the endocrine system - psd202.org

ELAINE N. MARIEB

EIGHTH EDITION

9

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University

ESSENTIALS

OF HUMAN

ANATOMY

& PHYSIOLOGY

PART B

The Endocrine System

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Thyroid Gland

▪ Found at the base of the throat

▪ Consists of two lobes and a connecting

isthmus

▪ Produces two hormones

▪ Thyroid hormone

▪ Calcitonin

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Thyroid Gland

Figure 9.6

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Thyroid Hormone

▪ Major metabolic hormone

▪ Composed of two active iodine-containing

hormones

▪ Thyroxine (T4) – secreted by thyroid

follicles

▪ Triiodothyronine (T3) – conversion of T4

at target tissues

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Calcitonin (Thyroid Gland)

▪ Decreases blood

calcium levels by

causing its

deposition on bone

▪ Antagonistic to

parathyroid hormone

▪ Produced by C

(parafollicular) cells

Figure 9.9

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Parathyroid Glands

▪ Tiny masses on the posterior of the thyroid

▪ Secrete parathyroid hormone

▪ Stimulate osteoclasts to remove calcium

from bone

▪ Stimulate the kidneys and intestine to

absorb more calcium

▪ Raise calcium levels in the blood

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Adrenal Glands

▪ Two glands

▪ Cortex – outer glandular region in three

layers

▪ Medulla – inner neural tissue region

▪ Sits on top of the kidneys

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Hormones of the Adrenal Cortex

▪ Mineralocorticoids (mainly aldosterone)

▪ Produced by outer adrenal cortex

▪ Regulate mineral, water, and electrolytes in blood to keep them in balance

▪ Cause the kidney tubules to reabsorb sodium and water

▪ Production stimulated by the enzyme, renin(which is made by the kidneys) when blood pressure is low, stimulating the production of aldosterone to reabsorb sodium and water in an effort to raise blood pressure

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Hormones of the Adrenal Cortex

Figure 9.10

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Hormones of the Adrenal Cortex

▪ Glucocorticoids (including cortisone and cortisol)

▪ Produced in the middle layer of the adrenal

cortex

▪ Help resist long-term stressors

▪ Suppress inflammation/decrease edema

▪ Increase blood glucose levels

▪ Released in response to increased blood levels of

ACTH

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Hormones of the Adrenal Cortex

Figure 9.10

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Hormones of the Adrenal Cortex

▪ Sex hormones

▪ Produced in the inner layer of the adrenal

cortex

▪ Androgens (male) and some estrogen

(female)

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Hormones of the Adrenal Cortex

Figure 9.10

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Hormones of the Adrenal Medulla

▪ Produces two similar hormones (Catecholamines)

▪ Epinephrine

▪ Norepinephrine

▪ Prepare the body to deal with short-term stress

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Figure 9.12

Roles of the Hypothalamus and Adrenal

Glands in the Stress Response

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Pancreatic Islets

▪ The pancreas is a mixed gland

▪ The beta cells in the islets of the pancreas

produce hormones

▪ Insulin – allows glucose to cross plasma

membranes into cells from beta cells

▪ Glucagon – allows glucose to enter the

blood from alpha cells

▪ These hormones are antagonists that

maintain blood sugar homeostasis

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Pancreatic Islets

Figure 9.13

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Pancreatic Hormones and Blood Sugar

Figure 9.14

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Pineal Gland

▪ Found on the third ventricle of the brain

▪ Secretes melatonin

▪ Helps establish the body’s wake and sleep

cycles

▪ May have other as-yet-unsubstantiated

functions

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Thymus

▪ Located posterior to the sternum

▪ Largest in infants and children

▪ Produces thymosin

▪ Matures some types of white blood cells

▪ Important in developing the immune

system

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Hormones of the Ovaries

▪ Estrogens

▪ Development of secondary female characteristics

▪ Prepares the uterus to receive a fertilized egg

▪ Stimulates menstruation

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Hormones of the Ovaries (Corpus

Luteum)

▪ Progesterone

▪ Helps bring about the menstrual cycle

▪ Helps maintain pregnancy

▪ Prepares breasts for milk production

▪ Small amount of estrogen made by the corpus

luteum

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Hormones of the Testes (Androgens)

▪ Interstitial cells make the hormones

▪ Androgens – male hormones

▪ Testosterone is the most important androgen

▪ Adult male secondary sex characteristics

▪ Growth and maturation of male reproductive system

▪ Required for sperm cell production

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Other Hormone-Producing Tissues and

Organs

▪ Parts of the small intestine

▪ Parts of the stomach

▪ Kidneys (renin)

▪ Heart

▪ Many other areas have scattered endocrine

cells

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Endocrine Function of the Placenta

▪ Produces hormones that maintain the

pregnancy

▪ Human chorionic gonadotropin (hCG)

▪ Estrogen

▪ Progesterone

▪ Relaxin – relaxes mother’s pelvic ligaments

and pubic symphysis

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Developmental Aspects of the Endocrine

System▪ Most endocrine organs operate smoothly until old

age

▪ Menopause is brought about by lack of

efficiency of the ovaries

▪ Problems associated with reduced estrogen are

common

▪ Growth hormone production declines with age

▪ Many endocrine glands decrease output with age

Growth Hormone

Hypersecretion- Gigantismlong bones grow abnormally long

during childhood and adolescence

Hyposecretion-Dwarfism• Slow bone growth

• Epiphyseal plates close

before normal height is

reached

• Treatment – Growth

Hormone therapy

• Hypersecretion of Growth

Hormone

• Happens after normal growth

has stopped

• Bones of hands, feet, cheeks,

and jaw thicken

• Soft tissues grow abnormally

Acromegaly

Addison’s Disease

• Hyposecretion of Adrenal Cortex hormones

• Bronze color to skin (hyperpigmentation)

• Symptoms include:• Severe fatigue

•Unintentional weight loss

•Gastrointestinal problems, such

as nausea, vomiting and abdominal pain

•Lightheadedness or fainting

• Salt cravings

•Muscle or joint pains

Cushing’s Syndrome

Hypersecretion of Adrenal

Cortex hormones or

administration of homrones•Weight gain

•Obesity

•“Moon face”

•Buffalo hump)

•Stretch marks

•Bruise easily

Goiter• Enlarged thyroid gland caused by iodine deficiency

• Iodine Deficiency causes thyroid to make nonfunctional thyroid hormones

• TSH keeps “calling for” more thyroxine

• Thyroid is overstimulated and enlarges, but still doesn’t make functional thyroid hormones

Graves DiseaseAutoimmune disorder that causes growth of thyroid and hypersecretion of thyroid hormones, with no negative feedback

• Enlarged thyroid (2-3x larger)

• Bulging eyes

• Increased metabolic rate, heat intolerance, increased sweating, weight loss, insomnia, tremor, and nervousness.

• Treatment

• surgical removal of part of thyroid gland

• radioisotopes to destroy some of the thyroid

• anti-thyroid drugs to block synthesis of the hormones.

CretinismHyposecretion of T3/T4 during fetal life and infancy.

•Dwarfism and mental retardation

•Testing newborns can prevent the disease

•Treatment - oral thyroid therapy.

Myxedema

Thyroid hyposecretion during adulthood

•Edema, slow heart rate, low body temp, dry hair and

skin, muscular weakness, lethargy, weight gain

•Treatment - Oral thyroid hormones reduce symptoms

Parathyroid Hormone too Low• Hyposecretion of parathyroid hormone results in low calcium levels

• If blood calcium levels fall too low, neurons become extremely irritable and overactive.

• Neurons deliver impulses to muscles so fast that they go into tetany and spasm

• Can lead to death

• Symptoms : polyuria, polydypsia, polyphagia, acidosis.

• Two types:Type I

• absolute insulin deficiency, with insulin administration.

• Patients < 20 years;

• autoimmune disorder where β-cells are destroyed;

• Hyperglycemia results.

• Cells can't use glucose so fat is broken down, releasing ketone bodies, causing ketoacidosis, lowering blood pH, and causing death.

• Complications include Atherosclerosis, CV disease, IHD, PVD, gangrene, blindness due to cataracts (lens) and retinal vascular disease; renal failure.

• Treatments• artificial pancreas that detects fall in glucose levels and automatically releases

insulin;

• transplant of pancreas or Beta cells.

Diabetes Mellitus

Diabetes Mellitus

•Symptoms : polyuria, polydypsia, polyphagia, acidosis.

•Two types:

Type II Diabetes• patients > 40 years, • overweight, • hypertension,• Problem is usually with receptors on target cells; • Controlled by diet, exercise, and weight loss;

Diabetes Mellitus

ADH Imbalances

•Diabetes Insipidus

•Hyposecretion of ADH from posterior pituitary•Diuresis, dehydration, thirst

• Treatment - ADH in nasal spray