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
________= “blood reservoirs”
- thin-walled and ________
- collapse when empty, expand easily
- have ______ blood flow (unlike pulses in arteries)
- subjected to relatively low ______ _______ (averages ____ mm Hg with little fluctuation)
Veins
- flaccid
- steady
- blood pressure (10 mm Hg)
Variations in Circulatory Pathways
1.
2.
3.
- Simplest pathway
- Portal System
- Anastomosis
Simplest Pathway
- _________–> _______–> ________–> __________—>__________–>_________
- in this route, blood passes through _______ _______ network of capillaries from the time it leaves the heart until it returns
- heart; arteries; arterioles; capillaries; venues; veins
- ONLY ONE
Portal system
- blood flows through ________ __________ capillary networks before returning to the heart
examples:
- between _____________ and ___________
- in __________
- between ____________ into _________
- two consecutive
- hypothalamus; anterior pituitary
- kidneys
- intestines; liver
Anastomosis
- convergence between _____ ____________ other than capillaries
- two vessels
- ______________: amount of blood flowing through an organ, tissue, or blood vessel in a given time (mL/min)
- at rest, total flow is quite ________ and is ______ to the cardiac output (5.25 L/min)
- ____________: flow per given volume or mass of tissue in a given time (mL/min/g)
- Blood flow
- constant; equal
- Perfusion
______________: physical principals of blood flow based on pressure and resistance
- The ________ the pressure difference between two points, the ________ the flow
- The ___________ the resistance the ______ the flow
- hemodynamics
- greater; greater
- greater; less
__________________= average systemic pressure minus central venous pressure (the pressure in the large veins at the end of diastole, this is close to 0 mmHg)
pressure difference
Three Factors of resistance
1.
- large blood vessel= ___________ resistance
- small blood vessel= ___________ resistance
2.
-
3.
- this _______ change on a moment to moment basis, but it is estimated for each pound of fat you gain, an estimated ______ miles of blood vessels are added!
- diameter of the blood vessel
- less
- more - blood viscosity (thickness of blood)
- increased viscosity, increased resistance - Length of blood vessels
- DOESN’T; 200
(water flowing down a stream into a lake)-> (goes fast down a stream but slower once it hits the lake)
Blood pressure (BP) two pressures:
1.
2.
- normal value for young adult: __________ mm Hg
- Systolic
- Diastolic
- 120/75
- _____________: important measure of driving force on circulation and of stress exerted on small arteries by pressure surges generated by the heart
- ____________: average blood pressure that most influences risk level for _______, _________ (_________), ____________, ______________, and ____________
- pulse pressure
- mean arterial pressure (MAP)
edema; fainting (syncope), atherosclerosis, kidney failure, aneurysm
Formulas for
- Pulse pressure=
- Mean arterial pressure (MAP)=
- Systemic vascular resistance (SVR)=
PP= systolic - diastolic pressure
MAP= diastolic pressure + 1/3 (pulse pressure)
SVR= MAP/CO
_______________
- high blood pressure
- Chronic resting BP > ________
- Consequences:
- can __________ arteries, cause _________, promote ____________
hypertension
- 140/90
- weaken; aneurysms; atherosclerosis
____________
- chronic low resting BP
- caused by _______ _______, ____________, _________
hypotension
- blood loss; dehydration; anemia
BP determined by three variables:
1.
2.
3.
- cardiac output
- Blood volume
- resistance to flow
_________________: opposition to flow that blood encounters in vessels away from the heart
peripheral resistance
Blood viscosity
- ______ count and _______ concentration raise viscosity the most- _________ resistance (_______ flow)
- low viscosity with ________ and _____________, ________ flow
- high viscosity with _____________ and ___________, _____ flow
- RBC; albumin; increase; decrease
- anemia; hypoproteinemia; speeds
- polycythemia; dehydration; slows
Vessel length
- farther liquid travels through tube, the more cumulative friction it encounters
- pressure and flow _________ with distance
- decline
