2006-2007 AP Biology

Endocrine SystemHormones

AP Biology

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

AP Biology

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

AP Biology

Regulation by chemical messengers

Axon

Neurotransmitter

Endocrine gland

Receptor proteins

Hormone carried by blood

Target cell

Neurotransmitters released by neurons Hormones release by endocrine glands

Receptor proteins

AP Biology

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

AP Biology

How do hormones act on target cells Lipid-based hormones

hydrophobic & lipid-soluble diffuse across membrane & enter cells bind to receptor proteins in cytoplasm & nucleus bind to DNA as transcription factors

Protein-based hormones hydrophilic & not lipid soluble

can’t diffuse across membrane trigger secondary messenger pathway activate cellular response

enzyme action, uptake or secretion of molecules…

AP Biologynucleus

cytoplasm

plasma membraneDNA

mRNA protein

steroid hormone blood

proteincarrier2

3

5

4

S

S

S

1S

Action of lipid (steroid) hormones

receptor protein

AP Biology

Action of protein hormones

3

4

GTPactivatesenzyme

activatesenzyme

activatesenzyme

Receptorprotein

cAMP

Proteinhormone

ATP

1

2

cytoplasm Produces an action

proteinmessengercascade

G protein

AP Biology

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

AP Biology

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

2005-2006AP Biology

Negative Feedback Model

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition

gland

2005-2006AP Biology

Body Temperature

high

low

nerve signals

sweat

nerve signals

brain

body temperature

shiver brain

dilates surfaceblood vessels

constricts surfaceblood vessels

FeedbackNervous System Control

2005-2006AP Biology

liver

pancreas

liver

Blood Sugar

blood sugar level

insulin

body cells takeup sugar

from blood

liver storessugar

reducesappetite

glucagon

pancreas

liver releases

sugartriggershunger

high

low

FeedbackEndocrine System Control

2005-2006AP Biology

nephron

low

Blood Osmolarity

blood osmolarityblood pressure

ADH

increasedwater

reabsorption

increasethirst

renin

increasedwater & saltreabsorption

high

FeedbackEndocrine System Control

pituitary

angiotensinogenangiotensin

nephronadrenalgland

aldosterone

AP Biology

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

AP Biology

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)

AP Biology

Homology in hormones

prolactin

mammals

milkproduction

birds

fatmetabolism

amphibians

metamorphosis& maturation

fish

salt &water

balance

growth& development

What does this tell you about these hormones?

growthhormone

same gene family

AP Biology

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

AP Biology

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

AP Biology

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

2005-2006AP Biology

corpusluteumovary

Female reproductive cycle

pregnancy

maintainsuterus lining

no

yes

Feedback

estrogenegg

matures &is released(ovulation)

builds up uterus lining

FSH & LH

progesterone

progesterone

fertilized egg(zygote)

HCG

corpus luteum breaks downprogesterone drops

menstruation

corpusluteum

maintainsuterus lining

GnRH

pituitarygland

hypothalamus

2005-2006 AP Biology

Any Questions??