Introduction Endocrine Systems & Receptors 2016 1 Flashcards
Define what a hormone is
A regulatory substance which allows communication between glands and other tissues, often at a distance, achieved by the secretion of this substance (hormone) into the blood stream and transport to a target site
Define what is meant by endocrine signalling
Endocrine cells secrete hormones or other products directly into the blood that then act on distant target cells in the body.
Define what is meant by autocrine
Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell.
Define what is meant by paracrine signalling
Paracrine signaling is a form of cell-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behavior or differentiation of those cells.
What are the 4 different chemical classes of hormones ?
- Modified amino acids (A) - e.g. adrenaline, thyroid hormones (T3 and T4).
- Steroids (S) - e.g. Cortisol, progesterone, testosterone
- Peptides (P) - e.g. Adrenocorticotropic hormone (ACTH), antidiuretic hormone (ADH), oxytocin
- Protiens (P) - e.g. Insulin
What are the main hormones secreted by the anterior pituitary gland?
- Adrenocorticotropic hormone (ACTH)
- Growth hormone (GH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin
- Thyroid-stimulating hormone (TSH)
Match the hormones secreted by the anterior pituitary to their target:
- Adrenocorticotropic hormone (ACTH)
- Growth hormone (GH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin
- Thyroid-stimulating hormone (TSH)
- Mammary glands (R)
- Adrenal cortex (M)
- Gonads (R)
- Thyroid (G, M)
- Gonads (R)
- Liver, bones, muscle (G)
- Adrenal cortex
- Liver, bones, muscle
- Gonads
- Gonads
- Mammary glands
- Thyroid
What is the main hormone secreted by the intermediate pituitary gland?
Melanotrophin-stimulating hormone (MSH)
What is the target of Melanotrophin-stimulating hormone (MSH)
Melanocytes
What are the main hormones secreted by the posterior pituitary gland and what are their main targets?
- Antidiuretic hormone (ADH) - targets the kidneys
- Oxytocin - targets Mammary glands (R), uterus (R)
What is the main hormones produced by the thyroid and what are their main targets?
- Thyroxine (T4)
- Tri-iodothyronine (T3)
Targets most tissues
What is the main hormones produced by the parathryroids and what are their targets ?
- Calcitonin
- Parathyroid hormone (PTH)
Targets Bone, gut
Fill in the missing spaces:
The main hormones produced by the adrenal cortex are ________, _________
The main hormones produced by the adrenal cortex are Glucocorticoids (including cortisol) and Aldosterone
What are the main hormones produced by the adrenal medulla ?
Adrenaline and noradreanline
What is the target of aldosterone ?
kidneys
What are the main hormones produced by the gonads in males and females and what do they act on ?
testosterone - testes
Oestradiol - overies and uterus
progesterone - overies and uterus
What are the 2 main effects hormones can have on there target ?
Can be complimentary e.g. adrenaline, cortisol, glucagon all contribute to the response of the body to short term tense exercise enhancing physical performance and preventing potential hypoglycaemia and hypokalaemia
Or can be antagonistic e.g. insulin lowers BG inhibiting glycogenolysis and gluconeogenesis
The transport of hormones - amine (modified amino acids), proteins & peptides - in the blood is by the same method, describe this method
- Amines, proteins & peptides are all pre-synthesied and stored in vesicles
- They are released in response to a stimuli by Ca2+ dependent exocytosis
- They are all hydrophilic and transported mainly ‘free’ in the plasma
(pic shows amine example, basically the same for proteins & peptides)
Describe the transport of steroids in the blood
- They are synthesised and secreted on demand
- They are hydrophobic so mainly transported bound to a carrier protein (90% bound, 10% unbound in the blood)
What state does a hormone have to be in to cross the capillary wall to activate receptors in target tissues?
Has to be in the unbound state
This presents a problem for steroid hormones, this is overcome though as the bound and unbound steroids are in a state of equilibrium with each other.
As free unbound hormone crosses, it is replaced by bound hormone dissociating from carrier protein.
