Chapter 2 - Chemical Messengers Flashcards
What are the two types of glands found in the body?
- Endocrine glands
- Exocrine Glands
How do Exocrine glands work?
Exocrine glands secrete into a duct that carries the secretion to the body surface or to one of the body cavities
What are four examples of Exocrine glands?
- Sweat glands
- Mucous glands
- Salivary glands
- Glands of the alimentary canal
How do Endocrine glands work?
Endocrine glands secrete hormones into the extracellular fluid that surrounds the cells that make up the gland - the secretion then usually passes into the capillaries to be transported by the blood
What are four examples of Endocrine glands?
- Hypothalamus
- Pituitary gland
- Thyroid gland
- Adrenal glands
What is a hormone?
A secretion of an endocrine gland
What may hormones be?
- Proteins
- Steroids
- Amines
What are amines?
Small molecules derived from amino acids
How are hormones transported?
They are transported throughout the body in the blood
What is a target cell?
A cell who’s activity is affected by a particular hormone
What is a target organ?
An organ who’s activity is affected by a particular hormone
What are paracrines? What is another name for paracrines?
Any chemical secreted by a cell that diffuses to and affects adjacent cells; also called a local hormone
What is saturation?
When all the receptor molecules are occupied by hormone molecules
What are hormone receptors?
Specific
What type of solublity are proteins/amines able for?
Water soluble - they cannot pass through the cell membrane (facilitated diffusion)
What type of solubility are steroids able for?
Lipid soluble - can easily pass through the cell membrane into the cytoplasm (diffusion)
What do proteins/amines bind to?
Receptor molecules on the cell membrane (extracellular fluid) - does not enter the cell membrane
What do steroids bind to?
Receptor proteins inside the cell, then binds to a recptor on the nucleus to form an active receptor complex
When amine hormones bind to a receptor, what is produced?
A secondary message response
What does the secondary message response do?
This response will activate particular enzymes in the cell
What occurs when steroids bind to receptors in the nucleus?
Enzymes are activated in the nucleus - particular genes will be able to form a particular protein
At what speed do amines/proteins act?
Fast acting - the effect occurs in seconds or minutes
At what speed do steroids act?
Slow acting - the effect occurs in hours or days
What are some examples of protein based hormones?
- Insulin
- The growth hormone
- Adrenaline
What are some examples of steroid based hormones?
- Oestrogen
- Testosterone
- Progesterone
What is enzyme amplification?
A series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules at the next step
Define releasing hormones
A hormone which is secreted by the hypothalamus that stimulates the release of hormones needed by the body
Define inhibiting factors
A hormone that slows the release of other hormones of which there may be too much of in the body
What is the difference between the location of the hypothalamus and pituitary gland?
Hypothalamus is located in the brain
Pituitary gland is located just underneath the brain
What is the infundibulum?
A stalk which connects the hypothalamus to the pitutary gland and is vital to the normal functioning of the body
What is the difference between what the hypothalamus and pituitary gland regulate?
Hypothalamus regulates basic body functions such as: - Heart rate - Water balance - Body Temperature The pituitary gland regulates body functions such as: - Growth - Metabolism - Reproductive cycles
What can the hypothalamus control?
Can control the release of hormones from the pituitary gland into the blood (anterior pituitary) to be transported via nerve network into the posterior pituitary
What does the hypothalamus act as?
It acts as a receptor
Will either secrete or inhibit hormones
Which hormones does the hypothalamus produce?
- Oxytocin
- Antidiuretic Hormone (ADH)
What type of hormones does the pituitary gland release?
It releases hormones that control other endocrine glands
What is the pituitary gland also known as?
The “Master Gland”
When are oxytocin and ADH released from the posterior lobe of the pituitary?
Are released when nerve impulses occur
What are the two lobes of the pituitary gland?
- Posterior Pituitary Lobe (Back)
- Anterior Piuitary Lobe (Front)
What is the difference about where hormones are produced in the posterior and anterior lobes?
Anterior: Hormones are produced and secreted from the anterior pituitary
Posterior: Hormones are produced in cell bodies in the hypothalamus, stores hormones in the posterior lobe
How is the anterior lobe connected to the hypothalamus?
Has no nerves connecting it to the hypothalamus, it has a complex blood vessel network
How does the posterior lobe receive the hormones from the hypothalamus?
Hormones are transported down the axons (neurons) to the posterior lobe
What is the difference about how the posterior and anterior lobe release hormones?
Anterior: Release hormones via chemical/hormonal stimulation
Posterior: Release hormones via nerve stimulation from the hypothalamus (does not secrete hormones)
