Lecture 23: Chemical Signals in Animals

1. What are the different types of chemical signals in animals?

i. Hormones

- What do they do?

ii. Neurotransmitter

- Nervous system, local level

iii. Pheromones

- Insects

- Humans?

2. How do hormones work?

i. Endocrine glands (compare to exocrine glands)

ii. Endocrine cell à blood streamà target cells à hormone receptor à response

iii. steroid hormones and gene expression

iv. amino acid derived hormones and signal transduction (first messenger, cell response)

v. examples of what hormones do, and how they interact

- annelid worm

- sea slug

- insects

3. Hormones in vertebrates

i. Tissues and organs that secrete hormones – and their targets

ii. Examples:

- Hypothalamus

- Pancreas (mostly exocrine tissue with small clusters of endocrine cells called Islets of Langerhans

- regulation of blood sugar (glucose homeostasis; insulin and glucagon)

- Diabetes (type I, Type II)

- Thyroid and calcium homostasis

- Gonads: Three major categories of gonadal steroids (androgens, estrogens, progestins)

- Pineal gland and biological rhythms

- Thymus and the immune system

- Thyroid

- homeostasis of blood pressure, heart rate, muscle tone, digestion and reproductive functions