Fundamentals & The Hypothalamo-Hypophysial axis Flashcards
Functions of the Endocrine System?
- Growth and development
- Sex differentiation
- Metabolism
- Adaptation to an ever-changing environment
Hormones function how?
They move through what to distant target sites of action?
WHat if they act more locally? 2
chemical messengers
blood/lymph
paracrine or autocrine messengers
- Endocrine intracellular communication happens how?
- Neuroendocrine intracellular communication happens how?
- Paracrine intracellular communication happens how?
- Autocrine intracellular communication happens how?
- Hormone is released from cell and travels through the blood to the target cell
- neuron relased hormone travels through the blood to the target cell
- Cell releases hromone, travels through interstitial fluid to target cell
- Hormone acts on the cell/tissue that released it
Factors Affecting Response of a Target Cell to a Hormone
3
- Blood level of the hormone
- Relative number of receptors
- Affinity of these receptors for hormones
How can the number of receptors be regulated?
2
Up-regulation
Down-regulation
Control of hormone levels can be affected in which type of way?
4
- Affected by fluctuations that vary with the sleep–wake cycle
- Secreted in a complicated cyclic manner
- Regulated by feedback mechanisms that monitor substances such as glucose (insulin) and water (ADH) in the body
- Regulated by feedback mechanisms that involve the hypothalamic-pituitary-target cell system
Examples of hormones that are Affected by fluctuations that vary with the sleep–wake cycle? 2
Example of a hormone that is Secreted in a complicated cyclic manner?
Growth hormone (GH) and adrenocorticotropic hormone (ACTH)
Female sex hormones
IF a hormones is water soluable what is needed for transport of the hormone to the target cell?
What about lipid/fat soluable hormones?
First messenger
Can diffuse through the lipid bilayer and into the nucleus of the cell for use in transcription
Beta blocker up or down regulate a cell?
down regulation (less binded, higher symtpathetic response, higher cardiac output)
What type of neurons act in the hypothalamus and what are their effects seen in?
4
- Autonomic neurons to preganglioinc to postganglioic to
Pancreatic islet releasing insulin - Autonomic neuron to preganglioic to adrenal gland to release adrenaline
- Magnocellular neurosecretory neuron to posterior lobe releases oxytocin and ADH
- Parvocellular neurosectretory neuron release releasing hormones to control a number of hormones in the anterior pituitary
What acts as the first messenger often in hormone effect on a target cell?
What about the second messenger?
What connects them? 2
Hormone itself
cAMP
transducer and effector (G-protein and adenyl cyclase)
What plays an important role in the affinity of insulin receptors?
pH of the body fluids
Where do fat soluable hormones usually bind in the cell?
Where do water soluable hormones usually bind in the cell?
receptor sites outside the cell and also inside the target cell (steroids)
usually only outside the cell (AA derivatives- epi and norepi)
- If capillary blood contains low concentration of Ca2 this will stimulate what?
- What type of stimuli is this an example of?
- Pregnanglionic SNS fiber stimulates adrenal medulla cells to secrete what?
- What kind of stimuli is this an example of?
- The hypothalamus secretes hormones that stimulate the anterior pituitary. What are three examples of organs that this works on?
- What kind of stimuli is this an example of?
- Parathyroid gland to secrete PTH
- Humoral
- catecholamines
(epi and norepi) - Neural
5. Thyroid gland Adrenal cortex Gonad (testes) 6. Hormonal
Diurnal variation in glucocorticoid secretion. Peak glucocorticoid levels are present sometime between?
8 and 9 AM (cardiac events happen when you first get up)
Lowest around midnight
What is the first 14 days of the ovarian cycle called and what are the four (3.5 phases) in it?
What are the last 14 days or so of the ovarian cycle and what are the 2.5 phases in it?
Follicular phase
- primary follicle
- Secondary follicle
- Vesicular follicle
- Ovulaiton
Luteal phase
- Ovulation
- Corpus luteum
- Degenerating corpus luteum
What are the phases of the uterine cycle and on what says do they occur?
3
Days 1-5 menstrual cycle
Days 5-13 Proliferative phase
Days 13-28 secretory phase
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Categories of Hormones According
to Structure?
4
(Cat 2 has 5 in its group)
- Biogenic amines
- Amino acids,
peptides,
polypeptides,
proteins, and
glycoproteins - Steroids
- Fatty acid derivatives
Peptide and Protein Hormones released?
- Hypothalamus -5
- Anterior pituitary -6
- Posterior pituitary -2
- Thyroid -1
- Pancreas -3
- Liver -1
- Parathyroid -1
1. TRH GnRH CRH GHRH Somatostatin
2. ACTH TSH FSH LH PRL GH
- Oxytocin
ADH - Calcitonin
- Glucagon
Insulin
Somatostatin - Somatomedin
- PTH
Peptide and Protein Hormones released?
- Placenta -3
- Kidney -1
- Heart -1
- G.I. tract -6
- Adipocyte -1
- HCG
HCS
HPL - Renin
- ANP
4. Gastrin CCK Secretin GIP Somatostatin GLP-1
- Leptin
There are two groups of hormones derived from the amino acid tyrosine:
2
Name the three specific hormones?
- Thyroid hormones are basically a “double” tyrosine with the critical incorporation of 3 or 4 iodine atoms.
- Catecholamines include epinephrine and norepinephrine, which are used as both hormones and neurotransmitters.
- Thyroxine
- Epinephrine
- Norepinephrine
So tyrosine can either become thyroxine or Epi
What does the initial insulin sequence start as?
When the signal sequence is cleaved what is the chain called?
What is cleaved to make proinsulin into insulin?
preproinsulin
proinsulin
Chain C
What are the three zones in the renal cortex and what do they each make?
middle - 2
outside- 1
inside- 1
What is the important intermediiate for all these?
Zona fasciclutata- cortisol and corticosterone
Zona glomerulosa- aldosterone
Zona reticularis- Androstenedione
Pregenolone
Adipose tissue creates what kind of hormones?
5
What are the hormones called collectively?
adiponection resistin LEPTIN-saitety TNF alpha IL6- paracrine
adipokines
The hypothalamic releasing or inhibitiing hormones are transported through the anterior pituitary how?
Portal vessels
ADH and oxytocin are produced by what kind of cells?
They are then transported through what to the posterior pituitary?
Through what arteries is the pituitary blood supply come from?
nerve cells
supraoptic and paraventricular nuclei of the hypothalamus
inferior and superior hypophyseal arteries
The hypophyseal portal system begins where?
ANd drains where?
hypothalamus
anterior pituitary
What are the acidophils that the anterior lobe of the pituitary secretes?
2
What are the basophils that the anterior pituitary secretes?
GH and prolactin
TSH ACTH FSH LH beta- LH
What does the intermediate lobe of the pituitary secrete?
MSH (melanin stimulating hormone)
Describe what the release of a releasing hormone in the hypothalamus stimulates?
3
- anterior pituitary to release a tropic hormone to excite the target gland.
- This target gland releases a hormone which acts on the target cell
- but also produces inhibiting effects on the ant. pit and the hypothalamus
What stimulates the anterior pituitary to release GH?
What does this inhibit alternatively?
somatotropin releasing hormone
directly inhibits SRH on the hypothalamus (neg feedback)
What does the release of GH from the Anterior pituitary do?
2
- inhibits the hypothalamus from releasing SRH and somatostatin
- Stimulates the liver to produce somatomedin
What does somatomedin stimulate? 2
The present of somatostatin released from what three organs causes what?
- increased levels of somatostatin
- inhibits SRH
Hypothalamus
Anterior Pit
Liver
Inhibits the release of more somatostatin (neg feedback)
The hypothalamus releases what thyroid related hormone?
This affects what organ?
This causes the release of what?
Which works on what?
To release what?
TRH
Thyrotroph cells in the ant pit
TSH
Thyroid follicles to release
thyroid hormones (T3, T4)
What stimulates the production of testosterone?
What stimulates sperm production in men?
Where are these produced and what stimulates the production of these?
LH
FSH
Produced in the anterior pituitary and stimulated by GnRH from the hypothalamus
Five Cell Types of the Anterior Pituitary Gland
Thyrotrophs Corticotrophs Gonadotrophs Somatotrophs Lactotrophs
- Thyrotrophs produce what? 1
- Corticotrophs produce what? 1
- Gonadotrophs produce what? 2
- Somatotrophs produce what? 1
- Lactotrophs produce what? 1
- produce thyrotropin, also called thyroid stimulating hormone (TSH)
- produce corticotrophin, also called adrenocorticotropic hormone (ACTH)
- produce the gonadotropins—leutenizing hormone (LH) and follicle-stimulating hormone (FSH)
- produce growth hormone (GH)
- produce prolactin
