Heart Flashcards
Describe the position of the heart in the thoracic cavity.
What space in the thoracic cavity does it occupy?
It is on the ___ surface of diaphrgam. 2/3 of heart is to the R/L of midsternal line. It is ___ to the vertebral column, ___ to the sternum.
Base leans toward ___. Apex points to ___. Apical impulse palpatated between the __ and __ ribs, just below the ___.
-In mediastinum between second rib and fifth intercostal space
- On superior surface of diaphragm
- Two-thirds of heart to left of midsternal line
- Anterior to vertebral column, posterior to sternum
- Base (posterior surface) leans toward right shoulder
- Apex points toward left hip
- Apical impulse palpated between fifth and sixth ribs, just below left nipple
What does AV valve stand for and what do they do? What are the 2 types? Are they L or R?
- atrioventricular valve
- Prevent backflow into atria when ventricles contract
- Tricuspid valve (right AV valve)
- Mitral valve (left AV valve, bicuspid valve)
What is the function of the chordae tendinee? (2)
anchor cusps to papillary muscles & Hold valve flaps in closed position
___ carries blood away from the heart and ___ carries blood to the heart
arteries = away veins = towards
What are the 2 transport systems of the heart?
Where do the two receiving chambers from the heart receive blood from?
Where do the two Pumping chambers of heart pump blood to?
right = pulmonary circuit left = systemic
receiving chamber
right = systemic circuit
left = pulmonary circuit
pumping chamber
right = pulmonary
left = systemic
What are the coverings of the heart called? What are its layers?
pericardium
Where is the pericardial cavity located? What is the function of the pericardial cavity?
-between the visceral and parietal layer -decreases friction
What is the function of the fibrous pericardium? (3)
Protects, anchors to surrounding structures, and prevents overfilling
What are the 3 layers of the heart wall and what are their functions?
epicardium - Visceral layer of serous pericardium
myocardium = spiral budles of cardiac muscle cells that make the cardiac skeleton
endocardium = endothelial lining of blood vessels
Discuss the structure and significance of the endocardium.
- continuous with endothelial lining of blood vessels
- Lines heart chambers
- covers cardiac skeleton of valves
___ separates the atria and the ___ separates the ventricles
atria = interatrial septum ventricles = interventricular septum
___ is the remnant of foramen ovale of fetal heart. What did it used to do?
- fossa ovalis
- connected the two atria together when they were babies
What are the 3 sulcus? Where are they?
- coronary sulcus: Encircles junction of atria and ventricle
- Anterior interventricular sulcus in the front and Posterior interventricular sulcus in the back, both separate the ventricles
What are auricles?
Appendages that increase atrial volume
Where are pectinate muscles located? Where are they not located?
located in R atrium, abscent in L atrium (only in auricles)
Are atria wall thin or thick? Do they contribute to the propulsion of blood?
What veins empty into the right atrium? the left?
-Small, thin-walled
-Contribute little to propulsion of blood
-Three veins empty into right atrium:
Superior vena cava, inferior vena cava, coronary sinus
-Four pulmonary veins empty into left atrium
The ___ ventricle is most of the anterior, and the ___ ventricle is most of the posteroinferior surface.
- Right ventricle - most of anterior surface
- Left ventricle – posteroinferior surface
Where are Trabeculae carneae located? What are they?
ventricles
irregular ridges of muscle on walls
What muscles anchor the chordae tendinae?
papillary muscles
Are ventricles walls thick or thin? Its function is to ___. R ventricle pumps blood into ___ and the L ventricle into the ___.
R ventricle into pulmonary trunk
L ventricle into aorta
Describe blood flow in the heart. What is the pulmonary circuit? Systemic?
vena cava > R atrium > tricuspid valve > R ventricle > pulmonary semilunar valve > pulmonary trunk > pulmonary arteries > lungs > pulmonary veins > L atrium > mitral valve > L ventricle > aortic semilunar valve > aorta > body/systemic circulation
pulmonary circuit from R atrium to L atrium
L atrium to the vena cava is systemic
The thicker side of the heart is always the ___ side because it pushes de/oxygenated blood to the ___.
left because pushes oxygenated blood to the body
What is the function of heart valves? What do AV valves do? What is the R AV valve called? The Left? WHat holds valve flaps in closed position?
What do semilulmar (SL) valves do? What are the 2?
- Ensure unidirectional blood flow through heart
- atrioventricular (AV) valves Prevent backflow into atria when ventricles contrats
- R AV valve = tricuspid
- L AV valve = mitral
- Chordae tendineae anchored to papillary muscles
- Prevent backflow into ventricles when ventricles relax
- Aortic semilunar valve
- Pulmonary semilunar valve
What are the steps to the closing and openings of AV valves?
What are the steps to opening and closing of the SL valves?
What are the steps to opening and closing of the SL valves?
un/Equal volumes of blood are pumped to pulmonary and systemic circuits.
Pulmonary is short/long and low/high-pressure circulation.
Systemic is short/long and high/low friction.
This explains why L ventricle is thicker than the R.
- Equal volumes of blood pumped to pulmonary and systemic circuits
- Pulmonary circuit short, low-pressure circulation
- Systemic circuit long, high-friction circulation
What is coronary circulation? When is it delivered? Which area does has the most blood supply? What do anastomoses do? Can it compensate for occlusions?
- Functional blood supply to heart muscle itself
- Delivered when heart relaxed
- Left ventricle receives most blood supply
- Provide additional routes for blood delivery
- no
what capillaries carry blood to the heart?
Where do the coronary circulation arteries arise from? What does the L coronary artery branch into? The R coronary artery?
-coronary arteries
- arise from aorta
- L coronary artery > circumflex artery & anterior interventricular artery
- R coronary artery > right marginal artery & posterior intraventricular artery
In coronary circulation, which veins collect blood from capillary beds? ___ empties into right atrium. It is formed by merging ___ (3). ___ empty into the right atrium anteriorly
- Cardiac veins collect blood from capillary beds
- Coronary sinus empties into right atrium; formed by merging cardiac veins (great, middle, small)
- Several anterior cardiac veins empty directly into right atrium anteriorly
What is the difference between cardiac muscle and skeletal muscle? (10)
- cardiac muscles are branched, skeletal muscles not
- cardiac muscles have 1 or 2 nuclei, skeletal muscles are multinucleated
- cardiac has numerous mitochondria
- cardiac T tubles are less wide/numerous
- cardiac SR is simpler
- cardiac have intercalated desks with gap junctions that allow for rapid movement of ions
- cardiac muscle are held together by desmosomes
- <1% of cells have automaticity/do not need nerve system stimulation
- behave as a contractile unit
- long refractory periods
What is functional syncytium?
when heart behaves are a single coordinated unit due to intercalated discs
What are some similarities between cardiac and muscle contraction?
- Depolarization opens few voltage-gated fast Na+ channels
- Depolarization wave down T tubules → SR to release Ca2+ → Excitation-contraction coupling occurs
- Ca2+ binds troponin → filaments slide
What is the difference between cardiac and skeletal muscle contraction?
- cardiac slow release of Ca channels in sarcolemma
- Ca surge prolongs depolarization phase into a plateu
- Action potential and contractile phase last much longer
- Repolarization result of inactivation of Ca2+ channels and opening of voltage-gated K+ channels
What is the AP pathway of a cardiac muscle contraction?
cardiac muscle greatly depends on an/aerobic respiration.
aerobic
True or false
Heart depolarizes and contracts without nervous system stimulation
Rhythm can be altered by autonomic nervous system
true
What are autorhythmic cells called? They are self ___.
- pacemaker
- self-generating (of AP)
___ have unstable resting membrane potentials due to ___
pacemaker due to opening of slow Na+ channels
What is the pathway of AP of a pacemaker in the heart? What does this produce?
produces rhythmic contractions
LABEL
What is the intrinsic cardiac conduction system and action potential succession during one heartbeat?
-subendocardial conducting network also called Purkinje fibers
AV bundle = bundle of his
Heartbeat is modified by ___ via ___. Para/sympathetic increase/decrease HR. They are called the ___ center.
- Heartbeat modified by ANS via cardiac centers in medulla oblongata
- Sympathetic → ↑ rate and force (Cardioacceleratory cente)
- Parasympathetic → ↓ rate (Cardioinhibitory center)
What does an ECG/EKG show? What are the 3 waves and its process?
-action potentials generated
What are the 2 heart sounds produced by? What does a pause indicate?
-Two sounds (lub-dup) associated with closing of heart valves
-first = First as AV valves close (begins systole)
-Second = SL valves close (begins diastole)
Pause indicates heart relaxation
What consists of a cardiac cycle in terms of systole and diastole?
What is systole and diastole?
-Blood flow through heart during one complete heartbeat: atrial systole and diastole followed by ventricular systole and diastole
Systole—contraction
Diastole—relaxation
What is end diastolic volume (EDV)?
volume of blood in each ventricle at end of ventricular diastole
What is cardiac output (OC)? What is the formula?
Volume of blood pumped by each ventricle in one minute
CO = heart rate (HR) × stroke volume (SV)
What are the 3 main factors that affect SV (stroke volume)?
Preload - degree of stretch of cardiac muscle cells before they contract (Frank-Starling law of heart)
Contractility - contractile strength
Afterload - pressure ventricles must overcome to eject blood
What are inotropic agents? What are positive inotropic agents? negative?
- affect contractility
- increase: Thyroxine, glucagon, epinephrine, digitalis, high extracellular Ca2+
- decrease: Acidosis, increased extracellular K+, calcium channel blockers
What do positive and negative chronotropic factors do?
Positive chronotropic factors increase heart rate
Negative chronotropic factors decrease heart rate
what hormone of the Sympathetic nervous system (activated by emotional or physical stressors) causes pacemakers to fire more rapidly?
norepinephrine
what chemical stimulates the parasympathetic nervous system to slow HR? How?
Acetylcholine hyperpolarizes pacemaker cells
___ increases heart rate; enhances effects of norepinephrine and epinephrine
Thyroxine
What are Other Factors that Influence Heart Rate?
Age, gender, exercise, body temperature
- Fetus has fastest HR
- Females faster than males
- Exercise Increases HR
- HR Increases with increased body temperature
What are factors involved in determining cardiac output?
- venous return - amount of blood returning to heart
- End diastolic volume (EDV): volume of blood in each ventricle at end of ventricular diastole
- Contractility - contractile strength at given muscle length
- ESV - volume of blood remaining in each ventricle after systole (contraction)
What happens with vagus nerve stimulation is excessive? Which branch does it stimulate? What happens if you cut it?
- excessive vagus nerve stimulation = heart stop beating
- stimulate the parasympathetic nervous system
- cut it = HR increase
What is the best donor blood? Why?
O-
it has no antigen
When you add anti-D and the blood clots, is it Rh- or Rh+?
Rh+
What blood type is the universal recipient?
AB
What is the most rare blood? Why is it okay that it is?
AB
because universal recipient (can receive any blood type)
What blood does a type B take? (2)
B & O
What blood can type O take? Why?
O because have both anti-A and anti-B
AB blood produces antibody ___
A
B blood
O blood
AB = no antibody A = antibody B B = antibody A O = antibody A and B
