16.1 The endocrine system is one of the body's two major control systems
Neuroendocrines
Along with neural functions, they also produce and release hormones; nervous system and endocrine effects
Hormones
Chemical messengers secreted by cells into the extracellular fluid
LONG
Duration of endocrine system responses:
SHORT
Duration of nervous system responses:
Diffuse locations where targets can be anywhere blood reaches
Endocrine system acts at what type of location?
SLOW responses
Endocrine system initiates:
Scattered apart
Endocrine systems are not grouped together but are...
Example of neuroendocrines
Epinephrine and dopamine
Certain prostaglandins released by smooth muscle cells cause those smooth muscle cells to contract
Example of autocrines
Tissues with endocrine functions
Gonads, pancreas, and placenta
They are arranged in cords and branching networks, which maximizes contact between them and the surrounding capillaries
How are most of the hormone reducing cells in endocrine cells arranged?
By means of hormones
How does the endocrine system influence metabolic activity?
Long distances
In the endocrine system hormones act over?
Short distances
In the nervous system neurotransmitters act over?
Hormones
Long distance chemical signals that travel in blood or lymph throughout the body
Specific locations determined by axon pathways
Nervous system acts at what type of location?
RAPID responses
Nervous system initiates:
Endocrine glands
Produce hormones and lack ducts; release hormones into the surrounding tissue fluid and typically have rich vascular and lymphatic drainage that receives their hormones; travel through the blood to a distant organ
Autocrines
Short distance chemical signals that exert their effects on the same cells that secrete them
Example of paracrines
Somatostatin released by one population of pancreatic cells inhibits the release of insulin by a different population of pancreatic cells
pituitary, thyroid, parathyroid, adrenal, and pineal glands
The endocrine glands include?
Hormones released into the blood
The endocrine system acts via:
Neuroendocrine organ
The hypothalamus, along with its neural functions, produces and releases hormones
Action potentials and neurotransmitters
The nervous system acts via:
Reproduction, growth and development, maintenance of electrolytes, mobilization of body defenses, and regulation of cellular metabolism and energy balance
What are the major processes that hormones control and integrate?
Responses that typically occur after a lag period of seconds of even days
What does binding of a hormone to cellular receptors initiate?
They only contain endocrine tissue and do not function as a gland itself.
Why are the gonads, pancreas and placenta not considered an endocrine gland?
Exocrine glands
produce nonhormonal substances, such as sweat and saliva, and have ducts that carry these substances to a membrane surface
Paracrines
short-distance chemical signals that act locally (within the same tissue) but affect cell types other than those releasing the paracrine chemicals
Endocrinology
the scientific study of hormones and endocrine organs