Hormones Flashcards
Describe the 1st experiment on hormones
Loss of function: castrate chickens.
- if you castrate, they will develop without the wattle/tail and be non agressive/won’t mount.
- if you reintroduce testes when young into the abdomen (no innervation) it restores appearance and behavior.
- if you reintroduce later in life, no effect, no restoration of function.
Activational effects, but timing is critical.
Chemical signals via the blood.
what is a hormone?
released primarily by glands Ibut also other tisses) into bloodstream (but also locally) by animals (but also some alamones in plants)
Exocrine: out (sweat/tears)
Endocrine: chemical within the body
What are the different crines and mones?
Endocrine: into bloodscream
Neurocrine: nervous system standard synapse
Autocrine: hormones and NT. On the same cell, negative feedback mechanisms
Paracrine: release locally, not into bloodstream always. (extracellular fluid in local area) signal weakens and diffuses as it spreads out.
Pheromone: within same species
Allomone: to other species.
What are the general rules of hormone function.
- much slower effects, gradual. (hours-weeks)
- early exposure can have lifelong effects, whereas NT can just last minutes.
- No polarity (on off behaviors) but more “increased likelihood” of a behavior (i.e. during mating season reptiles are more likely to engage in sex?)
- Hormones influence ur behaivor and behavior influences your hormoens. Reciprocal.
- mulciplicity: different hormoens cause same effects in one target and same horrmones can cause different effects in different targets. Mediated by receptor types.
- Pulsatile and rhythmic: hormones released to a rhythm (circadian, menstrual), its in little burts with long lasting effects, don’t need a steady drip
- Hormones interact with other hormones or with cofactors.
- Hormones need receptors to act (like NT)
- DOn’t have to be on plasma membrane, can be intracellualr!
Describe the hypothalamus and neuroendrocrine cells.
Hth: junction between NS and endrocrine system. HTh contains neuroendocrine cells (neurosecretory).
Where the BBB is less existant/more porous. Need the communication between hypothalamus and bloodstream. Behaves mostly like neurons. Post synaptic potential released hormone instead of transmitter.
Some hormones are also NT (epi and noepi)
What are the types of hormones?
Peptides: small proteins/large??
Amine: single amino acid, monoamine can be same as NT (noepi, epi). Only some can cross plasma membrane.
Steroid: 4 ring structure, can pass plasma membrane.
What are the hormone receptor types?
At the membrane: GCPR: faster (versus NT where they’re slower) no entry, no pore. only g coupled proteins that run off and do jobs for us. Activating kinases, enzymes, protein complexes. Small signals that cause large signal cascades.
Intracellular: usually near nucleus, TRANSCRIPTION FACTOR so steroid hormone goes through membrane, becomes activated when steroid binds with receptor and become transcription factor. they regulate gene transcripton (up or down) Takes a LOT longer. Steroid hormones can have GPCRs too !!
How do we measure hormones and receptors.
Radioactivity: release positrons to be measured
Antibodies: targets like antigens, you can see wehre tis bonding with a fluorescent marker.
Radioimmunoassay: measure hormone levels in the blood. Behavior then blood sample, radioactive antibody that will bind to hormone in the blood.
Autoradiopraphy: brain areas effected by the hromone. Insert radioactive hormone, when it circulates and binds, kill animals and shows where its bound in the brain.
Immunohistochem: stain tissue: immunocytochemistry cells in a sepcific subsection. Use antibody technique. antibody will bind where receptors are.
In Situ Hybridization: target messenger RNA, create complementary strnad, label it, insert into tissue slice, shine light and see wehre that RNA is. See changes in RNA expression in response to events/neg feedback etc..
Where can you find negative feedback mechanisms?
Autocrine: neg feedback
Hypothalamus: change in behavior and perceptions sent to hypothalamus.
Pituitary and hypo.
*** becca
Whats the pituitary gland like in GENERAL?
NS/endocrine intersection. Connected by infundibulum (pit stalk) Release hormones (Hth) which cause tropic hormones to be released from pituitary which causes hormones to be released from the gland and then get them to the target!!
Describe posterior pituitary. What do the areas do?
HTh has neuroendocrine cells in paraventricular and supraoptic nuclei. Axons travel dwon infundibulum to post pituitary. These Hth axons terminate on capillaries which release OXYTOCIN and ADH (vasopressin/antidiuretic hormone) into the blood. Both paraventricular and supraoptic release both oxy and adh.
oxytocin: uterine contractions, milk letdown, pitocin: artificial oxytocin to induce labour. Sucking and conditioned response to baby crying will induce letdown.
vasopressin: constricts blood vessels and aids in water retention. Special type of calcium L channels inhibited when you drink alcohol which inhibits ADH release, meaning you have to pee a lot - become dehydrated.
L type calcium channels usually used for exocytosis
Describe the anterior pituitary
Neuroendocrine cells Terminate at median eminence, HTh release hormones, carried 2mm by the hypophyseal portal veins. When they reach targets in ap, the ap releases tropic hormones into the bloodstream which go to glands to cause further hormone release.
What are the hormones of the anterior pituitary?
ACTH: adrenal cortex
TSH: thyroid
LH and FSH: lutinizing and follicle stimulating: testes and ovaries (gonads) (from GnRH at the hypothalamus)
Prolactin: mammary glands. parental behavior and promote lactation.
GH: bones: many things while you’re sleeping mostly.
Somatotropic horone (released from hypothalamus during sleep) INfluence protein metabolism. Related to chronic stress (less GH release)
Describe the adrenal gland
Adrenal cortex (80%): get signals from anterior pituitary.
- releases steroid hormones
- glucorticoids (cortisol)
- regulate glucose metabolism
- mineralocorticoids (aldosterone) ionic balance. Mineral corticoids. Sodium levels in body for aldosterone act on KIDNEYS to stop urination for salt retention.
- sex steroids (antrostenedione) organizing body hair.
- MADE ON DEMAND. can’t have them running about in the body cause they can cross plasma membranes.
Adrenal medulla: get signals from direct innervation from ANS (para and sympathetic NS- efferent)
- release amine hormones like epi and noepi.
- increase heart rate, take in more air, blood retained in core, noepi in your brain under stressful events too.
FAST ACTING stress hormones.
What’s the thyroid gland?
Release thyroid hormones (around adams apple)
- thyroxine, triiodothyronine which regulate basic metabolism.
- and calcitonin: promote calcium storage in bones. If you have thyroid issues, you have bones and calcium retention.
-They are Amines that act like steroids (can cross plasma membrane)
- Iodine is used in the thyroid, changes in diet can change thyroid function (iodized salt)
Regulate growth and metabolism.
Hyperthyroidism: changes in alertness, awakeness, cognition, depression.
Diet is big contributor.
