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