What is the endocrine system responsible for?
Long-term, body wide coordination and development of cellular function, which is most dramatically seen in the transformation of morphology and behavior during puberty.
What are the two kinds of glands the body contains?
Exocrine:(sudoriferous, sebaceous, and digestive) secretes their products through ducts into body cavities or onto body surfaces. (has ducts)
Endocrine:by contrast, secrete their products(hormones)into the extracellular spaces around the secretary cells, rather than into ducts. The secretion then DIFFUSES into capillaries and is carried away by the blood.(ductless)
What is the endocrine system consisted of?
Endocrine glands and several organs that contain endocrine tissue.
What is the science concerned with the structure and function of the endocrine glands and the treatment of disorders of the endocrine system?
Together, the nervous and endocrine systems coordinate functions of all body systems. Describe their roles.
1. The nervous system controls homeostasis through nerve impluses(action potentials) conducted along axons of neurons.
2. In contrast, the endocrine system releases its messenger molecules, called hormones, into the bloodstream. The circulating blood then delivers hormones to virtually all cells throughout the body.
3. Certain parts of the nervous system stimulate or inhibit the release of hormones. Hormones, in turn, may promote or inhibit the generation of nerve impulses.
How do they accompish this?
The nervous system causes muscles to contract and glands to secrete.
The endocrine system affects virtually all body tissues-altering metabolic activities, regulating growth and development, and guiding reproductive processes(mitosis and meosis).
Which are generally more rapid in producing their effects, nerve impulses or hormones?
Nerve impulses. The effects of the nervous system are also quite brief compared with those of the endocrine system.
What do hormones regulate?
Internal environment, metabolism, and energy balance.
They also help regulate smooth and cardiac muscular contraction, grandular secretion, and certain immune responses.
Hormones play a role in ________?
the integration of growth and development, and in the maintenance of homeostasis despite emergency environmental disruptions, and contribute to the basic processes of reproduction.
Hormones only affect specific ______ _______ that have receptors to recognize a given hormone.
___________, like other cellular proteins, are constantly synthesized and broken down.
What happens when a hormone(or neurotransmitter) is present in excess?
The number of receptors may decrease(down-regulation), thereby decreasing the responsiveness of target cells to the hormone.
What happens when a hormone(or neurotransmitter) is deficient?
The number of receptors may increase(up-regulation), making the target tissue more sensitive to the stimulating effect of the hormone.
What are hormones that pass into the blood to act on distant target cells called?
Circulating hormones or endocrines
What are hormones that act on target cells close to their site of release called?
Local hormones(paracrines or autocrines)
Chemically, hormones are classified as what?
Steroids and Eicosanoids(fat or lipid soluble)-carried attached to transport proteins.
Biogenic amines and protein and peptides(water soluble)-circulate in free form in the blood.
What does the response to a hormone depend on?
Both the hormone and the target cell; various target cells respond differently to the same hormone.
How do steroid and thyroid hormones affect cell function?
By binding to and activating an intracellular receptor(usually in the nucleus), consequently altering gene expression.
How do water soluble hormones alter cell function?
By activating plasma membrane receptors, which initiate a cascade of events inside the cell.
After a water-soluble hormone is released from an endocrine gland, it circulates in the blood, reaches a target cell, and brings a specific message to that cell; since such a hormone can deliver its message only to the plasma membrane, it is called the ______ ______?
A _____ ______ is needed to replay the message inside the cell where hormone-stimulated responses can take place.
What is the best know second messenger?
What are a common feature of most second messenger systems?
The symptoms of cholera are a direct result of the cholera toxin on G-proteins in the intestinal lining.
Cyclic AMP does not directly produce a particular physiological response, but instead activates one or more enzymes. What is this known as?
The responsiveness of a target cell to a hormone depends on the hormone's ________ and __________.
concentration and the number of receptors
The manner in which hormones interact with other hormones is also important. What are the three hormonal interactions?
1. the permissive effect
2.the synergistic effect
3. the antagonistic effect
Hormone secretion is controlled by what?
Signals from the nervous system, by chemical changes in the blood, and by other hormones.
Most often, _____ _____ _____ regulate hormonal secretions.
negative feedback systems
What is the major integrating link between the nervous and endocrine systems?
What do the hypothalamus and the pituitary gland(hypophysis) regulate?
Virtually all aspects of growth, development, metabolism, and homeostasis.
Where is the pituitary gland located?
In the sella turcica of the sphenoid bone and is differentiated into the anterior pituitary(adenohypophysis, or glandular portion), the posterior pituitary(neurohypophysis, or nervous portion) and pars intermedia(acascular zone in between)
What are the five pricipal types of glandular cells?
Corticotrophs-secrets ACTH and MSH
Gonadotrophs-secretes FSH and LH
Stimulates body growth through somatomedins and is controlled by GHIH and GHRH. Disorders associated with improper levels are pituitary dwarfism, giantism, and acromegaly
Human Growth Hormone (hGH, GH, or somatotropin)
regulates thyroid gland activities and is controlled by TRH (thyrotropin releasing hormone)
regulates the activities of the ovaries and testes and is controlled by GnRH(gonadotropin releasing hormone)
helps initiate milk secretion and is controlled by PIH(prolactin inhibiting hormone) and PRH(prolactin releasing hormone) from the hypothalamus
Prolactin(PRL, or lactogenic hormone)
increases skin pigmentation and is controlled by MRH(melanocyte-releasing hormone) and MIH(melanocyte-inhibiting hormone)
regulates the activities of the adrenal cortex and is controlled by CRH(coriticotropin releasing hormone)