FINAL - Transport System Flashcards
Label the structures of the human heart (and know the function of each).
Atria receive blood
Ventricles pump blood
Valves prevent back flow, maintain timing
Outline the flow of blood to, through, and from the heart (including pulmonary and systemic circulation).
- Deoxygenated blood pumped to lungs / oxygenated pumped to other organs
- Each side has atrium and ventricle
- Left atrium receives blood from lungs and right receives from body tissues
- Left ventricle pumps blood via aorta / right pumps via pulmonary artery
- Oxygenated/deoxygenated blood kept separate, all tissues receive blood w high oxygen
Outline the benefits of the double circulation.
- Oxygenated and deoxygenated blood stays separate
- So the whole body can receive blood with high oxygen content
- Pressure difference:
Lungs require low pressure blood because it would damage them
High pressure is required to pump blood to the body
Describe the myogenic, autonomic (medulla), and endocrine (adrenal gland) control of the heartbeat.
Sinoatrial node specialized group of muscle cells located in right atrium
- acts as a pacemaker
- sends out electrical signals to stimulate contraction
Medulla can change the rate of SAN firing
- through sympathetic nervous system
Epinephrine and adrenaline increase heart rate
- part of fight or flight response
Describe the role/ functions of valves in the human heart.
- Prevents back flow
- Open valves allow blood through
- Closed valves allow pressure in ventricles to rise
- Valves open when pressure is higher upstream
- AV valves prevent back flow from ventricle to atria
- Semilunar valves prevent backflow form artery to the ventricle
Explain the events of the cardiac cycle
- Refers to one complete heart beat in which both atria and ventricles contract and then relax
*Systole: contraction - higher blood pressure reading
*Diastole: relaxation - lower blood pressure reading
1. Blood flows freely from atria to ventricles until ventricles almost full (70%)
2. SA node fires, atrial systole to fill ventricles to max capacity.
3. AV node activates, sends signal (via Bundle of HIS) to Purkinje fibers - ventricular systole.
d) Increased ventricular pressure causes AV to close (between atria + ventricles) (“lub.”)
a) Increased ventricular pressure causes semi-lunar valves to open (blood flows away from heart, decreasing pressure in ventricles, closes semilunar valves causing second heart sound “dub”)
b) Blood flows freely into atria (atrial diastole)
c) Pressure in ventricles drops below pressure in atria (ventricular diastole) allowing AV valves to open - cardiac cycle starts again.
Explain the heart sounds.
- Produced by the closing of valves
- First sound (lub) is closing of AV valves
- Second sound (dub) is closing of semilunar valves
- Healthy heart sounds like “lub-dub”
Explain the reasons for a delay between atrial and ventricular contractions.
- Impulses from atria do not pass directly to ventricles
- Impulses travel via atrioventricular node in wall of right atrium
- Impulses from AVN sent along bundle of His/purkinje fibers
- Ensures atria have ejected their blood into ventricles first before they contract
Explain how the structure of cardiac muscle cells is adapted to their function.
Y-shaped cells: allow for faster coordinated contractions
Intercalated discs: keep cells together to resist mechanical stress
Gap Junctions: allows for rapid propagation of electrical stimuli between cells
Diagram the P, QRS, and T waves in an ECG trace and explain what happens in the heart during each.
P - Atrial Systole
QRS - Ventricular depolarization (contraction)
T- Ventricular diastole (relaxation)
Calculate heart rate using an ECG trace.
- Use the R-R interval to determine the time it takes for ONE heart beat (usually in seconds)
- Convert seconds to minutes using the conversion 60 seconds = 1 minute
Outline the factors that can affect heart rate.
Age, exercise, emotions, disease, temperature
Explain the use of a defibrillator.
- Defibrillator is electrodes placed on patient’s chest
- Device determines when fibrillation is happening
- Series of electrical shocks delivered to depolarize heart muscle
- To re-establish function of SA node
Explain the use of an artificial pacemaker.
- A pace maker connects to heart by wires
- Detects that hearts natural rhythm is incorrect
- Sends electrical impulses to correct heartbeat
- Provides a regular rhythm
