Heart Flashcards
(41 cards)
Name the 4 layers of the pericardium and what they are made of from external to internal
- Fibrous pericardium: connective tissue
- Parietal layer of serous pericardium: simple squamous
- Pericardial cavity: pericardial fluid
- Epicardium: simple squamous
Name the 3 layers of the WALL of the heart from external to internal with their purpose
Epicardium: simple squamous epithelium: protection
Myocardium: cardiac muscle tissue: contraction
Endocardium: simple squamous epithelium: smooth surface for BF
Describe the path of blood starting in the right atrium
Right atrium>tricuspid>right ventricle>pulmonary semilunar valve> pulmonary trunk> pulmonary arteries> lungs> pulmonary veins> left atrium> bicuspid valve> left ventricle> aortic semilunar valve> aorta> body
Describe the structure of cardiac muscle tissue
- mostly cardiocytes
- striated: rows of contractable proteins
- intercalated discs: 1 cardiocyte meets neighbor allowing faster communication
- Capillary: lighter strand supplying CMT with blood
- Nucleus, mitochondria, myoglobin, glycogen
What is the cardiac skeleton
connective tissue dividing atria from ventricles preventing action potential from hitting both
Give the 10 steps to skeletal muscle contraction
- Neuron releases neurotransmitter
- NT (acetylcholine) binds to receptor on skeletal muscle cell membrane
- Receptor is also chemically gated ion channel
- channel opens allowing sodium into cell
- cell depolarizes, activates voltage gated ion channel
- voltage gated channels domino transmitting AP
- traveling change in voltage goes down t-tubules next to sarcoplasmic reticulum
- Sarcoplasmic reticulum releases calcium into cytoplasm of muscle cell
- calcium binds to troponin moving tropomyosin revealing binding site on actin
- Thick filament myosin grabs actin pulling = contraction
Give the 6 steps to a muscle cell contraction
- autorythmic cells start AP
- AP spreads to contractile cells via intercalated discs
- AP opens voltage gated calcium channels and triggers sarcoplasmic reticulum to release calcium into cytoplasm
- calcium binds to troponin, moving tropomyosin, reveals actin binding sites
- myosin pulls on actin=contraction
- AP spreads to neighboring cells via intercalated discs
What is the cardiac conduction system
2 groups of autorythmic cardicoytes forming electrical wiring rapidly spreading AP
Describe path of AP in the heart
Sinoatrial node> atrial myocardium> AV node> AV bundle> Purkinje fibers> Ventricular myocardium
Describe each wave of the EKG
- P wave: atrial systole with ventricular diastole: SA node fires, atria depolarizes and contracts
- QRS: Ventricular systole with atrial diastole: AV node fires, ventricles depolarize and contract, atria repolarizing
- T wave: diastole of atria and ventricles: ventricle repolarization and passive filling of heart
What causes the first and second heart sounds
S1: AV valves shut
S2: Semilunar valves shutting
What causes a heart murmur
problems with valves closing (damage to chordae tendonae or semilunar cusps)
What percentage of ventricular blood volume comes from passive filling vs atrial contraction
90-10
What is a cardiac cycle
Events of heart from 1 beat to next
Give the cardiac cycle by the numbers (avg EDV, SV, ESV,)
- EDV: 130 mL
- SV: 70 mL
- ESV: 60 mL
What do EDV, SV, and ESV mean
- EDV: end diastolic volume, amount of blood in 1 ventricle before contraction
- SV: stroke volume, amount of blood leaving 1 ventricle during systole
- ESV: amount of blood in 1 ventricle at the end of contraction
What is ejection fraction, how is it calculated, and what is the average
- SV/EDV x 100
- % of blood in ventricles that is pumped out in a stroke
- 55-70% can rise up to 90%
Summarize the process of the nervous system communicating with the heart
- Medulla Oblongota receives info, travels to heart via nerves
- Axon terminals release neurotransmitter onto myocardium
- NT binds to receptors in cell membrane of cardiocytes
- receptor affects transmembrane potential, inhibiting or enhancing action potential
Describe the basics of sympathetic heart stimulation
- HR: increase
- Innervates: cardiac nerve in spine
- Target: autorythmic cells
- NT: catecholamines- norepinephrine, epinephrine
- Ion: Ca2+ and NA+
Describe the basics of parasympathetic heart stimulation
- HR: decrease
- Innervates: vagus nerve in brain
- Target: autorythmic cells: muscarinic receptors
- NT: Acetylcholine
- Ion: K+ channels
What is Preload and what factors into the amount
- Preload= EDV
- Higher BV and higher venous return to heart= increase preload
- High HR over 180 bpm= not enough time between contractions
What is Afterload and what affects it
- pressure blood has to reach to eject blood from ventricle through semilunar
- affected by hardening of arteries and increased blood pressure
- high bp is hard to push blood in
What is the relationship between afterload and stroke volume
increase afterload=decrease stroke volume
what is contractility and what affects it
- contraction strength
- affected by NS stimulation
