L2. Neuro-endocrinology and Reproductive Endocrinology Flashcards
How many grams of hormone-producing tissue are there in the body?
Only about 100 g
What is an example of a purely endocrine organ?
The pituitary gland
What are 2 examples of partial endocrine glands?
The pancreas and the gonads
What are some examples of marginally endocrine glands? (2)
Adipose tissues making leptin (satiety hormone)
Enteroendocrine: G cells making gastrin, duodenum making CCK
What are the three broad types of hormone and how are they sorted?
Sorted by chemical composition and solubility
- Amino acid derivatives (includes both catecholamines and thyroid hormones)
- Peptide derivatives
- Lipid derivatives
What are the three forms of endocrine regulation?
- Hormonal
- Neural
- Humoral
Which type of hormone has the shortest half-life?
What are the 3 modes of hormone action?
- Endocrine - acts far away
- Paracrine - acts locally
- Autocrine - acts on itself
There are two types of hormone recognition, what are they, which is faster, and why?
Indirect is much faster, the cascade of messengers causes there to be amplification/potentiation between levels due to signal transduction (converting one type of signal to another) resulting in a very fast and powerful response.
Direct works slower, as it binds directly to genes and causes a response - which prevents it from working elsewhere, etc.
What are four factors that affect how effective a hormone will be at a target cell?
- Receptor affinity to hormone
- Number of receptors
- Hormone (ligand) concentration - needs to be at a physiological level to achieve response
- Receptor up and down-regulation (also known as sensitisation/desensitisation; linked to the number of receptors)
What is an example of an antagonistic hormone pair?
Glucagon and insulin (with the exception of a high protein meal, when these hormones will be synergistic)
What is an example of a synergistic hormone pair?
Glucagon and adrenaline, one enhances the other by changing the receptor action
What is an example of a permissive hormone pair?
Thyroid hormone being necessary for steroid hormones to trigger the development certain parts of the reproductive system
How can you terminate a hormonal signal? (3)
What are the three parts of the hypothalamus-pituitary axis? (Hint: two of the three are listed in the name)
Hypothalamus
Pituitary gland
Infundibulum
Oxytocin and ADH are made by what specific nuclei in the hypothalamus? (2)
Paraventricular and supraoptic nuclei
What is the name of the neural component of the hypothalamus-pituitary axis?
Hypothalamic-hypophyseal tract
Is the neural part of the pituitary gland anterior or posterior?
Posterior - neural section is closer to the brain. Duh
Paraventricular nucleus (produces oxytocin)
Supraoptic nucleus (produces ADH)
What is the name of the hypothalamus-adenohypophyseal connection of the hypothalamus-pituitary axis?
Hypothalamohypohyseal portal system
What is the hypophyseal portal system comprised of?
What are the three nuclei of the hypothalamohypophyseal portal system?
If you’re going through a portal, don’t forget to take a MAP
Medial pre-optic
Arcuate
Paraventricular
The pituitary gland is located below the ______ in the ______ ______ of the _____ bone
The pituitary gland is located below the hypothalamus in the sella turcica of the sphenoid bone
The pituitary gland secretes at least ____ different hormones
Nine
The anterior part of the pituitary gland, the adenohypophysis, is derived from an _________ of the _______ _______ towards the brain; it is specifically called?
The anterior part of the pituitary gland, the adenohypophysis, is derived from an evagination of the oropharynx ectoderm towards the brain; it is specifically called Rathke’s pouch
What is Rathke’s pouch?
The specific name for the evagination of the oropharynx ectoderm that will ultimately form the adenohypophysis
What specific parts of the adenohypophysis will be formed by Rathke’s Pouch? (3)
- Pars distalis
- Pars intermedia
- Pars tuberalis
What is the posterior part of the pituitary, the neurohypophysis, derived from?
A down growth of the neuroectoderm of the brain floor
What specific parts of the pituitary gland does the neurohypophysis make up? (2)
The infundibulum and the pars nervosa
Somatotropes and lactotropes are both examples of?
Acidophilic endocrine cells
What are two examples of acidophilic endocrine cells?
Somatotropes and lactotropes
Corticotropes and gonadotropes are both examples of?
Basophilic endocrine cells
What are two examples of basophilic endocrine cells?
Corticotropes and gonadotropes
What are chromophobes?
Chromophobes are pituitary cells that by light microscopy lack stainable cytoplasmic secretory granules, and represent degranulated chromophils, inactive reserve cells, and/or undifferentiated stem cells.
What does the pars nervosa do?
Stores and secretes (but does not produce) the two neurohormones, oxytocin and ADH
Why isn’t the pars nervosa a true endocrine gland?
Does not produce the neurohormones, only stores and secretes them
Oxytocin is made by? (Specific nucleus)
Hypothalamic paraventricular nuclei
In addition to being secreted by the paraventricular nuclei, oxytocin is also secreted by? (2)
Uterus and fetus
Oxytocin acts on? (4)
Uterine smooth muscle, breast, vas deferens, and prostate
Oxytocin is controlled by?
Neuroendocrine reflex (positive feedback loop)
ADH is secreted by? (specific nuclei)
Hypothalamic supraoptic nuclei
What is the role of AHD?
Increase reabsorption of water in the distal renal tubules
Where is oxytocin made? (Specific nuclei)
What other locations, aside from the neurohypophysis, secrete it?
What tissues does it act on?
How is it controlled?
What is another name for ADH?
Vasopressin
What is another name for vasopressin?
ADH
Neurosecretery (Herring) bodies
Site of the release of oxytocin or ADH upon neural stimulation
Pituicytes
Supporting glial cells in the neurohypophysis, the most numerous cells present
Name the three layers of the adrenal cortex and the type of hormones they produce/excrete.
Name from superficial to deep
From the ___ week of development, foetal testis secrete testosterone under the influence of?
From the 5th week of development, foetal testis secrete testosterone under the influence of human Chorionic Gonadotropin (hCG)
How does testosterone affect the development of the foetal CNS?
It programs the hypothalamic centres for GnRH secretion
What is KISS 1?
Kisspeptin 1
54 AA neuropeptide transmitter made in the infundibular nuclei, and rostral preoptic areas of the hypothalamus, in humans.
Controls the release of GnRH
Using FSH as an example, briefly describe the 5 steps of a G-protein associated second messenger system
Somatotrophs release what hormones?
Thyrotrophs release what hormones?
Corticotrophs release what hormones?
Lactotrophs release what hormones?
Gonadotrophs release what hormones?
Where does prolactin act upon? What is it regulated by?
What hormones influence ACTH levels?
