The Endocrine System Flashcards
What is the endocrine system?
A series of organs and glands that work together to synthesize, store and secrete different hormones for a variety of purposes
What are the functions of the endocrine system?
*Play a key role in maintaining homeostasis by regulating things like: smooth muscle, cardiac muscle, alter metabolism, reproductive processes, and circadian rhythms
* Plays a major role in the developmental changes that occur during puberty
How does the nervous system control bodily functions?
by action potentials and the release of
neurotransmitters
How does the endocrine system control bodily functions?
releases chemical mediators to regulate body systems called hormones
What is a hormone?
a molecule released by an organ or gland that has an effect on tissues or cells somewhere within the body. Usually carried to the target site via the blood stream.
How do neurotransmitters and hormones release their effects?
binding to receptors on or in a target cell (lock and key)
True or False:
Some chemicals in the body can act as both neurotransmitters and hormones
True:
Depending on where they are released.
Ex. norepinephrine
Are responses of the endocrine system typically faster or slower than the nervous system?
Slower
Do responses of the endocrine system typically last longer or shorter than the nervous system?
Longer
True or False:
It is common for both the nervous system and endocrine system to work together to regulate certain functions
True:
Ex. The nervous system can inhibit or stimulate the release of certain hormones
What is an exocrine gland?
Secretes products into ducts that carry their secretions into body cavities, the lumen of an organ, or to the outer surface of the body
What is an endocrine gland?
Secrete hormones into interstitial fluid, where they then diffuse into the circulatory system
True or False:
The endocrine system is heavily reliant on the cardiovascular system for distribution
True:
The cardiovascular system/circulatory system plays a key roll in hormone distribution, endocrine glands are highly vascular
What are the 5 endocrine glands?
-Pituitary
-Thyroid
-Parathyroid
-Adrenal
-Pineal
What are the endocrine organs/tissues?
-Hypothalamus
-Thymus
-Pancreas
-Ovaries/testes
-Kidneys
-Stomach
-Liver
-Small intestine
-Skin
-Heart
-Adipose tissue
-Placenta
What are hormone receptors?
For a hormone to exert its effect on a given cell or tissue, it must bind to a specific hormone target receptor designed to accept that hormone (lock and key)
What are hormone receptors made of?
Made up of proteins that are constantly being synthesized and broken down as needed
What occurs in down-regulation?
excess exposure to a hormone will reduce the amount of target cell receptors (target cells are less sensitive to the hormone)
What occurs in up-regulation?
hormone deficiency may increase the amount of target cell receptors (makes the target cell more sensitive to the hormone)
What are circulating hormones?
secreted by glands/tissues/organs into interstitial fluid and then diffuse into blood
What are local hormones
act locally on neighboring cells or on the same cell that secreted them without entering the bloodstream
What are paracinres?
Local hormones that act on neighboring cells
What are autocrines?
Local hormones that act on the cell that secreted it
Hormones are divided into which two categories?
Lipid-soluble and water-soluble
What are some lipid soluble hormones?
-steroid hormones
-thyroid hormones
-nitric oxide (NO)
What are some water soluble hormones?
-Amine hormones
-Peptide and protein hormones
-Eicosanoids (Prostaglandins and Leukotrienes)
How do water soluble hormones circulate in the blood?
Independently
How do most lipid soluble hormones circulate in the blood?
By binding to a transport protein
True or False:
Hormones always have the same effect regardless of where on the target cell it binds to
False:
Hormones can have an entirely different effect depending on where on the target cell it binds to.
Ex. Insulin stimulates glycogenesis in the liver cells and synthesis of triglycerides in adipose tissues
Where do lipid-soluble hormones bind to target receptors?
Within a target cell (can pass through lipid bilayer)
Where do water-soluble hormones bind to target receptors?
on the plasma membrane of target cells (cannot pass through lipid bilayer)
How do lipid-soluble hormones take action?
- Lipid-soluble hormone is released from a transport protein, diffuses from the blood to interstitial fluid and through lipid bilayer of cell
2.Hormone binds to target cell and activates receptors (turns genes on or off)
3.New mRNA forms, directs synthesis of new protein (often an enzyme)
4.Newly formed proteins alter cell activity and cause the responses typical of that hormone
How do water-soluble hormones take action?
- Water soluble hormone diffuses from the blood, to the interstitial fluid and binds to its receptor on the outer surface of the target cell
- Activation of the receptor triggers a process that creates a secondary messenger (Ex. cAMP)
- Process involving different types of proteins continues to produce different physiological response
- An enzyme called phosphodiesterase inactivates cAMP
Why do water-soluble hormones not require high concentrations to induce their effects?
Because of the exponential chain reaction that occurs within the cell when a hormone binds to the target receptor on the plasma membrane
The responsiveness of a target cell to a hormone depends on which 3 factors?
- Hormone concentration in the blood
- Abundance of hormone receptors in or on the target cell
- Influences exerted by other hormones
What is a synergistic effect?
Two hormones working together create greater results
What is a permissive effect?
One hormone increases the effect of another hormone
What is an antagonistic effect?
Two hormones oppose each other’s actions
True or False:
The release of most hormones occurs in short bursts, with little or no secretion between bursts
True
Secretion is regulated in which3 different ways (mostly via negative feedback)?
-Signals from the nervous system
-Chemical changes in the blood
-Other hormones
The hypothalamus is a major link between which systems?
The nervous and endocrine systems
What is the pituitary gland?
A small spherical gland that attaches to the base of the hypothalamus
What are the two anatomically and functionally separate portions of the pituitary gland?
The anterior pituitary and posterior pituitary
What hormones are secreted by the anterior pituitary gland?
-Human growth hormone (hGH)
-Thyroid Stimulating Hormone (TSH)
-Adrenocorticotropic Hormone (ACTH)
-Melanocyte Stimulating Hormone (MSH)
-Follicle-Stimulating Hormone (FSH)
-Luteinizing Hormone (LH)
-Prolactin (PRL)