Introduction to the Endocrine System Flashcards
Define the endocrine system
A system that integrates and controls organ function via the secretion of chemicals from tissues or glands which are then carried in the blood to target organs distal from the site of hormone synthesis.
How do tissues detect hormones?
Presence of specific receptors for that chemical on/in the cell
Describe the term autocrine
Cells secrete chemicals that bind to receptors on the same cell
Describe the term paracrine
Chemicals diffuse in ECF to affect neighbouring cells
What is the basic function of hormones?
To bring about a change in the activity of their target cells and tissues (increase/decrease a particular activity)
What are the features of an endocrine hormone?
Produced by a cell or group of cells
Secreted from those cells into the blood
Transported via the blood to distant targets
Exert their effects at very low concentrations
Act by binding to receptors on target tissues
Have their action terminated, often via negative feedback loops
What are the classification of endocrine hormones?
Peptide or protein hormones
Steroid hormones
Amine hormones
What are some examples of peptide hormones?
TRH
FSH
Insulin
What is a preprohormone?
Initial peptide protein produced, large and inactive
How do preprohormones become pro hormones?
Cleaved into smaller units in the RER to become smaller, inactive proteins
How prohormones become hormones?
Packaged into vesicles in golgi apparatus along with proteolytic enzymes, causing activation through breakdown
What is C-peptide?
Inactive fragment cleaved rom insulin pro hormone
How can C peptide be used?
C peptide in plasma or urine measured to indicate endogenous insulin production from the pancreas
What signalling pathways are used by peptide hormones?
GPCR
Tyrosine kinase linked
How do the signalling pathways used by peptide hormones work?
Phosphorylate existing proteins in cell and modify their function
