Biology 107

Lecture Notes: Chemical Signals I.

Reading: Chapter 45 in text.

An introduction to regulatory systems

The activities of the various specialized parts of an animal are coordinated by the two major systems of internal communication: the nervous system and the endocrine system

• Endocrine glands:

• Exocrine glands:

Relationships between the endocrine system and the nervous system

• neurosecretory cells:

Chemical signals and their mode of action

• Intracellular

• Cell to cell

• Tissue to tissue

• Organ to organ

• Organism to organism

Local regulators may affect neighboring cells

• paracrine signaling

• autocrine signaling

• Nitric oxide (NO)

• Growth factors

• Prostaglandins (PGs)

Chemical signaling molecules bind to receptor proteins within target cells or on their surface

· Most chemical signals bind to plasma-membrane proteins, initiating signal-transducing pathways

· Steroid hormones, thyroid hormone, and some local regulators enter target cells and bind with intracellular receptors

The vertebrate endocrine system

• Tropic hormones:

The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system

· The adenohypophysis, or anterior pituitary

o Releasing hormones

o Inhibiting hormones

· The neurohypophysis, or posterior pituitary

· Posterior pituitary hormones

o Oxytocin

o Antidiuretic hormone (ADH)

· Anterior pituitary hormones

o Growth hormone (GH)

o Prolactin (PRL)

o Follicle stimulating hormone (FSH)

o Lutenizing hormone (LH)

o Thyroid stimulating hormone (TSH)

o pro-opiomelanocortin

· Adrenocorticotropin (ACTH)

· Melanocyte-stimulating hormone (MSH)

· Endorphins