homeostatsis
- Created by: Emilyburkee
- Created on: 22-05-22 15:16
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- homeostasis + cell physiology
- homeostasis= the adjustment of internal conditions to maintain a near constant internal enviroment
- negitive feedback loops
- decrease in conditions due to an increased stimuli or visa versa
- postive feedback
- the chnage in conditions in the same direction as the stimuli
- eg birth and oxytocin
- the chnage in conditions in the same direction as the stimuli
- feedback loops
- sensor
- sensory neurone
- comparator
- motor neurone
- effector
- failure in any of these can lead to disease
- negitive feedback loops
- body fluids
- ecf -14l
- intracellular 28l
- intersital 10.2
- plasma 3-5l
- distribution of Ions
- high K+ and A- in intracellular compartments
- Na and CL higher in extra cellular space
- osmosis = high water pot to low water pot
- osmotic pressure - movement of water mols can excert pressure on walls
- eg cap walls - proteins accumulate in ec space causing odema
- Oncotic pressure, or colloid osmotic-pressure, is a form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel's plasma
- eg cap walls - proteins accumulate in ec space causing odema
- Osmolarity: • The total number of dissolved particles (ions, molecules or mix of both) per litre of solution.
- Osmolality: • The total number of dissolved particles (ions, molecules or mix of both) per Kg of water
- osmotic pressure - movement of water mols can excert pressure on walls
- Action potentials
- Na and K+ are asymetrically distributed across the membrane - by NA/K ATPase
- K is greater inside cells - this means it tends to diffuse out = neg charged membrane
- if K outside were to decrease the less would diffuse out therefore membrane would be more positive
- VG channels = allow K out and NA in - only open when the membrane is depolaried enough
- ligand gated = allow NA or K in/out when ligand binds to surface
- are cation-selective (mainly Na+ flow into the cell). When activated cause depolarisation and make the cell more excitable
- excitable. • Some ligand-gated channels are anionselective (mainly Cl- flow into the cell). These channels when activated cause hyperpolarisation
- propergation of an AP
- myelination- increases conduction velocity as less SA needs to be depolarised
- salitory conduction
- myelination- increases conduction velocity as less SA needs to be depolarised
- Na and K+ are asymetrically distributed across the membrane - by NA/K ATPase
- nervous system
- somatic
- vountary action
- one neurone
- autonomic
- non-voluntray
- sympathetic
- pre release acetylcholine binds to nicotinic
- post release noradrenaline bind to andrgenic
- adreanal medulla
- relases catacholine
- innervated by preganglionic neurones.
- parasympathetic
- 'rest and digest'
- pre and post ganglionic neurones = acetylcholine
- pre = nicotinic. post = murengic
- somatic
- muscles
- tension length relationships
- no shortening but increase in passive tension = active twitch
- isometric
- starlings law in heart = variation of lengths
- The functional contractile unit
of a striated muscle fibre
• The region of the myofibril
between two successive Z discs
•Composed of myofilaments
made up of contractile proteins
- during contration = migrated to m disk
- no shortening but increase in passive tension = active twitch
- motor unit = the mucles and the nerve its innervated with
- NM junction
- ca = faclitates relase of ACH which binds to nitcotinc receptors- ca relased from SR = binds to tropomyosin
- tension length relationships
- homeostasis= the adjustment of internal conditions to maintain a near constant internal enviroment
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