lecture 1 Flashcards
What is a hormone
- chemical substances
- made from the endocrine glans (ductless)
- circulated in the blood stream
- trigger signal transduction events via receptors on target cells
What is endocrine signalling
- hormones are secreted from the endocrine cells where they then travel in the blood stream to the receptors of distant target cells (cell membrane)
true or false; a hormone is a ligand
true
What hormone is an example of endocrine signalling
insulin
- secreted from the B-cells of the pancreas
true or false; hormones also maintain homeostasis
true
What is Autocrine signalling
Autocrine signals act upon the same cell type they are released from
What is an example of an Autocrine signal
growth factors
What are Paracrine signals
paracrine signals are released from cells to act upon adjacent cells
- the secretory cell releases the extracellular signal which then binds to the receptors of an adjacent target cell
What is an example of a paracrine signal
acetylcholine at the neuromuscular junction
What is cell-cell signalling
The extracellular signal is attached to the cell membrane of the cell which initiates the signalling; which makes direct contact with the target cell
What is an example of cell-cell signalling
Immune system; T-cell activation of proteins on antigen presenting cells
How do hormones maintain homeostasis
via a feedback system
how do hormones and other extracellular signals initiate a chain of events in the cell?
by activating receptors
true or false; receptors are strategically poised to control what happens inside the cell
true
true or false; a receptor recognizes one hormone only
true eg. glucagon receptors and insulin receptors
- makes receptors good targets for medicines
What are the 2 main classes of hormones
steroid
non-steroid
Where does a steroid act?
inside the cell; has intracellular receptors
Where does a non-steroid act?
outside the cell
true or false; only when the hormone engages with the correct receptor can it activate the receptor and trigger intracellular signalling leading to physiological response
true
Define receptor
a molecule on the surface or within a cell that recognizes and binds with specific molecules producing a specific effect in the cell eg. the cell-surface receptors for antigens or cytoplasmic receptors for steroid hormones
Define signal transduction
cascade of processes by which an extracellular signal interacts with a receptor at the cell surface, causing a change in the level of a second messenger and ultimately effects a change in the cells functioning
true or false; signal transduction enables extracellular signals to be transmitted into responses
true
true or false; receptors trigger changes in cellular chemicals which produces these responses
true
What kind of proteins are the receptors for non-steroid hormones
transmembrane proteins
true or false; hormones also influence growth and development
true
