PSL300 term test 1 Questions and Correct
Answers
3 methods of local control via intercellular communication
- gap junctions (eg. cardiac muscle)
- contact-dependent (eg. immune)
-autocrine (molecules move a small distance through interstitial fluid
neurohormones
chemicals released by neurons into blood for action at distant targets
simple vs complex reflex
simple - either nervous or endocrine system
complex - both systems, several integrating systems
in reflex control, cells at a distant site control the response (vs. local change)
types of sensors
central receptors (eg. eyes, ears), peripheral receptors (eg. chemo and osmoreceptor), cell
membrane/intracellular receptor proteins
neural vs endocrine reflex-specificity
neuron terminates in single target cell(s); most cells are exposed to hormone, response
depends on if cell has receptor
neural vs endocrine reflex - nature of signal
neural has electrical signal through neuron, then chemical neurotransmitters; endocrine has
chemical signals secreted in blood
,neural vs endocrine reflex - speed
neural is faster
neural vs endocrine reflex - duration of action
neural is shorter
neural vs endocrine reflex - coding for stimulus intensity
neural signals are identical in strength, code with increased frequency; in endocrine, stimulus
intensity relates to amount of secreted hormone
key features of hormones
can be made in different places, chemicals made by cells in specific endocrine glands,
transported in blood to distant targets, bind specific receptors, may act on multiple tissues,
action must be terminated
synthesis, release, transport in blood, examples of hydrophilic and hydrophobic
hormones
hydrophilic- made in advance and stored, release by exocytosis, dissolved in blood, eg.
peptide/protein hormones, catecholamines
hydrophobic - made on demand, released by diffusion, bound to carrier proteins in blood, eg.
steroid and thyroid hormones
peptide hormones
3 or more AA, synthesized like secreted proteins, short half life in plasma, eg. insulin,
hydrophilic so dissolved in plasma
post-translational processing of peptide hormone
,preprohormone bound to signal sequence, signal gets cut off, peptide fragments on
prohormone get off, produce active hormone
disulfide bonds on proinsulin
regions with disulfide bonds can get off, forming insulin, and the remaining C-peptide is a
byproduct and can be used to indirectly measure insulin release
preprohormones
- can contain several copies of same hormone
- can contain more than one type of hormone
- active peptides released depends on specific proteolytic processing enzymes and cell type
steroid hormones
derived from cholesterol, longer half-life, eg. sex steroids like estrogen, cortisol, hydrophobic
and bulky so bound to transport proteins in blood
type of steroid hormone made depends on which enzymes are present in the cell
eg. cholesterol can be made into aldosterone or cortisol in adrenal cortex or estradiol in ovary
monoamine hormones
derived from single AA (Trp or Tyr), eg. catecholamines like epinephrine, thyroxine,
hydrophilic so dissolved in plasma
Trp vs Tyr derivatives
Trp: melatonin (behaves like peptides or steroids)
Tyr: catecholamines - dopamine, norepinephrine, and epinephrine (behave like peptides),
thyroid hormones - thyroxine, T4, triiodothyronine, T3 (behave like steroids)
melatonin
, darkness hormone, secreted at night, made in pineal glannd
synthesis of catecholamines (pathway from Tyr)
made in adrenal medulla, stored in vesicles and released via exocytosis, goes from Tyr -
DOPA - dopamine - norepinephrine - epinephrine
how do stimuli trigger hormone release from endocrine cells
- change membrane potential
- increased [Ca2+] in cytosol
- change enzymatic activity
- increase transport of hormone substrates into cell
- alter transcription of genes coding for hormones or for enzymes needed for hormone
synthesis
- promote survival, sometimes growth of endocrine cell
glucose stimulation of insulin release in pancreatic beta cell
glucose uptake by GLUt2 transporter, glucokinase phosphorylates, glycolysis leads to
increased ATP, ATP blocks K+ efflux from ATP-sensitive potassium channel,
depolarization, opening of voltage-gated calcium channel, stimulate movement of vesicles,
release insulin (remember, it's a peptide hormone)
hypothalamus-pituitary axis
peripheral endocrine gland hormone (eg. cortisol from adrenal cortex) has negative feedback
on anterior pituitary hormone and hypothalamic hormone; anterior pituitary hormone has
negative feedback on hypothalamic hormone
anterior pituitary
Answers
3 methods of local control via intercellular communication
- gap junctions (eg. cardiac muscle)
- contact-dependent (eg. immune)
-autocrine (molecules move a small distance through interstitial fluid
neurohormones
chemicals released by neurons into blood for action at distant targets
simple vs complex reflex
simple - either nervous or endocrine system
complex - both systems, several integrating systems
in reflex control, cells at a distant site control the response (vs. local change)
types of sensors
central receptors (eg. eyes, ears), peripheral receptors (eg. chemo and osmoreceptor), cell
membrane/intracellular receptor proteins
neural vs endocrine reflex-specificity
neuron terminates in single target cell(s); most cells are exposed to hormone, response
depends on if cell has receptor
neural vs endocrine reflex - nature of signal
neural has electrical signal through neuron, then chemical neurotransmitters; endocrine has
chemical signals secreted in blood
,neural vs endocrine reflex - speed
neural is faster
neural vs endocrine reflex - duration of action
neural is shorter
neural vs endocrine reflex - coding for stimulus intensity
neural signals are identical in strength, code with increased frequency; in endocrine, stimulus
intensity relates to amount of secreted hormone
key features of hormones
can be made in different places, chemicals made by cells in specific endocrine glands,
transported in blood to distant targets, bind specific receptors, may act on multiple tissues,
action must be terminated
synthesis, release, transport in blood, examples of hydrophilic and hydrophobic
hormones
hydrophilic- made in advance and stored, release by exocytosis, dissolved in blood, eg.
peptide/protein hormones, catecholamines
hydrophobic - made on demand, released by diffusion, bound to carrier proteins in blood, eg.
steroid and thyroid hormones
peptide hormones
3 or more AA, synthesized like secreted proteins, short half life in plasma, eg. insulin,
hydrophilic so dissolved in plasma
post-translational processing of peptide hormone
,preprohormone bound to signal sequence, signal gets cut off, peptide fragments on
prohormone get off, produce active hormone
disulfide bonds on proinsulin
regions with disulfide bonds can get off, forming insulin, and the remaining C-peptide is a
byproduct and can be used to indirectly measure insulin release
preprohormones
- can contain several copies of same hormone
- can contain more than one type of hormone
- active peptides released depends on specific proteolytic processing enzymes and cell type
steroid hormones
derived from cholesterol, longer half-life, eg. sex steroids like estrogen, cortisol, hydrophobic
and bulky so bound to transport proteins in blood
type of steroid hormone made depends on which enzymes are present in the cell
eg. cholesterol can be made into aldosterone or cortisol in adrenal cortex or estradiol in ovary
monoamine hormones
derived from single AA (Trp or Tyr), eg. catecholamines like epinephrine, thyroxine,
hydrophilic so dissolved in plasma
Trp vs Tyr derivatives
Trp: melatonin (behaves like peptides or steroids)
Tyr: catecholamines - dopamine, norepinephrine, and epinephrine (behave like peptides),
thyroid hormones - thyroxine, T4, triiodothyronine, T3 (behave like steroids)
melatonin
, darkness hormone, secreted at night, made in pineal glannd
synthesis of catecholamines (pathway from Tyr)
made in adrenal medulla, stored in vesicles and released via exocytosis, goes from Tyr -
DOPA - dopamine - norepinephrine - epinephrine
how do stimuli trigger hormone release from endocrine cells
- change membrane potential
- increased [Ca2+] in cytosol
- change enzymatic activity
- increase transport of hormone substrates into cell
- alter transcription of genes coding for hormones or for enzymes needed for hormone
synthesis
- promote survival, sometimes growth of endocrine cell
glucose stimulation of insulin release in pancreatic beta cell
glucose uptake by GLUt2 transporter, glucokinase phosphorylates, glycolysis leads to
increased ATP, ATP blocks K+ efflux from ATP-sensitive potassium channel,
depolarization, opening of voltage-gated calcium channel, stimulate movement of vesicles,
release insulin (remember, it's a peptide hormone)
hypothalamus-pituitary axis
peripheral endocrine gland hormone (eg. cortisol from adrenal cortex) has negative feedback
on anterior pituitary hormone and hypothalamic hormone; anterior pituitary hormone has
negative feedback on hypothalamic hormone
anterior pituitary
