Chapter 2.1 - Endocrine system ✓ Flashcards
What are the 12 endocrine glands and how many are there in each human?
-Pineal gland (1)
-Hypothalamus (1)
-Pituitary gland (1)
-Thyroid gland (1)
-Parathyroid glands (usually 4)
-Thymus (1)
-Adrenal glands (2)
-Kidneys (2)
-Pancreas (1)
-Ovaries (2 in females)
-Testes (2 in males)
-Uterus (1 in females)
What are the two types of glands in the body?
Exocrine glands and endocrine glands
What is the function of the exocrine gland?
Its a gland that secretes into a duct that carries the secretion to the surface of the body cavity
What is the function of the endocrine gland?
Its a gland that secretes hormones into the bloodstream
What are some examples of exocrine glands?
-Sweat glands
-Mucous glands
-Salivary glands
Define hormone
Its a chemical that is secreted by an endocrine gland and affects the functioning of a cell or organ (often carried in blood).
What are three ways hormones can affect cell activity?
Hormones may:
-activate certain genes in the nucleus so that a particular enzyme or structural protein is produced
-change the shape or structure of an enzyme so that it is turned ‘on’ or ‘off’
-change the rate of production of an enzyme or structural protein by changing the rate of transcription or translation during protein production.
What type of cells or organs do hormones affect?
-All the cells of the body
-Only particular groups of cells (target cells)
-Only particular organs (target organs)
What are the three types of hormones?
-Steroids
-Proteins (peptide)
-Amines
Are steroid hormones lipid-soluble or water-soluble?
Lipid-soluble, meaning they do not dissolve in water.
Describe the process of steroid hormone-receptors when they are released into the bloodstream and reach a target cell
-Steroid hormones travel in the bloodstream by binding to transport proteins.
-Once at the target cell, they diffuse across the membrane and bind to an intracellular receptor in the cytoplasm or nucleus, forming a hormone-receptor complex.
-This complex then enters the nucleus (if not already there) and binds to a specific DNA sequence in the promotor region of a gene.
-This interaction either stimulates or inhibits transcription, regulating protein synthesis.
How do steroid hormones compare in terms of speed and duration of their effects?
Steroid hormones are slow to have an effect but the effect is long lasting.
Are protein and amine hormones lipid-soluble or water soluble?
water-soluble meaning they are unable to diffuse across the cell membrane.
How do protein and amine hormones pass through the cell membrane?
They attach to receptor proteins in the membrane of the target cell.
What happens when a protein or amine hormone binds to its receptor.
-It causes a secondary messenger substance to diffuse through the cell and activate particular enzymes.
What is an example of when a protein or amine hormone binds to its receptor?
The hormone insulin binds to a receptor protein and this leads to an increases in glucose absorption by the cell.
How do protein and amine hormones compare in terms of speed and duration of their effects?
Protein and amine hormones tend to be quick to cause an effect but the effect is short lasting.
Define hormone receptor
A cell protein that binds to a SPECIFIC hormone.
How does the lock and key model relate to hormone receptors?
-Since hormone receptors are specific it will only bind to a specific molecule like the lock and key model.
-The lock, the receptor protein, will only work with the correct key, the binding molecule.
What happens when all receptor proteins in a cell membrane are occupied by molecules?
Since there are a limited amount of receptor proteins, there will be no further increase in the cell’s activity even if the binding molecules increase. This means saturation can occur.
Define enzyme amplification
Enzyme amplification is a series of chemical reactions in which the products of one step is an enzyme that produces an ever greater number of product molecules at the next step.
What effect does enzyme amplification have?
The effect of enzyme amplification is when one hormone doesn’t just effect one molecule but its has cascading effects and effects multiple molecules at a time
Define hormone clearance
Hormone clearance is once a hormone has produced the required effect, the hormone must be turned off.
How are hormones turned ‘off’?
Hormones ate turned ‘off’ by breaking down the hormone molecules.
Where do the ‘off’ hormones go?
-Some break down in their target cells but most are broken down in the liver or kidneys.
-Then they excrete it in either bile or urine.
How to maintain homeostasis with hormone production?
To maintain homeostasis, the amount of hormones produced must be closely regulated.
What happens if hormones over secrete or under secrete?
It will cause the body to function abnormally.
How are hormone secretions regulated?
-They are regulated by negative feedback systems.
Define negative feedback
Its feedback that reduces the effect of, or eliminates the original stimulus.
