Introduction To The Endocrine System Flashcards
What are the characteristics of a control system?
- Communication (Nervous system, afferent and efferent branche/endocrine -hormones-paracrine and autocrine)
- Control centre: determines the reference set point, analyse afferent input and determine the appropriate response
- Receptors: chemoreceptors, thermoreceptors, proprioceptors or nociceptors
- Effectors: ie sweat glands
- Feedback: the output (effect) has an effect on the control centre
What are the two important control centres in the brain?
Hypothalamus in the diencephalic
Medulla oblongata in brain stem
What is a benefit to negative feedback?
Give stability to control system and allows the set point to be controlled within fine limits.
What glands secrete hormones?
Endocrine glands
What are the 4 types of hormones?
- Peptide/polypeptide: amino acids
- Glycoproteins: large protein molecules with carbohydrate side chains
- Amino acid derivatives (amines): small molecules synthesised from amino acids
- Steroid hormones: cholesterol derived
Give examples of a peptide/polypeptide hormone
Insulin
Glucagon
Growth hormone
Placental lactogen
*all water soluble
Give an example glycoprotein hormone
Luteinizing hormone (LH)
Follicle stimulation hormone (FSH)
Thyroid stimulating hormone (TSH)
*secreted by the anterior pituitary glands
** all water soluble
Give an example amino acid derivative hormone
Adrenaline (from tyrosine)
Noradrenaline (from tyrosine)
Thyroid hormones (from tyrosine)
Melatonin (from tryptophan)
Adrenal medulla hormones- water soluble
Thyroid hormones- lipid soluble
Give an example of a steroid hormone
Cortisol
Aldosterone
Testosterone
Oestrogen
- all lipid soluble
- *work on intracellular receptors
How are polypeptide hormones and catecholamines normally stored?
Within vesicles
How are steroid hormones usually stored within tissues?
Not as mature hormones but as precursors (cholesterol) in form of lipid droplet
How does the thyroid gland stores its hormonal products?
Outside the cell in the form of a protein colloid
Hydrophilic hormones such as polypeptides, glycoproteins and adrenaline are transported in the blood stream dissolved in the plasma, how are steroid and thyroid hormones transported and why?
Need specialised transport proteins because they are hydrophobic (lipophilic)
In the case of hormones that are bound to proteins in the blood, what specific concentration is it that effects the response of target tissues?
The concentration of the free (UNbound) hormones
Those that are bound are biologically inactive
What happens if someone has a growth hormone deficiency?
They dont grow properly
What causes acromegaly?
An excess of growth hormone
*this has metabolic effects as well as characteristic changes to the shape of the face and body
Above what blood glucose concentration is insulin secreted?
5mM (ie following a meal)
Hormones, instead of being controlled by negative feedback (like insulin), are controlled by another hormone. What is the name given to the stimulating hormone involved in this mechanism?
Tropic hormones
Where are most tropic hormones secreted from?
Anterior pituitary gland
Name some organs and tissues around the body that produce hormones, name the hormones that each produces
Heart: ANP and BNP Liver: IGF1 Stomach: gastrin, ghrelin Placenta: inhibin, placental lactogen Adipose: leptin Kidney: erythropoietin, renin, calcitriol
What are the roles of hormone carrying proteins?
- Increase solubility of hormone in plasma
- Increase half-life
- Really accessible reserve
What are the 3 main factors determining the hormone levels in the blood?
- Rate of production
- Rate of delivery (high blood flow to particular organ will deliver more hormone)
- Rate of degradation
What receptors do water soluble hormones bind to?
Cell surface receptors
Ie GPCR eg adrenaline
Tyrosine kinase eg insulin receptor
What effect does a ligand have on a tyrosine kinase receptor?
It causes auto-phosphorylation of specific tyrosine (adding phosphate group to itself) and recruits adaptor proteins and signalling complex
