Introduction Flashcards
What is homeostasis?
The state of steady internal physical and chemical conditions maintained by living systems
Dynamic equilibrium at all levels
What are the features of a control system?
Stimulus
Receptor - detects stimuli
Afferent pathway
Control centre - determines set point
Efferent pathway
Effector - causes change
What is the circadian rhythm?
‘Biological clock’
Regulated by neurones in suprachiasmatic nucleus
What cues regulate circadian rhythm?
Light Temperature Exercise Eating/drinking pattern Social interaction
What hormone is involved in the circadian rhythm?
Melatonin
Where is melatonin produced?
Pineal gland
What is negative feedback?
Response in a way to reverse direction of a change
What is postive feedback?
Response in a way to increase the change in the same direction
Name the endocrine glands of the body
Hypothalamus Pituitary gland Pineal gland Thyroid Parathyroid glands Thymus Adrenal glands Pancreas Ovaries Testes
What other organs release hormones?
Heart Liver Stomach Kidney Adipose tissue Placenta
What is autocrine communication?
Hormone signal acts back on the cell of origin
What is paracrine communication?
Hormone signal carried over to adjacent cells via interstitial fluid
What is endocrine communication?
Hormone signal released into bloodstream and carried to distant target cells
What is neurocrine communication?
Hormone originates in neurone, is released into bloodstream from axon, and is carried to distant cells
What are the different classes of hormones?
Peptide
Amine
Glycoproteins
Steroids
What is the solubility of peptide hormones?
Water soluble
What are some examples of peptide hormones?
Insulin
Glucagon
Growth hormone
What is the solubility of amine hormones?
Adrenal medulla - water soluble
Thyroid hormones - lipid soluble
What are some examples of amine hormones?
Adrenaline/Noradrenaline
Thyroid hormones
Melatonin
What is the solubility of glycoprotein hormones?
Water soluble
What are some examples of glycoprotein hormones?
LH
FSH
TSH
What is the solubility of steroid hormones?
Lipid soluble
What are some examples of steroid hormones?
Cortisol
Aldosterone
Testosterone
How are hormones transported?
Some are free in blood
- peptides
- adrenaline
Others bound to proteins
