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There are 8 major endocrine glands 1. Pituitary gland 2. Thyroid gland 3. Thymus 4. Pancreas 5. Gonads (testis/ovaries) 6. Adrenal gland 7. Parathyroid gland 8. Pineal gland
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There are 8 major endocrine glands 1.Pituitary gland 2.Thyroid gland 3.Thymus 4.Pancreas 5.Gonads (testis/ovaries) 6.Adrenal gland 7.Parathyroid gland.

Jan 18, 2018

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Eunice Davidson

a. Nervous system: acts through electrical impulses and neurotransmitters To cause muscle contraction and glandular secretion Effect: short duration, measured in seconds, localized b. Endocrine system: acts through chemical messengers (hormones) Hormones influence growth, development, and metabolic activities Action is measured in minutes, hours, or weeks and is more generalized 3 Comparison of the Endocrine and Nervous Systems
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Page 1: There are 8 major endocrine glands 1.Pituitary gland 2.Thyroid gland 3.Thymus 4.Pancreas 5.Gonads (testis/ovaries) 6.Adrenal gland 7.Parathyroid gland.

There are 8 major endocrine glands1. Pituitary gland2. Thyroid gland3. Thymus4. Pancreas5. Gonads (testis/ovaries)6. Adrenal gland7. Parathyroid gland8. Pineal gland

Page 3: There are 8 major endocrine glands 1.Pituitary gland 2.Thyroid gland 3.Thymus 4.Pancreas 5.Gonads (testis/ovaries) 6.Adrenal gland 7.Parathyroid gland.

a. Nervous system: acts through electrical impulses and neurotransmitters To cause muscle

contraction and glandular secretion

Effect: short duration, measured in seconds, localized

b. Endocrine system: acts through chemical messengers (hormones) Hormones influence

growth, development, and metabolic activities

Action is measured in minutes, hours, or weeks and is more generalized

3

Comparison of the

Endocrine and Nervous Systems

Page 4: There are 8 major endocrine glands 1.Pituitary gland 2.Thyroid gland 3.Thymus 4.Pancreas 5.Gonads (testis/ovaries) 6.Adrenal gland 7.Parathyroid gland.

Critical ThinkingWhat is the difference in an exocrine

gland and an endocrine

gland?4

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Comparison of Exocrine andEndocrine Glands

1. Exocrine glands: have ducts that carry their secretory product to a surface Examples: sweat, sebaceous, and mammary

glands and glands that secrete digestive enzymes

2. Endocrine glands: secrete hormones directly into the into blood which carries them throughout body, they have no ducts

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Critical Thinking

What are hormones

made up of?

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Characteristics of Hormones Chemical classification

a. Proteins: make up most of the hormones in the body Difficult to administer orally

Inactivated by acid and pepsin in stomach Must be given by injection

(example: insulin)

b. Steroids: make up sex hormones and hormones secreted by the adrenal cortex May be given orally

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Characteristics of Hormones

The specific cells that respond to a given hormone have receptor sites for that hormone “Lock and key” mechanism If a hormone fits the

receptor site: there will be an effect

If a hormone and a receptor site do not match: there is no reaction

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Characteristics of Hormones Target tissue: a tissue

(cells) that responds to a particular hormone because it has receptor sites for that hormone May be localized in a

single gland or organ May be diffuse and

scattered throughout body Many areas are affected

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Endocrine Glands

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The Pituitary Gland The “Master Gland” Small-size of a pea Connected to

hypothalamus by a slender stalk: infundibulum

Two regionsa. Adenohypophysis:

anterior portion b. Neurohypophysis:

posterior portion

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Growth hormone (GH) Thyroid stimulating hormone (TSH) Adrenocorticotrophic hormone

(ATCH) Gonatrophic hormone Follicle stimulating hormone (FSH) Leutinizing hormone (LH) Prolactin hormone (PRH)

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Hormones of the Anterior Lobe (Adenohypophysis)

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1. Growth hormone (GH) Stimulates growth of bones, muscles, and other organs Influences height Too little GH in a child: pituitary dwarf of normal proportions

but small stature Excess of GH in a child: individual becomes exceptionally tall After ossification is complete (bone length no longer possible) Excess GH in adult causes enlargement in the diameter of the

bones: acromegaly bones of the hands and face become abnormally large

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Hormones of the Anterior Lobe (Adenohypophysis)

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2. Thyroid-stimulating hormone (TSH) Causes glandular cells of

thyroid to secrete thyroid hormone

Hypersecretion of TSH: thyroid gland enlarges and secretes too much thyroid hormone

Hyposecretion of TSH: results in atrophy of thyroid gland and too little thyroid hormone

HINT: this is not the same hormone that is produced by the thyroid gland!

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Hormones of the Anterior Lobe (Adenohypophysis)

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Thyroid Gland

Vascular organ: located in neck Consists of two lobes: one on each

side of tracheaThyroxine and Triiodothyronine Thyroid hormone consists of:

Thyroxine: 95% Triiodothyronine: 5%

Requires iodine for synthesis

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Thyroid Gland

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Iodine and the Thyroid Gland Iodine is required for synthesis of thyroid

hormone Iodine deficiency: thyroid cannot make

sufficient hormone and the thyroid gland increases in size in an attempt to produce more thyroid hormone.

Known as simple goiter or iodine deficiency goiter

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Thyroid Gland

Help to regulate the metabolism of carbohydrates, proteins, and lipids Increases rate at which cells release energy

from carbohydrates Enhances protein synthesis Necessary for normal growth and

development Stimulates nervous system

Do not have a single target organ Affect most of the cells in the body

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Hypothyroidism Deficiency of thyroid

hormonea. Cretinism: in a child

Mentally retarded dwarf with abnormal skeletal features

Tx: thyroid hormone therapyb. Myxedema: in an adult

Lethargy, weight gain, loss of hair, low metabolic rate

Thyroid hormone therapy: usually alleviates symptoms

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Hyperthyroidism Enlarged thyroid gland that

produces too much hormone Symptoms: High metabolic

rate, hyperactivity, insomnia, nervousness, irritability, chronic fatigue Exophthalmos: protruding eyes due to swelling in tissues behind the eyes

Treatment: removal or destruction of a portion of the thyroid gland

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Grave’s Disease

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Thyroid Gland

Calcitonin Secreted by thyroid gland Reduces the calcium level in the blood by:

Reducing rate at which calcium is released from bone

Increasing rate of calcium excretion by kidneys

Reducing calcium absorption in intestines

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Parathyroid Glands

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1. Four small masses of epithelial tissue located on the posterior surface of the thyroid glands

2. Secrete parathyroid hormone (PTH)

3. When blood calcium levels become low the PTH is released to increase levels

4. Vitamin D is necessary for dietary calcium to be absorbed in intestines

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Parathyroid PTH has opposite effect of calcitonin from

the thyroid gland Hypoparathyroidism: insufficient

secretion of PTH can cause increased nerve excitability due to low blood calcium levels

Hyperparathyroidism: excessive secretion of PTH Excess calcium in the blood:

May precipitate in abnormal locations Causes kidney stones

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3. Adrenocorticotropic hormone (ACTH) Reacts with receptor sites in

the cortex of adrenal gland To stimulate secretion of

cortical hormones (cortisol) Affects melanocytes in the

skin: increases pigmentation

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Hormones of the Anterior Lobe (Adenohypophysis)

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Adrenal Glands (Suprarenal)

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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1. Paired glands: one located near upper portion of each kidney

2. Divided into 2 regions:a. Adrenal cortex:

outer regionb. Adrenal medulla:

inner region

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Hormones of the Adrenal Cortex

1. Mineralocorticoids: Regulate the concentration of mineral electrolytes in the blood (Aldosterone)

2. Glucorticoids: Produce cortisol which helps to maintain glucose levels and counteract inflammation

3. Gonadocorticoids: Sex hormones Androgens: Males Estorgens: Females

4. Addison’s disease: hyposecretion5. Cushing’s syndrome: hypersecretion

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Hormones of the Adrenal Medulla

1. Epinephrine and Norepinephrine 2. Prepares body for strenuous activity

Sometimes called fight-or-flight hormones3. Effect on body: increased heart rate,

increased respiratory rate, increased blood supply to skeletal muscles

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4. Gonadotropic hormones React with receptor sites in the gonads

(ovaries and testes) To regulate development, growth, and function

of these organs Follicle-stimulating hormone (FSH)

Stimulates development of eggs in the ovaries and sperm in testes

Stimulates estrogen production in female

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Hormones of the Anterior Lobe (Adenohypophysis)

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Luteinizing hormone (LH) Female: causes ovulation, production and

secretion of female sex hormones1) Progesterone2) Estrogen Male: sometimes called interstitial cell-

stimulating hormone (ICSH) Stimulates interstitial cells of testes

1) To produce and secrete testosterone (male sex hormone)

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Hormones of the Anterior Lobe (Adenohypophysis)

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Without gonadotropins: Ovaries and testes decrease in size Ova and sperm are not produced Sex hormones are not secreted

Prolactin (PRL) Promotes development of glandular tissue in

female breast during pregnancy Stimulates milk production after birth of

infant

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Hormones of the Anterior Lobe (Adenohypophysis)

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Hormones of the Posterior Lobe (Neurohypophysis)

1. Antidiuretic hormone (ADH) Promotes reabsorption of water by the

kidney tubules Less water is lost as urine Conserves water for the body

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Hormones of the Posterior Lobe (Neurohypophysis)

b. When not enough ADH is produced there is excessive water loss in urine Large amounts of dilute urine: known as

diabetes insipidusc. Large amounts of ADH: cause blood vessels

to constrict Increases blood pressure ADH sometimes called vasopressin

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Hormones of the Posterior Lobe (Neurohypophysis)

2. Oxytocin Causes contraction of smooth muscle in wall

of uterus Stimulates ejection of milk from lactating

breast Pitocin: commercial preparation of this

hormone Used to induce labor

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Endocrine Glands andTheir Hormones

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Pancreas Islets of

Langerhans Long, soft organ Located posterior

to stomach Exocrine portion:

secretes digestive enzymes Carried through a

duct to duodenum

Endocrine portion: secretes hormones into blood

Alpha cells: secrete glucagon

Beta cells: secrete insulin

Glucagon & insulin regulate blood glucose levels

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Glucose GlucosePrimary energy source for nervous systemIf glucose levels too low nervous system does

not function properlyIf glucose levels too high kidneys produce

large volumes of urine that can lead to dehydration

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Pancreas

Glucagon Secreted by alpha cells in pancreatic islets

In response to low concentration of glucose in blood

Action: raises blood glucose levels Stimulates liver to break down glycogen into

glucose Prevents hypoglycemia from occurring

Between meals When glucose is being used rapidly

Given in response to severe hypoglycemic episodes in injection form

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Insulin

Insulin Secreted by beta cells in pancreatic islets

In response to a high concentration of glucose in blood

Action of insulin: decreases blood glucose level (opposite or antagonistic to glucagon) Promotes cellular uptake and use of glucose

for energy Stimulates liver and muscle to remove

glucose from blood Stores it as glycogen

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Pancreas When the liver has stored all the glycogen

possible: Glucose is converted to fat

Hypoactivity of insulin Insufficient insulin secretion Insufficient receptor sites on target cell

membranes Defective receptor sites that do not

recognize insulin Leads to diabetes mellitus (abnormally high

blood glucose)

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Gonads

Primary reproductive organs Testes: male secrete androgens Ovaries: female secrete estrogen and

progesterone

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.

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Gonads (Testes and Ovaries)

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Pineal Gland Extends from third ventricle of brain Synthesize melatonin

Secrete it directly into cerebrospinal fluid: takes it into blood

High levels: secreted at night Low levels: secreted during day Regulation of circadian rhythms Example: sleepiness/wakefulness cycle

Increased plasma melatonin levels (night): associated with sleepiness

Plays a role in hunger/satiety cycles, mood changes, and jet lag

Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc. 42