Introductory Questions #8 1)Name the nine major endocrine glands found in the body. Which one is called the master gland? 2)Name three major local regulators.

Introductory Questions #8

1) Name the nine major endocrine glands found in the body. Which one is called the “master gland”?

2) Name three major local regulators that act on nearby target cells. (pgs. 947-948)

3) Name three key molecules that play a role in the signal transduction pathway (typical reactions in the endocrine system).

4) How is the anterior part of the pituitary gland different from the posterior part? Name the hormones secreted from each area. Which region secretes fewer types of hormones?

5) Using the table on pg. 949, name the hormone(s) that:-Raises blood-calcium levels

-maintains metabolic processes

Homeostasis & Osmoregulation

Chapter

• It assists the kidneys by– making urea from ammonia– breaking down toxic chemicals

The liver is vital in homeostasis

Homeostasis: regulation of internal environment

• Thermoregulation internal temperature

• Osmoregulation solute and water balance

• Excretion nitrogen containing waste

Regulation of body temperature• Thermoregulation• 4 physical processes:• Conduction~transfer of heat between

molecules of body and environment• Convection~transfer of heat as

water/air move across body surface• Radiation~transfer of heat produced

by organisms• Evaporation~loss of heat from liquid

to gas

• Sources of body heat:• Ectothermic: determined by

environment• Endothermic: high metabolic rate

generates high body heat

• Bears don’t technically hibernate– They do enter a dormant state, when their body

temperature drops by several degrees

• Bears are endotherms– Endothermic animals derive

most of their body heat from metabolism

– Ectothermic animals warm themselves mainly by absorbing heat from their surroundings

Let Sleeping Bears Lie

• Dormant bears have internal homeostatic mechanisms that compensate for fluctuations in the external environment

– Thermoregulation maintains the body temperature within

a tolerable range– Osmoregulation controls the

gain and loss of water and dissolved solutes

– Excretion is the disposal of metabolic wastes

• Body temperature regulation requires adjustment to heat gained from or lost to an animal’s environment

Heat is gained or lost in four ways

Figure 25.1

Convection Radiation

Evaporation

Conduction

• Hormonal changes may increase heat production by raising the metabolic rate

– Fur and feathers help the body retain heat– Shivering, as these honeybees are doing, also

increases metabolic heat production

Figure 25.2A

Regulation during environmental extremes

• Torpor~ low activity; decrease in metabolic rate

• 1- Hibernation long term or winter torpor (winter cold and food scarcity); bears, squirrels

• 2- Estivation short term or summer torpor (high temperatures and water scarcity); fish, amphibians, reptiles

• Both often triggered by length of daylight

AP Biology 2004-2005

Chapter 45.

Endocrine SystemHormones


Regulation Why are hormones needed?

chemical messages from one body part to another

communication needed to coordinate whole body

homeostasis & regulation metabolism growth development maturation reproduction

growth hormones


Regulation & Communication Animals rely on 2 systems for regulation

endocrine system ductless gland which secrete

chemical signals directly into blood chemical travels to target tissue slow, long-lasting response

nervous system system of neurons, central

nerve system transmits “electrical” signal to

target tissue fast, short-lasting response


Regulation by chemical messengers

AxonNeurotransmitter

Endocrine gland

Receptor proteins

Hormonecarried by blood

Target cell

Neurotransmitters released by neurons Hormones release by endocrine glands


Classes of Hormones Protein-based hormones

polypeptides small proteins: insulin, ADH

glycoproteins large proteins + carbohydrate: FSH, LH

amines modified amino acids: epinephrine, melatonin

Lipid-based hormones steroids

modified cholesterol: sex hormones, aldosterone


How do hormones act on target cells Lipid-based hormones

lipid-soluble diffuse across membrane & enter cells

bind to receptor proteins in cytoplasm & then this hormone-receptor complex moves into nucleus

bind to receptor proteins in nucleus bind to DNA as transcription factors


Nucleus

Cytoplasm

Steroid hormone (S) passes through plasma membrane.

Inside target cell, the steroid hormone binds to a specific receptor protein in the cytoplasm or nucleus.

Hormone-receptor complex enters nucleus & binds to DNA, causing gene transcription

Protein is produced.

Protein synthesis is induced.

Plasma membrane

DNAmRNA

Protein

Steroidhormone

Blood plasma

Proteincarrier

1

2

2

3

3

5

5 4

4

S

S

S

1S

Action of steroid (lipid) hormones


How do hormones act on target cellsSignal molecule

Cell surface receptorenzyme

G proteincAMP

Targetprotein

Nucleus

Cytoplasm

ATP

Protein-based hormones hydrophilic & not lipid

soluble can’t diffuse across

membrane trigger secondary (2°)

messenger pathway transmit “signal” across

membrane “signal transduction”

usually activates a series of 2° messengers multi-step “cascade”

activate cellular response enzyme action, uptake or

secretion of molecules, etc.


Action of protein hormones

3

4

GTPactivatesenzyme

activatesenzyme

activatesenzyme

Receptorprotein

cAMP

Proteinhormone

ATP

1

2

Cytoplasm

Produces an action

proteinmessengercascade

G protein


adrenal gland

Action of epinephrine (adrenalin)

3

4

GTPactivates

protein kinase-A

activatesphosphorylase

activates adenylyl cyclase

Receptorprotein cAMP

Epinephrine

ATP

1

2

Cytoplasm

G protein

Liver cell

GlucoseGlycogen

releasedto blood


Benefits of a 2° messenger system

Amplification!

Signal molecule Receptor protein Activated adenylyl cyclase

Amplification

Amplification

Amplification

Amplification

GTP G protein

2

1

3

4

5

6

7

Enzymatic product

Enzyme

Protein kinase

cAMP

Not yetactivated


Ductless glands release hormones into blood

Tropic hormones= a hormone that has another endocrine gland as a target

Endocrine system

Duct glands = exocrine(tears, salivary)


Major vertebrate hormones (1)


Major vertebrate hormones (2)


Endocrine & Nervous system links Hypothalamus = “master control center”

nervous system receives information from nerves around body

about internal conditions regulates release of hormones from pituitary

Pituitary gland = “master gland” endocrine system secretes broad range

of hormones regulating other glands


Thyroid gland

Hypothalamus

Anteriorpituitary

Gonadotropic hormones:Follicle-stimulatinghormone (FSH) & luteinizing hormone (LH)

Mammaryglandsin mammals

Musclesof uterus

Kidneytubules

Posteriorpituitary

Thyroid-stimulating Hormone(TSH)

Antidiuretic hormone(ADH)

Adrenalcortex

Boneand muscle Testis

Ovary

Melanocytein amphibian

Adrenocorticotropic

hormone (ACTH) Melanocyte-stimulating hormone(MSH)

OxytocinProlactin (PRL)

Gro

wth

hor

mon

e (G

H)



Homology in hormones

prolactin

mammals birds amphibiansfish

milkproduction

fatmetabolism

metamorphosis& maturation

salt &water

balance

growthhormone

growth& development

What does this tell you about these hormones?

same gene family


Hormones & Homeostasis Negative feedback

stimulus triggers control mechanism that inhibits further change body temperature sugar metabolism

Positive feedback stimulus triggers

control mechanism that amplifies effect lactation labor contractions

Anterior pituitary

Inhibition

–

Inhibition

Target glands

Hypothalamus

Releasing hormones(TRH, CRH, GnRH)

Tropic hormones(TSH, ACTH, FSH, LH)

–

(thyroid, adrenal cortex, gonads)

Hormones

AP Biology

Regulating blood sugar levels Islets of Langerhans Alpha cells:

•glucagon~ raises blood glucose levels

Beta cells:

•insulin~ lowers blood glucose levels

Type I diabetes mellitus

(insulin-dependent; autoimmune disorder)

Type II diabetes mellitus

(non-insulin-dependent; reduced responsiveness in insulin targets)


- triggers release of glucose by liver

- stimulates appetite

Regulating blood sugar levels

- triggers uptake of glucose by body cells

- triggers storage in liver

- depresses appetite

pancreas

pancreas

beta islet cells

alpha islet cells

Islets of LangerhansAlpha cells: •glucagon~ raises

blood glucose levelsBeta cells: •insulin~ lowers

blood glucose levelsType I diabetes mellitus (insulin-

dependent; autoimmune disorder)Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness

in insulin targets)


Regulating blood osmolarityIf amount of dissolved material in blood is too high, need to dilute blood

ADH

Dehydration Lowers blood volume & pressure

Increased waterretention

Increasedvasoconstrictionleading to higherblood pressureReduced

urine volume

Osmotic concentrationof blood increases

ADH synthesized in hypothalamus

ADH released from posterior pituitary into blood

Osmoreceptors NegativefeedbackNegative

feedback


Regulating metabolism Hypothalamus

TRH = TSH-releasing hormone

Anterior Pituitary TSH = thyroid stimulating hormone

Thyroid produces thyroxine hormones metabolism & development

bone growth mental development metabolic use of energy blood pressure & heart rate muscle tone digestion reproduction

tyrosineiodine

thyroxine


GoiterIodine deficiency causes thyroid to enlarge as it tries to produce thyroxine


Homology in hormones

Days from emergence of forelimb

TRH rises

TRH TSH Thyroxine

–35 –30 –25 –20 –15 –10 –5 0 +5 +10

Th

yro

xin

e s

ecre

tio

n r

ate

Thyroxine stimulates metamorphosis in amphibians


Regulating blood calcium levels

Increased blood Ca++

Thyroid

ParathyroidsLow blood Ca++

Parathyroidhormone (PTH)

Increased absorptionof Ca++ from intestine due to PTH activation of Vitamin D

Reabsorption of Ca++ &excretion of PO4

Osteoclasts dissolve CaPO4crystals in bone, releasing Ca++

–Negativefeedback

The Gonads• Steroid hormones: precursor is cholesterol

– Androgens (testosterone)• sperm formation• male secondary sex characteristics; gonadotropin

– Estrogens (estradiol)• uterine lining growth• female secondary sex characteristics• gonadotropin

– Progestins (progesterone)• uterine lining growth


Any Questions??

Introductory Questions #8 1)Name the nine major endocrine glands found in the body. Which one is called the master gland? 2)Name three major local regulators.

Documents

high body heat slide

body temperature regulation

homeostasis slide

transfer of heat

molecules of body

loss of heat

animals environment

gas sources of body