Chapter 2: Chemical Messengers Flashcards
What is an exocrine gland?
Glands that secrete into a duct that carries the secretion to the surface of the body or to one of the body cavities.
What are some examples of exocrine glands?
- sweat glands
- salivary glands
- mucous glands
What are endocrine glands?
Glands that secrete hormones into the extracellular fluid that surrounds the cells that make up the gland. The secretion usually then passes into the capillaries to be transported by the blood.
What are some examples of endocrine glands?
- pituitary
- thymus
- thyroid
What is a hormone?
The secretion of an endocrine gland
What is a target cell?
A cell whose activity in affected by a particular hormone.
What is a target organ?
An organ whose activity is affected by a particular hormone.
What is a paracrine?
Any chemical secreted by a cell that diffuses to and affects adjacent cells, also called a local hormone
What are the characteristics of protein and amine hormones?
- water soluble
- receptor outside and secondary messenger
How do protein and amine hormones work?
- Hormone attaches to the corresponding receptor protein in the membrane of the target cell.
- This combination causes a secondary messenger substance to diffuse through the cell and activate particular enzymes.
What are the characteristics of steroid hormones?
- lipid soluble
- crosses membrane, attaches to receptor inside
What is enzyme amplification?
The process in which one hormone molecule causes the manufacture or activation of thousands of enzymes
What occurs once the hormone has produced the required effect?
It must be turned off. The hormone molecules are broken down in the target cells, or mostly liver and kidneys and are then excreted in bile or urine.
What is a negative feedback system?
Where the response produced by the hormone is opposite of the stimulus that caused the secretion.
What are releasing factors?
Hormones secreted by the hypothalamus that stimulate the release of a hormone