2a Flashcards
What are the steps in pulmonary circulation?
-deoxygenated blood exits the right side of the heart through the pulmonary SL valve
- gas exchange occurs in the lungs
- oxygenated blood goes through pulmonary veins to the left side of the heart
What are the steps in systemic circulation
- blood leaves the left ventricle through the aorta and is delivered to the tissues
- tissues take O2 and a gas exchange happens at the tissues
- deoxygenated blood returns to the right side of the heart to the superior or inferior vena cava
What are the steps in the cardiac cycle?
- deoxygenated blood enters the right atrium through the superior or inferior vena cava
- blood goes to the coronary sinus
- blood goes from the RA to the RV through the tricuspid AV valve
- pulmonary trunk takes RV blood into arteries
- blood leaves the heart through the pulmonary SL valve
- Blood is taken by arteries to the lungs where gas exchange occurs
- blood is now oxygenated
- blood is taken through pulmonary veins to LA
- blood goes through the bicuspid AV/ mitral valve into the LV
- blood is pumped from the ventricle by Aorta into the tissues
- tissues take in O2 and gas exchange occurs
- deoxygenated blood is carried by veins to the heart where the cycle takes over
What is coronary circulation?
blood circulation to and from heart tissues
What do coronary arteries do?
- branch from the aorta off of the LV
- carries oxygenated blood to the musculature of the heart where gas exchange occurs
What do coronary veins do?
-carry deoxygenated blood
-converge at coronary sinus and drain into the RA
What type of blood does the right side of the heart deal with?
Deoxygenated blood
What type of blood does the left side of the heart deal with?
oxygenated blood
Where do veins carry blood?
to the heart
Where do arteries carry blood?
away from the heart
Can the atrium and ventricles contract at the same time?
no
Can the atrium and ventricles relax at the same time?
yes
Can the AV and SL valves be open at the same time
no
Can the AV and SL valves be closed at the same time?
yes
What pumps together?
The atriums pump together and the ventricles pump together
Do the atria stop receiving blood?
no, the atria always receive blood since they don’t have valves
What region of the heart has the thickest wall?
left ventricle
What is the base of the heart made of?
receiving chambers
What is the apex of the heart made of?
pumping changes
What is the pericardium?
-mechanical protection for heart and big vessels
What does the pericardium do?
- protects heart
- lubricates to prevent friction between the heart and surrounding structures
What is the pericardium made of?
- fibrous pericardium
-parietal pericardium - pericardial cavity
- visceral pericardium
What is the fibrous pericardium?
attaches pericardium to diaphragm and great vessels
What is the parietal pericardium?
- closest to fibrous pericardium, furthest away from heart
What is the pericardial Cavity?
- filled with serous fluid to prevent friction
What is the visceral pericardium?
the section closest to the heart and furthest from the fibrous layer (epicardium)
What is pericarditis?
- inflammation of the pericardium resulting in excess fluid leaving blood and filling a pericardial cavity
- limits hearts movements and prevents chambers from filling properly
- can be fatal
What are the great vessels?
- arteries ( aorta, pulmonary trunk + arteries)
- veins ( vena cava and pulmonary veins)
What are arteries?
attach to the heart at the ventricles and carry blood away from the heart
- carries deoxygenated blood from the right ventricle to the lungs
What does the aorta do?
transports oxygenated blood from the left ventricle to systemic tissues
What is myocardial infration?
- the death of a region of heart muscle due to the loss of blood flow to the area, due to an obstruction of coronary arteries
- most commonly due to thrombosis (blood clot)
- angioplasty procedure opens narrowed or blocked coronary arteries through a balloon catheter or by inserting an expandable balloon
What do veins do?
great veins attach to heart and carry blood towards it and intro atria
What does the vena cava do?
- carries deoxygenated blood to the RA
What do pulmonary veins do?
drain oxygenated blood into the Left atrium
Where do great veins attach?
the atria
What is in the right atria?
- vena cava
- coronary sinus
What is in the left atria?
-pulmonary veins (4 openings)
What separates the atrias?
interatrial septum
- fossa ovalis present on right side as ruminant of fetal foramen ovule
- interior contains pectinate muscles compose of parallel ridges
Where do great arteries attach?
ventricles
What does the right ventricle do?
take unoxygenated blood into the pulmonary trunk to be taken to lungs
What does the left ventricle do?
-pumps oxygenated blood into the aorta for systemic circulation
What separates the ventricles?
-interventricular septum
- contains papillary muscles with chordae tendineae to AV valves
What do av valves work with?
other av valves
Where is the bicuspid valve?
left atria
where is the tricuspid valve?
right atria
Where is the pulmonary SL vlave
on the right to carry deoxygenated blood
Where is the aortic SL valve?
on the left to carry oxygenated blood
What do valves do?
prevent the backflow of blood
What does the fibrous skeleton do?
-provides structural support at the boundary of atria and ventricles
- functionally and physically separates atrium from ventricles
- acts as an electrical insulator which prevents the atrium and ventricles from contracting at the same time by synchronizing contractions
- forms fibrous support for valve stabilizing them and acting as an attachment site for cardiac muscle
What is the atrial contraction pattern?
compresses wall of chambers to move blood into ventricles and narrows heart
What is the ventricular contraction pattern?
contraction begins at apex and compresses superiorly into great arteries shortening heart
What are the three layers of the heart?
endocardium, myocardium, epicardium
What is the endocardium?
- continuous with the inner lining of blood vessels
- smooth surface meant for blood flow
what is the myocardium?
- heart muscle, thickest part of heart wall?
What is the epicardium?
-the visceral layer of serous pericardium
- has adipose tissue
What are myocytes?
- short branched cells that are interconnected allowing cells to contract together in a wavelike pattern
- increases surface area
- like interlocked fingers
What are intercarlated disks?
at cell to cell junctions where the cells connect
What are desmosomes?
- prevent cardiac muscle from pulling apart
-spot welds
-structural support
What are gap junctions?
- allows for molecules, ions, and electrical signals (AP) to move continuously along the sarcomere
- necessary for synchronous contraction
- AP is related to the movement of ions creating changes in membrane potential, gap junctions allow this to happen in synchrony
- petal= proteins that leave gaps in cell
What is the sarcoplasmic reticulum?
releases Calcium in response to AP initiating contraction causing an increase in intracellular calcium
What are transverse tubulues?
invagations of the sarcolemma which transfer AP to cell
What are myofibrils?
- have actin and myosin (calcium is required for this)
- calcium comes from the sarcoplasmic reticulum and voltage-gated channels
- more calcium= stronger contraction
- elongated contractile protein units that make up the majority of the muscle cell interior
- optimal length (max overlap of filaments) is seen when the heart is stretched by blood filling the chambers
- allows filaments to contract with greater force
What are myofibrils?
- have actin and myosin (calcium is required for this)
- calcium comes from the sarcoplasmic reticulum and voltage-gated channels
- more calcium= stronger contraction
- elongated contractile protein units that make up the majority of the muscle cell interior
- optimal length (max overlap of filaments) is seen when the heart is stretched by blood filling the chambers
- allows filaments to contract with greater force
What cell is the pacemaker cell?
the SA node
What cell is the pacemaker cell?
the SA node
How does the SA node send signals?
-AP is generated at SA node and spreads to the gap junction between cardiac muscle cells throughout the atria to AV node triggering contraction of the atria
- AP is delayed at AV node before passing to the AV bundle in the interventricular septum
AV
- AV bundle conducts AP to left and right bundle branches to purkunje fibers
- Purkinje fibers carry AP to cells of ventricles where it spreads via gap junctions between cardiac muscle cells throughout the ventricles
What are Purkinje fibers equivalent to?
Purkinje is to ventricles as av is to atrium, everything else serves as a messenger
How do nodal cells generate heart beats?
through spontaneously generating ap
What happens if the SA node stops working?
the av node takes over for it
what does autorythmic mean?
-doesn’t require stimulation unlike neurons
- doesn’t have stable resting membrane potential
-RMP gradually increases to threshold without stimulation (pacemaker potential)
How does the SA node fully get charged?
- algorithmic
-depolarization occurs with the entrance of calcium into cells - has voltage-gated K+ Ca channels
(sodium enters and potassium leaves) - RMP around - 60
What is RMP?
- Resting membrane potential
- around -60
- the difference in charges between outside and inside of cells
- innerface is negative compared to outerface
-Sodium and calcium greater outside the cell - K+ greater inside the cell
Where do SA node signals travel?
- AP spreads to atria leading to a contraction, the signal stops at the av Node
-the delay between SA and AV node is so the ventricles can contract
_ Av bundle acts as a messenger between the AV node and the bundle of HIS
What are the steps in SA node depolarization?
- reaching threshold
- depolarization
- repolarization
What happens during threshold reaching?
- Na channel influx
- NA_ channels are slow voltage-gated and open as soon as the resting state is reached
the influx of NA changes membrane potential from -60 to -40
What is resting state?
when all channels are closed
What happens during depolarization?
-fast voltage-gated CA2+ channels open
- inflow of Ca2+ changes membrane potential from -40 to +10
What happens during Repolarization?
- fast voltage-gated Ca2+ channels close
- voltage-gated K+ channels open allowing for K+ outflow
-membrane potential returns to RMP - K+ channels close
How do muscle contractions occur?
- ATP to cardiac muscle to right and left atria to ap turning into calcium to actin and myosin to SA node to AV branches to Purkinje fibers in the right and left ventricles
How do myocytes work?
- AP is initiated by the conduction system (nodal cells) and passes to myocytes through gap junctions
- AP travels from muscle cell to muscle cell through gap junctions at intercalated disks allowing muscle tissue to act as a function synctsium
- electrical signals ultimately cause calcium to be release inside the cell triggering the interaction of contractile proteins
When do channels open?
in response to stimmulation by conduction system propigating AP
How does cardiac contraction happen in the cell?
- AP sent down sarcolemma travels into the cell through t-tubules
- increases intracellular CA2+ results from interstitial fluid and sarcoplasmic reticulum
- allows for interaction of contractile proteins in the myofibrils
- decreased intracellular Calcium levels lead to muscle relaxation f
- calcium channels close and pumps move it into the SR and out of cell
What are the steps in cardiac blood flow and contraction (graph)
- late ventricular diastole
- atrial systole
- early ventricular systole
- late ventricular systole
- early ventricular diastole
cycle repeats
What is late ventricular diastole
- AV open
-SL closed - atria relaxed
- ventricles relaxed
- atrial pressure greater than ventricle pressure
- arterial trunk pressure greater than ventricle pressure
What is atrial systole?
- av valve open
- sl valve closed
- atria contracts
- ventricles relax
- atrial pressure is greater than ventricle pressure
- arterial trunk pressure is greater than ventricle pressure
Early ventricular systole?
- blood volume stays constant
- the pressure is increasing but not enough to open valves
- atria is relaxed
- ventricles contract
- ventricle pressure is greater than arterial pressure
- arterial trunk pressure is greater than ventricle pressure
-av valve closed - sl valve open
WHat is late ventricular systole?
- blood moving in heart
- aka period of ejection
- AV valve closed
-SL valve open - ventricular pressure is greater than atrial pressure
- ventricular pressure is greater than arterial trunk pressure
- atria relaxed
- ventricles relaxed
What is early ventricular diastole?
- pressure decreases but not enough to open valves
- av valve is closed
- sl valve is closed
- ventricular pressure is greater than atrial pressure
- ventricular pressure is greater than arterial trunk pressure
- atria relaxed
- ventricles relaxed
What happens to pressure if all valves are closed?
pressure stays constant
What is notable about the atria during contraction?
Except for atrial systole atria is relaxed
What controls heart valves
pressure changing and pressure gradients
How does blood move?
from high pressure to low pressure
What is the dicrotic notch?
dip in aortic pressure following the closure of the SL valves and onset of ventricular diastole
What is stroke volume?
the volume of blood ejected from a ventricle at each beat of the heart?
How much can 1 atp do?
1 atp can initiate all the events in a single heart beat
How is stroke volume calculated?
difference between edv and eds
edv-eds
What is cardiac output?
amount of blood pumped by a single ventricle in one minute at rest
What does cardiac output measure?
effectiveness of the cardiovascular system
What is cardiac reserve?
an increase in cardiac output resulting from increased activity
How is cardiac output calculated?
HR x SV
How is the time the heart beats related to the heart rate?
the higher the heart rate the less time in between the beats
How fast does the heart typically beat?
inherent SA node rate is 100 bpm but varies due to autonomic intervention (parasympathetic or sympathetic) contains hormones and drugs
What are chronotropic agents?
factors that change heart rate by altering productivity of nodal cells
What do positive chronotropic agents do?
increase heart rate
What are examples of positive chronotropic agents?
-caffeine, nicotine, cocaine, th, sympathetic nervous system stimmulation
What are sympathetic nervous system chronotropic agents?
- norepinephrine neurotransmitters from neurons
-epinephrine and norepinephrine secreted by the adrenal medulla
-epi/ ne bind to B1- adrenergic receptors
How is TH a positive chronotropic agent?
- increases b1- adrengic receptors
How is nicotine a positive chronotropic agent?
- it increases the release of NE by neurons
How is cocaine a positive chronotropic agent?
-inhibits NE reuptake
-leads to fast irregular HB
-possibly fatal
What are negative chronotropic agents?
things that decrease heart rate
How is the parasympathetic nervous system a negative chronotropic agent?
- causes the opening of muscarinic receptors resulting in K+ efflux
- results in hyperpolarization and delays threshold
What are the negative chronotropic agents?
the parasympathetic nervous system, beta-blocker drugs
What do beta-blocker drugs do?
- negative chronotropic agents that interfere with epi/ NE binding to B1-adrenergic receptors
What is tachycardia?
- constantly high heart rate (over 100)
- caused by heart disease, fever, anxiety
What is brachycardia?
-persistently low heart rate in adults (lower than 60)
- normal in athletes
-abnormal causes are hypothyroidism, electrolyte imbalance, congestive heart failure
What affects stroke volume?
- venous return
- afterload
- inter-optic agents
-edv
How does venous return affect stroke volume?
- positively correlated with stroke volume
- increased venous return occurs with greater venous pressure or slower heart rate because the heart has more time to fill
How does edv affect stroke volume?
- increased edv- an increased stretch of ventricular wall (preload)
- stimulates additional cross-bridges to form therefore increasing the strength of contraction and subsequent stroke volume
- decreased venous return occurs with lower venous pressure (hemorrhaging or rapid heart rate (less time to fill)
How does afterload affect stroke volume?
- negatively/ inversely correlated
-represents how hard ventricles must work to eject blood
-atherosclerosis further negatively impacts
What is atherosclerosis?
deposition of plaque on the inner lining of arteries decreasing the diameter of the artery and increasing resistance and overload, therefore, decreasing stroke volume
What does a positive interoptic agent do?
increase contraction strength and stroke volume
What does a negative interoptic agent do?
decreases contraction strength and stroke volume
What are examples of negative interoptic agents?
-same as chronotropic agents
- calcium channel blocker
What is afterload?
resistance in arteries to ejection of blood
What is an interoptic agent?
substance that acts on myocardium to alter contractility
What are examples of positive interoptic agents?
- same as chronotropic agents
Hoe do Ca channel blockers work?
- decreases available calcium in cardiac muscle cells reducing cross-bridges and weakening contraction
- prevents calcium channels from opening
How does calcium effect contraction strength
-more calcium= stronger contraction
How is contractility measured?
ejection fraction= sv/edv (typically between 50-75% at rest
