Hormones Flashcards
Definition of a hormone
chem substance released in small quantities from endocrine glands into the circulatory system to elicit a response in target tissues
T or F CO2 is a hormone
false
secretion of hormones is controlled by the nervous system or the hormones work on the nervous system
neuroendocrine system
3 categories of hormones
steroids
aa derivatives
peptides and protiens
derived from cholesterol
steroid hormone
aa derived hormones are derived from ______
tyrosine
hormone message is transmitted across a synaptic cleft
synaptic
homrone message is transmitted by diffusion in interstitial space
paracrine and autocrine
hormone message is transmitted by circulating body fluids
endocrine and neuroendocrine
effects of hormones transmitted this way is…
general?
local?
general: endocrine and neuroendocrine
local: synaptic (paracrine and autocrine are locally diffuse)
ductless glands
endocrine glands
specificity of hormone secreted via synapses depends on
anatomical location and receptors
specificity of hormone secreted via paraendocrine or autocrine control depends on
receptors
specificity of hormone secreted via endocrine control depends on
receptors
specificity of hormone secreted via neuroendocrine control depends on
receptors
Steroid hormones:
Glucocorticoids Mineralocorticoids (ADH) Antrogens Estrogens Progesterone vit D
AA derived hormones
Catecholamines (Epi, NE, DA)
Thyroid hormones (T3 and T4)
Melatonin
increasing the number of high affinity receptors will (increase or decrease) the response
increase
*and vice versa
dose response curves
look at em’
specificity vs capacity
What type of hormone bind intracellular recetors
steroids and thyroid hormones
What are the functions of secondary messangers?
amplify and disperse signal throughout the cell
What is permissiveness? Give and example.
a hormone will allow another hormone to work better
ex: TH alone –> no FA release
Epi alone –> very little FA release
TH + Epi –> LOTS of FA released
Do you get a bigger change in response if the number of receptors is increased or decreased?
decreased
The conc needed to produce max biological response is considerably smaller than the conc needed to fill the number of receptors. What is this called and what is the significance?>
spare receptors
very little hormone is needed to get a response bc target is ~over expressed?
prevents hormones from being excreted in the kidney
binding proteins
active form of hormone
free
i.e. acts on target tissues
acts on feedback sensors
free hormone
is able to cross capillaries
free hormone
how are hormones usually measured
competitive binding assays
pattern of secretion when hormone is released 1x a day. example
circadian or diurnal
cortisol (well ACTH bc it causes cortisol to be released)
pattern of secretion when hormone is released multiple times a day. example
ultradian
and pulstile, which is a type of ultradian rhythm
LH
testosterone, circadian or ultradian?
circadian
insulin has what type of secretion pattern?
stimulus induced
What are the 3 ways that blood levels of a hormone can be altered
inc/dec secretion, degradation, or conc of plasma binding protein
Endocrine diseases are often cuased by excess or deficient production of a hormone. What are 3 other general causes
alterations in receptor number or affinity
post-receptor events
altered metabolism of hormone (liver or kidney dz)
more hormone exists in free or bound state
free
What happens if you increased the conc of a hormone’s binding protein?
the conc of free hormone will transiently decrease. but the body will sense the hypo state and produce more hormone to return to baseline (~new set point)
*recall, free hormone acts on the feedback control mechanisms
When is cortisol normally secreted? WHat are the exceptions?
1 hr before we get up
jet lag and shift work
diff in synthesis between steroid, protein, and catecholamines (aa derived), and thyroid hormones
protein/peptides and catecholamines are nearly continuously produced
steroids are not made until stimulated, little made
TH is partially produced, i.e. the precursor is made and then once there is a stim T3 anf 4 are made
diff in storage between steroid, protein, and catecholamines (aa derived), and thyroid hormones
protein/peptides and catecholamines are stored in granules
steroids are not really stored since they are made when they are needed
TH is stored in precursor form, Tg
What types of hormones typically circulate bound to proteins
steroids and TH
What types of hormones typically circulate freely
protein/peptides and catecholamines
Type of hormone with the longest half life
TH (1-6 days)
What types of hormones whose secretion is more tightly regulated
protein/peptides and catecholamines
*steroids are secreted as they are made and TH are more or less continuously secreted
What types of hormones typically bind cell surface receptos
protein/peptides and catecholamines
What types of hormones typically work by activating genes
steroids and TH
= bind nuclear receptors
how are protein/peptides degraded?
to aa in liver, kidneys are target tissues
how are catecholamines degraded?
COMT or MAO
What type of hormone is excreted in urine
steroid (free) bc water soluble
what type of hormone has v. little excretion? how does that work?
proteins/peptide hormones are broken down into their aa
TH due to enterohepatic circulation
are protein/peptide hormones activated?
no, renin is the exception
What are the 3 types of hormone pathways and give an example of each
- direct: gland –> hormone –> target –> effects
- 2 endocrine glands and hormones: ex: parathyroid secretes PTH –> kidneys which secrete vit D –> target –> effect
- 3 glands and hormones: hypothalamus secretes RH –> ant pituitary which secretes TH –> thyroid which secretes T3/4 –> target –> effects`
the endocrine’s response to a stimulus reinforces that stimulus
positive feedback
Example of positive feedback
stretch of cervix leads to OT release which cuases the cervix to stretch more
give 2 examples of negative feedback. Hint glucose
insulin negates inc in plasma glc
inc plasma glucose –> inc insulin secretion –> inc plasma insulin conc.–> inc glucose uptake and utilization by muscle and adipose tissue –> dec plasma glucose back toward normal (fasting level)
glucagon negates dec in plasma glc
dec plasma glucose conc. –> inc glucagon secretion –> inc plasma glucagon –> inc hepatic glucose release –> inc plasma glucose conc. back toward normal.
What bringd glucagon back to basal level after it falls with dec blood glc levels?
NE or E
