Endocrine System Overview

Functions of HormonesO 1) Control, regulation, and

maintenance ofa. Growth and development b. Reproduction

O 2) Maintenance of internal environment ie. Homeostasis

HormonesO Cellular signals that signals to a cell

to alter its metabolism or function

Brain-Gut hormone connection

Two types of HormonesO Peptide Hormones – hormones are composed of amino

acids.

A peptide hormone binds to a cell-surface receptor, it does not enter the cell.

Results: Enzymes are activate causing a chemical reaction

O Steroid Hormones – Steroid hormones enter the cell and bind to receptors in the cytoplasm.

Ex. The hormone-receptor complex enters the nucleus where it binds with chromatin and activates specific genes. Genes (DNA) contain information to produce protein.

Results: When genes are active, protein is produced.

Peptide Hormones

O How Peptide Hormones Work

Steroid Hormone

How do hormones bind?

O Receptor- site on the surface or interior of a cell that binds with substances such as hormones, antigens, drugs, or neurotransmitters.

O Ligand- An ion or molecule that bind to another chemical/molecule forming a complex with different properties.

O Substrate- The substance acted upon by an enzyme.

O Enzyme- acts as a catalyst in living organisms, regulating the rate at which chemical and biochemical reactions occur.

How hormones bind?

Types of Glands

Exocrine vs. EndocrineO Exocrine - A secretion

deposited into a body cavity through a duct

O Endocrine – A secretion sent directly into the bloodstream

Endocrine vs. Exocrine Glands

Ten Endocrine Glands

Types of feedback loopsNegative Feedback Loop- controls the rate of a process to avoid accumulation of a product.

Positive Feedback Loop - occurs when the rate of a process increases as the concentration of the product increases ie. Will continue to accelerate as long as substrate is available.

Menstrual cycle

Hormone Replacement Therapy

O Hormone Replacement Therapy

Some physician’s are skeptical about efficiency of using oral medications to replace hormones.

Mixed results

Experimental results are mixed and vary for the individual, however many women had fewer reproductive tract problems and decrease in osteoporosis.

Concept Check

1. Since hormones travel through the bloodstream why don’t all cells react?

2. What is the differences between positive and negative feedback loops?

3. What is the difference in end result between peptide and steroid hormones?