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A & P 202 CH. 16
A & P 202 CH. 16
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Anatomy
03/12/2010

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Term
What interacts to maintain homeostasis?
Definition
Chemical, thermal and neural factors
Term
Three interdependent components of control mechanisms?
Definition
Receptor (stimuli, responds to changes), Control Center (determines the set point), Effector (provides the means to respond to stimuli)
Term
Negative Feedback
Definition
turns off something, makes it less powerful. Example: Regulation of room temperature
Term
Endocrine System
Definition
the body's second great controlling system influences metabolic activities of cells by means of hormones.
Term
Endocrine Glands
Definition
Pituitary Gland, Thyroid, parathyroid, adrenal, pineal, and thymus
Term
What produces hormones and exocrine products?
Definition
pancreas and gonads
Term
What is the Hypothalamus?
Definition
a neuroendocrine organ
Term
What is a hormone?
Definition
a chemical substance produced and secreted in one part of an organism and transported via the ECF (extracellular fluid) to another organ where it has a specific effect.
Term
Receptors may be:
Definition
intracellular or on the plasma membrane
Term
Hormones produce one or more of what cellular changes?
Definition
Alter plasma membrane permeability
Stimulate protein synthesis
Activate or deactivate enzyme systems
Induce secretory activity
Stimulate mitosis
Term
Target cell activation depends on 3 factors
Definition
Blod levels of the hormone
Relative number of receptors on the target cell
The affinity of those receptors for the hormone
Term
Concentrations of circulating hormone reflect:
Definition
Rate of release
Speed of inactivation and removal from body
Term
Hormones are removed from the blood by:
Definition
Degrading enzymes
The kidneys
Liver enzyme systems
Term
Blood Levels of Hormones:
Definition
Vary only within a narrow desirable range
Are typically controlled by negative feedback systems
HUMORAL stimuli (blood)
NEURAL stimuli (nerves)
HORMONAL stimuli (hormones triggering another)
Term
Humoral Stimuli
Definition
secretion of hormones in direct response to changing blood levels of ions and nutrients
Term
Sample of Humoral Stimuli
Definition
declining blood Ca2+ concentration stimulates the parathyroid glands to secrete PTH (parathyroid hormone)

PTH causes Ca2+ concentrations to rise and the stimulus is removed
Term
Neurol Stimuli
Definition
nerve fibers stimulate hormone release
Term
Example of Neurol Stimuli
Definition
Preganglionic sympathetic nervous systems (SNS) fibers stimulate the adrenal medulla to secrete catecholarmines
Term
Hormonal Stimuli
Definition
release hormones in response to hormones produced by other endocrine organs
Term
Example of Hormonal Stimuli
Definition
The hypothalamic hormones stimulate the anterior pituitary

In turn, pituitary hormones stimulate targets to secrete still more hormones
Term
Endoctine Organs
Definition
Hypothalamus and Pituitary (Hypophysis)
Term
Why do we have DNA?
Definition
To make protein
Term
Pituitary gland
Definition
two-lobed organ that secretes nine major hormones
Term
Neurohypophysis
Definition
posterior lobe (neural tissue) and the infundibulum. Receives, stores, and releases hormones from the hypothalamus
Branchy
Term
Adenohypophysis
Definition
anterior lobe, made up of glandular tissue. Synthesizes and secretes a number of hormones
Cellular
Term
Anterior Lobe
Definition
There is a hypothalamic-pituitary relationship of the anterior lobe as a vascular connection. The hypophyseal portal system, consists of:
The primary capillary plexus
The hypophyseal portal veins
The secondary capillary plexus