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chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
hormones reach all parts of the body but only what cells are equipped to respond?
how many hormones are there
more than 70
the endocrine system secretes what?
- hormones that coordinate slower but longer- acting responses including
the nervous system conveys what?
high-speed electrical signals along specialized cells called neurons which regulate other cells
exogenous chemicals or endocrine disruptors
- chemicals that have been identified to interfere with hormone signaling
- insecticides, herbicides, dyes, plastics, detergents
- DDT, PCB's and red dye #3
how do hormones work?
- chemical signals bind to receptor proteins on target cells (only target cells respond to the signal)
- these include
- local regulators
exocrine glands have ducts and secrete what?
- substances onto body surfaces or into body cavities
- tear ducts
- sweat glands
- salivary glands
- mammary glands
- chemical signals that travel over short distances by diffusion
- help regulate blood pressure, nervous system function, and reproduction
- divided into two types: paracrine and autocrine
signals act on cells near the secreting cell
signals act on the secreting cell itself
neurons (nerve cells) contact target cells at what?
at synapses neurons
neurons often secrete chemical signals called neurotransmitters
- diffuse a short distance to bind to receptors on the target cell
- play a role in
- chemical signals that are released from the body and used to communicate with other individuals in the species
- mark trails to food sources, warn of predators, and attract potential mates
- (7 types of pheromones)
cause conspecifics to flee
cause short term changes
cause developmental changes
three major classes of molecules function as hormones in vertebrates they are
- polypeptides (proteins and peptides)
- Amines derived from amino acids
- steroid hormones
anobolic steroids can cause what 7 effects?
- liver damage
- gynecomastia (male develop breasts)
- testicular atrophy
lipid soluble hormones (steroid hormones) and water soluble hormones (polypeptides and amines) which pass through a cell membrane easily?
- lipid soluble
- water soluble do not
the solubility of a hormone correlates with?
the location of receptors inside or on the surface of target cells
water- soluble hormones are secreted by?
exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
lipid-soluble hormones diffuse across?
cell membranes, travel in bloodstream bound to transport proteins, and diffuse through the membrane of target cells
binding of a hormone to its receptor intitates a signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression
the response to a lipid-soluble hormone is usually a change in what?
for a lipid pathway, steroids, thyroid hormones, and hormonal form of vitamin D enter target cells and bind to protein receptors in what?
- the cytoplasm or nucleus
- protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes
vitamin D is formed where?
- in the skin of vertebrates
- feathers and fur block the skin
- oily secretions on fur generate the vitamin and licking absorbs it
vitamin D is then transported to?
- to the liver
- converted to physiological active form
vitamin D regulates
- calcium and phosphate in the blood
- cell proliferation and aptosis
- neuromuscular function
hormone diseases are caused by
- either an overbalance or a limitation of a hormone
- gland hyposecretion
- gland hypersecretion
- usually multiple symptoms
- adrenal glands do not produce sufficient glucorticoids
- light headedness
- muscle weakness
- regulate immune responses
- cardiac function
- and homeostatic responses
in addison's disease, the decrease in glucocorticoids causes a feedback where?
- hypothalamus to produce CRH
- CRH recieved by the pituitary which then produces ACTH to signal the adrenal glands to produce more glucocorticoids
- MSH and ACTH share the same precursor molecule POMC
- with the upregulation of ACTH there is also an increase in MSH
- darkening of creases of the hands, inside of the cheeks and old scars are common
treatment for addison's disease and causes
- oral steroids
- medicines for other illnesses interfere with steroid synthesis
- infections damaging the adrenal glands