a&p chapter 16
What are the functions of melatonin? (3)
1. Inhibits reproductive functions (may control human sexual maturation) 2. Protects tissues from free radicals. 3. Maintains daily physiological changes, aka circadian rhythms.
What are the primary hormones of growth regulation?
1. Insulin 2. PTH and calcitriol 3. Thyroid hormones 4. Reproductive hormones 5. Growth hormone
What are three common causes of hormone hyposecretion?
1. Metabolic factors - key hormone substrate deficiency 2. Physical damage - delivery or damage to target cells 3. Congenital disorders - unable to produce normal amounts of hormone
What causes increased release of oxytocin?
Childbirth, nursing, sexual arousal, sensory input (neuroendocrine reflex).
What is the function of regulatory hormones?
Control anterior pituitary gland endocrine cells.
What stimulates the release of adrenocorticotropic hormone?
Corticotropin-releasing hormone
What are the chemical messengers of the endocrine system termed?
Hormones
What does it mean for two hormones to have integrative effects? What is a pair of hormones that exhibits that?
Hormones produce different but complementary effects, such as calcitriol and PTH in calcium metabolism.
What is the function of parathyroid hormone?
Increasing calcium levels in extracellular fluids
What inhibits follicle-stimulating hormone?
Inhibin, released by the gonads
What two pancreatic hormones have opposing effects, and are the primary hormones in controlling blood glucose levels?
Insulin and glucagon
What is type 1 diabetes otherwise known as?
Insulin-dependent diabetes
What is the effect of insulin on growth regulation?
It delivers nutrients to growing cells.
What types of hormones are amino acid derivatives?
Thyroid hormones, catecholamines (epinephrine, norepinephrine, dopamine) and melatonin.
What occurs in response to decreasing blood pressure, after renin is released (1 thing, that leads to 3 things).
Renin-angiotensin activation system, which leads to: 1. Secretion of aldosterone 2. Secretion of ADH 3. Stimulation of thirst
What is the function of oxytocin?
Stimulate constriction of smooth muscle walls of uterus and mammary gland myoepithelial cells releasing milk
What is the function of growth hormone?
Stimulates cell growth and reproduction by stimulating rate of protein synthesis
What is the function of melanocyte-stimulating hormone?
Stimulates melanocytes of skin to increase melanin production.
What is the function of adrenocorticotropic hormone?
Stimulates release of steroid hormones from adrenal cortex, specifically those that affect glucose metabolism
What is the function of thyroid-stimulating hormone?
Stimulates release of thyroid hormones
What are the two thyroid hormones that require iodine?
T4 (thyroxine) and T3
Where is the thyroid gland located?
The anterior side of the trachea, inferior to thyroid cartilage.
Where is the pituitary gland located?
Within sella turcica of sphenoid bone.
Where is the location of the pancreas?
Within the abdominopelvic cavity, deep to the stomach.
What is the function of prolactin?
Works with other hormones to stimulate mammary gland development and milk production.
What is the location and structure of the adrenal glands?
Yellow, pyramid-shaped glands superior to each kidney.
What are the three groups of hormones based on chemical structure?
amino acid derivatives, peptide hormones, lipid derivatives
The hypothalamus contains ______ neurons that stimulate release of hormones from _____.
autonomic (sympathetic), adrenal medulla
What is the transmission method, chemical mediators and distribution of effects for endocrine communication?
method: bloodstream chemical mediator: hormones distribution of effects: target cells are primarily in other tissues and organs and must have appropriate receptors
What is the transmission method, chemical mediators and distribution of effects for paracrine communication?
method: extracellular fluid chemical mediator: paracrine factor distribution of effects: primarily limited to the local area, where paracrine factor concentrations are relatively high; target cells must have appropriate receptors
Parathyroid hormone (stimulates/inhibits) release of calcitriol by kidneys; what does this do?
stimulates; calcitriol enhances PTH effects and increases calcium and phosphate absorption in intestine
What structure in the brain is the pineal gland part of? Where is it located?
Part of the epithalamus, the pineal gland lies in the posterior portion of the third ventricle roof.
What types of hormones will require a plasma membrane receptor?
Water-soluble hormones.
How does the parathyroid gland mobilize calcium from the bone?
1. Inhibits osteoblasts, which reduces deposition rate of bone. 2. Increase osteoclast production by releasing growth factor (osteoclasts erodes bone matrix)
Approximately what percentage of the volume of the pancreas is dedicated to endocrine functions?
1%
What is the effect of the reproductive on growth regulation? (2)
1. Affect osteoblast activity at various locations. 2. Stimulate target cell growth and differentiation.
What occurs in response to rising blood pressure, after natriuretic peptides have been released (4 things)?
1. Dilation of blood vessels 2. Suppression of thirst 3. Inhibition of antagonistic hormones 4. Sodium ion and water loss from kidneys.
Seven effects of thyroid hormones on peripheral tissues
1. Elevated rates of oxygen and energy consumption; may lead to elevated body temperature in children. 2. Increased heart rate and force of contraction, usually resulting in a rise in blood pressure. 3. Increased sensitivity to sympathetic stimulation. 4. Maintenance of normal sensitivity of respiratory centers to changes in oxygen and carbon dioxide concentrations. 5. Stimulation of red blood cell formation and thus enhanced oxygen delivery. 6. Stimulation of activity in other endocrine tissues. 7. Accelerated turnover of minerals in bone.
What are the two main responses of the alarm phase?
1. Energy reserves, mainly glucose, are mobilized 2. Fight or flight response
What are five clinical problems that can occur as a result of diabetes mellitus?
1. Hemorrhaging at the retina, which may cause partial or complete blindness (diabetic retinopathy). 2. Degenerative blockages in cardiac circulation, causing early heart attacks. 3. Degenerative changes in kidneys, which can lead to kidney failure (diabetic nephropathy). 4. Abnormal blood flow to neural tissues, which can lead to abnormal autonomic function (diabetic neuropathy). 5. Poor blood flow to distal portion of the limbs, with tissue damages as a result.
What three symptoms are indicative of diabetes mellitus?
1. Hyperglycemia - abnormally high blood glucose 2. Glycosuria - glucose in urine 3. Polysuria - excessive urine production
What are three effects of decreasing blood glucose levels, after glucagon has been secreted?
1. Increased breakdown of glycogen to glucose in liver and skeletal muscle. 2. Increased breakdown of fat to fatty acids in adipose tissue 3. Increased synthesis and release of glucose in liver.
What are five effects of rising blood glucose levels, after insulin has been secreted?
1. Increased rate of glucose transport into target cells. 2. Increased rate of glucose utilization and production of ATP. 3. Increased conversion of glucose into glycogen. 4. Increased amino acid absorption and protein synthesis. 5. Increased triglyceride synthesis in adipose tissue.
What is the cycle of how thyroid hormones are produced?
1. Negatively charged iodine ions (I-) are actively transported into a follicle cell. 2. (I-) diffuses to the apical surface of the follicle cell, and is converted to (I+). During this process, one to two activated ions are attached to tyrosine portions of a thyroglobulin molecule. 3. T3 and/or T4 are packaged inside thyroglobulin in the follicle cavity. 4. Thyroglobulin is moved from follicle cavity back to the follicle cell via endocytosis. 5. Thyroglobulin is broken down by lysosomal enzymes, and the hormones and amino acids enter the cytoplasm; the amino acids are eventually used to make more thyroglobulin. 6. T3 and T4 diffuse across the basement membrane into the bloodstream. 7. A large portion of those hormones become attacked to thyroid-binding globulins, which transport the hormones around.
What percent of thyroid hormones in the blood travel attached to a transport protein? What is that protein called?
75%; thyroid-binding globulins
What is thyroglobulin?
A molecule which contains the building blocks for the amino acid tyrosine.
What must a cell possess in order to be sensitive to a specific hormone?
A receptor that is sensitive to that hormone.
What are three layers of the adrenal gland?
Adrenal capsule, adrenal cortex, adrenal medulla.
What is the effect of growth on growth regulation in adults? In children?
Adults: assists in energy metabolism and storage Children: support protein synthesis and cellular growth in skeletal and muscular development
What, generally, do steroids do intracellularly?
Affect DNA transcription rate and protein synthesis; change synthesis of enzyme and structural proteins affecting cell's metabolic activity and structure.
What, generally, do thyroid hormones do intracellularly?
Bind to receptors on mitochondria, affecting energy production; bind to receptors in nucleus, affecting cell's metabolic activity and structure.
After how long does the resistance phase occur?
After experiencing a few hours of stress.
What are the three phases of the stress response?
Alarm phase, resistance phase, exhaustion phase
What hormone do alpha cells secrete? What does that hormone do?
Alpha cells secrete glucagon, which raises blood glucose by increasing liver glycogen breakdown.
Which pancreatic cells respond to decreasing blood glucose levels? What do they do?
Alpha cells will secrete glucagon. This causes glucose release and liver breakdown of glycogen.
What are the four types of cells in the endocrine pancreas?
Alpha cells, beta cells, delta cell F cells.
What is a G protein?
An enzyme complex coupled to a receptor that is involved in plasma-membrane hormone reception.
What can antidiuretic hormone be inhibited by?
An increase in extracellular fluid volume and alcohol.
What are the two posterior pituitary hormones?
Antidiuretic hormone (ADH), oxytocin (OXT)
What two hormones does the hypothalamus secrete and where specifically are they created? What structure releases them?
Antidiuretic hormone from supraoptic nucleus and oxytocin from paraventricular nucleus are released from posterior pituitary.
What hormone do beta cells secrete? What does that hormone do?
Beta cells secrete insulin, which lowers blood glucose by increasing glucose uptake and utilization by cells. It also increases glycogen production in liver and skeletal muscles.
Which pancreatic cells respond to increasing blood glucose levels? What do they do?
Beta cells will secrete insulin. This brings glucose into target cells.
Where are C (clear) cells located? What do they secrete and what is that secretion's purpose?
Between follicular cells in the thymus. They secrete calcitonin, which aids in calcium regulation.
What is the function of antidiuretic hormone?
Decrease water lost from kidney, also causes vasoconstriction
What hormone do delta cells secrete? What does that hormone do?
Delta cells secrete a peptide hormone that is identical to growth hormone-inhibiting hormone, which suppresses the release of glucagon and insulin. It also slows rates of food absorption and enzyme secretion in digestive tract.
How do T3 and T4 enter the bloodstream?
Diffusion across the basement membrane.
What are the four mechanisms of intracellular communication?
Direct communication, paracrine communication, endocrine communication, synaptic communication.
What is a generic example of lipid-derived hormones? What are two specific examples of that?
Eicosanoids; two examples are leukotrienes and prostaglandins
How is thyroglobulin removed from follicles?
Endocytosis
What occurs in the exhaustion phase?
Energy stores can no longer be maintained, so organ systems begin to fail. There are mineral and electrolyte imbalances as well, which contribute to body issues.
How is iodine bound and what is it bound do to create T4 and T3?
Enzymes activate iodide, and attaches it to tyrosine portions of a thyroglobulin molecule.
What is secreted when blood pressure decreases? What do they do?
Erythropoietin and renin: activate renin-angiotensin system, which leads to fluid intake and retention.
What hormone do F cells secrete? What does that hormone do?
F cells secrete pancreatic polypeptide, which inhibits gallbladder contraction and reduces digestive activity of pancreas and digestive tract.
(T/F) The endocrine system includes organs whose primary or secondary function is hormone release.
False. The endocrine system only includes primary endocrine organs.
What is the stress response otherwise known as?
General adaptation syndrome
What are the dominant hormones in the resistance phase? What is the overall effect?
Glucocorticoids are dominant, with involvement from epinephrine, GH and thyroid hormones. They mobilize body's energy reserves while maintaining glucose stores for neural tissues.
What is growth hormone released in response to?
Growth hormone-releasing hormone and growth hormone-inhibiting hormone
What does it mean for two hormones to have antagonistic effects? What are two pairs of hormones that exhibit this?
If both are present, then the observed effects are weaker than if one or the other were present by itself. Examples: PTH and calcitonin, insulin and glucagon.
What is the function of luteinizing hormone?
In females, induces ovulation, promotes secretion of estrogens and progestins. In males, stimulates production of sex hormones (primarily testosterone)
What is the function of follicle-stimulating hormone?
In females, promote ovarian follicle development, stimulate secretion of estrogen (in conjunction with luteinizing hormone) In males: promotes maturation of sperm
What differentiates type 1 and type 2 diabetes, with respect to insulin production?
In type 1 diabetes, beta cells cannot produce enough insulin, whereas in type 2 diabetes, there is enough insulin but target cells do not respond properly to it.
What occurs in response to decreasing blood pressure, after erythropoietin is released? (1 thing)
Increased RBC production
What is antidiuretic hormone released in response to?
Increased solute concentration in blood or a decrease in blood pressure or volume.
What is the function of the hypothalamus?
It secretes hormones involved with fluid balance, smooth muscle contraction, and control of hormone secretion by the anterior pituitary gland.
What types of hormones are capable of diffusing through the plasma membrane? What are two types that do this?
Lipid-soluble hormones such as steroids and thyroid hormones travel through the plasma membrane.
What is secreted when blood pressure increases (2 hormones)? What does each of those hormones do?
Natriuretic peptides: promotes sodium ion and water loss at kidneys, inhibits release of renin and ADH. Aldosterone: overall effect is reduction of blood volume and pressure
What type of feedback normally controls hormone secretion?
Negative!
What types of cells are located in the pineal gland?
Neurons, neuroglia and secretory cells (specifically pinealocytes).
How many and what class of hormones does the pituitary release?
Nine peptide hormones
What are two possible receptor locations for hormones?
On the plasma membrane or as receptor in the cytoplasm or nucleus.
Where are the parathyroid glands located?
On the posterior surface of the thyroid gland (four of them).
What does it mean for two hormones to have permissive effects? What is an example of this?
One hormone is needed for second to produce its effect. An example is epinephrine, which requires the presence of a thyroid hormone to change rate of cellular energy consumption.
Natriuretic peptides are secreted in response to what?
Overstretching of the heart walls.
What are the two cell populations of the parathyroid glands? What is their function?
Oxyphil cells - no known functions Parathyroid cells - produce parathyroid hormone, monitor calcium levels in blood
What two hormones have opposing effects on calcium homeostasis?
PTH and calcitonin
What is the endocrine structure of the pancreas called? What is their structure?
Pancreatic islets, which are small groups of cells that are scattered in clusters.
What hormones does the adrenal medulla produce? What is the function of those hormones?
Produces epinephrine and norepinephrine, which increase cardiac activity, blood pressure and glycogen breakdown and blood glucose.
Describe the function of the adrenal cortex.
Produces more than 24 steroid hormones collectively known as adrenocortical steroids or corticosteroids.
What is prolactin inhibited by?
Prolactin-inhibiting hormone
What is the effect of PTH and calcitriol on growth regulation?
Promote calcium salt absorption for proper bone formation.
What is the effect of the thyroid hormones on growth regulation?
Promote proper nervous and skeletal system development.
What are two types of regulatory hormones?
Releasing and inhibiting
What is the endocrine function of the gonads?
Secrete hormones affecting growth, metabolism and sexual characteristics, as well as hormones coordinating the activities of organs in the reproductive system.
What is the endocrine function of the kidneys?
Secrete hormones that regulate blood cell production and the rates of calcium and phosphate absorption by the digestive tract.
What is the function of the parathyroid glands?
Secretes a hormone important to the regulation of calcium ion concentrations in body fluids.
What is the endocrine function of the heart?
Secretes hormones involved in the regulation of blood volume.
What is the endocrine function of the thymus?
Secretes hormones involved in the stimulation and coordination of the immune response.
What is the function of the adrenal glands?
Secretes hormones involved with mineral balance, metabolic control and resistance to stress; the adrenal medullae release E and NE during sympathetic activation.
What is the function of the pancreas (pancreatic islets)?
Secretes hormones regulating the rate of glucose uptake and utilization by body tissues.
What is the function of the thyroid gland?
Secretes hormones that affect metabolic rate and calcium levels in body fluids.
What is the function of the pineal gland?
Secretes melatonin, which affects reproductive function and helps establish circadian rhythm.
What is the function of the pituitary gland?
Secretes multiple hormones that regulate endocrine activities the adrenal cortex, thyroid gland and reproductive organs, and a hormone that stimulates melatonin production.
What is the endocrine function of the digestive tract?
Secretes numerous hormones involved in the coordination of system function, glucose metabolism and appetite.
Seven of the hormones released by the pituitary are released from where specifically? What are those seven generally referred to as? Where are the other two released?
Seven released from anterior pituitary, or adenohypophysis, called tropic hormones because they "turn on" other endocrine glands. The other two are released from the posterior pituitary, or neurohypophysis.
What does it mean for two hormones to have additive effects? What is a pair of hormones that exhibits this?
The net result of two hormones acting together is greater than if they were acting by themselves. The glucose-sparing action of GH in the presence of glucocorticoids is an example of this.
What is secreted by follicular cells of the thyroid gland?
Thyroglobulin
What is the middle layer of the adrenal cortex called? What hormones does it produce? What are the functions of those hormones?
The zona fasciculata produces glucocorticoids, mostly cortisol and coricosterone. They have many functions, including increasing the rates of liver glucose and glycogen formation, stimulating the release of amino acids from skeletal muscles and lipids from adipose tissue and promoting lipid metabolism. It can have an anti-inflammatory effect and can exhibit all supplement glucose-sparing effects of GH.
What is the outermost layer of the adrenal cortex called? What hormones does it produce? What is the function(s) of those hormones?
The zona glomerulosa produces mineralocoricoids, mostly aldosterone. They increase renal reabsorption of sodium ions and water and accelerate renal loss of potassium ions.
What is the inner layer of the adrenal cortex called? What types of hormones does it produce? What is the function of those hormones?
The zona reticularis produces androgens in small amounts. They stimulate the growth of pubic hair before puberty.
What occurs initially in the alarm phase? What is the dominant hormone involved?
There is an immediate sympathetic response to stress, with epinephrine dominating.
What, generally, do water-soluble hormones do once bound?
They activate a second messenger (such as cyclic-AMP [cAMP] or calcium ions) that changes cellular metabolism.
From where are regulatory hormones released? How are they transported to the pituitary?
They are released from the median eminence of infundibulum, transported to pituitary through the hypophyseal portal system.
How do the nine pituitary hormones interact with cells?
They bind with membrane receptors, using cAMP as a second messenger.
What is the function of pinealocytes?
They produce and secrete melatonin.
What are peptide hormones initially synthesized as? What eventually must happen to them?
They start of as inactive hormones, or prohormones. They must therefore be activated before or after their release.
Describe the structure of the adrenal capsule.
Thin, outer connective tissue
What are the seven anterior pituitary hormones?
Thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), growth hormone (GH), prolactin (PRL), melanocyte stimulating hormone (MSH)
What stimulates the release of thyroid-stimulating hormone?
Thyrotropin-releasing hormone
(T/F) Parathyroid hormone enhances reabsorption of calcium ions by kidneys.
True
What is the structure of the thyroid gland?
Two lobes connected by isthmus
What is the result of underproduction of glucocorticosteroids? Overproduction?
Underproduction - Addison disease Overproduction - Cushing disease
What is the result of underproduction of insulin? Overproduction?
Underproduction - Diabetes mellitus, type 1 Overproduction - excess insulin production
What is the result of underproduction of ADH? Overproduction?
Underproduction - diabetes insipidus Overproduction - SIADH (syndrome of inappropriate ADH secretion)
What is the result of underproduction of mineralcorticoids? Overproduction?
Underproduction - hypoaldosteronism Overproduction - aldosteronism
What is the result of underproduction of PTH? Overproduction?
Underproduction - hypoparathyroidism Overproduction - hyperparathyroidism
What is the result of underproduction of T4 or T3? Overproduction?
Underproduction - myxedema, cretinism Overproduction - hyperthyroidism, Grave disease
What is the result of underproduction of epinephrine (or norepinephrine)? Overproduction?
Underproduction - none identified Overproduction - pheochromocytoma
What is the result of underproduction of GH? Overproduction?
Underproduction - pituitary growth failure Overproduction - gigantism, acromegaly
What is the result of underproduction of estrogens? Overproduction?
Underproduction: hypogonadism Overproduction: adrenogenital syndrome, precocious puberty
What is the result of underproduction of androgens? Overproduction?
Underproduction: hypogonadism Overproduction: androgenital syndrom, precocious puberty
What is the main characteristic of diabetes mellitus?
Very high glucose concentration, which overwhelms kidney reabsorption.
What is the transmission method, chemical mediators and distribution of effects for direct communication?
method: gap junctions chemical mediators: ions, small solutes, lipid-soluble materials distribution of effects: limited to adjacent cells of the same type that are interconnected by connexons
What is the transmission method, chemical mediators and distribution of effects for synaptic communication?
method: synaptic clefts chemical mediator: neurotransmitters distribution of effects: limited to very specific area; target cells must have appropriate receptors.
What is type 2 diabetes otherwise known as?
non-insulin dependent diabetes