Flashcards in Hormones/Signal Transduction Deck (64)
What two hormones does the pancreas produce?
Insulin and Glucagon
What is the role of insulin and glucagon
Control glucose in the blood
What does insulin control
Insulin is produced when blood glucose levels needs decreasing
What does glucagon control
Glucagon acts if there is too little glucose in the body
Where is insulin produced??
Beta cells of the pancreas
Where is glucagon produced??
Alpha cells of the pancreas
Explain negative feedback if there is an increase in blood glucose
Stimulus- Increase in blood glucose
Effector- Pacreatic beta cells will release insulin
Response-Liver and muscle cells uptake glucose and store as glycogen
Feedback- Blood sugar levels decrease
Explain negative feedback in regards to, too little glucose in the blood
Stimulus- decrease in blood glucose
Effector- Pacreatic alpha cells will release glucagon
Response-Liver and muscle cells will break down glycogen and release as glucose
Feedback- Blood sugar levels increase
Explain how insulin promotes the uptake of glucose
Changes the permeablity of the cell membrane to glucose
Why do cells need to communicate
Control and regulation of systems
What are signalling molecules also known as??
What are receptors and hormones
What are the three types of signals??
Define Autocrine Signals
A cell secretes a hormone into extracellular fluid and binds to its own receptors
Define Paracrine Signals
Signals being released by cells into extracellualr medium acts on nearby target cells, so this type of signal is a local signal.
Define Endocrine Signals
Signals that are produced in the endocrine gland are secreted in the blood stream, therefore distributed throughout the whole body, but only stimulate those with specific receptors
Defintion for Hormone
An organic molecule produced in a cell, either acting within the cell or diffusing or being transported to other cell. Hormones travel via extracellular fluid and act on specific target cells.
Where do hormones usually travel
In the blood stream of tissue fluid
What are the three different classification of hormones?
-Amino acid derivative
Explain steroid hormones
-Tend to have a long life span
-Created on demand from precursors in the cell
-Made from chloesterol therefore lipophilic and hydrophobic
-Steroids pass through the cell membrane via simple diffusion
-Need a carrier protein when travelling through blood
Example of a steroid hormone
Explain Protein/Peptide Hormones
-Made in advance and stored in cells secretory vesciles
-Cannot pass through the membrane so they leave via exocytosis
-Short life span
- They are hydrophilic and can easily travel through the blood stream but need assistance when passing through the membrane
example of protein/peptide hormones
Explain Amino Acid Dervative Hormones
-Small molcules that have the same structure as an amino acid
- Made in advance and stored in the secretory vescilces, leave via exocytosis.
-Short Life span
-Water soluble so they can travel through the blood stream easily but need assitance when passing through the cell membrane
Are hormones slow or fast
Do they work for a long period or time or short?
Where are steriod receptors in regards to the cell?
Lipid based hormones are able to pass through the membrane easily and therefore their receptor is located on the inside of the cell in the cytosol.
Where are the peptide and amino hormones located?
-Situated on the outside of the cell.
-This is due to not being able to pass through the membrane
-The receptors then activate a protein on the inside of the membrane
Define Signal Transdution
Refers to the cascade of events originating outside the cell in leading to a specific cellular response. This is the process in which a cell converts one kind of kind into another by a series of relay molecules.