Catalyst: (pg. 100) Name one hormone that you read about this week

• Agenda • Catalyst • Endocrine system • MELCon Summary Homework

• Objectives: SWBAT • Identify the function of hormones within the human

body • Explain how the nervous and endocrine systems work

together to maintain homeostasis

Maintaining Homeostasis• Animals rely on 2 systems for regulation of

Homeostasis – endocrine system • system of glands

– secrete chemical signals directly into blood– chemical travels to target tissue– target cells have receptor proteins– slow, long-lasting response

– nervous system• system of neurons

– transmits “electrical” signal & release neurotransmitters to target tissue

– fast, short-lasting response

2007-2008

Endocrine System &Hormones

• Why are hormones needed?– chemical messages from one body part

to another– communication needed to coordinate

whole body– daily homeostasis • solute levels in blood – glucose, Ca++, salts, etc.

• metabolism• growth• development• maturation• reproduction

The Endocrine System Produces Hormones

growth hormones

Regulation by chemical messengers

axon

endocrine gland

receptor proteins

target cell

• Neurotransmitters released by neurons• Hormones release by endocrine glands

receptor proteins

hormone carried by blood

neurotransmitter

Lock & Keysystem

Learning Check

1. How do hormones maintain homeostasis? 2. What are the two systems are the source of

the body’s chemical signals?3. What system is composed of neurons? 4. What system is composed of glands?5. How are nerve signals different than

hormone signals?

Classes of Hormones• Protein-based hormones

– Stored in endocrine cells until needed• Metabolism• Growth • Reproduction

– Insulin, growth hormones • Amino Acid based hormones

– Bind to receptors OUTSIDE of the cell – Activate gene expression from DNA and the

building of proteins • Lipid-based hormones

– Steroids• Sex hormones (estrogen, androgen,

progesterone)• Pass into the nucleus of a cell and bond to

specific receptors that activate gene expression from DNA

insulin

Maintaining homeostasis

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition

gland

Negative FeedbackModel

Nervous & Endocrine systems are linked

• Hypothalamus = “master nerve control center”– nervous system– receives information from nerves around body about

internal conditions – releasing hormones: regulates release of hormones from

pituitary

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

of “tropic” hormones regulating other glands in body

hypothalamus

pituitary

posterior

anterior

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

Testes Ovaries

Melanocytein amphibian

adrenocorticotropic

hormone (ACTH)melanocyte-stimulating hormone(MSH)

oxytocin

prolactin (PRL)

grow

th ho

rmon

e (GH)

tropic hormones = target endocrine glands

Learning check 2 1. What are the three classes of hormones?2. For each class identify where they activate within

the body (where the receptors are) 3. Is your bodies use of hormones considered positive

or negative feedback? EXPLAIN your answer using the definition of the feedback loop you chose.

4. What are the ‘master controls’ in the nervous AND endocrine system?

5. Where are they found in the body? 6. How do they work together to maintain

homeostasis?

MELCon Summary• Purpose: Describe how the endocrine system and the

nervous system work together to maintain homeostasis. • M- What is homeostasis? What internal balances are

maintained by your body? How do your body systems work together to maintain balance?

• E- Use 2 examples from this week to explain how the endocrine system and the nervous system work together

• L- Use the examples to explain homeostasis• Con- Restate the big idea and connect examples back to

the main idea.