Chapter 18 - Endocrine System Flashcards
Which two body systems act together to coordinate functions of all body systems?
Nervous System
Endocrine System
How does the nervous system act on other body systems?
Generates action potentials (nerve impulses) conducted along axons of neurons that trigger the release of neurotransmitters
What is a hormone?
A mediator molecule that is released in one part of the body but regulates the activity of cells in other parts of the body
How do hormone travel throughout the body?
Hormones enter the interstitial fluid, then the blood stream
- circulating blood delivers hormones throughout the body
How does an endocrine response differ from a nervous system response?
Endocrine system is often slower
- some hormones act within seconds, others take minutes
Nervous system effects are more brief
Nervous system acts of specific muscles or glands
Endocrine system effect are much more broad
What are exocrine glands?
Glands that secrete their products into ducts that carry the secretions into body cavities
What are some examples of exocrine glands?
Sudoriferous (sweat) glands, sebaceous (oil), mucous & digestive glands
What are endocrine glands?
Glands that secrete their products into interstitial fluid surrounding the secretory cells rather than into ducts
What are some examples of endocrine glands?
Pituitary, thyroid, parathyroid, adrenal and pineal glands
What are some examples of ORGANS that secrete hormones?
Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue and placenta
What constitutes the endocrine system?
All of the endocrine glands & hormone secreting cells (organs)
What are the functions of hormones?
- Regulate chemical composition & volume of interstitial fluid
- Regulate metabolism & energy balance
- Regulate contraction of smooth & cardiac muscle fibres
- Regulate glandular secretions
- Regulate immune system activities
- Control growth & development
- Regulate operation of reproductive systems
- Help establish circadian rhythms
What is the function of hormone receptors?
Bind to specific hormones
- specific hormone affects only specific target cells b/c of hormone receptors
What is the target cell?
The cell(s) that a specific hormone will influence
What is down-regulation?
If a hormone is present in excess, the number of target-cell receptors may decrease
- makes target cells LESS SENSITIVE to the hormone
What is up-regulation?
If a hormone is deficient, the number of receptors may increase
- makes target cells MORE SENSITIVE to the hormone
What happens if a hormone is prevented from interacting with its receptors?
The hormone cannot perform its normal functions
What are circulating hormones?
Hormones that pass from the secretory cells into interstitial fluid, & then into the blood
What are local hormones?
Hormones that act on neighboring cells or on the same cell that secreted them without first entering the bloodstream
What are paracrines?
Local hormones that act on neighboring cells
What are autocrines?
Local hormones that act on the same cell that secreted them
What are the two kinds of local hormones?
- Paracrines
2. Autocrines
Which kind of hormones is inactivated quickly, which linger longer?
(Circulating vs. Local)
Local are inactivated quickly
Circulating linger in the bood
What are the two broad classes of hormones?
- Lipid-soluble hormones
2. Water-soluble hormones