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Endocrine System Hormones. 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.

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Endocrine System Hormones

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Endocrine system hormones

Endocrine System

Hormones


Regulation

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

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

Regulation by chemical messengers

  • Neurotransmitters released by neurons

  • Hormones release by endocrine glands

Endocrine gland

Neurotransmitter

Axon

Hormone carried by blood

Receptor proteins

Receptor proteins

Target cell


Classes of hormones

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

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…


Action of lipid steroid hormones

Action of lipid (steroid) hormones

cytoplasm

steroid hormone

blood

S

S

1

protein

carrier

S

2

receptor protein

4

S

3

DNA

5

mRNA

plasma membrane

protein

nucleus


Action of protein hormones

Action of protein hormones

1

Protein

hormone

activatesenzyme

G protein

cAMP

Receptor

protein

3

2

ATP

protein

messengercascade

activates

enzyme

GTP

activates

enzyme

4

cytoplasm

Produces an action


Action of epinephrine adrenalin

Action of epinephrine (adrenalin)

liver cell

1

epinephrine

activatesadenylyl cyclase

adrenal gland

G protein

cAMP

3

receptor

protein

2

ATP

activates

protein kinase-A

GTP

releasedto blood

activates

phosphorylase

4

cytoplasm

glycogen

glucose


Benefits of a 2 messenger system

Benefits of a 2° messenger system

Amplification!

1

Receptor protein

Activated adenylyl cyclase

Signal molecule

Not yet

activated

Amplification

2

4

Amplification

cAMP

3

5

GTP

G protein

Protein kinase

6

Amplification

Enzyme

Amplification

7

Enzymatic product


Negative feedback model

high

low

Negative Feedback Model

hormone 1

lowersbody condition

gland

specific body condition

raisesbody condition

gland

hormone 2


Body temperature

high

low

Nervous System Control

Feedback

Body Temperature

nerve signals

brain

sweat

dilates surfaceblood vessels

body temperature

brain

constricts surfaceblood vessels

shiver

nerve signals


Blood sugar

pancreas

high

liver

low

pancreas

liver

Endocrine System Control

Feedback

Blood Sugar

insulin

body cells takeup sugar from blood

liver storessugar

reducesappetite

blood sugar level

liver releasessugar

triggershunger

glucagon


Blood osmolarity

increasethirst

pituitary

nephron

high

low

adrenalgland

nephron

Endocrine System Control

Feedback

Blood Osmolarity

ADH

increasedwaterreabsorption

blood osmolarity

blood pressure

increasedwater & saltreabsorption

renin

aldosterone

angiotensinogen

angiotensin


Endocrine nervous system links

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 rangeof hormones regulating other glands


Endocrine system hormones

Hypothalamus

Thyroid-stimulating

Hormone

(TSH)

Antidiuretic

hormone

(ADH)

Posterior

pituitary

Thyroid gland

Anterior

pituitary

Kidney

tubules

Adrenocorticotropic

hormone (ACTH)

Oxytocin

Muscles

of uterus

Gonadotropic

hormones:

Follicle-

stimulating

hormone (FSH)

& luteinizing

hormone (LH)

Melanocyte-stimulating hormone

(MSH)

Growth hormone (GH)

Prolactin (PRL)

Adrenal

cortex

Melanocyte

in amphibian

Mammary

glands

in mammals

Bone

and muscle

Ovary

Testis


Homology in hormones

same gene family

growthhormone

birds

fish

amphibians

fatmetabolism

salt &waterbalance

metamorphosis& maturation

growth& development

Homology in hormones

What does this tell you about these hormones?

prolactin

mammals

milkproduction


Regulating metabolism

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

tyrosine

iodine

thyroxine


Goiter

Goiter

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


Regulating blood calcium levels

Regulating blood calcium levels

Thyroid

Parathyroids

Low blood Ca++

Parathyroid

hormone (PTH)

Negative

feedback

Increased absorption

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

Reabsorption of Ca++ &

excretion of PO4

Osteoclasts

dissolve CaPO4

crystals in bone, releasing Ca++

Increased blood Ca++


Female reproductive cycle

corpusluteum

ovary

yes

corpusluteum

no

Feedback

Female reproductive cycle

eggmatures &

is released(ovulation)

builds up uterus lining

estrogen

progesterone

FSH & LH

fertilized egg(zygote)

maintainsuterus lining

HCG

pituitarygland

pregnancy

progesterone

GnRH

corpus luteum breaks down

progesterone drops

menstruation

maintainsuterus lining

hypothalamus


Any questions

Any Questions??


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