Endocrine System Flashcards
What are the main communication pathways in the body?
Endocrine and nervous system
List the main features of a control system (5)
Communication Control centre Receptor Effector Feedback
What is the different between the afferent branch and the efferent branch of the nervous system?
Afferent is sensory input
Efferent is motor output
What is the role of the control centre?
Determine a set point
Analyse the afferent input
Coordinate an appropriate response
Name two important control centres in the brain and state what they do
Medulla oblongata - ventilation and cardiovascular system
Hypothalamus - control of the endocrine system
Name some receptors
Chemoreceptors
Thermoreceptors
Proprioreceptors
Nocicereceptors
What happens in negative feedback?
The output inhibits the effect of the control centre and the effector acts to oppose the stimulus.
What happens in positive feedback?
The stimulus produces a response which increases its effect
Give two examples of positive feedback
Blood clotting
Ovulation
What is the total body water content in a 70kg male and what percentage?
42 litres
50-60%
What are the three main components water is contained in? Percentages and litres?
Interstitial fluid - 28L, 35%
Extracellular fluid - 9.4L, 12%
Blood plasma - 4.6L, 4-5%
What does anti-diuretic hormone do?
Increases permeability to water of collecting duct in kidney, increasing the reabsorption of water into the blood from the urine.
What are hormones?
Chemical messengers involved in communication that travel via the bloodstream
What are steroids derived from?
Cholesterol
List the four chemical types of hormones
Polypeptide
Glycoprotein
Amino acid derivatives
Steroids
Which types of hormones need to be transported by proteins?
Thyroid and steroids
What is a trophic hormone?
A hormone whose production is controls the secretion of another hormone
What are the six main hormones that the anterior pituitary gland secretes?
Growth hormone Thyroid stimulating hormone FSH LH ACTH Prolactin
How do hormones affect the target cell?
Bind to receptors in/on the cell
This triggers changes such as activity of enzymes and proteins, and affecting rate of gene expression.
Where are hormones inactivated?
Liver, kidney, sometimes the target tissue.
What can cause disorders of the endocrine system?
- Over/under secretion of hormones
- Production of structurally abnormal and less effective hormones
- Responsiveness of endocrine tissues may be altered by circulating abnormal proteins eg antibodies
- Physiolologically effective conc of hormones altered due to binding to circulating proteins.
- Changes in responsiveness of target tissues due to changes in receptors/post receptor events
In the HPA axis, what is released from where?
CRH from the hypothalamus
ACTH from the anterior pituitary
Cortisol from the cortex of the kidneys
