Endocrine System -13.1 Flashcards
What two body systems facilitate cellular communication and control?
Endocrine System and Nervous System
What are endocrine glands?
Glands that secrete chemical messengers called hormones into the blood stream
- Bloodstream transports hormones throughout the body
What are hormones?
Chemical messengers sent to many parts of the body to produce a specific effect on a target cell of organ.
Describe the action of the pancreas
The pancreas secretes hormone - insulin - into the blood stream
Insulin affects target cells (adipose tissue, liver) - makes them more permeable to glucose
What makes up the endocrine system?
The Endocrine Glands and the hormones that they release
What does homeostasis depend on?
The close relationship between the nervous system and the endocrine system.
What chemical functions as both a neurotransmitter and a hormone?
Epinephrine
Why is epinephrine considered both a neurotransmitter and a hormone?
- It acts as a neurotransmitter between certain neurons in the nervous system
- Acts a hormone released by the adrenal glands in the flight or fight response
What regulates the nervous system and endocrine system?
Negative feedback loops
Who had the first experiment to test the link between hormones and their activity on target cells?
Arnold Adolph Berthold
What did Arnold Adolph Berthold do?
Removed testes from rooster - became a capon
- did not fight, did not mate, did not crow, did not grow plumage like other roosters
What caused the developmental changes in the bird?
The lack of the hormone testosterone
What is the concentration of hormones in the blood stream?
10-8 to 10-12 mol/L
What can trigger a hormone release?
- Environmental factors
- may follow a pattern repeated over hours, weeks, or every year
What has allowed scientists to look at glands, hormones, and target cell membranes in great detail?
- Nuclear scanning devices (like PET)
- High powered microscopes
How are fluorescent stains used to see hormones and glands?
Fluorescent stains are used to colour different hormones in a tissue sample
How are endocrine glands viewed in a living body?
A capsule containing a small amount of radioactive material is ingested (same amount as that someone would receive from standard x ray)
Radioactive material accumulates in a specific gland - easy to see on PET or other nuclear scanning devices
How does each hormone work with its target cell?
Each hormone fits with its receptor protein like a lock and key - each hormone has a unique molecular shape that fits into a receptor proteins on its target cell
What target cells does hgH interact with?
liver, muscles, and bone cells
What are hormones composed of?
Lipids or amino acids
What hormones can easily diffuse through the lipid layer of the cell membrane?
Steroid hormones:
Testosterones, estrogen, cortisol
Where do the steroid hormones bind to their protein receptors?
Inside the target cell
How do steroid hormones affect target cell?
Activates specific genes - causing changes in the cell -
What are water soluble hormones?
Epinephrine, insulin, thyroxine, hgh - amino based - cannot diffuse across cell membrane
How do water soluble hormones cause reactions then?
They bind to protein receptors on the surface of the target cell - which starts a cascade of reactions inside the target cell
What happens once a hormone has been delivered?
Enzymes inactivate the hormone - as lingering affects can be disruptive
How does a negative feedback loop work?
When a certain blood concentration of hormone has been reached
When target cells have responded to specific hormone - endocrine gland releasing the hormone is inhibited (hormone stops coming out)
What hormones regulate water reabsorption by the kidneys?
Antidiuretic hormone and aldosterone
What is the process of ADH being released (blood concentration)
Blood plasma becomes to concentrated
Receptors in blood plasma become to concentrated
Receptors in hypothalamus detect this and send neural signals to pituitary gland to release ADH
How does ADH work on target cell?
ADH targets the nephrons of kidneys - tubules become more permeable to water
More water is reabsorbed - body excretes less (but more concentrated urine) - blood pressure increases
Hypothalamus detects this - signals posterior pituitary to stop releasing ADH
What is the result of an inability to produce ADH?
Diabetes insipidus - person produces large volumes of urine - resulting loss of ions from the body
What is a name given to hypothalamus and the anterior pituitary hormones?
Tropic hormones - their targets are other endocrine glands
What do tropic hormones do?
Stimulate endocrine glands to release other hormones
