Exercise 28

Endocrine SystemGlucometer

Portland Community CollegeBI 232

The endocrine system

• Diverse collection of organs and tissues that contain endocrine glands.

• Glands secrete chemicals called hormones into blood capillaries

• Hormones are transported to target cells at a distant location

• Hormone binds to a specific receptor and the cell responds to message.

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Endocrine and Exocrine

• Exocrine glands secrete substances into ducts, which transport the secretions internal cavities of organs or to surface of the skin.

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Effects of Hormones

• Areas receptive to hormones are called target cells and may be tissues or organs.

• Can have many effects such as growth, development, metabolism, etc.

• Many organs produce hormones such as heart, stomach and kidneys.

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Pineal Gland

• Secretes:• Melatonin

• Involved in circadian rhythms

• Day melatonin, Night melatonin

• Produces sleepiness

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Hypothalamus and Pituitary Gland (Hypophysis)• Hypothalamus produces a

number of releasing hormones and inhibiting hormones.

• Stored in posterior pituitary (neurohypophysis)

• ADH (antidiuretic hormone)• Reduces urine output by increasing

water reabsorption in the kidney• Plays small role in blood pressure

regulation• Also called vasopressin

• Oxytocin• Causes uterine contractions in labor• Causes milk let down in lactating

mothers

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Anterior lobe (Adenohypophysis)• ACTH (adrenocorticotropic

hormone)• Regulates the activity of the

cortex of the adrenal gland• TSH (thyroid stimulating hormone)

• Stimulates production and release of thyroid hormone

• GH (growth hormone)• Stimulates growth of bones,

cartilage, muscle• Timing and amount released

determines body size

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Endocrine Organs in Head• PRL (prolactin)

• Stimulates breast development• Promotes and maintains

lactation after childbirth• FSH (follicle stimulating hormone)

• Causes formation of ovarian follicles and stimulates them to produce estrogen

• Stimulates sperm development in men

• LH (luteinizing hormone)• Initiates ovulation, maintains

corpus luteum• Regulates testosterone

production in males

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PituitaryHistology

Intermediate lobe (part of the anterior lobe) produces melanocyte stimulating hormone

Thyroid Gland• Secretes:• Thyroid Hormone

• Regulates metabolic rate of the entire body

• Important in development of the nervous system

• Calcitonin• Decreases bone reabsorption,

lowering serum calcium levels• PTH (parathyroid hormone)

• Increases serum calcium • Decreases serum phosphorus

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Thyroid Histology

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Thyroid Histology

• Follicular cells produce the colloid (contains precursors to thyroid hormone)

• Parafollicular cells secrete calcitonin

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Parathyroid Histology

Thymus

• Active in young individuals and plays a part in immunocompetency.

• Produces thymosin which causes maturation of T cells.

• T cells start out in bone marrow and migrate to thymus

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The T cells migrate to lymph nodes and spleen to carry out their functions.

Hormones secreted by heart• Heart: If blood volume is

elevated above normal, cardiac muscle cells in the heart was secrete natriuretic peptides.

• Act on the kidneys to promote the loss of sodium ions and water.

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Pancreas

• Secretes:• Insulin (alpha cells)

• Released in response to high blood sugar

• Increases cellular absorption of glucose

• Increases rate of lipogenesis and formation of glycogen in the liver

• Glucagon (beta cells)• Released in response to low blood

sugar• Elevates blood glucose levels by

promoting the breakdown of glycogen.

Somatostatin (delta cells)inhibit both Insulin and glucagon and may increase efficiency in digestion.

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Pancreas

•Acinar cells secrete digestive enzymes (exocrine)

•Islet cells secrete insulin (beta cells) and glucagon (alpha cells)

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Adrenal Glands

Adrenal Glands

• Secrete:• Glucocorticoids (Cortisone)

• Released in response to stress• Increases formation of glucose

from protein and fat breakdown

• Decreases inflammation• Aldosterone

• Increases blood volume by causing kidneys to retain sodium (where sodium goes water goes too) in exchange for potassium

• Increased blood volume will increase blood pressure

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Adrenal Glands

• Androgens• Are male sex hormones that

are produced in small quantities and converted to estrogens (female sex hormones) when they enter the blood

• Epinephrine & Norepinephrine• Fight or flight response• Increase heart rate, increase

skeletal muscle blood flow, decrease skin blood flow

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Adrenal Histology

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Adrenal Cortex

Zona Glomerulosa:Aldosterone

Zona Fasiculata:Glucocorticoids (Cortisone)

Zona Reticularis:Androgens

Hormones from the Kidneys

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• Erythropoietin• Stimulates RBC

production

• Calcitriol• Stimulates calcium and

phosphate absorption

• Stimulates calcium release from bone

• Inhibits PTH secretion

Gonads

• Ovaries in females produce estrogens

• Testes in males produce testosterone

• Both are stimulated by FSH from anterior pituitary

• Influenced by LH which increases the level of hormone produced

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Testis

• Produce testosterone responsible for secondary sex characteristics such as facial hair and expansion of larynx.

• Inhibin involved in negative feedback providing regulation of testosterone production

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Testes

• seminiferous tubules where the sperm are produced

• The interstitial areas contain interstitial (Leydig) cells where the testosterone is produced.

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Ovary

• Produce oocytes (eggs) and have an endocrine function by producing estrogen and progesterone

• Responsible for secondary sex characteristics in women.

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Endocrine physiology experiment

• LH stimulates the final maturation of the oocyte and causes ovulation.

• About 24-36 hours prior to ovulation there is a spike.

• Are there any students in the middle of your ovarian cycle like to volunteer to test for the presence of LH?

• If a woman has significant amounts of LH then the test strip produces a color (usually blue)

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Glucometer Exercise

• We need 4 volunteers to let us test their blood glucose levels at 30 minute intervals.

• Measure glucose level

• Drink soda or juice

• After 30 min test again

• 1 hour after drinking test again

• If levels haven’t gone down after test again after 2 hours

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Diabetes

• Type 1: Insulin Dependent Diabetes

• AKA: juvenile diabetes

• Caused by a lack of insulin

• Autoimmune disorder • Immune system destroys beta cells in the pancreas

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Diabetes

• Type 2: Non-Insulin Dependent

• Caused by an insensitivity of cells to insulin.

• Diabetes mellitus marked by hyperglycemia urine production (polyuria) thirst (polydipsia) eating (polyphagia)

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Diagnosing Diabetes Mellitus

• Normal blood glucose levels: 70-100 mg/dl• Diabetes mellitus:

• A fasting glucose level above 140 mg/dl on two separate occasions, or

• A blood sugar over 200 mg/dl 2 hours after oral glucose tolerance test with 75gm of glucose

• Impaired Glucose Tolerance (Pre-Diabetes)• A fasting glucose level between 100-126 mg/dl on two

separate occasions, or

• A blood sugar between 140-200 mg/dl 2 hours after oral glucose tolerance test with 75gm of glucose

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The End