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hormones
chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
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hormones reach all parts of the body but only what cells are equipped to respond?
target cells
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how many hormones are there
more than 70
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the endocrine system secretes what?
- hormones that coordinate slower but longer- acting responses including
- reproduction
- development
- energy
- metabolism
- growth
- behavior
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the nervous system conveys what?
high-speed electrical signals along specialized cells called neurons which regulate other cells
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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
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how do hormones work?
- chemical signals bind to receptor proteins on target cells (only target cells respond to the signal)
- these include
- hormones
- local regulators
- neurotransmitters
- neurohormones
- pheromones
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exocrine glands have ducts and secrete what?
- substances onto body surfaces or into body cavities
- tear ducts
- sweat glands
- salivary glands
- liver
- pancreas
- mammary glands
- stomach
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local regulators
- 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
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paracrine regulators
signals act on cells near the secreting cell
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autocrine regulators
signals act on the secreting cell itself
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neurons (nerve cells) contact target cells at what?
synapses
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at synapses neurons
neurons often secrete chemical signals called neurotransmitters
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neurotransmitters
- diffuse a short distance to bind to receptors on the target cell
- play a role in
- sensation
- memory
- cognition
- movement
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pheromones
- 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)
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alarm phermones
cause conspecifics to flee
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releaser pheromones
initiate behavior
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signal pheromones
cause short term changes
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primer pheromones
cause developmental changes
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sex pheromones
attract mates
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three major classes of molecules function as hormones in vertebrates they are
- polypeptides (proteins and peptides)
- Amines derived from amino acids
- steroid hormones
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anobolic steroids can cause what 7 effects?
- aggression
- violence
- mania
- psychosis
- liver damage
- gynecomastia (male develop breasts)
- testicular atrophy
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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
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the solubility of a hormone correlates with?
the location of receptors inside or on the surface of target cells
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water- soluble hormones are secreted by?
exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
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lipid-soluble hormones diffuse across?
cell membranes, travel in bloodstream bound to transport proteins, and diffuse through the membrane of target cells
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signal transduction
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
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the response to a lipid-soluble hormone is usually a change in what?
gene expression
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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
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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
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vitamin D is then transported to?
- to the liver
- converted to physiological active form
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vitamin D regulates
- calcium and phosphate in the blood
- cell proliferation and aptosis
- neuromuscular function
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hormone diseases are caused by
- either an overbalance or a limitation of a hormone
- gland hyposecretion
- gland hypersecretion
- tumor
- usually multiple symptoms
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addisons disease
- adrenal glands do not produce sufficient glucorticoids
- symptoms
- fatigue
- light headedness
- muscle weakness
- fever
- vomiting
- hyperpigmentation
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glucocorticoids
- regulate immune responses
- cardiac function
- metabolism
- and homeostatic responses
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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
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hyperpigmentation
- 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
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treatment for addison's disease and causes
- oral steroids
- genetic
- autoimmune
- medicines for other illnesses interfere with steroid synthesis
- infections damaging the adrenal glands
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