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Cardiovascular Physiology Chapter 14
Terms in this set (126)
circulatory system made up of a heart, blood vessels, and blood
microscopic vessels where blood exchanges material with the interstitial fluid
the primary function of the cardiovascular system
the transport of materials to and from all parts of the body
substances transported by the cardiovascular system can be divided into 3 categories:
-nutrients, water, and gases that enter the body from the external environment
-materials that move from cell to cell within the body
-wastes that the cells eliminate
blood vessels that carry blood away from the heart
blood vessels that return blood to the heart
the heart is divided by a central wall called the
_____ receives the blood returning to the heart from the blood vessels, and the _____ pumps blood out into the blood vessels
What side of the heart receives blood from the tissues and sends it to the lungs for oxygenation?
the Right side
What side of the heart recieves newly oxygenated blood from the lungs and pumps it to tissues throughout the body?
the left side
When blood is deoxygenated, it has no oxygen. True or False.
False, it is not completely deprived of oxygen. It simply has less oxygen than blood going from the lungs to the tissues
what is the only artery that is deoxygenated?
what is the only vein that has oxygenated blood?
the blood vessels that go from the right ventricle to the lungs and back to the left atrium
the veins from the upper part of the body join to form the ____ ____ ____
superior vena cava
the veins from the lower part of the body join to form the ___ ___ ___
inferior vena cava
the three portal systems of the body
-Hepatic portal system
-renal portal system
-hypothalamic-hypophyseal portal system
Why does blood flow?
the liquids and gases flow down pressure gradients from regions of higher pressure to regions of lower pressure
the force exerted by the fluid on its container
if fluid is not moving, the pressure it exerts is called
-the force is exerted equally in all directions
the pressure exerted by moving fluid has two components:
-dynamic, flowing components that represents the kinetic energy of the system
-lateral, the hydrostatic pressure(potential energy) exerted on the walls of the system
the pressure created in the ventricles, it is called driving pressure because it is the force that drives blood through the blood vessels
flow through the tube is indirectly proportional to the pressure gradient. True or false.
False, flow through the tube is directly proportional to the pressure gradient
the higher the pressure gradient, the greater the fluid flow. True or False
something that opposes flow
Flow is inversely proportional to resistance. True or False
-if resistance increases, flow decreases
resistance is influences by three components
-the radius of the tube
-the length of the tube
-the viscosity of the fluid
-the resistane to fluid flow offered by tube increases as the length of the tube increases
-resistance increases as the viscosity of the fluid increases
-resistance decreases as the tube's radius increases
blood viscosity is determined by
-the ratio of red blood cells to plasma
-how much protein is in the plasma
the main variable that affects resistance in the systemic circulation
the radius of the blood vessels
a decrases in blood vessel diameter is known as
an increases in blood vessel diameter is called
the flow of blood in the cardiovascular system is indirectly proportational to the pressure gradient in the system. True or False
False, the flow of the blood in cardiovascular system is directly proportional to the pressure gradient in the system
the flow of the blood in the cardiovascular system is inversely proportional to the resistance of the system to flow. True or False.
-the volume of blood that passes a given point in the system per unit time
- how much
velocity of flow
-the distance a fixed volume of blood travels in a given period of time
Velocity of flow is faster in narrow sections, and slower in wider sections. True or False.
the pressure reservoir of the heart
the primary driving force for blood flow
-mean arterial pressure
Mean arterial pressure is influenced by two parameters:
what is cardiac output?
the volume of blood the heart pumps per minute
what is peripheral resistance?
the resistance of the blood vessels to blood through them
the heart is encased in a tough membranous sac called the
the function of the pericardium
it contains a pericardial fluid that lubricates the external surface of the heart as it beats within the sac.
what supplies the heart with blood?
what is the function of fibrous connective tissue
-it acts as an electrical insulator, blocking most transmission of electrical signals between the atria and the ventricles
two sets of heart valves that ensure one-way flow
-the atrioventricular valves
-the semilunar valves
two structures that assist with the opening and closing of the atrioventricular valves
difference between the atrioventricular valves and the semilunar valves
-the AV valves have chordae tendinae
- the semilunar valves' shape does not need connective tissue to perform its function
is the heart myogenic?
-Yes, its contraction can originated from within the heart muscle itself
the signal for myocardial contraction comes from specialized myocardial cells called
another name for autorhythmic cells
-because they set the rate of the heart beat
5 differences between the cardiac muscle and the skeletal muscle
-cardiac myofibers are smaller and are single nucleated
-cardiac myofibers contain intercalated disks
-cardiac myofibers have larger t-tubules
-the cardiac sacroplasmic reticulum is smaller due to its dependency on EC calcium to initiate contraction
-cardiac mitochondria occupy 1/3 the cell volume of the cell.
cardiac muscle consumes ____% of oxygen delivered to it by blood, more than twice the amount extracted by other cells in the body.
the two componenets of an intercalated disk
what is a desmosomes?
strong connections that tie adjacent cells together, allowing force created in one cell to be transferred to an adjacent cell
function of gap junction in intercalated disks
they allow waves of depolarization to spread rapidly from cell to cell
the process of EC coupling in cardiac muscle is also called
Calcium-induced calcium release(CICR) because the myocardial RyR channels open in response to calcium binding
Calcium released from the sacroplasmic reticulum provides about ____% needed for muscle contraction, with the remaining ____& entering the cell from its EC fluid
In skeletal muscle, calcium is transported back into the sacroplasmic reticulum with the help of what channel?
In cardiac muscle, calcium is removed from the cell by what channel?
-NCX exchanger (sodium-calcium exchanger)
-calcium is removed from the cell in exchange for sodium
in the NCX, how many sodium ions are transferred into the cell for every calcium ion?
3 sodium ions
Each Skeletal and cardiac muscle myofibers contract in an all-or-none fashion. True or False
False, cardial myofibers can vary their contractions via graded contractions
Factors that affect the force of contraction in cardiac muscle
-the force generated is proportional to the number of crossbridges that are active. (the number of active crossbridges is determined by how much calcium is bound to troponin
-the force of contraction is affected by the sacromere length at the beginning of contraction
the main difference between the AP of the myocardial contractile cell and those of skeletal muscle fibers and neurons is
the myocardial cells has a longer AP due to calcium entry
what causes the cardiac AP to plateau?(what causes the longer AP)
The combination of calcium influx and decreased potassium efflux causes the AP to flatten out into a plateau during repolarization
what is the advantage of the longer action potential in cardial muscle?
-the longer myocardial action potential helps prevent the sustained contraction called tetanus
-prevention of tetanus in the heart is important because cardiac muscles must relax between contractions so the ventricles can fill with blood.
the time following an action potential during which a normal stimulus cannot trigger a second action potential
What allows the pacemaker potential to reach threshold quickly?
-If channels are permeable to both potassium and sodium
-when If channel open at a negative membrane potential, it allows sodium influx to exceed potassium efflux, as the potential nears the threshold, the If channel closes, and calcium channels open and create the steep depolarization.
what is the main pacemarker of the heart and where is it located
-the sinoatrial node(SA node)
-in the right atrium
why is it necessary to direct electrical signals through the AV node?
-if electrical signals from the atria were conducted directly into the ventricles, the ventricles would start contracting at the top.
-then blood would be squeeze downward and would become trapped in the bottom of the ventricles
what is the advantage of the AV node delay?
-this delay allows the atria to complete their contraction before ventricular contraction begins
complete heart block
-the conduction of electrical signals from the atria to the ventricles through the AV node is disrupted
-the ventricle will its own autorhythmic cells to contract, however ventricular autorhythmic cells are slower than the SA node.
-they will both be firing at different speeds, this will disrupt blood flow
-shows the summed electrical activity generated by all cells of the heart
ECG is the recording of one AP in the heart. True or False.
False, the ECG is an extracellular recording that represents the sum of multiple action potentials taking place in many heart muscle cells
the two components of an ECG
waves and segments
the three major waves of an ECG
-P wave=corresponds to depolarization of the atria
-QRS complex= represents the progressive wave of ventricular depolarization, and atrial repolarization
-T wave= represents the repolarization of the ventricles
ECG through a single contraction-relaxation cycle
a normal resting heart rate is
60-100 beats per minute
-premature ventricular contractions
-extra beats that occur when an autorhythmic cell other than the SA node jumps in and fires an AP out of sequence
the two phases of cardiac cycle
-diastole=the time during which cardiac muscle relaxes
-systole=the time during which the muscle contracts
the five mechanical events of the cardiac cycle
-late diastole=both set of chambers are relaxed and ventricles fill passively
-Atrial systole=atrial contraction forces a small amount of additional blood into the ventricles
-Isovolumic ventricular contraction=first phase of ventricular contraction pushes the AV valves closed but does not create enough pressure to open semilunar valves
-Ventricular ejection= as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected
-Isovolumic ventricular relaxation=as ventricles relax; pressure in the ventricles falls, blood flows back into cusps of semilunar valves and snaps them closed
what is isovolumic contraction?
when both sets of valves are closed, but the ventricle continues to contract, increasing the pressure. The volume is not changing
the first heart sound is caused by
-the vibrations following the closure of the AV valves
the second heart sound is caused by
-the vibrations following the closure of semilunar valves
listening to the heart via stethoscope
the maximum filling that occurs at the end of ventricular relaxation(diastole)
the amount of blood left in the ventricle at the end of contraction
-the amount of blood pumped by one ventricle during a contraction
-volume of blood before contraction- volume of blood after contraction=stroke volume
the volume of blood pumped by one ventricle in a given period of time
Heart rate x stroke volume
Cardiac output is the same for both ventricles. True or False.
how does the parasympathetic slow down HR
-parasympathetic neurotransmitters ACh activates muscarinic cholinergic receptors that influence potassium and calcium channels in the packemaker cells
-this hyperpolarizes the cell so that the pacemaker potential begins at a more negative value
-At the same time, calcium permeability of the pacemaker decreases
-the combination of these two effects causes the cell to take longer to reach threshold,delaying the onset of the AP in the pacemaker and slowing the HR.
how does the sympathetic speed up HR?
-sympathetic neurotransmitters catecholamines: norepinephrine(from sympathetic neurons) and epinephrine (from the adrenal medulla) increases ion flow through both If channels and calcium channels
-this causes the cell to reach threshold faster and increasing the rate of AP firing
-when the pacemaker fires AP more rapidly, HR increases
tonic control of heart rate is dominated by the ______ branch
Two ways that HR can be increase
-decrease parasympathetic activity
-increase sympathetic, thus norepinephrine binds to beta-1 receptors speend up depolarization rate of the autorhythmic cells and increases HR
the force of ventricular contraction is affected by two parameters
-the length of muscle fibers at the beginning of contraction
-the contractility of the heart
what is contractility?
the intrinsic ability of a cardiac muscle fiber to contract at any given fiber length and is a function of calcium interaction with the contractile filaments
in the heart and skeletal muscles, the longer the muscle fiber and sacromere when a contraction begins, the greater the tension developed, up to a maximum. True or False
what is preload?
-the degree of myocardial stretch before contraction begins
-the stretch represents the load placed on cardiac muscles before they contract
Frank-Starling law of the heart
states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume)
the six factors that affect venous return
-Skeletal muscular pump
-Sympathetic incr. in HR
-Starling's Law of heart
what is the skeletal muscle pump? and how does it work?
-skeletal muscle contractions that squeeze veins(particularly in the legs), compressing them and pushing blood toward the heart
-during periods of sitting or standing motionless, the skeletal muscle pump does NOT assist venous return
what is the respiratory pump? and how does it work?
-created by movement of the thorax during inspiration (breathing in)
-as the chest expands and the diaphragm moves toward the abdomen, the thoracic cavity enlarges and develops a sub-atmospheric pressure. This low pressure decreases pressure in the inferior vena cava as it passes through the thorax, which helps draw more blood into the vena cava from veins in the abdomen.
-the respiratory pump is aided by the higher pressure palced on the outside of abdominal veins when the abdominal contents are compressed during inspiration
what is an inotropic agent and inotropic effect?
any chemical that affects contractility and its influence(inotropic effect)
Chemicals with negative inotropic effects decrease contractility. True or False
contractility increases as the amount of calcium available for contraction decreases. True or false.
False, contractility increases as the amount of calcium available for contraction increases
increasing sarcomere length makes cardiac muscle more sensitive to calcium. True or False
function of the regulatory protein phospholamban
enhances calcium-ATPase activity in the sacroplasmic reticulum.
two examples of catecholamines
Norepinephrine and epinephrine
catecholamines shorten the duration of contraction. True or False.
-True, catecholamines(assisted by the regulatory protein phospholamban) enhances calcium-ATPase speeds up removal of calcium from the cytosol.
what effect does glycosides have on the heart?
-glycosides increase contractility by slowing calcium removal from the cytosol
-used for as a remedy for heart failure
difference between catecholamine and glycoside
-catecholamine speeds up contraction
-glycoside slows down contraction
-however, they both increase the force of the contraction
the combined load of EDV and arterial resistance during ventricular contraction
percentage of EDV ejected with one contraction (stroke volume/EDV)
Diastolic murmur occurs when
the heart muscle relaxes between beats.
Systolic murmur occurs when
the heart muscle contracts.
what heart sound occurs when AV valve closes, SL valve opens
the first heart sound (LUB)
what heart sound occurs when SL valve closes, AV valve opens
the second heart sound (DUB)
what is the equation of pulse pressure
systolic pressure - diastolic pressure
equation for MAP
-mean arterial pressure
-Diastolic + 1/3(pulse pressure)
-Diastolic + 1/3(systolic pressure-diastolic pressure)
Closer diastolic # is to systolic # shows a
decrease in elasticity of blood vessels
Postural effects on blood pressure
-supine: blood pressure is lowest here;
-sitting: blood pressure is second highest;
-standing:blood pressure is highest when standing up because of gravity
when you quickly stand up and you feel dizzy due to the quick drop of blood pressure
Incr. BP is detected by baroreceptors in what parts of the cardiovascular system
carotid arteries & aortic arch
the results of a cold pressor test
-Any cold stimulus to prevent heat loss, even if only on one hand, produces systemic vasoconstriction incr. BP
-Incr. BP is detected by baroreceptors in carotid arteries & aortic arch
-Cardiovascular control center in medulla info. sent via PNS to heart decr. HR & contract. strength decr. BP
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