Chapter 16: The Endocrine System Flashcards
What are some differences between endocrine and exocrine glands
Exocrine - has ducts, caries secretion to a surface or organ cavity
Endocrine - No ducts, capillary networks which allow hormones to be taken into the bloodstream, intracellular effects like altering target cell metabolism
The endocrine system uses ___________ while the nervous system uses ________.
Hormones and neurotransmitters
What do cells need to to in order to maintain homeostasis?
Communicate with eachother
What is a very specialized cell that looks/acts like a neuron but secretes hormones into the bloodstream called?
Neuroendocrine cells
What are the 3 principal mechanisms of communication between cells divided into?
Autocrine, paracrine and endocrine
What is the endocrine system composed of?
Glands, tissues and cells that secrete hormones
What’s are hormones?
Chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often a considerable distance away.
Why do target cells respond to hormones?
When they have the specific receptor for that hormone and when they express specific enzymes that activate otherwise inactive versions of hormones
What is the most importantly part of the endocrine system?
Hypothalamus
Where are and what are the functions carried out by the hypothalamus?
Many of the functions are carried out in the pituitary gland and they regulate functions like water balance, thermoregulation, sex drive, childbirth etc
What is tropic hormone?
A hormone that stimulates secretion of another hormone by another endocrine gland
How many hormones are produced in the hypothalamus?
8
How many releasing and inhibiting hormones are there that stimulate or inhibit the anterior pituitary and what are they called?
There’s 6 of them and they are TSH, PRL, ACTCH, FSH, LH and GH
What does PIH inhibit the secretion of?
Prolactin
What does somatostatin inhibit the secretion of and how?
The growth hormone (GH) and the thyroid-stimulating hormone (TSH) by the anterior pituitary
What are the other hypothalamic hormones that are both stored and released by the posterior pituitary?
Oxytocin and anti diuretic hormone (ADH)
What is oxytocin produced by?
The paraventricular nuclei
What is ADH produced by?
The supraoptic nuclei
What is adenohypophysis known and how much is there?
Anterior (3/4 of the pituitary)
What is the neurohypophysis known as?
Posterior (1/4 of the pituitary)
Where does the anterior pituitary arise from?
Hypophyseal pouch
Where does the posterior pituitary arise form?
The brain (extension of hypothalamus)
What are the 2 gonadotropin hormones that target gonads?
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
What is the function of TSH (thyroid-stimulating hormone)
Stimulates secretion of thyroid hormone
ACTH
Adrenocorticotropic hormone
What does ACTH do?
It stimulates the adrenal cortex to secrete glucocorticoids
What does prolactin do?
It stimulates mammary glands to produce milk
What does growth hormone do?
Stimulates mitosis and cellular differentiation
ADH and oxytocin are produced in the ___________ and transported to the ________
Hypothalamus and posterior lobe of the pituitary
What does ADH do?
Increases water retention, reducing urine volume and preventing dehydration
What is ADH also called and why?
Vasopressin because it can cause vasoconstriction
What are some functions of oxytocin?
Stimulates labor contractions during childbirth, lactation (breast milk release), promotes feelings of sexual satisfaction and emotional bonding between partners
When is GH mainly secreted?
At night
When does LH peak?
In the middle of menstrual cycle
When does oxytocin surge?
During labor and breast feeding
All hormones have ______.
Half-life
What is half-life?
Time required for 50% of hormone to be cleared from the blood
GH has a half-life of ____ while IFGs are about _____.
6 - 20 minutes and 20 hours
What sparring effects does GH have?
Glucose sparing and protein sparing
What stimulates and what suppresses GH synthesis?
Stimulants - Stress, hypoglycemia, trauma, high-protein meals, ghrelin
Suppress - High carb diets
What is ghrelin?
Stomach hormone mediating hunger
What is the second most important part of the endocrine system?
Pineal gland
What is the peak time for the pineal gland?
Peak secretion time from ages 1 - 5 and is 75% less by puberty due to involution
What is involution?
Shrinkage of an organ/gland
What does the pineal gland do?
It produces serotonin by day and converts it to melatonin at night, , playing a role in circadian rhythms and mood disorders
What is SAD and PMS?
SAD - Seasonal Affective Disorder
PMS - Premenstural Syndrome
What systems does the thymus play a role in?
The endocrine, lymphatic and immune systems
What hormones does the thymus secrete and what does this do?
Thymopoetin, thymosin and thymulin and this stimulates the development of other lymphatic organs
What is the largest pure endocrine gland?
The thyroid gland
What connects the 2 parts of the thyroid gland?
Isthmus
Whaat are the thyroid hormones?
Thyroxine (T4) and triiodothyronine (t3), called that because of the iodine atoms
What do the thyroid hormones do?
Increases metabolic rate, O2 consumption, heat production, appetite, growth hormone secretion
What’s is the shape of the follicular cells?
Simple cuboidal epithelium
What does the thyroid follicle do?
Secretes T3 and T4 in response to TSH
What do C (parafollicular) cells do?
Secrete calcitonin which stimulates osteoblast activity and bone formation, decreasing blood calcium levels
How many parathyroid glands are there usually?
4 embedded in the posterior surface of the thyroid gland
What does the parathyroid gland secrete?
The parathyroid hormone
How do the parathyroid glands increase blood calcium levels?
Promotion of synthesis of calcitriol
Increases absorption of Ca
Decreases Ca excretion
Increases bone resorption
What nervous system is the adrenal medulla a part of?
The sympathetic nervous system
What does the adrenal medulla do?
Prepares the body for physical activity, increases alertness, anxiety or fear, BP, heart rate, airflow
What are the catecholamines?
Epinephrine and norepinephrine
What surrounds the medulla and secretes hormones known as corticosteroids?
Adrenal cortex
What surrounds the medulla and secretes hormones known as corticosteroids?
Adrenal cortex
What are the 3 layers of the adrenal cortex?
Zona glomerulosa (outer)
Zona fasciculata (middle)
Zona reticularis (inner)
What kind of hormone is found in the zona glomerulosa?
Mineralococorticoids
What kind of hormone is found in the zona fasciculata?
Glucocorticoids
What kind of hormone is found in the zona reticularis?
Sex steroids like androgen and estrogen
What cell secretes glucagon?
Alpha cells
What cells secrete insulin, and what does this antagonize?
Beta, anatogonizing glucagon
What cells secrete somatostatin?
Delta cells
Whst is the difference between hyperglycemic and hypoglycemic hormones and give examples of each.
Hyperglycemic hormones raise blood glucose concentration eg. Glucagon, GH, cortisol and corticosterone
Hypoglycemic hormones lower blood glucose eg insulin
Ovaries and testes are both ___ and _____.
Endocrine and exocrine
Examples of ovarian hormones
Estradiol, progesterone, inhibin
Examples of testicular hormones
Testosterone, weaker androgens, estrogen and inhibin
What does the secretion of inhibin by the ovaries and the testes suppress?
FSH
What does the skin do in regards to the endocrine system?
Keratinocytes convert a cholesterol-like steroid into cholecalciferol (D3) using UV from the sun
What does the liver do in regards to the endocrine system?
Converts D3 (cholecalciferol) into calcidiol
Secretes 15% of erthropoeietin
What does the kidney do in the endocrine system?
Produces 85% of erythropoietin and secretes renin
What part of the body converts calcidiol to calcitriol?
Kidney
What does the heart do for the endocrine system?
It releases the atrial natriuretic peptide with an increase in BP
What are 2 hormones the stomach secretes?
Gastrin and ghrelin
What are the 2 hormones the small intestine secretes?
Cholecystokinin and peptide YY
What does adipose tissue secrete?
Leptin, slowing appetite
What is secreted by osteoblasts?
Osteocalcin
What does placenta secrete?
Estrogen, progesterone and others
What are the 3 classes of hormones?
Steroid hormones, peptide hormones and mono amines
Monoamines and peptides are both _____.
Hydrophilic
Steroids and thyroid hormones are ______.
Hydrophobic
Where are most transport proteins in blood plasma made?
Liver
What are the the 3 hormone interactions?
Synergistic, permissive and antagonist
Describe synergistic effect in hormone interactions.
When hormones work together for greater affect than separate (FSH and testosterone on sperm production)
Describe permissive effect in hormone interactions.
This is when one hormone allows another hormone to have its full effect eg thyroid hormone hormone having permissive effect on epinephrine
Describe antagonistic effect in hormone interactions.
Opposes each other (Insulin lowers blood glucose and glucagon raises it)
Where are most hormones taken up and degraded?
In the liver and kidney
What are chemical messengers that diffuse short distances and stimulate nearby cells?
Paracrine secretions eg. Histamine, nitric oxide, somatostatin, catecholamines
What are some examples of anti-inflammatory drugs?
Aspirin, ibuprofen and Celecoxib
What are the causes of endocrine disorders?
Hypersecretion - Excessive hormone release (tumor or autoimmune disorder)
Hyposecretion - Inadequate hormone release (tumor or lesion destroys gland)
What is acromegaly caused by and what kind of disorder?
Hyper secretion of growth hormone and is a pituitary disorder, thickening of cones and soft tissues in adults
Also gigantism
What disease would occur with hyposecretion of growth hormone?
Pituitary dwarfism
What are some thyroid/parathyroid disorders?
Congenital hypothyroidism - Low
Myxedema - Low
Goiter (graves) -High
Hypoparathyroidism and hyperparathyroidism
Explain some adrenal disorders
Cushing syndrome - Excess cortisol secretion
Adrenogenital syndrome - Adrenal androgen hypersecretion
The most prevalent metabolic disease in the world is ____ and it is caused by.
Diabetes mellitus and caused by issues with metabolism due to hyposecretion or inaction of insulin
What percentage of cases of diabetes mellituis is type 1?
5 to 10%
What is always used to treat type 1?
Insulin
What percent of diabetics have type 2 and what is the problem?
Problem is insulin resistance - Failure of target cells to respond to insulin resistance
How can you treat type 2 diabetes?
Weight-loss program and exercise
How can you treat type 2 diabetes?
Weight-loss program and exercise
