Introduction to the endocrine system S6L2 Flashcards
What are the 4 main components of a control system?
1) stimulus
2) receptor to detect stimulus
- communication via afferent pathways
3) control centre
- communication via efferent pathways
4) effector
Define negative feedback
In neg feedback the output inhibits the function of the control centre and the effector acts to oppose the stimulus.
Does insulin decrease or increase the level of glucose in the blood?
decrease
Can positive feedback cause rapid, catastrophic change?
yep
Give two examples of positive feedback
Blood clotting, ovulation (build up of FSH causes release of oocyte)
The set point of a control centre can change. In case of cortisol, when does it peak and trough?
Peak: 7am
Trough: 7pm
What hormone is involved in setting the body’s biological clock?
Melatonin released from the pineal gland
Define osmolarity and osmolality
Osmolarity: the number of osmoles per litre of solution
Osmolality: the number of osmoles per Kg of solution
What receptors in the hypothalamus detect osmolality?
Osmoreceptors
If there is a high blood osmolality, what hormone is released from the posterior pituitary gland?
Anti diuretic hormone (ADH) also known as vasopressin
What effect does ADH have on the kidney?
Increases reabsorption of water from the urine into the blood
Are hormones present in the blood in high or low concentrations?
Very low
What are the 4 main classifications of hormones?
1) petptide/polypeptide (largest group)
2) glycoproteins
3) amino acid derivatives
4) steroids
Give some examples of peptide/polypeptide hormones
Insulin, glucagon, growth hormone
Examples of amino acid derivative hormones..
adrenaline, noradren, thyroid hormones
What are steroids all derived from?
cholesterol
Examples of steroid hormones..
cortisol, aldosterone, testosterone, oestrogen
Are steroid hormones and thyroid hormones hydrophobic or hydrophilic?
hydrophobic
Thyroid hormones bind specifically to what protein in the blood?
Thyroxine Binding Globulin (TBG), some is also bound nonspecifically to other proteins such as albumin
In many cases the secretion of one hormone is controlled by another. The second hormone is known as what?
a tropic hormone
Releasing and Inhibiting hormones travel to the pituitary gland via what vessels?
hypophyseal portal vessels
Lipophilic hormones bind to receptors inside cell. True or false?
True
Where is the appetite centre located?
The arcuate nucleus in the hypothalamus
What can the primary neurones in the arcuate nucleus be divided into?
excitatory and inhibitory types
The excitatory neurones stimulate appetite via the release of what?
neuropeptide and agouti-related peptide (AgPR)
The inhibitory neurones suppress appetite via what?
POMC
Does Ghrelin stimulate or suppress appetite?
stimulate
Leptin, released from adipocytes, suppresses appetite. True or false?
True
