ch 46 - exam 4 Flashcards
hormones
what are the types of chemical signals and what are they called?
- autocrine: self
- paracrine: other cells near
- endocrine: blood
- neural signal: neuron to neuron
- neuroendocrine: neuron to blood
What is the technical definition of a hormone?
a regulatory substance produced in an organism and transported in blood to stimulate specific cells or tissues into action
What is the endocrine system?
collection of organs/cells that secrete chemical signals to distant target cells by bloodstream
Describe feedback inhibition and its role in coupling the nervous system with the endocrine system.
estradiol low - negative feedback on LH, tells brain not to release egg
estradiol high - positive feedback on LH, tells brain to release egg
progesterone - negative on both LH and FSH, tells brain not to release egg
What is the purpose of Schwann cells?
prevent ion leakage back out of the cell. makes fast signaling possible in small diameter axons
Presynaptic vs postsynaptic neuron
pre - axon extending signal
post - dendrites receiving signal
Are neurotransmitters perminant?
No, they are temporary
What does tetrodotoxin do?
puffer fish, blocks Na+ voltage gated channels so they dont open
What does spooky toxin do?
golden centipede, blocks K+ voltage gated channels so they dont open
How do we typically identify and quantify a hormone?
radioimmunoassay - quantifies amount of specific hormone in a blood sample
What are the 3 classes of hormones and how do they target cells? Lipid vs water soluble?
- polypeptides/peptides: water soluble
- amino acids: water soluble
- steroids: lipid soluble, can get into cell!
What is estradiol vs epinephrine?
estradiol is a steroid for female reproduction, - leads to production of NEW proteins
epinepherine is an amino acid for stress response, activates EXISTING proteins
What hormones are involved in frog metamorphosis?
T3 (thyroid)
What hormones are involved in insect metamorphosis?
Ecdysone + Juvenile Hormone
What does primary sexual development look like in vertabrates?
sex chromosomes form gonads, in utero
What does secondary sexual development look like in vertabrates?
puberty - growth hormone enhanced by sex hormones
How do melatonin and the photoperiod relate in mating?
photoperiod = daylight hours, more hours, less night = more mating time
mammals have photoreceptors in retinas which send signals to pineal gland which can produce melatonin depending on signal
less night = less melatonin, so hypothalamus stimulates gonads to make sex hormones: mating ensues
What do hormones do overall?
coordinate acivities of cells in 3 areas:
- development, growth and reproduction
- response to environmental changes (temp)
- maintaining homeostasis
describe steroid hormone action process
- hormones diffuse into target cell
- hormone binds to receptor - conformational change
- hormone-receptor complex enters nucleus and binds to DNA, induces start of transcription (makes mRNA)
- many mRNA transcripts produced, amplifying signal
- each transcript is translated many times (by ribosomes into proteins), further amplifying signal
What does the Pineal Gland do?
responds to photoperiod/receptors
What are endocrine disruptors and how does pollution interact?
chemicals that disrupt normal function of endocrine system, mimic hormones, typically pesticides or heavy metals or industrial chemicals, ex: xenoestrogens
What hormones are involved in short-term stress? Impacts?
epinephrine - fight/flight, inc blood glucose, inc bp, inc O2 consumption by brain, inc pulse rate
What hormones are involved in long-term stress? Impacts?
cortisol - ensure glucose in blood, energy costly
What hormones are involved in homeostasis? What are their effects?
insulin - blood sugar
ADH - water balance
EPO - blood O2
aldosterone - electrolyte conc. + water retention
