Endocrine system
acts with nervous system to coordinate and integrate activity of body cells
Endocrine system responses are _____ than nervous system responses
slower but longer lasting than nervous system responses
Endocrinology
study of hormones and endocrine organs
Endocrine system controls and integrates:
Exocrine glands
- Have ducts to carry secretion to membrane surface
Endocrine glands
- Lack ducts
List the Endocrine glands
pituitary, thyroid, parathyroid, adrenal, and pineal glands
Hypothalamus is a
neuroendocrine organ
Some have exocrine and endocrine functions
Pancreas, gonads, placenta
Hormones
long-distance chemical signals; travel in blood or lymph
Autocrines:
chemicals that exert effects on same cells that secrete them
NOT hormones
Paracrines
ocally acting chemicals that affect cells other than those that secrete them
NOT hormones
Amino acid–based hormones
Amino acid derivatives, peptides, and proteins
-water-soluble
Steroids
Synthesized from cholesterol
Gonadal and adrenocortical hormones
-lipid-soluble
Target cells
tissues with receptors for a specific hormone
Hormone act on target cells any of the following:
Which hormone act on G protien?
Water-soluble hormones
Amino acid–based hormones, except thyroid hormone, exert effects through
second-messenger systems
Cyclic AMP (cAMP) signaling mechanism
PIP2-calcium signaling mechanism
Hormone-activated G protein activates a different effector enzyme: phospholipase C
-splits into two second messengers
Lipid soluble hormone mechanism
Blood levels of hormones controlled by
Controlled by negative feedback systems
Increased hormone effects on target organs can inhibit further hormone release
Hormone release is triggered by:
Endocrine gland stimuli
Nervous system modulation
Endocrine glands are stimulated to synthesize and release hormones in response to one of three stimuli:
Humoral stimuli-Changing blood levels of ions and nutrients directly stimulate secretion of hormones
Neural stimuli-Nerve fibers stimulate hormone release
Hormonal stimuli-Hormones stimulate other endocrine organs to release their hormones