Summary
Summary PSL300 Final Exam Review
- Course
- PSL300 (PSL300)
- Institution
- University Of Toronto (U Of T )
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PSL300Final Exam Review
Lecture 1:
Physiology
- The science of how the body functonss It spans from molecules to organismss Molecules -> cells
-> tssues -> organs -> organ systems -> Organisms -> populatons of organisms
Homeostasis
- The process of maintaining a constant internal environment despite changing conditonss Claude
Bernard 1880s: “The constancy of the internal environments Cannon 1920’s: Regulaton of
internal environment
Local Control
- Change in immediate vicinity
- Paracrine or Autocrine
Reflex Control
- Coordinaton of the reacton lies outside the organ that carries out the response
- Nervous system, endocrine system, or both
Positive Feedbaac$
- An inital stmulus leads to a response, producing the same stmulus, looping back to the
responses An outside factor stops the loop via feedback
Negative Feedbaac$
- Inital stmulus leads to a response, cause an increase or decrease in stmulus
- Much more common than positve feedback
Feedb forwardb
- Antcipatory response (ises salivaton, antcipate foodt
Bloodb Pressure regulation
- When blood pressure is low, sensory receptors in the aortc and carotd sinuses sense it
- The signal goes to the regulatory center in the brain
- The arterial wall constricts
- Reversal, BP rises
- Constrictng arterial walls results in an increase in blood pressure
,Oxytocin andb uterine contractions
- Baby pressed against cervix, causing uterine stretch
- Oxytocin release, uterine contractons, causing the baby to press against cervix more
- Loop ends when the baby drops
Feedbaac$ control
- Stmulus receptor/sensor, aferent pathway Integratng center eferent pathway
Target of efector response
- Aferent = going towards something (no aferent in endocrine relext
- Eferent = going away from something
- Efector = target
- Aferent = informaton towards brain
- Eferent = informaton away from brain
Biological Rhythms
- Result from changes in a set point, ises body temperature drops at night, raises towards noon,
drops at night
- Cortsol increases in morning, peaks at noon, lowest at night
Endbocrine Systems
- No response unless the cell has a receptor on it
Maintaining homeostasis andb other aodby functions requires intracellular communications
at Gap Junctons: ises for Calcium, ATP, found in heart, kidney, direct cytoplasmic transfer
bt Contact dependant Junctons: membrane protein interactons, reeuires Cell Adhesion
Molecules, which act as receptors, linked to cytoskeleton, intracellular enzymes
ct Autocrine signals : same cell
dt Perecrine: actvated on one cell, difuses out, example: histamine, released upon injury
Where are hormones prodbucedb?
Primary endbocrine organs
- Pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal
gland, pancreas, ovaries, testes, placenta
Secondbary
- Heart, stomach, liver, kidney, small intestne, skin, adipose tssues
Nervous system
, - Localized/specific efect
- 1t Neurotransmitters are chemicals secreted by neurons that difuse across a gap to the target
- 2t Neurohormones: released into the blood for acton by diferent targets
- 3t Neuromodulators: neurocrine that acts slowly as paracrine or Autocrine signal
Systems:
- Exocrine system Into a duct
- Endocrine: into the blood
How were early hormones idbentiiedb?
- Remove gland, check efect
- Replace gland/extract
- Implant gland/extract to create excess, observe efect
- Purify extract and test for efect in biological assay
Lecture 2: Classiication of Hormones andb control of release
221-232
Hormone Features:
- Can be made in diferent parts of body ises somatostatn made in hypothalamus and pancreas
- Chemicals made by cells in specific endocrine glands of other tssues
- Transported in blood to distant target
- Binds to specific receptors
- May act on many tssues
- Alter actvity of target cells
- Acton must be terminated
- Maintain homeostasis or precipitate change in many physiological processes
Posterior Pituitary
- Secretes vasopressin and oxytocin
Anterior Pituitary
- Secretes prolactn, TSH, ACTH, GH, FSH, LH
- Hormones stored in vesicles, brought from hypothalamus to the pituitary
Singe preprohormone can contain several copies of the same gene
- Splitting of PPH gives a hormone, other peptdes and a signal seeuence
- Can give more than one type of hormones
- Synthesis of peptde hormone:
, 1t MRNA on the ribosome binds AAs into a peptde chain called a preprohormones The chain is
directed into the ER lumen by a signal seeuence of AAs
2t Enzymes in the ER chop of the signal seeuence, creatng an inactve prohormone
3t The prohormone passes from the ER through the Golgi complex
4t Secretory vesicles containing enzymes and prohormone bud of the Golgis The enzymes
chop the prohormone into one or more actve peptdes plus additonal peptde fragments
5t The secretory vesicle releases its contents by exocytosis into the extracellular space
6t The hormone moves into the circulaton for transport to its target
Peptidbe/Protein hormone (Processingi
- Formaton of disulfide bonds
- Glycosylaton
- Insulin synthesized as single prohormone
- Disulfide bonds and cleavage, c part clipped
Steroidb Hormones
- Synthesized only from cholesterol
- Made on demand
- Released by simple difusion
- Water insoluble (bound to carriers in blood that protect themt
- Long half life
- Cytoplasm or nuclear receptors are targets (but in some cases, also act on plasma membrane
receptors which gives a rapid efect, ises testosterone
3 Types of hormones
- Peptde/protein (3 AAst
- Steroid (derived from cholesterolt
- Amine (single AA derivedt
Peptidbe Hormones i.e. glucagon
- Most hormones
- Made in advance
- synthesized like secreted proteins
- Stored in vesicles
- Released by exocytosis upon a signal
- Water soluble (dissolve in plasmat
- Short half-life ises 30 minutes
- Binds to membrane receptors
- Most protein hormones are prohormones
- Need to mature in the ER, reeuires cleavage, fragments are inactve
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