Chapter 13.1-13.4
What is electrical activity of the heart
contracts the heart
what is heart rate determined by
fastest paced fibers
what is the semilunar valve?
regulate blood flow out of the heart into the aorta
what is the myocardium
(middle) -cardiomyocytes -cardiac muscle cells
What is the atrioventricular valve?
-AV valves lie between the atria and teh ventricles. Right AV vale - -Tricuspid. Left AV - Mitrial, Bicuspid. -AV Vales prevent backflow into the atria when ventricles contract. Chordae tendineae anchor AV valves to papillary muscles. **Try before you Buy**
how is heart rate controlled by pacemaker cells
-auto-rhythmic cells have pacemaker (conducting cells) potentials -spontaneous depolarization caused by closing K channels and opening two types of channels -depolarization to threshold -repolarization
What are the functions of the cardiovascular system?
-gas exchange -nutrients to tissues -get waste away from tissues -immune function transport of hormones
what is extra contraction
-premature atrial contraction (PAC) followed by a extra ventricular contraction -jamming in extra heart rates -ectopic firing of the atria (makes ventricle contract again when its not supposed to ) -premature atrial contraction
how is excitation coupling in cardiac similar to smooth muscle
-sooth uses Ca for contraction but relies mostly on extracellular Ca where cardiac uses some extracellular and some SR -cardiac has gap junctions
what is the advantage of parallel blood flow?
-there are ways around the "issue" to get blood to other parts of the body -regulates blood flow to tissues
what are the 5 phases of cardiac contractile cells
0: depolarization -increase Na permeability 1: decrease Na -dip back down (brief repolarization) 2: increase Ca permeability -slight increase in K -plateau 3: repolarization -Ca decreased -uptake of K 4: resting membrane potential -stable potential
what are the steps to initiation and conduction of an impulse
1. AP initiated in the SA node 2. signal travels to the interatrial and internodal via inter-nodal pathway 3. atrioventricular node to the bundle of His 4. bundle branches (bundle of His splits in 2) 5. purkinje fibers witch run back up the walls
what are the 5 types of blood vessels
1. Arteries 2. Arterioles 3. Capillaries 4. Venules 5. Veins
decrease HR steps
1. activate ACh 2. bind to muscarinic receptor 3. can increase K channel permeability (more ions in) -decrease potential 4. close Ca channels -less positive coming in 5. drop lower than normal (overcome more before firing again) -longer to depolarize
what are the excitation coupling steps
1. depolarize of cells to threshold through gap junctions 2. open Ca channels in plasma membrane for extracellular Ca -help open SR channels 3. AP travels down T tubules 4. Ca is released from SR 5. calcium binds to troponin 6. etc.. same as skeletal muscle
to increase HR steps
1. epinephrine (adrenal) and norepinephrine (sympathetic) bind to beta 1 receptor 2. activation of Na and Ca channels 3. greater influx of sodium and Ca which increase depolarization 4. pacemaker potentials will happen faster
what are the functions of valves
1. maintain unidirectional blood flow -normal direction of flow 2. mechanism that drives blood flow -pressure: high to low 3. valve open and close based on: pressure -passive process
what are the two circuits of blood flow
1. pulmonary 2.coronary
Steps of excitation relaxation
1. remove Ca from cytosol 2. troponin and tropomyosin returns to their position covering myosin binding sites on actin 3. same as skeletal but some Ca is pumped out of the cell
pulmonary veins
Deliver oxygen rich blood from the lungs to the left atrium -splits in two
what is a recording of the heart called
ECG -can be recored from electrodes on the skin -noninvasive
What is the superior and inferior vena cava?
It brings blood from the upper/lower body to the heart.
What is the semilunar valve?
Prevents back flow of blood into the ventricles
what is ischemia
ST intervals is under everything (depressed -insufficient blood flow
what two things are involved in increasing HR
Sympathetic and adrenal medulla
why is the heart a closed system
all blood is contained within vessels
what is the P wave
atrial depolarization
SQ segment
atrial relaxation
bicuspid (mitral) valve
between left atrium and left ventricle
What are platelets?
blood clotting -stop blood loss then repair
what are the capillaries function
bring O2 and remove waste
how do you test for abnormalities in HR
by looking at sinus rhythms on ECG
what is a atrial fibrillation ECG look like
can live with this with meds or a pacemaker
what does a ventricular fibrillation ECG look like
cannot live with (dead) -"code" -ventricles are filling at random and this "flutters the heart" -no real contraction
How is excitation coupling in cardiac similar to skeletal
cardiac cells have T-tubules too -Ca is from the SR and some from extracellular but skeletal muscles only have Ca come from SR -Cardio looks like skeletal muscle set up
what are capillary muscles and what do they do
cardiac tendineae -help to keep valves shut when ventricles contract
whats the difference between cardiac contraction and skeletal contraction
cardiac: long refactory, short contractile -250-300 msec skeletal: long contraction, short refractory -1-2 msec
What does the aorta do?
carries blood from the left ventricle to the body -expands when blood flows in like a balloon -works through diastol -aorta goes back to normal: blood flows in both directs (blood that flows backwards goes to coronary arteries)
what are arteries function
carry blood away from the heart -all oxygenated except for the pulmonary artery
where is the heart located
center mass -size of fist -tilted, bottom points to the left
What is pulmonary circulation?
circulation between heart and lungs -right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> aorta -oxygenated blood -goes through body circuit where exchange occurs
ST interval
contracting
what is the PQ interval
depolarization of the atrium and contraction
What is the pericardium?
double-walled sac that encloses the heart -very outside
What are formed elements?
erythrocytes, leukocytes, platelets
What is tachycardia?
fast heart rate -from inverted T waves with lots of QRS complexes - can mean heart block (bundle branch block)
What is coronary circulation?
flow of blood to and from the tissues of the heart -parallel -heart has own set of capillaries -blood circulation to the heart -through coronary arteries -capillaries are supplied by coronary arteries (left to right) that arise from the aorta
what is in parallel blood flow
go from A to B and then branch in two directions to go to both C and D -to get to different parts faster
what are nodes
grouping of pacemaker cells
what is a myocardial infarction
heart attack -elevated ST segment
what are Leukocytes
immune cells
what is the endocardium
inner lining of the heart -endothelial cells
what is plasma
liquid portion of blood and everything disolved in it
aortic semilunar valve
located between the left ventricle and the aorta
cardiac contraction
long duration (250-300 msec) -longer refractory period than contractile period -must relax to continue to pump blood if no relaxation it will never fill with blood
what is the diaphragm
muscle under the rib cage involved in breathing -separates thoracic from abdominal cavity
What is the epicardium?
outer two layers of the heart
what is in series blood flow
overall flow -flow from a to b to c...
what are erythrocytes
oxygen carrying red blood cells -gas extange
What are autorhythmic cells?
pacemaker cells -make rhythm of the heart -provide pathway . for passing current through the heart tissues
graph of pacemaker
pacemaker potential: decrease K Increase Na depolarization: increase Ca Peak: decrease K repolarization: increase K
what two things are involved in decreasing HR
parasympathetic and vagus nerve stimulation
Are valves active or passive?
passive
conduction fibers
rapidly conduct action potentials initiated by pacemaker cells to myocardium -all cardiomyocyte based but no contractile ability (modified heart cells)
what are arterioles function
responsible for regulating blood pressure - high resistance to blood flow- based on large vasomotion -large change in size
pulmonary semilunar valve
right ventricle to pulmonary artery
what are the two layers of the epicardium and their functions
serious: membrane on the outside surrounding but not touching (inner) fibrous: outermost layer of the heart (protective layer of the heart) (outermost)
what are intercalated discs
sets of desmosomes (cannot pull away from each other)
what are the rates of each node/branch/pathway
sinoatrial node (SA): fastest 70-80 atrioventricular node (AV): 40-60 internodal pathway: 20-40 interatrial pathway: 20-40 bundle of His: 20-40 bundle banches: 20-40 purkinje fibers: 20-40
what is brachycardia
slow HR -not always bad -athletes have this from training
what are veins functions
some musculature -motion -smushed / not as good of a shape as arteries
What are pacemaker cells?
specialized cells of the electrical conduction system of the heart -set rhythm -spontaneous depolarization -no stimulus to cause AP -leak ions - sodium in particular
what is the conduction pathway of the heart
spread of excitation between the cells -gap junctions -atria contract --> ventricle contract
what are the venules function
start bringing blood back to the heart -look like veins/capillaries -thin walls -little to no musculature -cannot change size
what is autorhythmicity
the ability to generate own rhythm
tricuspid valve
valve between the right atrium and the right ventricle
when the heart contracts does the atriums or ventricles have higher pressure
ventricles (the one that just received blood)
What is the QRS complex?
ventricular depolarization -atrial repolarization
QT interval
ventricular relaxation
T wave
ventricular repolarization
what is third degree heart block
(Complete heart block) the atria and ventricles are paced independently and there is no relationship between the P waves and QRS complex
what is the direction of blood flow through vessels
1. arteries 2. arterioles 3. capillaries 4. venules 5. veins
what are the two ways blood flows?
1. in series 2. in parellel