Endocrine System - 18 Flashcards
What does testosterone do?
- promotes the production of functional sperm
- maintains the secretory glands of the male reproductive tract
- stimulates growth
- determines male secondary sex characteristics such as the distribution of facial hair and body fat
- effects metabolic operations
- stimulates protein synthesis and muscle growth
- produces aggressive behavioral responses
what are androgens?
male hormones
what is paracrine communication?
the use of chemical messengers to transfer information from cell to cell within a single tissue
paracrine factors can have primary and secondary effects. What is the difference?
primary affects occur in the tissue of origin and secondary effects occur in other tissues and organs.
when secondary effects occur, paracrine factors are acting as
hormones
hormonal regulation is suitable for directing gradual coordinated processes but is unable to handle situations that require immediate responses. That kind of “crisis management” is operated by what system?
the nervous system
when released into the serum, norepinephrine and epinephrine are called hormones. When released across synapses they are called
neurotransmitters
the endocrine system includes
all the endocrine cells and tissues of the body which produce hormones or paracrine factors that have effects beyond their tissues of origin
What is one difference between endocrine cells and exocrine cells?
Endocrine cells are glandular secretory cells that release their secretions into the extracellular fluid as where exocrine cells which secrete their products onto epithelial surfaces generally by the way of ducts.
Which hormones are released from the posterior lobe of the pituitary gland?
oxytocin and ADH
Name the two parts of the adrenal glands that release hormones.
The adrenal medulla and the adrenal cortex.
What hormones are released from the adrenal medulla?
Epinephrine (E) and norepinephrine (NE).
What hormones are released by the adrenal cortex?
Cortisol, corticosterone, aldosterone, and androgens.
What hormones are released from the thyroid gland?
Thyroxine (T4), triiodothyronine (T3), and calcitonin (CT).
What hormones are released by the kidneys?
Renin, erythropoietin (EPO), and calcitriol.
What hormones are released by adipose tissue?
Leptin and resistin.
What hormones are released by the heart?
The natriuretic peptides ANP and BNP.
What hormone is released by the pineal gland?
Melatonin.
Hormones can be divided into three groups on the basis of their chemical structure:
- amino acid derivatives
- peptide hormones
- lipid derivatives
What are prohormones?
inactive molecules that are converted to active hormones either before or after they are secreted.
What are the two classes of lipid derivatives and where are they derived from?
- Steroid hormones that are derived from cholesterol
2. Eicosanoids derived from arachidonic acid
What are eicosanoids?
Small molecules with a five-carbon ring at one end. These compounds are important paracrine factors that coordinate cellular activities and affect enzymatic processes that occur in extracellular fluids. Some of the eicosanoids also have secondary roles as hormones.
Explain the equilibrium state between free hormones and bound hormones.
As the free hormones are removed and inactivated they are replaced by the release of bound hormones. The bloodstream contains a substantial reserve (several weeks) of hormones at any time.
What are the catacholamines?
- epinephrine (E)
- norepinephrine (NE)
- dopamine
Where are hormone receptors located?
Either on the cell membrane or inside the cell.
Any hormone that is not lipid soluble can only bind to a receptor on the cell membrane and as such does not have direct affects on the target cell. These types are hormones are referred to as:
first messengers - any substance that causes the appearance of a second messenger in the cytoplasm.
What is the function of a second messenger?
To act as either an enzyme activator, inhibitor, or cofactor, with the net result being a change in the rates of various metabolic reactions.
What are the most important second messengers?
- cyclic-AMP
- cyclic-GMP
- calcium ions
Several hormones of the hypothalamus and pituitary gland are released in sudden bursts called:
pulses
What is another name for the pituitary gland?
Hypophysis
