Unit 1: Communication within Multicellular Organisms Flashcards
In animals communication is mediated by
nervous transmission and hormonal secretion
In a hormonal secretion, what is the nature of the signal?
Extracellular signalling molecules
In a nervous transmission, what is the nature of the signal?
Electrical impulses and extracellular signalling
In a hormonal secretion, what is the method of transmission of the signal?
Through the bloodstream
In a nervous transmission, what is the method of transmission of the signal?
Along the axons of neurons
In a hormonal secretion what are the target cells?
Any cells
In a nervous transmission, what are the target cells?
Any cells with connections to neutrons (effectors)
What is the response time of a hormonal secretion in comparison to a nervous transmission?
Slower
What is the response time of a nervous transmission in comparison to a hormonal secretion?
Faster
The duration of a hormonal secretion is ______ than a nervous transmission which is transient
longer lasting
The extent of response to a hormonal secretion is ?
widespread
The extent of a response to a nervous transmission is ?
localised
Co-ordination allows what type of response to be made?
integrated homeostatic
Extracellular signalling: Stage 1, specific signalling molecules are released as a result of what?
A change in internal state
Extracellular signalling: Stage 2, signalling molecules are carried to where?
Target cells
Extracellular signalling: Stage 3, signalling molecules arrive at target cells and the cell responds with
a change in the internal state of cells
Different cell types produce specific _______ molecules?
signalling
How far an effect can a neurotransmitter have (roughly)?
1µm
How far an effect can a hormone have (roughly)?
1m
How far an effect can animal pheromones have (roughly)?
Up to over 1km
How does a target cell ‘know’ that it should respond to a specific signal?
Cells only detect and respond to signals if they possess a specific receptor
True or False? Cells can also show a specific tissue response to the same signal
True
The ligand adrenaline can bind to a receptor and produce a different response in salivary gland cells and in liver cells. What are the two responses?
In the salivary gland: Amylase release is stimulated
In the liver cells: Glycogen breakdown is stimulated
When a hydrophobic signalling molecule binds to a nuclear receptor what is it regulating?
Gene Transcription
What type of hormone is a hydrophobic signalling molecule?
Steroid hormones
Inactive transcription factor: Stage 1, an inhibitor protein is blocking what binding site on the receptor protein?
DNA binding site
Inactive transcription factor: Stage 2, the binding of a steroid hormone to a receptor site cause what to happen?
DNA Binding site becomes exposed as inhibitor protein is removed.
Thyroxine is released from where in the body?
The thyroid
What is thyroxine?
A hydrophobic hormone that regulates metabolic rate
Thyroxine: Stage 1, The transcription of what gene is being inhibited because of the (empty) thyroid receptor bound to DNA?
Na+/K+ATPase gene is inhibited
Thyroxine: Stage 2, Thyroxine is released and the receptor protein undergoes what type of change?
A conformational change
Thyroxine: Stage 3, Transcription of the Na+/K+ATPase gene takes place now because?
It is no longer being inhibited by the thyroid receptor
Thyroxine: Stage 4, This allows more Na+/K+ATPase in the cell membrane, therefore what molecule becomes degraded faster?
ATP
Thyroxine: Stage 5, Degrading of ATP increases the _________?
metabolic rate
Hydrophillic ligands: What is a hydrophillic ligand?
A molecule that binds to sites on the target proteins (receptors) at the surface of cells to trigger signal transduction.
Hydrophillic ligands: Binding of a hydrophillic ligand triggers what?
The receptor protein to undergo a conformational change
Peptide hormones are?
Short chains of amino acids
Give two examples of relevant peptide hormones?
Anti-diuretic hormone and Insulin
What is a neurotransmitter?
Chemical signals that are released from nerve endings that alter the activity of target cells.
A good example of hydrophillic signal transduction is the _________ cascade?
Adrenaline (Epinephrine) G-Protein
Protein kinase activity: Stage 1, Insulin binds to the ____
receptor
Protein Kinase activity: Stage 2, Kinase enzyme ________ itself.
phosphorylates
Protein Kinase activity: Stage 3, Receptor phosphorylates insulin receptor substrate called?
IRS-1
Protein Kinase activity: Stage 4, Phosphorylated IRS-1 acts on what to trigger cell responses?
effectors
Insulin regulates the _____ concentration of the blood
blood glucose
Stages of insulin production: Stage 1, Blood glucose concentration rises and a change is detected. This triggers what cells in what organ to produce more insulin?
Beta-cells in the pancreas
Stages of insulin production: Stage 2, Insulin is then transported in the blood and what peptide hormone is released and what does it do?
ADH and it acts on adipose, liver and muscle cells
Stages of insulin production: Stage 3, More glucose is taken up by cells resulting in?
Blood glucose concentration falls
The recruitment of GLUT 4 is induced by?
exercise
Diabetes Mellitus: This is a disease caused by what?
Defects in the insulin signalling system
What is the cause of type 1 Diabetes Mellitus?
Destruction of beta cells in the pancreas by immune system
What is the cause of type 2 Diabetes Mellitus?
Exact cause is unknown, obesity is a risk factor
What is the nature of defect in type 1 Diabetes Mellitus?
Pancreas does not produce any insulin
What is the nature of defect in type 2 Diabetes Mellitus?
Target cells develop insulin resistance due to loss of receptor function
What is the general treatment of type 1 Diabetes Mellitus?
Daily insulin injections and management of diet to control blood glucose concentration
What is the general treatment of type 2 Diabetes Mellitus?
Eat less sugar and saturated fat, regular exercise and medication to lower blood glucose concentration
ADH regulates what in the body?
The body’s water balance
ADH regulation: Stage 1, Blood water concentration rises and a change is detected so the body does what?
Release ADH from the pituitary gland
ADH regulation: Stage 2, ADH is transported via the blood and ADH acts on what part of the kidney?
The kidney collecting ducts
ADH regulation: Stage 3, ADH on the collecting ducts causes more water to reabsorbed into the blood, what effect does this have on urine and blood water concentration?
Less urine is made and blood water concentration falls.
Mechanism of action of ADH: ADH binds to ADH receptor causing what to happen?
Activation of protein kinase A
Mechanism of action of ADH: Activation of protein kinase A causes what to happen?
Protein phosphorylation
Mechanism of action of ADH: Phosphorylation of proteins in the collecting duct of the cell cause what to happen in the lumen
Fusion of vesicles containing AQP 2 water channel proteins
Aquaporins are protein channels that allow?
efficient transmembrane movement of water
Diabetes insipidus is a disease in which ?
the water concentration mechanism of the kidney fails
There are two types of diabetes insipidus which are?
Central diabetes insipidus and nephorgenic diabetes insipidus
In central diabetes insipidus, insufficient quantities of what are produced?
ADH
In nephrogenic diabetes insipidus, cells in the lining of the collecting duct are?
unable to respond to ADH
Symptoms of diabetes insipidus are?
Excessive thirst and large quantities of dilute urine