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Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?
- Paracrine – local signaling between neighboring cells- Endocrine – distance signaling thereby using the circulatory system- Review Ch 11: Cell communication
- Reception- G protein-linked receptors- Tyrosine kinase receptors- Ion channel receptors- Steroid hormone receptors – intracellular
- Transduction- 2nd messengers – Ca+2 ions, cAMP, IP3 & DAG- Phosphorylation cascades – protein kinases
- Response- Gene activation aka transcription - Enzyme activation- Cell division
} Membrane bound
Figure 45.3 Mechanisms of hormonal signaling: a reviewSECRETORYCELL
Hormonemolecule
VIABLOOD
Signal receptor
TARGETCELL
Signaltransductionpathway
Cytoplasmicresponse
Nuclearresponse
NUCLEUS
DNA
OR
SECRETORYCELL
Hormonemolecule
VIABLOOD
TARGETCELL
Signalreceptor
Signaltransductionand response
DNA
mRNA
NUCLEUS
Synthesis ofspecific proteins
(a) Receptor in plasma membrane (b) Receptor in cell nucleus
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?
- Simple endocrine- Simple neurohormone- Simple neuroendocrine
Figure 45.2 Basic patterns of simple hormonal control pathwaysPathway Example
Stimulus Low bloodglucose
Receptorprotein
Pancreassecretesglucagon ( )
Endocrinecell Blood
vessel
LiverTarget
effectors
Response
Pathway Example
Stimulus Suckling
Sensoryneuron
Hypothalamus/posterior pituitary
Neurosecretorycell
Bloodvessel
Posterior pituitarysecretes oxytocin( )
Targeteffectors
Smooth musclein breast
Response Milk release
Pathway Example
Stimulus Hypothalamicneurohormonereleased inresponse toneural andhormonalsignals
Sensoryneuron
Hypothalamussecretes prolactin-releasinghormone ( )
Neurosecretorycell
Bloodvessel
Anteriorpituitarysecretesprolactin ( )Endocrine
cell
Bloodvessel
Targeteffectors
Response
Mammary glands
Milk production
(c) Simple neuroendocrine pathway
(b) Simple neurohormone pathway
(a) Simple endocrine pathway
Hypothalamus
Glycogenbreakdown,glucose releaseinto blood
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Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?
- Different receptor types on different cells- Different intracellular signal molecules
Figure 45.4 One chemical signal, different effectsDifferent receptors different cell responses
Epinephrine
a receptor
Epinephrine
b receptor
Epinephrine
b receptor
Vesselconstricts
Vesseldilates Glycogen
breaks downand glucose is releasedfrom cell
Intestinal blood vessel
(a) Skeletal muscle blood vessel
(b) Liver cell(c)
Different intracellular proteins different cell responses
Glycogendeposits
Figure 45.6 Human endocrine glands surveyed in this chapter
Hypothalamus
Pineal gland
Pituitary gland
Thyroid glandParathyroid glands
Adrenal glands
Pancreas
Ovary(female)
Testis(male)
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?4. What are some common endocrine glands?5. How does the hypothalamus control the anterior & posterior pituitary
differently?- posterior – directly via neurohormones- anterior – indirectly via releasing hormones (tropic hormones)
Figure 45.7 Production and release of posterior pituitary hormones
Hypothalamus
Neurosecretorycells of thehypothalamus
Axon
Anteriorpituitary
Posteriorpituitary
HORMONE ADH Oxytocin
TARGET Kidney tubules Mammary glands,uterine muscles
Figure 45.8 Production and release of anterior pituitary hormones
Tropic Effects OnlyFSH, follicle-stimulating hormoneLH, luteinizing hormoneTSH, thyroid-stimulating hormoneACTH, adrenocorticotropic hormone
Nontropic Effects OnlyProlactinMSH, melanocyte-stimulating hormoneEndorphin
Nontropic and Tropic EffectsGrowth hormone
Neurosecretory cellsof the hypothalamus
Portal vessels
Endocrine cells of theanterior pituitary
Hypothalamicreleasinghormones(red dots)
HORMONE FSH and LH TSH ACTH Prolactin MSH Endorphin Growth hormone
TARGET Testes orovaries
Thyroid Adrenalcortex
Mammaryglands
Melanocytes Pain receptorsin the brain
Liver Bones
Pituitary hormones(blue dots)
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?4. What are some common endocrine glands?5. How does the hypothalamus control the anterior & posterior pituitary
differently?6. How is the thyroid regulated?
- Regulates metabolism- T3 & T4 hormones- Triiodothyronine (T3) & thyroxine (T4) have 3 or 4 iodine atoms
Hypothalamus
Anteriorpituitary
TSH
Thyroid
T3 T4+
Figure 45.9 Feedback regulation of T3 and T4 secretion from the thyroid gland
TRH
What happens with a lack of iodine in the diet?Pg 33
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?4. What are some common endocrine glands?5. How does the hypothalamus control the anterior & posterior pituitary
differently?6. How is the thyroid regulated?7. How is homeostasis of blood calcium achieved?
- Thyroid & parathyroid glands
CalcitoninThyroid glandreleasescalcitonin.
StimulatesCa2+ depositionin bones
ReducesCa2+ uptakein kidneys
STIMULUS:Rising bloodCa2+ level
Blood Ca2+
level declinesto set point
Homeostasis:Blood Ca2+ level
(about 10 mg/100 mL)
Blood Ca2+
level risesto set point
STIMULUS:Falling bloodCa2+ level
StimulatesCa2+ releasefrom bones
Parathyroidgland
IncreasesCa2+ uptakein intestines
Activevitamin D
Stimulates Ca2+
uptake in kidneys
PTH
Figure 45.11 Hormonal control of calcium homeostasis in mammals
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?4. What are some common endocrine glands?5. How does the hypothalamus control the anterior & posterior pituitary
differently?6. How is the thyroid regulated?7. How is homeostasis of blood calcium achieved?8. How is homeostasis of blood glucose achieved?
- Insulin and glucagon
Figure 45.12 Maintenance of glucose homeostasis by insulin and glucagon
Beta cells ofpancreas are stimulatedto release insulininto the blood.
Insulin
Liver takesup glucoseand stores itas glycogen.
Body cellstake up moreglucose.
Blood glucose leveldeclines to set point;stimulus for insulinrelease diminishes.
STIMULUS:Rising blood glucose
level (for instance, aftereating a carbohydrate-
rich meal)
Homeostasis:Blood glucose level
(about 90 mg/100 mL)
Blood glucose levelrises to set point;
stimulus for glucagonrelease diminishes.
STIMULUS:Dropping blood glucoselevel (for instance, after
skipping a meal)
Alpha cells of pancreasare stimulated to releaseglucagon into the blood.
Liver breaksdown glycogenand releasesglucose intoblood.
Glucagon
Chapter 45: Hormones and the Endocrine System1. What is the difference between paracrine & endocrine?2. What are the 3 general types of signaling pathways?3. How can 1 ligand cause different effects?4. What are some common endocrine glands?5. How does the hypothalamus control the anterior & posterior pituitary
differently?6. How is the thyroid regulated?7. How is homeostasis of blood calcium achieved?8. How is homeostasis of blood glucose achieved?9. How does the body respond to short-term stress, ie fight or flight?
- epinephrine & norepinephrine
Spinal cord(cross section)
Nervesignals
Nervecell
Releasinghormone
Stress
Hypothalamus
Anterior pituitary
Blood vessel
ACTH
Adrenalgland
Kidney
Adrenal medullasecretes epinephrineand norepinephrine. Adrenal cortex
secretesmineralocorticoidsand glucocorticoids.
Effects of epinephrine and norepinephrine:1. Glycogen broken down to glucose; increased blood glucose2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity
Effects ofmineralocorticoids:
Retention of sodiumions and water bykidneys
Increased bloodvolume and bloodpressure
1.
2.
Effects ofglucocorticoids:
Proteins and fatsbroken down andconverted to glucose,leading to increasedblood glucose
Immune system maybe suppressed
2.
1.
(b) Long-term stress response(a) Short-term stress response
Nerve cell
Figure 45.13 Stress and the adrenal gland
Table 45.1 Major Human Endocrine Glands and Some of Their Hormones
Table 45.1