Lecture 4 Flashcards
Three variables govern stroke volume:
1.
2.
3.
- preload
- contractility
- afterload
__________: the amount of tension in ventricular myocardium immediately before it begins to contract
preload
Preload
- increased preload causes _________ force of contraction
- exercise ___________ venous return and stretches myocardium
- _______________ generate more tension during contraction
- _____________ cardiac output matches increased ____________ ___________
- increased
- increases
- cardiomyocytes
- increased; venous return
__________-_________ law of the heart: __________ is proportional to the ____________
- ventricles eject almost as much blood as they _____________
- the more _______, the harder they ________
Frank-Starling; stroke volume; end diastolic volume (EDV)
- receive
- stretch; contract
_____________ refers to how hard the myocardium contracts for a given preload
contractility
Contractility
_________________________ raise calcium to increase contractility
1. ______________: can cause strong, prolonged contractions and even cardiac arrest in systole
________________________ reduce contractility
1. __________________: can’t start excitation-contraction coupling which leads to no contraction
2. ________________: slows down repolarization. which decreases ability to start next contraction cycle
3. ________________: hyperpolarization
Positive inotropic agents
1. Hypercalcemia
Negative inotropic agents
1. Hypocalcemia
2. Hyperkalemia
3. Hypokalemia
________________: sum of all forces opposing the ejection of blood from ventricle
- Largest force is _____________ __________ in aorta and pulmonary trunk
- opposes the opening of ______ valves
- limits _________
Afterload
- blood pressure
- semilunar
- stroke volume
hypertension ___________ afterload and ___________ ventricular ejection
- anything that _________ arterial circulation can ___________ after load (e.g. _______ ___________)
increases; opposes
- impedes (obstructs); increase; lung diseases
Factors affecting Cardiac Output
Increased Heart Rate= ______________________
1.
2.
3.
4.
5.
6.
Positive chronotropic agents
1. Sympathetic nervous system
2. Epinephrine, norepinephrine
3. Thyroid hormone
4. Glucagon
5. Nicotine, caffeine
6. Hypocalcemia
Factors affecting Cardiac Output
Increased stroke volume
1.
____________________
2.
3.
4.
5.
6.
7.
- increased preload
Positive inotropic agents
2. sympathetic nervous system
3. epinephrine, norepinephrine
4. Glucagon
5. Digitalis
6. Nicotine, caffeine
7. Hypercalemia
Reduced heart rate=______________________
1.
2.
3.
4.
5.
Negative chronotropic agents
1. Parasympathetic nervous system
2. Acetylcholine
3. Hypercalcemia
4. Hypokalemia
5. Beta blockers
Reduced stroke volume
1.
2.
3.
__________________
4.
5.
- reduced preload
- reduced contractility
- increased after load
Negative inotropic agents
4. Hypocalcemia
4. Hyperkalemia
____________: amount ejected by each ventricle in 1 min
- _______ L/min at rest
- _______ L/min for a fit person during exercise
- _______ L/min for a world-class athlete during exercise
_____________: the difference between a person’s maximum CO and resting CO
- ____________ with fitness, _______________ with disease
cardiac output
- 5
- 21
- >40
cardiac reserve
- increases; decreases
- Exercise: hearts works harder and ________ CO
- Proprioceptors signal cardiac center which _______ CO via _____________ output
- Increased muscular activity _______ venous return which increases ________ and ultimately ______
- increases in _______ and ________ cause an increase in CO
- increases
- increases; sympathetic
- increases; preload; CO
- HR; SV
Walls of arteries and veins (but not the __________) have three layers (tunics)
1. _____________:
-
2. _____________:
-
-
-
3. _____________:
-
Capillaries
1. Tunica interna
- endothelial
- Tunica media
- smooth muscle
- collagen
- elastic tissue - Tunica externa
- connective tissue
________ to __________ sized arterial specializations
- _____________________: at the border between internal and media
- _____________________: at the border between media and externa
- __________ during systole and ________ during diastole
- ______________ takes pressure off smaller downstream vessels
- ___________ maintains pressure during relaxation, keeps blood flowing
medium; large
- internal elastic lamina
- external elastic lamina
- expand; recoil
- expansion
- recoil
____________ are exchange vessels
- where __________, ___________,________, and ___________ pass between blood and tissue fluid
- composed of ___________ and ___________
- absent or scarce in ______________, _____________,_____________,___________ and, __________ of the eye
Capillaries
- gasses; nutrients; wastes; hormones
- endothelium; basal lamina
- tendons; ligaments; epithelia; cornea; lens
Three capillary types distinguished by ___________
1.
2.
3.
permeability
1. Continuous capillaries
2. Fenestrated capillaries
3. Sinusoids
Continuous capillaries
- Occur in _______ tissues and organs
- Endothelial cells have _________ junctions
- form a continuous tube with ____________ ______
- allow passage of solutes such as ________
- _________ wrap around the capillaries and contain the same contractile protein as _________
- contract and regulate blood flow
- MOST
- tight
- intercellular clefts
- glucose
- pericytes; muscle
Fenestrated capillaries
- Found in organs that require…….
- examples: ________, _________, __________
- Endothelial cells riddles with holes called _________ __________ (fenestration= windows, openings)
- spanned by very thin glycoprotein layer
- allow passage of only _______ molecules
- proteins and larger particles stay in bloodstream
- rapid absorption and filtration
- kidneys, small intestine, choroid plexus (CSF)
- filtration pores
- small
Sinusoids
- found in ________, ________, __________
- ____________ blood-filled spaces with large ______________
- allow ________ (_________), __________ factors, and new ______ ______ to enter the circulation
- liver, bone marrow, spleen
- irregular; fenestrations
- protein (albumin); clotting; blood cells
Capillary beds are networks of ______ to ______ capillaries
- usually supplied by a single ________ or _______
- drain into _______ or distal end of __________
- at any given time, ____% of body’s capillaries are shut down
- most control involves constriction of _________ arterioles
10 to 100
- arteriole; metarteriole
- venule; metarteriole
- 75%
- upstream
_______________ control blood flow in capillary beds supplied with _____________
precapillary sphincters;metarterioles
Precapillary sphincter
- when sphincters are __________, capillaries are well perfused with blood
- when sphincter ________, they constrict the entry to the capillary and blood by passes the capillary
- relaxed
- contract
