Review and circulatory system

Posted by Deneb on April 19, 2006, at 16:06:53 [reposted on April 19, 2006, at 20:34:24 | original URL]

In reply to Me either... summer has set in (nm) » Deneb, posted by Gee on April 19, 2006, at 15:06:14

Okay, I'm desperate...
I'm going to write my study notes here. I need some incentive to study efficiently. I'm going to teach people here what I know. Here I go!
Please tell me if I'm incorrect in something!
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The hypothalamus links the nervous and endocrine system.
In the sympathetic system there are adrenergic fibres that release noradrenaline.
In the parasympathetic system there are cholinergic fibres that release ACh.
The adrenal gland is made up of the adrenal medulla, and the adrenal cortex. In the adrenal medulla there are chromaffin cells.
Stimulation of alpha adrenoreceptors cause vasoconstriction.
Stimulation of beta1 adrenoreceptors increase heart contraction rate and strength. ( ve chronotrophic and inotropic)
Stim. of beta2 receptors cause vasodilation.
Steroids and thyroid hormones are lipid soluble, are transcription factors, cause long lasting effects.
Peptides/proteins and catecholamines are lipid insoluble. Involve a 2nd messenger and amplificatiion. Rapid, short lived responses.
Hypothalamo-Hypohyseal complex
- hypothalamus
- pituitary gland
- infundibular stalk
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Circulation
Circulatory system functions
- transport of materials and heat
- production of force
Design of circulatory systems
- pump, vessels, circulating fluid
- kinds of pumps...positive and negative pressure pumps...chamber, persistalic
Open vs Closed systems
- open...incomplete vessels...haemolymph, high vol, low pressure, limited capacity to alter velocity and distribution of blood flow
- closed...high pressure, differential distribution of blood flow possible
Undivided vs Divided systems
- undivided...one circulation, no separation of oxygenated and deoxygenated blood
Fish
- single circulation
- 2 resistance beds, gills and tissues
- gills must withstand high pressure
Birds/Mammals
- separate systemic and pulmonary circulations
- equal blood flow in separate circuits
- lungs need low pressure, otherwise edema
Intermittent Air Breathers
- single circulation
- selective distribution of blood flow to lungs, skin and body
- eg. Lungfish...oxy blood to branchial arches 3 and 4 to tissues...deoxy blood to arches 5 and 6 (gills)...bypasses lungs via ductus
Heart
- atrioventricular, aortic and pulmonary valves
- sinoatrial node, atrioventricular nodes, atrialventricular bundle, Purkinje fibres
Action Potentials spread via gap junctions
Neurogenic vs myogenic hearts
Pacemaker potential is unstable b/c of Na leak
Chronotropic effects
- Parasym innervation...ACh increase k conductance of pacemaker cells
- Symp innervation and catecholamines...increase Na and Ca2 conductance...decrease K conductance
Cardiac Action Potential
- open voltage-gated Na channels
- slow opening of voltage-gated Ca2 channels
- closure of voltage-gated K channels
Electrocardiogram
- atrial depolarization - P
- atrial repolarization - lost in QRS
- Ventricular depolarization - QRS
- Ventricular repolarization - T
Tension is proportional to [Ca2 ]
Cardiac output = (stroke vol)(heart rate)
Q = SV*HR
Frank-Starling Relationship
- SV is proportional to diastolic filling
Delta P = QR
R is proportional to L*n/delta P
compliance = deltaV/deltaP
Windkessel vessels
- aorta, arteries
- large r, low R
- little P drop
- compliant elastic walls dampen pressure oscillations to maintain continuous flow
Precapillary resistance vessels
- small arterties, arterioles
- small r, high R, great P drop
Precapillary sphincters
Capillaries
- low velocity
Post-capillary resistance vessels
- venules, small veins
- r can be adjusted
- adjustment of P across capillary beds
Capacitance Vessels
- veins
- 50% of total blood vol
Fainting
- blood pools in veins
- decrease venous return
- decrease cardiac output
- decrease arterial pressure
- decrease blood flow to brain
Capillaries
- 1 mm long, 3-10 micrometer diameter
- endothelial cells, basement membrane
- Fick equation
Amount transferred = (gradient)(permeability)SA/T
- continuous capillary
- fenestrated capillary (kidney)- pores
- sinusoidal capillary - paracelluar gap
Fluid exchange
- Hydrostatic P
- Osmotic P
Starling-Landis Hypothesis
- arterial side - net filtration
- venous side- net absorption
Filtraion > Absorption
- Net fluid loss...need lympatic system
Oedema
- increased BP
- lympathatic failure
- reduced proteins
Blood
- Plasma...albumins, globulins, fibrinogens
- RBC, WBCs
- Haematocrite = %RBCs/vol
Blood Pressure
- Acute
deltaP = QR
- adjust heart rate and R
Baroreceptors
- respond to pressure as stretch of vessel walls
- located in carotid sinus and aortic arch
- increase BP...increase baroreceptor firing
- at normal BP, there is tonic baroreceptor firing
Decrease Arterial BP
- decreased baroreceptor firing
- decrease parasymp activity (vagus)... ve chronotropic, increase cardiac output
- increase symp activity... ve chronotropic, ve inotropic...increase cardiac output
- increase symp activity...vasoconstriction...increase peripheral R
Regional Circulation
- ischemia, hyperemia...active and reactive
Controlled by...
- local, neural and hormonal
- arterioles, pre-capillary sphincters
Sympathetic nerves (adrenergic fibres)
- norad
- alpha receptors...vasoconstriction
- brain, heart lact alpha receptors
Catecholamines (adrenaline) from adrenal medulla
- beta receptors
- beta2 vs beta1 in heart
Local control
- heat, nitric oxide, histamine
- metabolic activity...decrease O2, increase CO2, increase [H ], increase heat
Exercise
- increase O2 consumption 5-10x
- increase heat dissipation
- increase blood flow up to 7x
1. Hyperemia in muscles
- symp. cholinergic stim
- local metabolic changes
2.Increase cardiac output
- ve inotropic, ve chronotropic
= venous vasoconstriction...increase venous return
3. Peripheral vasoconstriction
- alpha1 receptors on gut, kidney, etc.
Constant BP
- muscle vasodilation > vasoconstriction therefore decrease R
- increase cardiac output
Exercise
- increase symp activity
- ACh and metabolic factors
- vasodilation in skeletal muscles
- Norad...gut and kidney..vasoconstriction
...heart...increase Q
...veins...increase venous return, increase cardiac output (Q)

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I can't study!!! Deneb 4/19/06
Me either... summer has set in (nm) » Deneb Gee 4/19/06
Review and circulatory system Deneb 4/19/06
Re: I can't study!!! Deneb 4/19/06
Re: I can't study!!! » Deneb muffled 4/19/06
Re: I can't study!!! Deneb 4/19/06
Re: I can't study!!! » Deneb Phillipa 4/19/06
Re: I can't study!!! poss. trig Deneb 4/19/06
Re: I can't study!!! Deneb 4/20/06

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