationship between blood flow, blood pressure and resistance (remember the equation)
-blood flow (F) is directly proportional to the blood (hydrostatic) pressure gradient
-this means that if pressure gradient increases, blood flow speeds up (increases)
-Blood flow is inversely proportional to peripheral resistance (R)
-this means that if resistance (R) increases blood flow decreases F= pressure gradient/ resistance
-resistance is more important in influencing local blood flow because it is easily changed by altering blood vessel diameter (affects resistance to the 4th power)
What are the two factors of arteries that arterial BP
reflects
Reflects two factors of arteries:
1. Elasticity (compliance or distensibility)
-as we age our arteries get stiffer… (ask what happens here)
2. Volume of blood forced into them at any time
What is the blood pressure near the heart, the relationship it has with ventricular systole and diastole
-pulsatile (this means between bolus)
-this is why we have diastolic and systolic
ventricular systole: blood ejection
ventricles diastole: the blood drains (this means that ones the blood bolus is pumped into the aorta and drains the blood into the rest of the systemic circuit)
Describe systolic and diastolic pressure and how it related to arterial blood pressure (remember bolus)
Systolic pressure: pressure exerted during ventricular contraction (this is the top number and it will always be bigger, this is also the pressure of the bolus of blood)
Diastolic pressure: lowest level of arterial pressure (this will always be lower and this is the bottom number, this is also the pressure of the blood in between the bolus of the blood)
-arterial pressure is the blood pressure
BP= systolic BP/ Diastolic BP
Describe the pulse pressure equation and where it can be felt
-pulse pressure= SBP(systolic blood pressure)- DBP (Diastolic blood pressure)
-it is felt in the corotid artery
-increases during exercise bc SBP gets higher
Describe Mean Arterial Blood Pressure
-aka MAP
-this is the pressure that propels blood to the tissues
-MAP=(Systolic)+2(Diastolic Pressure)/3
-pulse pressure and MAP both decline with increasing distance from heart
Why is there a 2 in the MAP equation
-heart relaxes twice as long as it contracts
Describe venous blood pressure
-changes little during cardiac cycle
small pressure gradient (~15 mm Hg)
-low pressure due to cumulative effects of peripheral resistance dissipating energy of arterial BP
why don’t the capillaries have a pulse
-bc they need more time to make exchanges happen
What are the requirement for maintaining blood pressure (also what happens if the BP is too high and too low) (Hint: everything works together)
-cooperation of heart, blood vessels and kidneys
supervision by brain
-is BP is too low then the brain has too little blood and you faint
-if the bp is too high then you blow a veins
what are the main factors influencing blood pressure
-cardiac output
-peripheral resistance (PR)
-blood volume (for example renin retains water which increases blood volume, therefore raising BP)
what is cardiac output equivalent to
- to blood flow in the entire system
what is the volume of blood at rest
about 5L
what is the relationship of blood pressure with cardiac output, Peripheral resistance and blood volume. Also are changes in these variables compensated (Hint Standing and sitting)
-Bp varies directly with Co, PR and blood volume, this means that when one these these things increases so does blood flow
-changes in one variable are quickly compensated for by changes in other variables (e.g. you stand and feel lightheaded b blood rushed to the legs and there is quick change in BP because of vasodilation and blood pressure drops
-sympathetic NS activated bc of the stress of feeling faint there is increased contractility and vessels vasoconstricts in the legs and the blood goes back to the brain
how is cardiac output determined
-it is determined by venous return, neural and hormonal controls
how is resting heart rate maintained and what controls the resting stroke volume (Hint: vagal tone)
maintained by cardioinhibitory center via parasympathetic vagus nerves (creating the vagal/ parasympathetic tone)
-resting stroke volume is controlled by venous return (EDV)
what happens to the cardiac output during stress (dont forget the MAP)
during stress the cardioacceleratory center increases heart rate and stoke volume via sympathetic stimulation
-stoke volume also changes because EDV increases (makes preload greater, which means thar more blood flows
-the ESV decreases (which means that the contractility increases) because of the SNS output
-MAP increases
what are the short term and long term controls for controlling blood pressure
Short term: neural and hormonal controls
-these counteract moment to moment fluctuations in Blood pressure by altering peripheral resistance, this is bc of the sympathetic nervous system vasoconstricting vessels
Long term: renal regulation
-counteracts fluctuations in blood pressure by altering blood volume
-long term reneal regulation uses the kidneys to manage urine out put and therefore increase or decrease blood volume
what is the endocrine system
-an internal system of cells, tissues and organs that secrete and respond to circulating chemicals messenger molecules (hormones)
what are some functions that the endocrine system controls
-salt and water balance (when you regulate salt concentration you can regulate water, and regulate plasma volume and then the blood pressure)
-blood pressure
-stress response (cortisol, epinephrine, norepinephrine)
-digestion (enteroendocrine cells are in the viscera and they are embedded here)
-cellular metabolism
-growth and development
-sexual maturation and desire (estrogen, progesterone and testosterone)
List the major endocrine organs, and describe their body locations
-pineal gland (in the brain)
-hypothalamus (in the brain)
-pituitary gland (in the brain)
-thyroid gland
-parathyroid glands (on the dorsal aspect of the thyroid gland)
-thymus
-adrenal glands (on top of the kidneys)
-pancreas
-ovary
-testis
what does the pineal gland secrete
-secretes melatonin
what does the thymus secrete and what is it the site of
T cell maturation and T cells
what does the ovary secrete
-estrogen and progesterone
what do the testis secrete
-testosterone
what does the pancreas secrete
-insulin and glucagon ( these regulate blood glucose)
what can disruptions in the normal endocrine function lead to (what can these conditions be managed by and explain if they are hard of easy to diagnose)
- a host of endocrine related disorders
-these are clinically often hard to diagnose but once accurately diagnosed, endocrine disorders can largely be managed by supplemented hormones
what other thing besides the brain controls the body
-the endocrine system is second means by which the brain controls the body
what are hormones
-they are basic chemical messengers
what can hormones do and what other organs can do this
-they secrete from endocrine gland into blood lymph, interstitial fluid
-the heart and skin can also secrete hormones
-circulate through the blood stream to target cells
what are the two classifications of hormones
Amino Acid based: there are several subcategories
-dopamine
-Amines, thyroxine (thyroid hormone), peptides (amino acids) and proteins (strings of amino acids)
-Amines are catecholamines (NE and Epinephrine)
-these would have to bind to the peripheral proteins on the outside of the membrane
Steroids: these pass through the cells lipid bilayer
-these can bind to the inside of the cell in the inside of the cell
-these are synthesized from cholesterol (fat)
-Gonadal (sex hormones) and adrenocortical hormones (come out of the adrenal cortex like cortisol)
-there are different types of hormones that have different chemical structures, properties and difference modes of action non target tissues
what are the two classifications of hormones
Amino Acid based: there are several subcategories
-dopamine
-Amines, thyroxine (thyroid hormone), peptides (amino acids) and proteins (strings of amino acids)
-Amines are catecholamines (NE and Epinephrine)
Steroids: these pass through the cells lipid bilayer
-these are synthesized from cholesterol (fat)
-Gonadal (sex hormones) and adrenocortical hormones (come out of the adrenal cortex like cortisol)
-there are different types of hormones that have different chemical structures, properties and difference modes of action non target tissues
Describe Tropic hormones
-these hormones are stimulatory and inhibitory
-regulate production and secretion of another hormone
E.g. thyroid stimulating hormone (TSH) released by anterior pituitary stimulates thyroid hormone secretion by thyroid gland
-maintains structural integrity of this gland by trying to produce thyroid hormone
what happens in the absence of TSH (hint: no enlargement)
-thyroid atrophies (shrinks) and produces low levels of it’s hormones (this makes hypothyroidism)
what are he ways that the brain controls the endocrine systems
-anterior pituitary hormone system
-posterior pituitary hormone system
-autonomic nervous system
what is important to keep in mind when talking about hormones
-some organs release hormones independent of brain
-the heart, kidneys, skin, bone, adipose tissue and the GI tract)
What can the ANS do to the Endocrine systems and give an example
-it can control modify, or override release of hormones
-SNS controls the release of epinephrine from the adrenal medulla
what tissues secrete hormones
-there is a wide range but we talked about the following:
-hypothalamus
-pituitary
-thyroid
-adrenal glands
-pancreas
-kidneys
what is the pituitary gland called, how many hormones does it secrete and what is it regulated by
-it is known as the master gland
-it secretes 8 different hormones and regulated many other endocrine glands
-it is regulated by the hypothalamus
describe the connection between the anterior pituitary gland and the hypothalamus and what does it control
-hypothalamic neuroendocrine cells produce small quantities of releasing and inhibiting hormones (E.G. CRH, TRH and GnRH)
-these are all tropic hormones, and they are all releasing hormones
what is the definition of portal and what travels through them
-unique vascular arrangement where venous blood flows directly from on capillary through a connecting vessel to another capillary bed
-since there is 2 capillary beds, this is a portal
-releasing and inhibiting hormones are released into pituitary portal system and travels directly to anterior pituitary
What are the hormones of the anterior pituitary, what organ corresponds with the hormones, and how many are secreted from the anterior pituitary gland
-Adrenocorticotropic hormone (ACTH) –> Adrenal Cortex
-Thyroid stimulating hormone (TSH)… this one stimulates and releases thyroid hormone–> thyroid gland
-Follicle-stimulating hormone (FSH)–> ovaries or testes
Luteinizing Hormone–> the ovaries or testes (secretion of most sex hormones)
Prolactin (PRL)–> mammary glands this hormone promotes milk production) (this is one of the hormones that is not tropic)
Growth Hormone (GH)–> skeletal muscle and bone, hormones (this is the other hormone that is not tropic)
List the hormones of the thyroid and describe the details
-1. tetraiodo- thyronine (T4 or thyroxine)
2. Tri-iodothyronine (T3)
-the prefixes tetra and tri and subscripts 4 and 3 denote number of incorporated iodine atoms
-thus thyroid hormones require iodine, which we get through our diet
what happens when there is low iodine (Hint negative feedback)
-no thyroid hormone
-hypothyroidism
-the thyroid gets enlarged bc it is regulated by negative feedback (causing goiter)
Describe hypothyroidism, how is it treated, how do we see this in children and adults
-is a hyposecretion of thyroid hormones (this is called Hashimoto’s disease)
-in children it causes slow body growth, alter brain development and delay onset of puberty
-if it is left untreated this can result in cretinism (condition of mental retardation and stunted growth)
-in adults: lethargy, weight gain, low BMR and low body temperature these are the symptoms bc we are done growing and developing
-we get colder because there is slower metabolism
-hyposecretion can be treated with thyroxine pills
Describe Hyperthyroidism, what are the symptoms
-hypersecretion of thyroid hormones
-increases BMR, hyperactivity, nervousness, agitation and weight loss
-since the BMR is higher then you get hotter
what is graves disease
-autoimmune disorder in which antibodies stimulate thyroid to produce excess thyroxine
-can result in protruding eyes caused by fluid accumulation behind the eyes
-this is called exothalmos
what does BMR stand for
-basal metabolic rate
What is the advantage of having the portal system
-bypass general circulation in absence of portal system hormones produces in HT would be returned to the heart by veins- travel to lungs back to heart and then finally enter the systemic arterial system for delivery to the body
what would happen if the portal system wasnt present
the process would be longer and the hormones would take longer to dilute
How do you treat hyperthyroidism
- radioactive Iodine (I-13) high levels destroy tissue and are not associated with increased cancer risk; low level destroy some tissue and expose rest to radiation, more likely causing cancer
- Antithyroid medicines
-Thyroidectomy
What are the 3 things that regulate hormone release, also talk about the blood levels of hormones)
-humoral (blood) stimuli (elevated blood glucose)
-neural stimuli (stimulation of sensory receptors breast feeding results in mechanoreceptors letting the brain know that there needs to be more milk produced)
-hormonal stimuli (FSH stimulates the ovaries to produce eggs and manages menstrual cycle, LH monitors ovulation)
-hormone release is also controlled (mostly) by negative feedback systems (oxytocin is one of the ones that is regulated by positive feedback system)
-vary only within a narrow desirble range
Describe the pancreas (Hint: islands)
-most of the pancreas is an exocrine gland (this means that it mostly secretes into ducts and it secretes digestive juices to help with digestion)
-small islands of endocrine cells (islets of Langerhans)
Describe Glucagon
-these are alpha cells
-activates when glucose is too low
-increase blood glucose
-glycogenolysis in liver and Amino Acid metabolism
-released by the pancreas
Describe insulin
-beta cells
-decrease blood glucose
-sugar storage liver, muscle, fat and inhibit protein breakdown
-allows glucose to open the doors to the cells and enter the cells thus reducing blood glucose
what happens when you have too much insulin
-blood glucose tanks and you get hypoglycemia
what happens when you have too little insulin
-high blood sugar
-hyperglycemia
Describe diabetes as a disease
-affects ~415 million people worldwide
-100 million in the US with diabetes or pre diabetes
Describe Diabetes Type 1
-autoimmune condition in which immune system destroys B cells (so you are not able to produce insulin)
-insulin deficiency and a reliance on exogenous sources
-5-10% of all diabetes cases are Type 1
-usually presents in childhood
Describe Type II diabetes
-insulin resistance: failure of insulin receptors to respond to insulin appropriately
-you have beta cells but the receptors are resistant to insulin
-90-95% of people wit diabetes have Type 2
-usually after age 45 may require exogenous sources of insulin to maintain blood glucose homeostasis
Describe the relationship between the anterior pituitary and hypothalamus and how the hormones travel through the portal system (what else is important to remember about the anterior pituitary
-when appropriately stimulated hypothalamus neurons secrete releasing and inhibiting hormones into the primary capillary plexus
-hypothalamic hormones travel through the portal veins to the anterior pituitary where they stimulate or inhibit release of hormones from the anterior pituitary
-anterior pituitary hormones are secreted into the secondary capillary plexus
-remember that the anterior pituitary is gland is epithelium glandular communication tissue
-also remember that the anterior pituitary is separate from the posterior pituitary
Describe the relationship between the posterior pituitary and the hypothalamus
-hypothalamic neurons synthesize oxytocin and ADH
-Oxytocin and ADH are transported along the hypothalamic- hypophyseal tract to the posterior pituitary
-oxytocin and ADH are stored in the axon terminals in the posterior pituitary
-oxytocin and ADH are released into the blood when hypothalamus neurons fire
-remember that this is neural tissue
