Boot camps Day 2.3 Flashcards
What is the circulation of the heart?
Explain the layers of the heart from superficial to deep (percardium and heart wall)
What is the function of the heart valves?
ensure unidirectional blood flow through
the heart
What are the two sets of valves?
- Atrioventricular (AV) valves
- Semilunar (SL) valves
Explain how the AV valves work?
Explain how the SL valves works
What is the blood flow path?
What are the major coronary arteries?
- right coronar artery
- right marginal artery
- post. interventricular artery
- left coronary artery
- circumflex artery
- ant. intervent. artery
What are the major cardiac veins
How does most coronary blood return to right atrium via what?
Most coronary blood returns to right atrium via the cardiac veins by way of the coronary sinus.
What is teh coronary sinus
– Large transverse vein in coronary sulcus on posterior side of heart
– Collects blood and empties into right atrium
What is present in the intercalated discs?
desosomes, gap jxns, and tight jxns
The intrinsic conduction system:
* Composed of what?
* Depolarization of the heart is what?
* What do 1% of cardiac cells have what?
* What ensures the heart contracts as a unit?
- Composed of an internal pacemaker and nerve- like conduction pathways through myocardium
- Depolarization of the heart is rhythmic and spontaneous
- About 1% of cardiac cells have automaticity (are self-excitable)
- Gap junctions ensure the heart contracts as a unit
What is the intrinsic conduction system?
What is the extrinsic regulation of heart activity?
What are electrocardiogram (ECG, EKG)
Electrocardiogram (ECG or EKG) the action potentials generated by nodal and contractile cells detected, amplified and recorded by electrodes on arms, legs, and chest
What are the p wave, QRS complex and T wave?
- P wave: depolarization of SA node
- QRS complex: ventricular depolarization
- T wave: ventricular repolarization
What is the cardiac cycle?
one complete contraction and relaxation of all four chambers of the heart
What are the cycle of events in heart?
- Systole: contraction-> 1/3 in time
- Diastole: relaxation-> 2/3 in time
Although “systole” and “diastole” can refer to contraction and relaxation of either type of chamber, they usually refer to what?
refer to the action of the ventricles
Explain the cardiac cycle
What is the cardiac output?
volume of blood pumped by each ventricle in one minute
How do you calcuate CO?
CO= heart rate (HR) x stroke volume (SV)
* HR = number of beats per minute
* SV = volume of blood pumped out by a ventricle with each beat
* CO sometimes also called Q
What is the normal CO?
What is the maximal CO in nonathletic people and trained athletes?
– Maximal CO is 4–5 times resting CO in nonathletic people
– Maximal CO may reach 35 L/min in trained athletes
What is the cardiac reserve?
– Cardiac reserve: difference between resting & maximal CO
What is tachycardia? Why does this happen?
resting adult heart rate above 100 bpm
– Stress, anxiety, drugs, hear tdisease, or fever
– Loss of blood or damage to myocardium
What is bradycardia? What is the reason?
resting adult heart rate of less than 60 bpm
– In sleep, low body temperature, and endurance-trained athletes
What are positive and negative chronotropic agents?
- Positive chronotropic agents — factors that raise the heart rate
- Negative chronotropic agents — factors that lower the heart rate
What is stroke volume? How do we calculate SV?
Volume of blood ejected from each ventricle per beat
* SV=EDV-ESV
What are the 3 main factors affects SV
preload, contractility and afterload
Preload:
* What is it?
* What is frank-starling law of the heart?
* Ventricles eject how much?
* Increase preload=
* Increased venous return=
Contractility
* What is it?
* Independent of what?
* impacts what?
* Increased contractility=
- how hard the myocardium contracts for a given preload
- independent of muscle stretch and EDV
- Impacts ESV
- Increased contractility = increased SV
What is the positive inotropic or negative inotropic agents?
Afterload:
* What is it?
* What must pressure do?
* Impacts what?
* Hypertension increases what?
* Increased afterload=
What are arteries?
– Carry blood away from the heart
– Oxygenated except for pulmonary circulation and umbilical vessels of a fetus
What are capillaries?
Contact tissue cells and directly serve cellular needs
What are veins?
– Carry blood toward the heart
– Deoxygenated except for pulmonary circulation and umbilical vessels of a fetus
What are the 3 layers of blood vessels?
Arterial system:
* Vary by what?
* What are the three types?
- Vary by size and function
Three types:
1. Conducting arteries
2. Distributing arteries
3. Arterioles
Capillary beds:
* What is it?
* What is happening at any given time?
* Most control of folow involves what?
- Networks of 10-100 capillaries
- At any given time, three-fourths of body’s capillaries are
shut down - Most control of flow involves constriction of arterioles that are upstream from the capillaries
Three structural types distinguished by ease with which substances pass through their walls (permeability): (3)
- Continuous capillaries
- Fenestrated capillaries
- Sinusoidal capillaries
Within the capillary bed, what controls the flow?
Within the capillary bed, precapillary sphincters control flow
– When sphincters are relaxed, capillaries are well perfused with blood
– When sphincters contract, they constrict the entry to the capillary and blood bypasses the capillary
Veins:
* What are they?
* Subjected to what?
* Collapse when?
* What is the characteristic?
* Larger veins have what?
- Capacitance vessels (blood reservoirs)…“Old Sock”
- Subjected to relatively low blood pressure
- Collapse when empty, expand easily
- Steady blood flow, low pressure
- Larger veins have some smooth muscle allowing venomotor response
What is the adaptations of veins?
- Larger lumens
- Valves prevent backflow of bloo
Blood supply to a tissue can be expressed in terms of what?
flow and perfusion
What is blood flow and perfusion?
– Blood flow: the amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min.)
– Perfusion: the flow per given volume or mass of tissue in a given time (mL/min./g)
- At rest, total flow is what?
- Average adult resting cardiac output is what?
- At rest, total flow is quite constant, and is equal to the cardiac output
- Average adult resting cardiac output= 5.25L/min
What are the pressures of the vena cava, aortic and the delta P
- ∆P for systemic blood flow =
- Central Venous Pressure (CVP) is what? What is special about that?
- ∆P for systemic blood flow = MAP – CVP
- Central Venous Pressure (CVP) is 2-8 mmHg…but this is so negligible that we ignore it and say that the driving pressure is equal to the MAP
Explain how BP changes with distance?
What is hypertension?
What is hypotension?
BP tends to rise with age: (2)
- Arteriosclerosis—stiffening of arteries due to deterioration of elastic tissues of artery walls
- Atherosclerosis—build up of lipid deposits that become plaques
BP determined by what?
cardiac output, blood volume, and resistance to flow
- CO regulated by what?
- Blood Volume regulated by what?
- Resistance influenced by what?
the most imp blood blood in the body is where?
the capillaries
Only through capillary walls are what?
exchanges made between
the blood and surrounding tissues
What is capillary exchange?
Venous return:
* What is it?
* What is the pressure gradient and the characterisitics?
* What drains blood from head and neck?
What are the otehr mechanisms of venous return?
