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60 Cards in this Set
- Front
- Back
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What are the two different types of glands in the body?
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exocrine and endocrine
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Exocrine
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secrete products locally into ducts
Examples: oil (sebaceous) and salivary glands |
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Endocrine
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release hormones to be transported in blood throughout the body
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endocrine system's main funcation
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Main function of the endocrine system along with the nervous system is to regulate and coordinate other body systems to maintain homeostasis
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Major endocrine glands
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Pituitary, thyroid, parathyroids (4), adrenals (2), pineal
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Many other organs have some endocrine tissue. which ones?
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hypothalamus, thymus, pancreas
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Hormone
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chemical message released by an endocrine gland that travels throughout the body via the bloodstream
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target cells
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Every cell in the body is exposed to the hormone, but only target cells can respond
Target cells contain protein receptors on the plasma membrane or inside the cell that recognize and bind to specific hormones |
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Two major types of hormones
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lipid or water soluble
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Lipid-soluble hormones
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Steroid hormones; derived from cholesterol
Released by the adrenal glands, testes and ovaries Easily diffuse through the plasma membrane phospholipid bilayer to bind to receptors in the target cell’s cytoplasm |
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Water-soluble hormones
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Often proteins or peptides
Cannot pass through the plasma membrane Hormone is a first messenger that binds to receptors on the target cell’s plasma membrane to activate second messengers in the cytoplasm that influence the activity of enzymes |
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Most hormone levels are controlled by a negative feedback mechanism
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(-) feedback: Gland releases a hormone and rising levels in the blood inhibits further release
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positive feedback
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Rising blood levels stimulate a process to continue
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Interactions between Hormones
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Hormones can be antagonistic (have opposite effects), synergistic (work together) or permissive (one hormone must be present for another to work)
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Pituitary gland
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is the size of a pea and dangles below the hypothalamus connected by a stalk
Two lobes: anterior and posterior that secrete different hormones |
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Anterior lobe
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largerproduces and secretes 6 hormones:
Growth hormone (GH) Prolactin (PRL) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) |
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Hypothalamus
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nerve cells secrete hormones that travel through the blood to the anterior lobe that stimulate (releasing hormones) or inhibit (inhibiting hormones) hormone secretion
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Posterior lobe
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tinyNerve cells from the hypothalamus project directly into the posterior lobe
Pituitary lobes then release hormones that may induce other glands to secrete hormones |
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Growth hormone (GH)
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induces cell division, particularly in bone, muscle and cartilage to promote growth
Growth hormone-releasing hormone (GHRH) and growth hormone-inhibiting hormone (GHIH) from hypothalamus regulate synthesis and release of GH |
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Giantism
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too much GH produced in childhood when the bones can lengthen
Can reach heights of 8-9 feet Often caused by a tumor on the anterior pituitary |
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Pituitary dwarfism
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too little GH produced in childhood
Maximum height is 4 feet Can treat with GH injections in childhood; can’t treat other forms of dwarfism |
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Prolactin (PRL
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stimulates mammary glands to produce milk after pregnancy
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Tropic hormones
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hormones that influence another endocrine gland
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Thyroid-stimulating hormone (TSH):
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stimulates the thyroid to synthesize and release thyroid hormones
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Adrenocorticotropic hormone (ACTH
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controls the synthesis and secretion of glucocorticoid hormones from the adrenal glands
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Gonadotropins
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stimulate the gonads - ovaries and testes (details in chapter 17
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Follicle-stimulating hormone (FSH
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promotes egg cell development and estrogen secretion from the ovaries
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Luteinizing hormone (LH):
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causes ovulation and estrogen/progesterone release from ovaries in females; testosterone release from testes in males
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doesn’t produce any hormones; stores and secretes two hormones that are produced by the
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hypothalamus
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Antidiuretic hormone (ADH):
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promotes water conservation by decreasing urine output from the kidneys (details in chapter 16)
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Oxytocin (OT)
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Stimulates contractions of the uterus for childbirth
Controlled by positive feedback until the baby is born Stimulates milk ejection from the mammary glands in response to nursing infant (Prolactin from anterior lobe stimulates milk production not ejection |
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Thyroid gland
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Follicle cells produce thyroglobulin from which thyroid hormone (TH) is made
Nearly all cells in the body are target cells for TH TH regulates the body’s metabolic rate, production of heat, and blood pressure Parafollicular cells secrete calcitonin (CT) hormone |
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thyroid hormone (TH)
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Follicle cells produce thyroglobulin from which thyroid hormone (TH) is made
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calcitonin (CT
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lowers blood calcium when it is high by stimulating absorption by bone and inhibiting the breakdown of bone
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goiter
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Iodine deficient diet can lead to a goiter: enlarged thyroid gland
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Low iodine leads to
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Low iodine leads to low TH triggering secretion of thyroid stimulating hormone (TSH) from the anterior pituitary
Thyroid increases production of thyroglobulin, but TH can’t be made without iodine Thyroid enlarges in an effort to filter more iodine from the blood |
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Hypothyroidism
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Under-secretion of TH leads to fatigue, depression, weight gain, decreased body temperature and decreased heart rate
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Hyperthyroidism
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Over-secretion of TH most commonly caused by Graves’ disease: autoimmune disease in which antibodies are produced that mimic TSH
Symptoms: increased heart rate, increased metabolic rate, weight loss, nervousness and sweating |
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When blood calcium is low
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the parathyroid glands release parathyroid hormone (PTH) – next section
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Experience Curve Effect
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Many firms expect the unit cost to drop significantly as the accumulated volume sold increases, the costs continue to drop, allowing further reductions in the price
As sales continue to grow, the costs continue to drop --> further reductions in price |
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PTH increases blood calcium by
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1) stimulating removal of Ca+ from urine to return to the blood, 2) increasing Ca+ absorption from the gastrointestinal tract, and 3) stimulating osteoclasts (cells that break down bone)
Calcium is stored in bones; osteoclasts are stimulated to dissolve bone and release Ca+ into the blood |
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Adrenal glands
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sit on top of the kidneys
Two regions: adrenal cortex (outer layer) and adrenal medulla (inner layer) |
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Cortex releases
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over 20 steroid hormones divided into three groups: 1) gonadocorticoids, 2) mineralocorticoids, and 3) glucocorticoids
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Medulla secretes
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two water-soluble hormones: 1) epinephrine (adrenaline) and 2) norepinephrine (noradrenaline
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Gonadocorticoids
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androgen (male) and estrogen (female) sex hormones
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Mineralocorticoids
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affect mineral homeostasis and water balance
Example: Aldosterone |
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Glucocorticoids
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increase glucose and fatty acids in the blood; inhibit the inflammatory response
Example: Cortisol |
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Addison’s disease
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autoimmune disorder that attacks the adrenal cortex leading to under-secretion of aldosterone and cortisol
Symptoms: weight loss, fatigue, electrolyte imbalance |
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Cushing’s syndrome
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caused by too much cortisol
Caused by adrenal tumor or treatment with glucocorticoid hormones to treat asthma, lupus or rheumatoid arthritis Symptoms: body fat redistribution, fluid accumulation in the face, fatigue, high blood pressure and high glucose |
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Adrenal medulla produces
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epinephrine (adrenaline) and norepinephrine (noradrenaline)
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fight or flight response
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Involved in the body’s sympathetic nervous system’s reaction to stressful, emergency situations
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pancreas
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is just posterior and inferior to the stomach
Contains exocrine and endocrine cells |
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Exocrine cells
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secrete digestive enzymes into ducts that empty into the small intestine
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Endocrine cells
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(pancreatic islets or islets of Langerhans) produce glucagon, insulin and somatostatin hormones
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Glucagon
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increases glucose levels in the blood between meals
When cells are using up glucose, blood glucose levels fall Glucagon is released stimulating the liver to convert glycogen to glucose |
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Insulin
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decreases glucose levels in the blood after meals by stimulating transport of glucose into cells for use as energy; promotes glycogen and fat storage
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Somatostatin
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regulates glucagon and insulin secretion
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Type I diabetes mellitus (mel, honey
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Used to be called “juvenile-onset” or “insulin-dependent”
Autoimmune disorder against pancreatic cells Inject insulin before meals or glucose can’t leave the blood and go into cells Symptoms: nausea, vomiting, thirst, excessive urination |
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Type II diabetes mellitus
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Used to be called “non-insulin dependent” or “adult-onset” Make enough insulin, but cells don’t respond
Target cells become desensitized perhaps due to down-regulation of insulin receptors Often associated with obesity Treatment: dietary restrictions, exercise and weight loss |
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Complications from uncontrolled diabetes
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Blindness, kidney disease, heart disease, high blood pressure, artherosclerosis, nerve damage
Poor circulation results in loss of feeling in lower limbs, and may require amputation |
