Chapter 18 - cardiovascular system Flashcards
What is the difference between the pulmonary and the systemic circuit?
P - arteries and veins that carry blood to and from the lungs (right side receives oxygen-poor blood from body - eliminated CO2 and uptake O2)
S- blood vessels that carry blood to and from body (left side receives oxygenated blood from lungs)
What is the difference in blood for the atriums and ventricles?
R atrium - receives blood from systemic circuit
L atrium - receives blood from pulmonary circuit
R ventricle - pumps blood through pulmonary
L ventricle - pumps blood through systemic
What is the location of the heart in the mediastinum?
between the second rib and fifth intercostal space
- between the sternum and vertebral column
- 2/3 left of the midsternal line
What is the pericardium and what are the layers?
Double-walled sac surrounding the heart.
- Superficial Layer: Fibrous pericardium—protects, anchors, prevents overfilling.
- Deep Layer: Serous pericardium—
- Parietal Layer: Lines fibrous pericardium.
- Visceral Layer (Epicardium): Covers heart.
- Pericardial Cavity: Fluid-filled space reducing friction.
What is pericarditis - cardiac tamponade?
- Inflammation causing friction rub (creaking sound).
- Excess fluid compresses heart, limiting pumping ability.
Treatment: Fluid removal via syringe.
What are the three layers of the heart?
Epicardium: Visceral layer of serous pericardium.
Myocardium: Bulk of heart wall, made of cardiac muscle; contains fibrous skeleton for support and action potential control.
Endocardium: Innermost layer, continuous with blood vessel lining; covers heart chambers and valves.
What separates the atriums and the ventricles?
interatrial septum
- fossa ovails: remnant foramen ovale of fetal heart
interventricular septum
what are the surface features of the chambers?
- coronary sulcus (atrioventricular grooves) - encircles junctions of atria and ventricles
- anterior interventricular sulcus - marks anterior position of interventricular septum
- posterior interventricular sulcus - similar landmark on posteroinferior surface of heart
What are the 3 types of pericardium?
fibrous pericardium: protects, anchor and prevents overfilling
serous pericardium: parietal layer - internal surface, visceral layer (epicardium) - external surface
pericardial cavity: decrease fiction
What are the layers of the heart wall?
epicardium: visceral layer of serous pericardium
myocardium: circular or spiral bindles of contractile cardiac cells - cardiac skeleton (non-excitable) - collagen and elastic - anchors muscle fibers, supports valves and limits propagations of AP
endocardium: lines blood vessels
What is the function of the coronary sinus?
returns blood draining from the myocardium
What is the difference between the posterior and anterior layers of the atrium?
A: contains muscle bundles called pectinate muscle
P: smooth walled
- separated by cristae terminalis
Where is pectinate only found?
in the atriums
What is the function of the trabeculae carneae and papillary muscle (+ chordae tendineae)
TC: irregular ridges of muscles mark internal ventricular walls
PM: projects into ventricular cavity
CT: anchor valves to pap muscle
what does pectinate muscles do?
increase the power of contractions without increase the mass of the heart
What is different between the work load of the left and right ventricles?
L- round - pumps longer distance - high resistance (friction), high pressure system - thicker (x3) than right
R- crescent shaped - pumps shorter distance - low resistance (friction), low pressure system
what is the difference between the left and right coronary arteries?
L (2 branches) - anterior interventricular artery (supplies interventricular septum and anterior ventricular walls), Circumflex (supplies left atrium and posterior wall of left ven)
R - right marginal artery (supplies right atrium and most right ven), posterior interventricular artery (supplies posterior ven wall)
What is the coronary sinus and what are the 2 veins?
collects blood from capillary beds of myocardium
- great cardiac (in ant interven sulcus)
- middle cardiac (in post inter ven sulcus)
- small cardiac ( from right inf margin)
Where does the coronary arteries derive from?
the base of the aorta, encircle heart in coronary sulcus
What are cardiac myocytes and endomysium?
CM - short, fat, branched and interconnected: with one or two central nuclei
E - loose connective tissue with capillaries - connect the CM to fibrous skeleton
What are intercalated discs?
junctions in CM containing desmosomes (hold cell together) and gap junctions (ion travel)
What is a functional syncytium?
single coordinated unit - in CM
Does CM contain triads?
No
Why is tetanic contractions not possible in cardiac muscles?
absolute refractory period is much long then skeletal muscles
How is Ca2+ important in contraction of the cardiac muscle?
release of Ca2+ from extracellular matrix triggers the release of it from the sarcoplasmic reticulum
- binds to troponin
- Ca2+ from matrix is pumped back out after
Why is cardiac muscle adaptable?
it is able to switch metabolic pathways to use whatever nutrients are available (including lactic acid)
What is angina pectoris?
- thoracic pain caused by deficiency inn blood delivery to myocardium
- weak cells due to limited oxygen
What is myocardial infarction (MI) or heart attack?
prolonged coronary blockage causing areas of myocardial cells death
- instead noncontractile scar tissue
- damaged left ven = very bad
What is the intrinsic cardiac conduction system?
initiates and distributes impulses to coordinate depolarization and contraction of heart. Formed by:
- gap junctions
- network of noncontractile (autorhythmic) cells
Why is AP initiated by pacemaker cells?
- unstable resting potential called pacemaker potentials
- continuously depolarize, drifting slowly towards threshold
- also influenced by ANS
Explain the pathway for AP in the heart.
Pacemaker potential: K+ channels close, Na+ channels open –> Na+ comes in (+)
Depolarization: at threshold (-40), Ca+ channels open –> influx of Ca2+ brings to AP
Repolarization: Ca2+ channels close, K+ channels open –> efflux of K+ causes interior to become (-) again
What are the different tracings of ECGs?
- normal
- junction rhythm (SA fails)
- second-degree rhythm (AV fails)
- vesicular fibrillation (disorganized)
What are the different feature of the ECG wave?
P wave: depol of SA node
PR interval: atrial depol/ vent depol
QRS complex: vent depol and atrial repol
QT interval: vent depol through vent repol
ST segment: entire vent myocardium depol
T wave: repol of vent
What is the difference between systole, diastole and cardiac cycle?
S: contraction
D: relaxation
C: all events associated with blood flow
What does isometric phase mean and the 2 types?
there are two periods when all four valves are closed and volumes cannot change
- isovolumetric contraction phases (systole)
- isovolumetric relaxation phases (diastole)
What is the difference between EDV and ESV?
EDV: volume of blood in vent, greatest at the end of diastole
ESV: volume of blood in vent, smallest at the end of systole
Heart murmurs - what is the difference between incompetent valves and stenotic valves?
IV: fails to close completely; allows blood backflow
SV: fails to open properly; restricts blood flow
What is the difference between the sounds at of the first and second lub dup?
First - AV - louder, longer, and more resonant
Second - SL - short and sharp
Which valves close slightly before the others?
First: mitral and aortic
Second: tricuspid and pulmonary
What is cardiac output?
the amount of blood pumped out by each ventricle in 1 min
- product of heart rate and stroke volume
What is stroke volume?
the volume of blood pumped out by each ventricle per beat
- correlated with force of contraction
What is the normal HR, SV, and CO?
HR: 75 beats/min
SV: 70 ml/beat
CO: 5.25 L/min
What is a cardiac reserve?
difference between resting and maximal CO
