Chapter 13: Overview of the Endocrine System Flashcards

Question

what 5 types of hormones does the anterior pituitary secrete

Answer 1

1. somatotrophs 2. thyrotrophs 3. corticotrophs 4. lactotrophs 5. gondotrophs

Answer 2

secrete growth hormone (GH) - also known as somatotropin the growth hormone stimulates general body growth and regulates aspects of metabolism

Answer 3

secrete thyroid stimulating hormones (TSH) - also known as throptropin TSH controls the secretions and other activities of the thyroid gland

Answer 4

secrete adrenocorticotropic hormone (ACTH) - also referred to as cortocptropin stimulates the adrenal cortex to secrete glucocorticodies such as cortisol

Answer 5

secrete prolactin - initiates milk production in the mammary glands

Answer 6

secrete two: follicle-stimulating hormone 9FSH) & luteinizing hormone (LH) FSH and LH both act on gonads (testes and ovaries) In men: stimulate the testes to produce sperm and to secrete testosterone In women: they stimulate the ovaries to produce eggs (oocytes) and to secrete estrogens and progesterone.

Answer 7

the hypothalamus secretes five releasing hormones: ● Growth hormone–releasing hormone (GHRH), also known as somatocrinin, stimulates secretion of growth hormone ● Thyrotropin-releasing hormone (TRH) stimulates secretion of thyroid-stimulating hormone ● Corticotropin-releasing hormone (CRH) stimulates secretion of adrenocorticotropic hormone ● Prolactin-releasing hormone (PRH)* stimulates secretion of prolactin ● Gonadotropin-releasing hormone (GnRH) stimulates secretion of FSH and LH.

Answer 8

● Growth hormone–inhibiting hormone (GHIH), also known as somatostatin, suppresses secretion of growth hormone ● Prolactin-inhibiting hormone (PIH), which is dopamine, sup- presses secretion of prolactin

Answer 9

is a type of vascular arrangement in which blood flows from one capillary network through a portal vein and then into a second capillary network without first returning to the heart

Answer 10

blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries in the anterior pituitary

Answer 11

1. Synthesis & Packaging - Neurosecretory cells in the hypothalamus synthesize releasing/inhibiting hormones and package them in vesicles. 2. Transport & Release - Action potentials trigger exocytosis, releasing the hormones into the hypothalamic–hypophyseal portal system. 3. Hormone Action at Anterior Pituitary - Hormones travel through portal veins, reach anterior pituitary cells, and stimulate or inhibit hormone secretion. 4. Systemic Distribution - Anterior pituitary hormones enter the bloodstream and reach their target organs

Answer 12

Regulation of anterior pituitary hormones occurs through negative feedback from the target gland hormones. Key Cells Affected by Negative Feedback: Thyrotrophs → Regulated by thyroid hormones (T3 & T4) Corticotrophs → Regulated by cortisol Gonadotrophs → Regulated by sex hormones (estrogens, progesterone, testosterone)

Answer 13

- most numerous hormone in the anterior pituitary - promotes the growth of body tissues (bones and skeletal muscles) , regulates certain aspects of metabolism

Answer 14

Produced in response to GH by: Liver (enters bloodstream — hormonal effect) Skeletal muscle, cartilage, bone (local effect — autocrine/paracrine) function: promote growth of bones and soft tissues

Answer 15

1. increase growth of bones and soft tissues --> stimulate osteoblasts, enhance protein synthesis 2. enhance lipolysis --> use of released fatty acids for ATP production 3. decrease glucose uptake --> maintain glucose for fasting or stress

Answer 16

stimulates the synthesis and secretion of the two thyroid hormones, triiodothyronine (T3) and thyroxine (T4), both produced by the thyroid gland

Answer 17

ACTH controls the production and secretion of cortisol and other glucocorticoids by the cortex (outer portion) of the adrenal glands. CRH is released in response to stress-related stimuli, such as low blood glucose or physical trauma, and interleukin-1, a substance produced by macrophages

Answer 18

initiates and maintains milk production by the mammary glands - ejection of milk from the mammary glands depends on the hormone oxytocin, which is released from the posterior pituitary together = milk production and ejection constitute

Answer 19

in females: initiates development of oocytes and induces ovarian secretion of estrogen in males: stimulates testes to produce sperm

Answer 20

triggers ovulation - the release of an egg by an ovary - stimulates secretion of estrogen and progesterone, ovulation and formation of corpus luteum in males: stimulates testes to produce testosterone

Answer 21

does not synthesize hormones, it does store and release two hormones made by hypothalamus ADH and oxytocin

Answer 22

Produced by: Neurosecretory cells in the paraventricular and supraoptic nuclei of the hypothalamus Hormones: Oxytocin & ADH (vasopressin) Transported via: Hypothalamic–hypophyseal tract Stored in: Axon terminals in the posterior pituitary

Answer 23

- Stimulus excites the hypothalamus - Action potentials trigger exocytosis of vesicles - Oxytocin or ADH is released into the bloodstream - Hormones travel to target tissues to exert effects

Answer 24

oxytocin affects two target tissues: 1. the mother’s uterus 2. breasts During delivery: oxytocin enhances contraction of smooth muscle cells in the wall of the uterus; after delivery, it stimulates milk ejection (“letdown”) from the mammary glands in response to the mechanical stimulus provided by a suckling infant - responsible in part of the feelings of sexual pleasure during and after intercourse

Answer 25

antidiuretic (anti- = against; dia = throughout; ouresis = urination) - decreases urine production - causes kidneys to return more water to the blood other name: vasopressin

Answer 26

1. rise in blood osmolarity 2. decrease in blood volume

Answer 27

butterfly-shaped is located just below the larynx (voice box) - Microscopic spherical sacs called thyroid follicles make up most of the thyroid gland. - the wall of each follicle consists primarily of cells called follicular cells, which producetwo hormones: thyroxine or T4 and T3

Answer 28

lie between the follicles of the thyroid gland. They produce the hormone calcitonin, which helps regulate calcium homeostasis

Answer 29

1. Pulling in Iodine - Your thyroid cells grab iodide (I⁻) from your blood. - This is called iodide trapping – they actively suck it in like a vacuum. 2. Synthesis of Throglobulin - At the same time, these cells are making a big protein called thyroglobulin (TGB). - They send TGB out into the middle space of the follicle (called the lumen). 3. Oxidation of Iodide - Iodide (I⁻) can’t be used yet. It needs to be changed into iodine (I₂). - This happens through oxidation, with help from an enzyme called thyroid peroxidase. 4. Sticking Iodine to TGB - Now the iodine sticks to tyrosine amino acids on the TGB protein. - One iodine = MIT (mono-iodo-tyrosine) - Two iodines = DIT (di-iodo-tyrosine) - This mix of TGB + iodine is called colloid. 5. Coupling of MIT and DIT Two MIT/DIT units combine to make the actual thyroid hormones: MIT + DIT = T3 DIT + DIT = T4 6. Taking It Back In The thyroid cell pinches in some colloid (like taking a scoop back). Inside the cell, it digests the TGB protein and frees the T3 and T4 hormones. 7. Releasing T3 & T4 into Blood - Since they are lipid-soluble, T3 and T4 just slide out of the cell and into the bloodstream. - Your body makes more T4 than T3, but T3 is the stronger one. - Most T4 is turned into T3 later, in your body cells. 8. Traveling in the Blood T3 and T4 don’t float around freely – they hitch a ride on a protein called TBG (thyroxine-binding globulin) so they don’t get lost

Answer 30

BMR = the amount of energy your body uses at rest Thyroid hormones raise the basal metabolic rate (BMR), the rate of energy expenditure (ATP) under standard or basal conditions (awake, at rest, and fasting)

Answer 31

key role in maintenance of normal body temperature - As cells produce and use more ATP, BMR increases, more heat is given off , and body temperature rises

Answer 32

make your body more sensitive to "fight or flight" signals Thyroid hormones have permissive effects on the catecholamines (epinephrine and norepinephrine) because they up-regulate βadrenergic receptors result: - faster heart rate - higher blood pressure

Answer 33

very important for pregnancy, infancy and childhood Thyroid hormones are necessary for the development of the nervous system and growth of the skeletal system

Answer 34

- increase basal metabolic rate - enhance action of catecholamines - regulate development and growth of nervous tissue and bones

Answer 35

reduces amount of Ca 2+ and HPO- released from bone into blood by inhibiting osteoclasts

Answer 36

a cold environment, hypoglycemia, high altitude, and pregnancy—increase the secretion of the thyroid hormones

Answer 37

small, round masses of glandular tissue that are partially embedded int he back surface of the thyroid gland

Answer 38

Chief cells that release parathyroid hormone (PTH) - PTH is the major regulator of the levels of calcium (Ca2+), magnesium (Mg2+), and phosphate (HPO4 2−) ions in the blood - PTH promotes formation of the hormone calcitriol, the active form of vitamin D in the kidneys

Answer 39

an outer adrenal cortex, which makes up about 85% of the gland and an inner adrenal medulla

Answer 40

epinephrine, norepinephrine, and a trace amount of dopamine

Answer 41

- The outer zone is the zona glomerulosa - secrete hormones called mineralocorticoids - The middle zone, or zona fasciculata is the widest of the three zones - secrete mainly glucocorticoids - inner zone, the zona reticularis - synthesize small amounts of weak androgens, steroid hormones that have masculinizing effect

Answer 42

- Aldosterone is the major mineralocorticoid - It increases blood level of Na+ and decrease blood level of K+ and helps adjust blood pressure and blood volume through renin–angiotensin–aldosterone (RAA) pathway - - Increases BP

Answer 43

which regulate metabolism and resistance to stress, include cortisol (most abundant ), corticosterone, and cortisone

Answer 44

Protein breakdown: increase the rate of protein breakdown, thus increase the liberation of amino acids into the bloodstream which may be used by body cells for synthesis of new proteins or for ATP production. Glucose formation: gluconeogenesis - formation of glucose from noncarbohydrate sources Lipolysis: stimulate lipolysis, the breakdown of triglycerides and release of fatty acids and glycerol from adipose tissue into the blood. Resistance to stress: work in many ways to provide resistance to stress. Anti-inflammatory effects: inhibit leukocytes that participate in inflammatory responses. Unfortunately, glucocorticoids also retard tissue repair and, as a result, they slow wound healing. Depression of immune responses: High doses depress immune responses

Answer 45

Assist in early growth of axillary and pubic hair in both sexes; in females, contribute to libido and are source of estrogens after menopause

Answer 46

Chromaffin cells are innervated by sympathetic preganglionic neurons of the ANS to produce 80% epinephrine and 20% norepinephrine Function: Produce effects that enhance those of the sympathetic division of the autonomic nervous system (ANS) during stress

Answer 47

- is a small endocrine gland associated with the brain - it secretes melatonin, an amine hormone derived from serotonin

Answer 48

- Influences circadian rhythms: Melatonin helps regulate circadian rhythms, patterns of biological activity (such as the sleep–wake cycle, secretion of certain hormones, and slight fluctuations in body temperature) that occur on a 24-hour cycle - Induces sleep: As more melatonin is liberated during darkness than in light, this hormone is thought to promote sleepiness. - Protects against free radicals: Melatonin is a potent antioxidant that protects against oxygen-derived free radicals, such as the hydroxyl (OH) and superoxide (O2 −) radicals - Inhibits reproductive functions: In animals that breed during specific seasons, Melatonin inhibits reproductive functions, but it is unclear whether melatonin influences human reproductive function

Answer 49

is an elongated, tapered gland located behind the stomach - contains both an exocrine portion (99%) --> secretes fluid containing digestive enzymes onto ducts and an endocrine portion (1%) --> consists of clusters of cells called pancreatic islets (islets of Langerhans) that secrete hormones

Answer 50

- 17% Alpha (α) cells - secrete glucagon. - 70% Beta (β) cells - secrete insulin. - 7% Delta (δ) cells - secrete somatostatin. - F cells - secrete pancreatic polypeptide

Answer 51

o Uptake of glucose: Insulin accelerates the facilitated diffusion of glucose into body cells o Formation of glycogen: Stimulates the conversion of glucose into glycogen (glycogenesis) in liver and skeletal muscle o Inhibition of processes that release glucose: achieves these functions by inhibiting enzymes required for glycogenolysis and gluconeogenesis o Uptake of fatty acids and formation of triglycerides: Insulin promotes the uptake of fatty acids into adipocytes. Although fatty acids can diffuse freely across the plasma membrane of an adipocyte, transporters help mediate this process  suppress the breakdown of triglycerides (lipolysis): Insulin does this by inhibiting hormone-sensitive lipase o Uptake of amino acids and formation of proteins: Insulin increases the uptake of amino acids into skeletal muscle fibers as well as other body cells.

Answer 52

1. Glucagon, a hormone, is released when your blood sugar is low. 2. It binds to receptors on liver cells (called hepatocytes). 3. This triggers a chain reaction inside the cell that leads to the production of cAMP, a messenger molecule. 4. cAMP activates an enzyme called protein kinase A (PKA). 5. PKA then activates another enzyme called glycogen phosphorylase. 6. Glycogen phosphorylase breaks apart glycogen, a stored form of glucose in the liver. 7. As a result, glucose molecules are released from glycogen. 8. The glucose exits the liver cell and enters the blood to raise blood sugar levels.

Answer 53

glucagon performs functions that oppose the actions of insulin - most of them promote catabolism (breakdown of larger molecules to small) main target cell: hepatocyte (liver cell) functions: 1) Breakdown of glycogen. Glucagon acts on hepatocytes to accelerate the breakdown of glycogen into glucose (glycogenolysis) 2) Formation of glucose from noncarbohydrate sources: Glucagon acts on hepatocytes to promote formation of glucose from lactic acid, certain amino acids, or glycerol (gluconeogenesis) 3)Breakdown of lipids: Glucagon promotes the breakdown of lipids (lipolysis) in adipocytes. Glucagon achieves this function by activating hormone-sensitive lipase 4)Inhibition of protein synthesis: Glucagon inhibits protein synthesis in hepatocytes

Answer 54

The principal action of insulin: is to lower the blood glucose level when it is too high (rises above normal) Glucagon: increases the blood glucose level when it is too low ( falls below normal).

Answer 55

- increased activity of the parasympathetic nerves that supply the pancreatic islets - elevated blood amino acid level, which occurs after a protein containing meal - incretins: provide a type of feedforward control that anticipates the increase in blood glucose that occurs after a typical meal

Answer 56

- Increased activity of the sympathetic nerves that supply the pan- creatic islets, as occurs during exercise. - A rise in blood amino acids if blood glucose level is low, which could occur after a meal that contained mainly protein

Answer 57

inhibits secretion of insulin and glucagon and slows absorption of nutrients from the gastrointestinal tract o Pancreatic polypeptide inhibits secretion

Answer 58

Inhibits somatostatin secretion, gallbladder contraction, and secretion of pancreatic digestive enzymes

Answer 59

organs that produce gametes - eggs (oocytes) in females and sperm in males

Answer 60

paired oval structures located in the female pelvic cavity - produce several steroid hormones, including two estrogens (estradiol and estrone) and progesterone - regulate the menstrual cycle and maintain pregnancy - Inhibin: inhibits secretion of FSH - relaxin: inhibits contractions of the uterus, making it easier for a fertilized egg to implant in uterine wall

Answer 61

are oval glands located in the scrotum main hormone produced and secreted by the testes is: androgen testosterone (principle male sex hormone) functions: - stimulates descent of the testes before birth, regulates production of sperm, and stimulates the development and maintenance of male secondary sex characteristics inhibin: inhibits secretion of FSH

Answer 62

produces cholecalciferol, or vitamin D 3, a substance that plays a role in the synthesis of calcitriol—the active form of vitamin D - calcitriol synthesis begins in the skin, continues in the liver, and ends in the kidneys

Answer 63

located just above the heart - secretes hormones that promotes immune function Thymosin and Thymopoietin: These thymic hormones promote the maturation of T cells (a type of leukocyte that destroys microbes and other foreign substances). Thymic hormones may also play a role in slowing down the aging process

Answer 64

heart: produces the hormone atrial natriuretic peptide (ANP) - inhibits reabsorption of sodium ions (Na+) and water by the kidneys so more is lost into the urine - actions increase excretion of Na+ in urine and increase urine output, which decreases blood volume and blood pressure

Answer 65

Gastrin: which stimulates secretion of gastric juice and increases motility (contractions) of the stomach. Ghrelin: plays a role in stimulating appetite

Answer 66

secretin: stimulates secretion of pancreatic juice that is rich in bicarbonate ions cholecystokinin: promotes contraction of the gallbladder to release stored bile, and brings about a feeling of fullness after eating glucose-dependent insulinotropic peptide (GIP) & glucagon like peptide (GLP): stimulate the release of insulin from the pancreas

Answer 67

Calcitriol: acts on the small intestine to increase the absorption of calcium (Ca2+) and phosphate (HPO42–) ions from food in the intestinal tract into the blood Erythropoietin (EPO): which increases the rate of erythrocyte production. The kidneys secrete EPO in response to low levels of oxygen in the tissues

Answer 68

produced by adipose tissue Leptin: acts on the brain to suppress appetite, thereby reducing food intake. Leptin also increases energy expenditure, which helps break down body fat reserves

Answer 69

forms during pregnancy and serves as the site of exchange of nutrients and wastes between the mother and fetus Human chorionic somatomammotropin: helps prepare the mammary glands of the breasts for lactation

Answer 70

Hypertrophy: cells of the body increase in size Hyperplasia: cells of the body increase in number

Answer 71

activity of the epiphyseal (growth) plate, a layer of cartilage located at the junction between the diaphysis and each epiphysis of a growing bone

Answer 72

(cartilage producing cells) that are constantly dividing - As a bone grows in length, new chondrocytes are formed on the epiphyseal side of the plate, while old chondrocytes on the diaphysial side of the plate are replaced by bone

Answer 73

- The appearance of the epiphyseal line signifies that the bone has stopped growing in length - if a bone fracture damages the epiphyseal plate, the fractured bone may be shorter than normal once adult stature is reached because damage to cartilage, which is avascular (lacks blood vessels)

Answer 74

As long bones lengthen, they also grow in thickness (width) Growth in thickness occurs in the following way: - osteoblasts (bone-building cells) add new layers of bone to the outer surface (work more slowley = when bones become thicker, marrow cavity also expands) - Meanwhile, osteoclasts (bone-breaking cells) remove bone from the inner surface near the marrow cavity

Answer 75

the ongoing replacement of old bone tissue by new bone tissue It involves - bone resorption (the removal of minerals and collagen fibers from bone by osteoclasts) and bone deposition (the addition of minerals and collagen fibers to bone by osteoblasts). - bone resorption results in the destruction of bone extracellular matrix, while bone deposition results in the formation of bone extracellular matrix

Answer 76

Genetics: help determine adult stature Minerals: such as calcium and phosphorus are essential for growing bones Vitamins: such as A,C,D, K, B12 - support bone cell activity and protein synthesis Aging: especially for women after menopause Exercise: weight bearing, strengthen bones, slow age related bone loss

Answer 77

- growth hormone (GH) - thyroid hormones (T3 and T4) - estrogen, testosterone - parathyroid hormone (PTH) - calcitonin

Answer 78

General Adaptation Syndrome which occurs in three stages: 1. initial the fight-or-flight response 2. slower resistance reaction 3. exhaustion

Answer 79

any stimulus that produces a stress response is a stressor - disturbance of the body (toxins, poisons, bleeding, emotional reaction, surgery) eustress: prepares us to meet certain challenges = helpful distress: harmful stress

Answer 80

is initiated by action potentials from the hypothalamus to the sympathetic division of the autonomic nervous system and the adrenal medulla. This response rapidly increases circulation, promotes ATP production, and decreases nonessential activities

Answer 81

is initiated by releasing hormones secreted by the hypothalamus, most importantly CRH, TRH, and GHRH Resistance reactions are longer lasting and accelerate breakdown reactions to provide ATP for counteracting stress

Answer 82

results from depletion of body resources during the resistance stage