The Endocrine System Flashcards
What is the main role of the autonomic nervous system?
- 1.contraction and relaxation often vascular and visceral smooth muscles
- all exocrine and certain endocrine secretions
- control of the heartbeat
- energy metabolism, particularly in the liver and skeletal muscles
Give examples of fast neurotransmitters and how they function
- Glutamate & GABA
- operate through ligand-gated ion channels
Give examples of slow neurotransmitters and neuromodulators and how they function
- DA, neuropeptides
- operate mainly through G-protein coupled receptors
What is the response when the Blood-brain barrier has dysfunction/ damage
- Injury causes oxidative stress, and the increased production of proinflammatory mediators
- there is an upregulation of expression of cell adhesion molecules on the surface of brain endothelium which promotes the influx of inflammatory cells into the traumatized brain parenchyma.
- this causes swelling and the following symptoms seen in a brain haemorrhage
What is the Endocrine System?
- collection of ductless glands produce hormones that regulate internal process
- metabolism
- growth
- development
- tissue function
- sexual & reproductive function
- sleep
- mood
What organs make up the Endocrine System?
- Pineal gland
- Hypothalamus
- Pituitary gland
- Parathyroid gland
- Thyroid gland
- Thymus
- Adrenal glands
- Kidneys
- Pancreas
- Ovary (females)
- Testes (males)
What are the six Anterior Pituitary hormones?
- FSH- Follicle-stimulating hormone
- LH- Luteinizing hormone
- GH- Growth Hormone
- TSH- Thyroid-stimulating hormone
- PRL- Prolactin
- ACTH- Adrencorticotropic hormone
What are the two Posterior Pituitary hormones
- Oxytocin
- ADH -Antidirutiec Hormone (vasopressin)
Give an overview of the biochemical pathway of the Anterior Pituitary Hormones
Describe the location of the Pituitary gland
- inferior to the hypothalamus and the Infundibulum
What is the overall role of the Thyroid and the Parathyroid gland?
- control of metabolic rate and calcium homeostasis
What is the overall role of the Adrenal glands?
- the inner medulla produces hormones related to the stress response
- NE and Epinephrine
- the outer cortex works to control, sodium and glucose
What is the overall role of the Pancreas
- secretes Glucagon and Insulin to control the blood glucose levels
What is the overall role of the Gonads?
- they secrete the female and male reproductive hormones responsible for the development of secondary sexual characteristics and reproduction
- Female: Oestrogen, Progesterone
- Male: Testosterone, Androsterone
What are the major receptor groups that interact with hormones?
- Steroid Hormone Receptors
- G-Protein Coupled receptors
- Tyrosine Kinase Receptors
these may be intracellular or membrane-bound
How do Steroid Hormones and their receptors work?
- Steroid Hormones (SHs) are lipophilic molecules derived from cholesterol and made in
- the adrenal cortex
- the testes
- the ovary and placenta
- they reach their target cells via the blood where they bind to carrier proteins and pass the cell membrane by simple diffusion (lipophilic nature)
- it then binds to the receptor which may be cytoplasmic or nuclear
- the hormone-receptor complex binds to the hormone response element of the DNA to influence gene transcription
- the receptor may be constitutively active ( resulting in the production of a second messenger in the absence of an agonist)
Explain hormone-receptor complexes removal after they have been internalised
- the hormone-receptor is internalised within a vesicle formed of clathrin-coated pits, which allows the hormone to be removed from its receptor
- in the vesicle arrestin, may replace the hormone on the receptor and prevent the receptor-interacting with its G-protein
- overall internalised receptors are inactive, broken down or recycled
Describe the biological characteristics of hormones
- the classes of hormones
- Peptide hormones
- chains of aa, highly water-soluble, susceptible to protease attach
- unable to cross cell membrane without a carrier protein
- act on membrane-bound receptors
- Steroid hormones (+ thyroid hormones)
- highly lipid-soluble, poorly water-soluble
- must be transported in the blood and bound to plasma protein
- only biologically active in its unbound state
- able to cross cell membrane and acts as intracellular receptor
Describe the biochemical characteristics of hormones
- the classes of hormones
- Peptide Hormones
- not orally active
- rapid onset and duration of action
- short plasma half-life
- synthesised and stored as an inactive precursor
- maybe ‘stored’ in platelets; plasma-protein bound steroids may be a storage reservoir
- Steroid & Thyroid Hormone
- orally active
- synthesised on demand
- slow onset of action
- long plasma half-life and duration of action
How is the endocrine system controlled?
- secretion from the anterior pituitary gland is controlled by the hypothalamus
- the hypothalamus secretes the releasing hormone
- the secretion of a hormone from a gland is controlled by the anterior
- the APG releases Stimulating (trophic) Hormone
Match the hormones released by the hypothalamus to those that it stimulates in the Anterior Pituitary gland
- Thyrotrophin Releasing Hormone (TRH)
- Corticotrophin Releasing Hormone (CRH)
- Gonadotrophin Releasing Hormone (GnRH)
- Growth Hormone Releasing Hormone (GHRH)
- Thyrotrophin Releasing Hormone (TRH)
- Thyroid Stimulating hormone
- Corticotrophin Releasing Hormone (CRH)
- Adrenocorticotrophic hormone (ACTH)
- Gonadotrophin Releasing Hormone (GnRH)
- Follicle-stimulating hormone (FSH)
- Growth Hormone Releasing Hormone (GHRH)
- Growth Hormone (GH)
Where do the hormones of the Anterior Pituitary gland act on?
- Thyroid Stimulating Hormone (TSH)
-
Thyroid Gland
- produces Thyroxine
-
Thyroid Gland
- Adrenocorticotrophic hormone (ACTH)
-
Adrenal Cortex
- produces Cortisol
-
Adrenal Cortex
- Follicle Stimulating Hormone (FSH)
-
Ovary
- produces Oestrogen
-
Ovary
- Luteinising Hormone (LH)
-
Ovary
- produces Progesterone
-
Ovary
Explain the effect of nocturnal ACTH (adrenocorticotropin) and Cortisol secretion and long or short sleep duration
- at the time of sleep the SSG (short sleep gp) had higher plasma cortisol levels compared to the LSG (long sleep gp)
- however, the ACTH levels were not reduced or tended to be higher in the LSG, whereas they were lower in the SSG
- this may be explained by the negative feedback effect high cortisol levels has on plasma ACTH,
Conclusions
- the transition from sleep to wakefulness in the morning, irrespective whether spontaneous or induced, stimulates ACTH and cortisol release
- the switch from darkness to lights on after awakening may have contributed to the awakening-dependent ACTH and cortisol peak.
- the decline of plasma ACTH and cortisol during wakefulness supports the view that quietly lying awake inhibits adrenocortical activity in the morning, as already suggested by results from previous studies
