Hormones Flashcards
What are Hormones?
Chemicals secreted by one cell group (glands) that travel through blood to act on organ cells
What are endocrine glands?
Glands that release hormones within the body
What are exocrine glands?
Glands that ue ducts to secrete fluids outside of the body (Sweat and tears)
What is the difference between Hormones and neural signalling?
NS: involves chemical release & diffusion across synaptic cleft
ES: involves hormones being releases into bloodstream to act on targets
What are the principles of Hormone Action?
- Hormones act in gradual fashion
- Act by changing the probability or intensity of a behaviour
- Relationship between hormones and behaviour is reciprocal
- A hormone may have multiple effects and one behaviour can be affected by multiple hormones
- Often have a pulsatile secretion pattern
- Some hormones are controlled by circadian clocks
- Hormones can interact with other hormones and can change their effects
What are the 3 ways hormonal communication is similar to neural communication?
- they both produce and store chemicals and release upon stimulation
- both NT’s and hormones bind to receptors to stimulate targets
- Some chemicals can act as either hormones or NTs depending area of release
What are the 4 was neural and hormonal communication differ?
- NC travels to precise points, HC spreads through whole body and is picked by cells with right receptor
- NC is faster (ms) than HC (seconds/minutes)
- Neural distance varies while hormones may travel over a metre
- NC can be under voluntary control while HC is involuntary
What are the major classes of hormones?
- Peptide/Protein hormone - string of amino acids
- monoamine hormones - a modified amino acid, could also be in brain as transmitters
- Steroid hormones - four rings of carbon acids
Hormone receptors are not in?
Ion channels
How do hormones effect cells?
Hormones bind to receptors and trigger release of intracellular second messengers which then spread throughout the cell and cause alot of physiological changes. Second messenger effect in cell are rapid
where are steroid hormone receptors?
Steroid hormone receptors are in cell freely floating in cytoplasm
What are steroid hormones?
Steroid hormones are all made from cholesterol (testosterone, estrogen, cortisol, etc) and they are lipophilic and can pass through cell memberane
What do steroid hormones do in cells?
The steroid receptor bind to DNA and acts as a transcription controlling gene expressions.
Transcription factor mediated mechanisms are slow (few hours) but are long lasting
What are the effects of hormones on the organs?
- Promote proliferation, growth, and differentiation of cells
- Modulate cell activity and metabolism
- Modulate hormone secretion from endocrine glands
What is the Pituitary Gland?
It is the master gland of the body, it secretes many different hormones, and regulates other hormone secreting glands in body
It is separated into 2 parts
