Lecture 3 Flashcards
Hormonal messengers can travel…
Anywhere in the body
1mm - 2 meters
Analogy of Neural transmission vs Hormonal communications
Neurotransmission: Train track (FAST))
Hormones: Bicycle (several paths but SLOW)
Hormone can have double action in diff tissues
e.g Epinephrine Hormone has double action in Liver cell with Beta receptor and blood vessel with beta receptor
Forms of Chemical Communication
Intractrine meditiation -> intracellular events
Autocrine -> Same cells that secreted them
Paracrine mediation-> affect adjacent cells
Endocrine mediation -> travel to distant targets
Ectocrine -> release into environment like pheromones
Diff between NT and Horomone
How they communicate
Neurohormone
Produced by neuron
Neuromodulator
Modulates response of a neuron to other factors(testorstorone)
Endocrine System
Endocrine glands - ductless, has rich blood supply, hormones secreted into the blood stream, can travel to virtually every cell in the body and can potentially interact with any cell that has appropriate receptors
Exocrine glands - outside the body
Pancreas
Pancreas
Has both endocrine and exocrine glands
Resistance
If we don’t have enough receptors then we have resistance
Type 2 diabetes is…
Insulin resistance
Regular levels of insulin secretion are not sufficient to uptake the sugar levels in blood and transport to the inside of the cell
Cross reaction
When the blood concentration of a hormone is high binding with receptors that are specific for other related hormones reactions can occur causing a biological response
Polypeptides
Hydrophilic
Insulin
Epinephrine
Steroids
Hydrophobic
Cortisol
Amines
Epinephrine - Hydrophilic (Water-soluble)
Thyroxine - Hydrophobic (Lipid Soluble)
Lipid-soluble horomones
Testosterones
Progesterone
Need a carrier protein
Water-soluble horomones
Do not need a carrier
Need a receptor to get into the cell
Pathway hormone goes through depends on
Action of hormone
Hormones to learn: Slide 9 (Study)
Insulin, thyroid hormone, parathyroid hormone
Steroids like estrogen androgens testosterone and cortisol
Hypothalamus
Control of hormone secretions
Thyroid
Growth and development; metabolic rate
Adrenal glands (on top of kidney)
Placenta -important female endocrine organ
Auxiliary organ necessary for embryonic development
Chorionic hormones are produced by placenta
Main releasing hormones:
thyrotropin releasing hormone (TRH)
growth hormone releasing hormone (GHRH, somatocrinin)
Main inhibiting hormones:
somatostatin (growth hormone, gonadotropin inhibitory hormone and dopamine DA)
Corticotropin Releasing Hormone (CRH) -Hypothalamus
Excitatory Hypothalamic hormones
Synthesized within the anterior portion of the paraventricular nuclei of the hypothalamus (Pva) and it stimulates the secretion of adrenocorticotropic hormone)
Nourishes the adrenal glands
Gonadotropin releasing hormone (GnRH) - Hypothalamus
Controls release of luteinizing hormone in the follicle stimulating hormone
LH and FSH are fundamental in communication with the gonads
Tropic
Nourishment`
Growth Hormone Releasing Hormone -Hypothalamus
Tells the gland that produces growth hormone to release the GH
Secreted in VMN and arcuate nuclues of the hypothalamus
Thyrotropin-releasing hormone (TRH) - Hypothalamus
Stimulates cells in the anterior pituitary gland to produce and release thyroid-stimulating hormone (TSH)
Melanotropin releasing hormone (MRH) - Hypothalamis
Hexapeptide that stimulates the secretion of melanotropin
Kisspeptin - Hypothalamus
Has an important role in initiating secretion of gonadotropin-releasing hormone (GnRH) at puberty, involved ins sexual maturation
Inhibitory Hypothalamic hormones - Hypothalmus
Dopamine (DA) -arcuate nucleus, primary prolactin-inhibitory hormones
Somatostatin (SOM) - growth hormone inhibiting hormone
Pituitary hormones
Pituitary receives a lot of commands from the hypothalamus
Anterior pituitaryvs
Develops from embryonic structure that comes from the roof of the mouth and migrates to the final location of the brain
Posterior pituitary
Outgrowth from base of the brain
Anterior pituitary hormones - SLid 16
Posterior pituitary hormones
Axonal projections from hypothalamus
Neurohormones are directly secreted into structure
Vasopressin - Pituitary Posterior
HPT
hypothalamus->pituitary->thyroid
Specific thyroid hormones
T3(triiodothyronine) and T4(thyroxine)
Thyroglobulin
Precursor of T3 and T4 that people get for thyroid treatment
Hyperthyroidism
Overactive thyroid
Hypothyroidism
Underactive thyroid
Three general effects of thyroid hormones in mammals
Affect metabolism
Alter growth and differentiation
Influence reproduction
Parathyroid hormones
Elevates blood levels of calcium (Ca2+)
Increases reabsorption of Ca2+ from the bone and from the gut
Calitonin
Released from the C cells of the thyroid
CT acts in opposition to parathyroid hormone to lower levels of calcium by inhibiting the release of Ca2+ from the bone
Both Parathryoid and Calcitonin hormones…
Are controlled by blood calcium levels (no releasing hormones acting)
Pancreatic hormones
Both endocrine and exocrine gland
Consists of exocrine cells that produce and secrete digestive juices into the intestines
Nested throughout the exocrine tissue are islands of endocrine tissue called islets of Langerhans
4 cell types in islets of Langerhans
alpha cells
beta cells
delta cells
polypetide secreting cells
alpha cells in pancreas
produce glucagon
glucagon travels to licer and stimulates glycogenolysis (breakdown of stored glycogen)
Acts in opposition to insulin
Serves to increase blood levels of glucose
beta cells
Insulin acts in these cells first
Diabetes is caused by decreased response to insulin
The insulin molecule is concserved through evolution
Insulin is the only known hormone that can lower blood sugar
Delta celles
Produce somatostatin (inhibitory)
inhibits the release of insulin and glucogons in the pancreas
also released from hypothalamus to to regulate the release of GH from the anterior pituitary
THE DISCOVERY OF INSULIN
Watch the video
