Test #1 Flashcards
What are the key characteristics of the endocrine system?
Regulate and maintain body functions by synthesizing and releasing hormones and chemical messengers.
Areas of control and integration responses to: -stress and injury-growth and development-absorption of nutrients-energy metabolism-water and electrolyte balance-reproduction-birth-lactation
Glands secrete chemical messengers (hormones) into circulatory system
Regulate activities of body structures
Why is the endocrine system also referred to as neuroendocrine?
The endocrine and the nervous system are very closely related and that is their collective name. Neural control centers in the brain control glands.
What are the characteristics of hormones?
Produced in small quantities
Secreted into intercellular space
Transported some distance in circulatory system
Acts on target tissues elsewhere in body
Half life?
The length of time it takes for half a dose of substance to be eliminated from the circulatory system.
Long half life: regulate activities the remain at a constant rate. Usually LIPID SOLUBLE and travel in plasma attached to proteins.
Short half life: water-soluble hormones as proteins, epinephrine, norepinephrine. Have rapid onset and short duration.
What is the main mechanism of control of hormonal secretion?
Negative feedback systems.
Most aren’t released at a constant rate, but their secretion is regulated by three different methods: -the action of a substance other than the hormone- neural control of endocrine gland - control of secretory activity of one endocrine gland by hormone or neurohormone secreted by another endocrine gland
What is hypothyroidism?
A disorder in which there is not enough stimulation of T3 and T4. Though TSH levels will be high when tested in blood.
How is hypothyroidism diagnosed?
A blood test is used, if TSH levels are found to be high with low T4 and T3 then it’s diagnosed
How is hypothyroidism treated?
Hormonal supplementation. If cancer or an autoimmune disease like Hashimotos destroys the thyroid gland it may have to be removed.
What’s is the most common cause of hypothyroidism?
Hashimotos and other autoimmune diseases
How is blood glucose regulated?
By insulin which decreses blood glucose levels by stimulating transport of glucose from the blood to tissues (muscles 80%). Thus increasing uptake of glucose and amino acids in cells.
And by glucagon which increases the breakdown of glycogen by liver and skeletal muscle into glucose that releases into the circulatory system.
Somatostatin which inhibits the secretion of insulin and glucagon
How is insulin regulated?
When blood glucose is high insulin is stimulated to be secreted and when blood glucose is normal or low somatostatin inhibits secretion.
Relationship between blood glucose, insulin, skeletal muscles and type II diabetes?
People with type II diabetes are insulin resistant so insulin has little effect on lowering blood glucose. However glucose will continue to be synthesized by the muscles and keep increasing blood glucose levels.
What are the symptoms of diabetes?
Type I - polyuria (frequent urination), polydipsia (increased thirst), polyphagia (increased hunger), and weight loss.
Type II - same as Type I but are less intense and many times ignored.
What are the key differences between membrane bound and lipid soluble hormones?
Membrane bound receptors bind to water-soluble or large-molecular-weighted hormones on membrane
Intracellular receptors bind to lipid soluble hormones
How can effects of hormones that are secreted in such a minute amount be so powerful?
The cascade effect!!
What hormones are under the control of the hypothalamus?
Growth Hormone releasing hormone (GHRH) - targets the anterior pituitary cells telling them to increase the secretion of growth hormone.
Growth hormone inhibiting hormone (GHIH) or somatostatin - targets the anterior pituitary cells telling them to decrease secretion of growth hormone.
Thyrotropin releasing hormone (TRH) - targets anterior pituitary cells and tells them increase the secretion of thyroid stimulating hormone.
Corticotropin releasing hormone (CRH) - targets the anterior pituitary cells telling them to increase secretion of adrenocorticotopic hormone.
Gonadotropin releasing hormone (GnRH) - targets anterior pituitary cells telling them to increase the secretion of luteinizing hormone and follicle stimulating hormone.
Prolactin releasing hormone (PRH) - targets anterior pituitary cells telling them to increase prolactin secretion.
Prolactin inhibiting hormone (PIH) - targets anterior pituitary cells telling them to decrease prolactin secretion.
What hormones are under the control of the anterior pituitary?
Growth hormone (GH) - promotes growth and regulation of metabolism of carbs, proteins and lipids
Prolactin (PRL) - promotes the growth of the mammary glands and lactation in females
Thyroid-stimulating hormone (TSH) - stimulates the thyroid to produce T3 and T4
Melanin stimulating hormone (MSH) - stimulates the the secretion of melanin in skin and hair
Adrenocorticotropic hormone (ACTH) - stimulates the secretions of corticoids
follicle stimulating hormone (FSH) - reproductive function, growth and development
Luteinizing hormone (LH) - reproductive function, stimulates ovulation, development of corpus luteum in females and devlopment of androgens in males
What are the hormones under control of the posterior pituitary and what is the key action of them?
antidiuretic hormone (ADH) - increased water reabsorption resulting in less urine
Oxytocin - contractions increase in uterus and ejection of milk from lactating breast
What are the physiological effects of cortisol?
Increase in fat and protein breakdown, glucose levels and antiinflammatory effects
What is hypocortisolism?
An insufficiency of adrenal glands. Causes fatique, weakness, anorexia, nausea, vomiting
How is hypocortisolism treated?
Corticoids, corticosteroids
What are the effects of aging on the endocrine system?
Gradual decrease in secretory activity of some glands
Decrease in GH, less decrease in those that exercise
Androgens decrease
Melatonin decreases
Thyroid hormones decrease and loss of muscle receptors, exercise helps both
Kidneys secrete less renin
familial tendency to develope type II diabetes increases with age
What are the functions of digestive system?
- ingestion: introduction of food into stomach
- mastication: chewing, chemical digestion requires large surface area so breaking down large particles mechanically facilitates chemical digestion
- propulsion: DEGLUTITION - swallowing PERISTALSIS - moves a wave of circular smooth muscle through digestive tract. A wave of circular smooth muscle relaxation moves ahead the bolus of food or chyme allowing the digestive tract to expand. Then a contraction wave of the circular smooth muscles behind the bolus of food or chyme propels it through the tract. MASS MOVEMENTS in large intestine
- mixing: segmental contractions that diffuse and break apart bolus
- secretion: lubricate, liquefy and digest - MUCUS - secreted along entire digestive tract, protects from from mechanical digestion, acid and other enzymes - WATER - makes food easier to digest and absorb - BILE - emulsifies fat - ENZYMES - chemical digestion
- digestion - Mechanical and Chemical
- absorption - movement from tract into circulation or lymph
- elimination - waste product removed from body, feces, defecation
Mastication reflex?
Medulla oblongata, descending pathways fro t he cerebrum provide conscious control, this is basic movement in chewing
