Quiz 3 Flashcards
Flow is governed by…
Pressure and resistance
Pressure
Moves fluid
Resistance
Opposes movement
By pulling back a syringe…
We increase the volume and decrease the pressure
The pressure outside the syringe is greater than the inside, so air moves in
By pushing on a syringe…
We decrease the volume and increase the pressure
The pressure outside the syringe is less than the inside, so air moves out
Heart Sounds
S1 and S2
S1
Closure of the AV valves
“Lub”
S2
Closure of the semilunar valves
“Dub”
Valvular Regurgitation
A condition in which blood leaks in the wrong direction because one or more heart valves closes improperly
Mitral valve prolapse is a common cause
Events of Ventricular Systole
Ventricular contraction Atrial relaxation (filling)
Events of Ventricular Diastole
Ventricular relaxation (filling) Atrial diastole continues throughout most of diastole Atrial systole (ejection into ventricles) occurs near the end of diastole
End Diastolic Volume
Volume in each ventricle at the end of diastole (120-130mL)
End Systolic Volume
Volume remaining after systole (50-60mL)
Stroke Volume
Volume ejected per beat (EDV-ESV)
Ejection Fraction
Blood at beginning of systole ejected during systole
(EF=SV/EDV)
Lower EF indicated you are not pumping as much blood per beat, so therefore not as much blood to tissues
Ventricular Diastole (Passive Filling)
30mL
Atrial Systole
40mL
Stroke Volume
-70mL
EF
0.53mL
Necessity of Balanced Ventricular Output
- Right ventricular output exceeds left ventricular output
- Pressure backs up
- Fluid accumulates in pulmonary tissues
- Left ventricular output exceeds right ventricular output
- Pressure backs up
- Fluid accumulates in systemic tissue
Nerve Supply to the Heart
Autonomous: Intrinsic Rate
Receives additional input from the CNS
Sympathetic and parasympathetic input
Autonomic Regulation
Sympathetic stimulation to the heart originates in the lower cervical to upper thoracic spinal cord
Speeds up the heart and increases blood flow and ventricular output
Parasympathetic Stimulation
Originates in the nuclei of the vagus nerve in the medulla oblongata
Vagus nerve innervates SA and AV nodes
Slows the heart
Cardiac Output
Amount of blood pumped per beat per minute
Affected by stroke volume and heart rate (HR increases CO the most)
Cardiac Reserve
Difference between maximum output and output at rest
Three Factors that Affect Stroke Volume
Preload
Contractility
Afterload
Preload
Starling’s Law of the Heart
Amount of tension on ventricular myocardium before it contracts
Increased Preload=Increased Contraction Strength
Starling’s Law of the Heart
Ventricles eject as much blood as they receive
The more they are stretched, the harder they contract
Contractility
Contraction force for a given preload
Increased interaction affects stroke volume
Positive Inotropes
Increase contractility
Negative Inotropes
Decrease contractility
Afterload
The pressure that must be overcome before a semilunar valve can open
The force the ventricle is pumping against
Increased afterload increases contractility
Chronic increase in afterload results in hypertrophy
Stroke Volume vs. Preload
Increased SV=Increased Preload Decreased SV=Decreased Preload Increased SV=Increased Contractility Decreased SV=Decreased Contractility Increased SV=Decreased Afterload Decreased SV=Increased Afterload
Sympathetic Stimulation
Increases HR, contractility, and stroke volume
Tachycardia
Parasympathetic Stimulation
Decreases HR
Bradycardia
Vagus nerve carries parasympathetic impulses to the heart
Coronary Artery Disease
Heart muscle receives insufficient blood supply due to the narrowing of vessels
Angina Pectoris
Heart pain from oxygen deprivation of cardiac muscle
Myocardial Infarction
Dead of area of heart muscle from lack of oxygen
Replaced by scar tissue
Circulatory Route
Heart–Aorta–Arteries–Arterioles–Capillaries–Venules–Veins–Vena Cava–Heart
Arteries
Carry blood from heart to capillaries in all tissues
Capillaries
Have thin walls to allow diffusion of oxygen, carbon dioxide, nutrients, and fluid
Veins
Bring blood from tissues back to heart
Arteries
Conducting arteries are the largest
Pulmonary, aorta, common carotid
All near the heart
“Main highway”
Medium Vessels
“Exit ramps”
Lots of smooth muscle
Distributing Arteries
Distribute blood to specific organs
Arterioles
Small arteries delivering blood to capillaries
Metarterioles form branches into capillary beds
Small Vessels
Resistance vessels
“Neighborhood”
Capillaries
Connect arterioles to venules
Sole source of exchange
Found near every cell in the body buy more extensive in highly active tissue (muscles, liver, kidneys, and brain)
Continuous Capillaries
Intercellular clefts are gaps between neighboring cells
Skeletal and smooth, connective tissue and lungs
4nm
Glucose, ions, amino acids
Fenestrated Capillaries
Plasma membranes have many holes
Kidneys, small intestine, choroid plexuses, ciliary process, and endocrine glands
20-100nm
H2O, retains proteins
Sinusoids
Very large fenestrations Incomplete basement membrane Liver, bone marrow, spleen, anterior pituitary, and parathyroid gland 30-40um How clotting factors enter circulation
