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BIOL1693 > Endocrine system > Flashcards

Endocrine system Flashcards

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1
Q

Describe the histology of the pancreas

A

Pancreatic islets (or islets of Langerhans) composed of Alpha cells (glucagon), Beta cells (insulin), Delta cells (somatostatin), PP cells (pancreatic polypeptide). Acinar cells: secretion of digestive enzymes.

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2
Q

Describe the location, anatomy and function of the pineal gland

A

Attached to the root of the third ventricle, inferior and posterior to the hypothalamus. Consists of secretory parenchymal cells called pinealocytes, neuroglial cells and scattered postganglionic sympathetic fibers. Secrete melatonin in a diurnal rhythm linked to light-dark cycles.

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3
Q

Describe the hormones and function of the thymus gland

A

Secretes hormones linked to immunity: thymosin, humoral thymic factor, thymic factor and thymopoietin. All promote the proliferation and maturation of lymphatic T cells (white blood cells involved in immunity).

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4
Q

Name two hormones present in most body tissues and their function

A

Prostaglandins: normally produced by damaged tissues. Leukotrienes: produced by leukocytes, stimulate the movement of white blood cells. Both alter the production of second messengers such as cAMP.

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5
Q

Name the hormones and their functions in the heart

A

Atrial natriuretic peptide (ANP): decrease blood pressure and Na+ concentration in response to increase in blood pressure.

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6
Q

Name the hormones and their function in the gastrointestinal tract

A

Aid in the digestion of food and buffering of stomach acids: Gastrin, Secretin, Cholecystokinin. Stimulate beta cells of pancreas to release insulin: Glucose-dependent insulinotropic peptide (GIP), Glucagon-like peptide 1 (GLP-1).

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7
Q

What are the hormones and their functions in the kidneys

A

Renin: stimulates the release of aldosterone after decline in blood flow. Calcitriol: aids in the absorption of calcium ions after the release of PTH. Erythropoietin (EPO): triggers the formation of red blood cells in bone marrow after detection of low oxygen levels.

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8
Q

Describe the effect and regulation mechanism of glucocorticoids

A

General effects: increase glucose levels and help to reduce long term stress. Specific effects: Breakdown of proteins, Formation of glucose, Lipolysis, Resistance to stress, Anti-inflammatory effects, Depression of immune response. Controlled by hypothalamus through corticotropic-releasing hormone (CRH) and anterior lobe of pituitary gland through adrenocorticotropic-stimulating hormone (ACTH).

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9
Q

Describe the homeostatic regulation of blood glucose

A

Homeostasis (70-110 mg/dL). If hyperglycemia: Beta cells release insulin, body cells take up more glucose from blood and use it for cell respiration, glucose is removed from the blood and stored as glycogen in the liver (inhibits glycogenolysis), amino acids and glycerol are not converted to glucose in ER (inhibits gluconeogenesis). Results in drop of glucose levels and return to homeostasis. If hypoglycemia: Alpha cells release glucagon, body cells absorb less glucose for cellular respiration, stimulation of glycogenolysis, stimulation of gluconeogenesis. Results in increase of glucose levels and return to homeostasis.

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10
Q

Define the tissue area, chemical class, hormones released and examples for each zone of the adrenal glands

A

Zona glomerulosa: mineralocorticoids, steroids, example of aldosterone. Zona fasciculate: glucocorticoids, steroids, example of cortisol. Zona reticularis: androgens, steroids. Adrenal medulla: stress hormones, amines, example of epinephrine and norepinephrine.

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11
Q

What is the effect of mineralocorticoids? Describe their regulation mechanism

A

In general, they increase sodium and water reabsorption and decrease potassium reabsorption, which increases blood volume and pressure. They are regulated by the concentration of sodium ions in the blood, as well as the renin-angiotensin pathway.

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12
Q

Define stressor

A

Any stimuli that produces stress like heat, cold, surgical operation, poison, fever, strong emotional response, etc.

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13
Q

Describe the negative feedback system that controls the regulation of thyroid hormones.

A

Stimulus: change in metabolic rate, or concentration of thyroxine (T4) or triiodothyronine (T3) (regulated by amount of iodine). If the stimulus is decreasing: Hypothalamus releases thyroid-releasing hormone (TRH), triggers the release of the thyroid-stimulating hormone in the anterior pituitary (TSH), triggers the release of T3 and T4, increases metabolic rate of body cells, increases body temperature, return to homeostasis. If the stimulus is increasing: 1. Hypothalamus stops TRH release. 2. Anterior pituitary stops TSH release. 3. Release of T3 and T4 stops. 4. Return to homeostasis.

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14
Q

Describe the effects of the parathyroid hormone and its regulation process

A

General effects: regulates the homeostasis of calcium and phosphate by increasing the amount of calcium and decreasing the amount of phosphate in blood. Specifically, the release of PTH triggers the increase in number and activity of osteoclasts, decrease in osteoblasts, increase in reabsorption by the kidneys, stimulation of vitamin D production for increased absorption of calcium in the intestines. Regulation process: negative feedback loop related to calcium levels in blood.

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15
Q

Describe how hormones interact with target-cell receptors (up and down regulation)

A

Hormones have powerful effects even in low concentrations, and can only interact with specific receptors on target cells. The receptors are constantly synthesized and broken down. Up-regulation: when a hormone is deficient, the number of receptors is increased. Down-regulation: when a hormone is in excess, the number of receptors is decreased.

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16
Q

What are the hormones and their function in the skeleton

A

FGF23: inhibits production of calcitriol and increases phosphate excretion following an increase in vitamin D or phosphate in the blood. Osteocalcin: increases insulin production.

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17
Q

What are the hormones and their function in adipose tissue and in the skin?

A

Leptin: promotes satiety in the brain after food consumption. Adiponectin: reduces insulin resistance. Cholecalciferol: modified form of cholesterol after exposure to UV, which will be modified to form vitamin D.

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18
Q

What are the hormones and their function in the liver?

A

Insulin-like growth factors: stimulates body growth. Angiotensin: raises blood pressure. Thrombopoietin: increases platelets. Hepcidin: blocks release of iron into body fluids.

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19
Q

Define the stress response and name its three aspects

A

The stress response occurs when a stress is extreme, unusual or long-lasting, and it disturbs the normal homeostasis, which triggers a set of bodily changes. The three aspects of the stress response are the alarm reaction, the resistance reaction, and exhaustion.

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20
Q

What are the two types of stress?

A

Eustress: productive stress. Distress: harmful stress.

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21
Q

Define the physiological elements of the alarm response

A

Increase in heart rate, increase in breathing rate, increase in glucose production, increase in blood volume, accelerated red blood cell production, decrease in production of saliva, stomach and intestinal enzymes.

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22
Q

Give chemical class, effect and lobe of pituitary gland of growth hormone

A

Protein, anterior lobe. Acts indirectly on tissues by promoting the synthesis and secretion of small protein hormone (insulin-like growth factor), which regulate various aspects of metabolism and body growth.

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23
Q

Give chemical class, effect and lobe of pituitary gland for prolactin

A

Peptide, anterior. Initiates and maintains milk secretion by the mammary glands.

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24
Q

Give chemical class, effect and pituitary lobe of the thyroid-stimulating hormone

A

Glycoprotein, anterior. Regulates thyroid gland activity.

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25
Give the steps of binding for a water-soluble hormone
Bind to cell membrane receptor (first messenger), receptor gets activated, activates a G protein, activates adenylyl cyclase, adenylyl cyclase catalyzes the conversion of ATP into cAMP, which becomes the secondary messenger. cAMP activates protein kinases, kinases phosphorylate proteins in the cytoplasm, which activates them, and allows them to alter cell activity.
26
Describe the three factors that control hormone secretion
Signals from nervous system (fight or flight response, signals from the hypothalamus), chemical changes in the blood (glucose levels), other hormones (work together in feedback loops).
27
Describe the negative feedback loop that regulates the release of adrenal glucocorticoids
1. Imbalance: hypothalamus perceives low blood concentrations of glucocorticoids via sensors in blood vessels. 2. Hormone release: hypothalamus releases corticotropin-releasing hormone (CRH). 3. Correction: CRH starts a cascade that triggers the anterior pituitary gland to secrete ACTH, and the adrenal glands to release glucocorticoids in the blood. 4. Negative feedback: hypothalamus perceives a normal concentration of glucocorticoids and stops releasing CRH. 5. Back to homeostasis.
28
Describe the location and anatomy of the pituitary glands
Slightly anterior and inferior to the hypothalamus. Connected by the infundibulum. Split into anterior and posterior lobes. Located in the hypophyseal fossa of the sphenoid bone. Anterior lobe is made of glandular tissue. Posterior lobe is made of nervous tissue.
29
Give the releasing hormone, stimulating hormone and target for all the hormones of the anterior pituitary gland
Gonadotropin releasing hormone (GnRH) --> Luteinizing hormone (LH) --> Reproductive system. Gonadotropin releasing hormone (GnRH) --> Follicle-stimulating hormone (FSH) --> Reproductive system. Thyroid releasing hormone (TRH) --> thyroid-stimulating hormone (TSH) --> Thyroid gland. Prolactin-releasing hormone (PRH) or Prolactin inhibiting hormone (PIH) --> Prolactin (PRL) --> Mammary glands. Growth hormone releasing hormone (GHRH) --> Human growth hormone (HGH) --> liver, bone, muscle. Corticotropin releasing hormone (CRH) --> adrenocorticotrophic hormone (ACTH) --> Adrenal glands.
30
Give the chemical class, lobe and effect of melanocyte-stimulating hormone
Peptide, intermediate zone. Stimulates melanin formation in melanocytes.
31
Give the releasing hormone and target for all the hormones of the posterior pituitary gland
Antidiuretic hormone (ADH) --> Kidneys, sweat glands, circulatory system. Oxytocin (OT) --> Female reproductive system.
32
Name stress related diseases
Gastritis, inflammatory bowel syndrome: ulcerative colitis, peptic ulcers, hypertension, asthma, rheumatoid arthritis, migraines, anxiety, depression, chronic diseases. Effect on immunity through interleukin-1 (stimulates release of ACTH).
33
How is the alarm reaction triggered?
By nerve impulses sent to the sympathetic division of the nervous system and the adrenal medulla.
34
Describe the resistance reaction
Initiated by the CRH, GHRH and TRH in the hypothalamus. CRH stimulates the adenophysis to increase ACTH, which stimulates the adrenal cortex to release glucocorticoids. Resistance reactions are long term and they accelerate catabolism to provide energy to counteract stress.
35
Describe the exhaustion reaction
Results from dramatic changes during alarm and resistance reactions. Created by: loss in potassium, loss in glucocorticoids, weakening of organs. If it is too great, it may lead to disease and death.
36
What is the function of sexual hormones?
Female: Development and maintenance of female sexual characteristics, reproductive cycle, pregnancy, lactation, normal reproductive function. Male: Development and maintenance of male sexual characteristics, normal reproductive function.
37
Give chemical class, effect and pituitary lobe of adrenocorticotropic hormone
Peptide, anterior. Controls the production and secretion of glucocorticoids.
38
Give chemical class, pituitary lobe and effect for follicle-stimulating hormone
Glycoprotein, anterior. Stimulates gametes production (as well as initiates follicle development in female).
39
Give chemical class, pituitary lobe and effect for Luteinizing hormone
Glycoprotein, anterior. Stimulates the secretion of sexual hormones (estrogen and progesterone from ovaries in females, and testosterone in interstitial cells of testes in males).
40
Give chemical class, pituitary lobe and effect for oxytocin
Peptide, posterior. Stimulates the contraction of uterus and ejection of milk from breasts.
41
Give chemical class, pituitary lobe and effect for antidiuretic hormone
Peptide, posterior. Stimulates water reabsorption by the kidneys and arteriolar constriction, decrease urine volume, conserves body water, primarily linked to osmotic pressure of the blood.
42
Describe the location and anatomy of the thyroid gland
Butterfly shaped, located between the larynx and the trachea. 4 parathyroid glands on the posterior side. Made of thyroid follicles, composed of follicular cells around a lumen containing colloid. Also composed of parafollicular cells outside of follicular cells.
43
Describe the effect and regulation of epinephrine and norepinephrine
Produce effects similar to sympathetic response in fight or flight. Released under direct innervation by the autonomic nervous system. Help resist short term stress, but are not essential to life.
44
Describe the formation, storage and release of thyroid hormones
Release of TRH and TSH. Iodide trapping: iodide ion uses sodium to get pumped into follicular cells, then into the lumen. Synthesis of thyroglobulin: TSH binds to receptors in the follicular cells and stimulates synthesis and release of TGB into the lumen. Oxidation of iodide: a peroxidase called TPO converts iodide into iodine. Iodination of tyrosine: TPO places iodine on the tyrosine amino acids of TBG, creating T1 and T2 complexes. Coupling of T1 and T2: mono or di-iodothyronine blocks are joined to form T3 (triiodothyronine) and T4 (thyroxine). Pinocytosis and digestion of colloid: protein is brought back into follicular cells via pinocytosis. T3 and T4 are isolated by lysosomes. Secretion of thyroid hormones: exocytosis into the bloodstream. Transportation in blood: thyroxine-binding globulin transports T3 and T4 into the blood.
45
Describe the chemical class and effects of the thyroid hormones
T3 and T4 regulate oxygen use and basal metabolic rate, cellular metabolism and development. They are lipid-soluble amines. Calcitonin lowers blood calcium levels, it is a peptide.
46
Describe the location and anatomy of the adrenal glands
Superior to the kidneys. Composed of 85% cortex, and medulla. Cortex composed of zona glomerulosa, zona fasciculate, and zona reticularis. Adrenal medulla composed of hormone producing cells called chromaffin, surrounding large blood-filled sinuses.
47
Explain the difference between endocrine and exocrine glands
Endocrine: secrete their products into interstitial fluid surrounding secretory cells, then diffuse into capillaries and move into the bloodstream. Exocrine: secrete their products into ducts, and the ducts carry the secretions to the target.
48
Describe the differences in functions between endocrine and nervous systems in regulating homeostasis
Signalling mechanisms: chemical (E) vs chemical or electrical (N). Primary chemical signal: hormones vs neurotransmitters. Distance traveled: long or short vs short. Response time: fast or slow vs always fast.
49
What are the principal endocrine glands and their locations?
Hypothalamus (brain, inferior to the thalamus), Pituitary gland (brain, inferior and anterior to the hypothalamus), Pineal gland (brain, posterior and inferior to the thalamus), Thyroid (between larynx and trachea), Parathyroid (posterior side of thyroid), Thymus (inferior to the thyroid), Adrenal glands (on top of kidneys), Pancreas (between kidneys), Ovaries and testes.
50
What are lipid soluble hormones?
Hormones derived from lipids (cholesterol) with long half-lives that attach to receptors inside the cells. ## Footnote Examples include steroid hormones like estrogen, testosterone, and aldosterone, T3 and T4, and nitric oxide.
51
What are water soluble hormones?
Hormones derived from amino acids with short half-lives that bind to receptors outside the cell. ## Footnote Examples include epinephrine, norepinephrine, melatonin, antidiuretic hormone, oxytocin, growth hormone, and insulin.
52
What are the steps of binding for lipid soluble hormones?
1. Diffuse through plasma membrane. 2. Bind to a receptor in cytoplasm to form the receptor-hormone complex. 3. Enter the nucleus and bind to a target gene in DNA to trigger transcription. 4. Messenger RNA is transcribed and translated into a protein by ribosomes. 5. Protein alters cell activity.
53
Which endocrine glands are under the hypothalamus-pituitary axis control?
Thyroid, adrenal cortex, and gonads are under control. ## Footnote Parathyroid, adrenal medulla, pancreas, thymus, and pineal gland do not obey.
54
What are the gonads and the hormones the release?
Gonads are organs that produce gametes (sperm and oocytes). In females, ovaries produce sex hormones (estrogen and progesterone), inhibin, and relaxin. In males, testes produce sex hormones (testosterone) and inhibin.
55
What are the functions of the endocrine system?
Regulation of blood chemical composition, reproductive processes, metabolism and energy balance, growth and development, stress coping, immune function, muscle contraction, and glandular secretion.
56
What are the hormones of the pancreas?
Insulin (triggers glucose uptake), Glucagon (stimulates glycogenolysis and gluconeogenesis), Somatostatin (inhibits glucagon and insulin release), Pancreatic polypeptide (role in appetite).
57
What is the definition of paracrine and autocrine glands?
- Paracrine: chemical signals act on nearby cells - Autocrine: act on the cells that release it
58
Relate efficiency of action and half life for water and lipid soluble hormones
- Water soluble hormones act quickly and have a short half life (cAMP is quickly deactivated), but their action is widespread and fast, because they can phosphorylate multiple proteins at the same time. - Lipid soluble hormones change the gene expression directly and have long half lifes, so they tend to have longer and slower effects
59
Define the role of the hypothalamus in endocrine function
It is the master regulator and integrating link between the nervous system and the endocrine system
60
What are two other names for the pituitary gland and lobes ?
Hypophysis, adenohypophysis (anterior) and neurohypophysis (posterior)
61
What regulates the concentration of T3 and T4?
The amount of iodine

BIOL1693 (12 decks)

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