Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4e) – Chapter 30

Learning Outcomes cont.30.5 Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads.. 30

The Endocrine

System

Learning Outcomes

30.1 Define the term endocrine glands.

30.2 Describe the general functions of the

endocrine system

30.3 Define the term hormone.

30.4 Explain the difference in hormone control by

positive and negative feedback loops

Learning Outcomes (cont.)

30.5 Describe the locations of the hypothalamus,

pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands,

pancreas, thymus, and gonads

30.6 List the hormones released by the pituitary

gland and give the functions of each

30.7 List the hormones released by the thyroid

gland and parathyroid glands and give the functions of each

Learning Outcomes (cont.)

30.8 List the hormones released by the adrenal

glands and give the functions of each

30.9 List the names of the endocrine cells of the

pancreas, the hormones released by them, and the function of each hormone

30.10 List the hormones released by the pineal

body, thymus, and gonads, and give the functions of each

Learning Outcomes (cont.)

30.11 Name the hormones produced by the

kidneys and heart, listing which organ produces the hormone, and the hormone’s function

30.12 Describe stressors and their effect on the

body

30.13 Describe the causes, signs and symptoms,

and treatment of various endocrine disorders

target tissues

Introduction

• The endocrine system includes the organs of the

body that secrete hormones directly into body

fluids such as blood

– Regulates chemical reaction in cells and therefore

control functions of the organs, tissues, and other cells

• Endocrine glands

– Ductless

– Release hormones

• Directly into target tissues

• Into bloodstream to be carried to target tissues

• Hormones – chemicals secreted by a cell

that affect the functions of other cells

Hormones (cont.)

• Many are derived from steroids that easily

cross the cell membrane

• Examples of steroidal hormones

– Estrogen

– Progesterone

– Testosterone

Hormones (cont.)

• Nonsteroidal hormones

– Made of amino acids or

proteins and cannot cross the cell membrane easily

– Bind to receptors on the

surface of the cells

– G-protein – activated by

the hormone-receptor complex

• Activates enzymes inside cell

• Prostaglandins

– Local, or tissue, hormones – Derived from lipid

molecules – Do not travel in the bloodstream

– Target tissues are located close by

– Produced by organs such as

Feedback Loops

• Control hormone levels

• Negative feedback loop

– Hormone release stops in response to

decrease in stimulus

• Stimulus (eating) raises blood glucose levels

• Pancreas releases insulin in response to elevated blood glucose

• Blood glucose decreases as it is used by the body

or stored in the liver

• Insulin release stops as blood glucose levels normalize

Feedback Loops (cont.)

• Positive feedback loop

– As long as stimulus is present, action of

Apply Your Knowledge

Match the following:

_ Chemicals that effect cell function A Nonsteroidal hormone

_ Easily cross cell membranes B Steroidal hormone

_ Activated by hormone-receptor E Hormones

complex

_ Cannot cross cell membranes easily

_ Estrogen and cortisol

• Hormones

– Oxytocin

– Antidiuretic hormone (ADH)

• Hormones transported to the posterior

pituitary for storage

• Directs posterior pituitary to release

hormones

Glands

Pituitary Gland

• Controlled by the hypothalamus

• Located at the base of the brain

– Protected by a bony structure called the sella turcica

– The optic chiasm is located just above the pituitary

Anterior Lobe

Growth hormone Prolactin

Adrenocorticotropic (ACTH)

Thyroid-stimulating (TSH)

Follicle-stimulating Luteinizing

Stimulates milk production

Stimulates the adrenal cortex

to release its hormones

Stimulates the thyroid gland to release its hormones

Females: stimulates estrogen production and maturation of the ova Males: stimulates sperm production

Females: stimulates ovulation

and estrogen production

Males: stimulates testosterone production

Pituitary Gland (cont.)

Stimulates increase in size

of muscles and bones

Posterior Lobe

Posterior Lobe

Antidiuretic hormone (ADH)

Oxytocin

Stimulates the kidneys to conserve water

Females: causes contraction of the uterus and ejection of breast milk

Males: stimulates contraction of the prostate and vas deferens during sexual arousal

Pituitary Gland (cont.)

Apply Your Knowledge

Match the following:

_ Stored in posterior pituitary A Follicle-stimulating hormone

_ Produced by hypothalamus C Luteinizing hormone

_ Stimulates sperm production D ADH

T 3 T 4

Thyroid Gland

 Located below the larynx

 Divided into follicles that store some of the hormones

Major hormones

Stimulate protein synthesis and

increase cellular energy

production

Lowers blood calcium levels by activating osteoblasts that build new bone tissue

Glands

Parathyroid Glands

• Four located on the posterior surface of

the thyroid gland

• Secrete parathyroid hormone (PTH)

– Agonist to calcitonin by raising blood calcium

levels through activation of osteoclasts (dissolve bone)

• As bone dissolves, calcium levels in blood increase

Glands

Apply Your Knowledge

True or False:

Thyroid hormones stimulate protein synthesis.

The thyroid gland does not store hormones.

PTH activates osteoblasts.

Calcitonin increases cellular energy production.

The four parathyroid glands are located on the thyroid gland.

Calcitonin lowers blood calcium levels.

Thyroid follicles store some hormones.

Adrenal Glands

• Located on top of each kidney

• Divided into the adrenal medulla and

Adrenal Glands (cont.)

– Decreases inflammation

Apply Your Knowledge

Match the following:

Adrenal medulla A Cortisol

Sodium retention B Epinephrine

Decreases inflammation C Aldosterone

Sympathetic effects D Norepinephrine

Maintains blood pressure

Released during stress

– Endocrine – secretes

hormones into

Pancreas (cont.)

• Islets of Langerhans secrete hormones into

bloodstream

– Alpha cells secrete glucagon

– Beta cells secrete insulin

Blood glucose concentrations Protein synthesis

Blood glucose concentrations Protein synthesis

Apply Your Knowledge

What are the effects of insulin and glucagon?

ANSWER: Insulin decreases blood glucose

concentration and increases protein synthesis.

Glucagon does just the opposite It increases blood

glucose and decreases protein synthesis.

Yippee

!

Other Hormone-Producing Organs

• Pineal body

– Small gland

– Located between

cerebral hemispheres

– Melatonin

• Regulates circadian rhythms

• May play a role in onset of puberty

• Thymus gland

– Located between lungs

– Thymosin

• Promotes production of

T lymphocytes

Glands

Other Hormone-Producing Organs (cont.)

Glands

Back

Apply Your Knowledge

Match the following:

The Stress Response

• Stressor

– Any stimulus that produces stress– Types

• Physical factors

• Psychological factors

• Positive stimuli

The Stress Response (cont.)

• Physiologic response to stress caused by

hormone release

– General stress syndrome

• Increased heart rate, respiratory rate, and BP

• Increase in glucose and fatty acids in blood, which leads to weight loss

• Increase in cortisol if stress prolonged

– Decreased body repair – Susceptibility to illness

Apply Your Knowledge

Match the following:

Common Diseases and Disorders

Disease/Disorder Description

Acromegaly Too much growth hormone produced in adults;

enlargement of bones and thickened skin

Addison’s disease Adrenal gland fails to produce enough

corticosteroids

Cretinism Extreme form of hypothyroidism present prior to or

soon after birth

Cushing’s disease Hypercortisolism; over-production of cortisol

Diabetes insipidus Kidneys fail to reabsorb water, resulting in

excessive urination; hyposecretion of ADH

Common Diseases and Disorders (cont.)

Occurs during pregnancy; usually temporary

Dwarfism Too little growth hormone (somatotropin)

produced during childhood

Common Diseases and Disorders (cont.)

Disease/Disorder Description

Gigantism Too much growth hormone produced during

childhood

Goiter Enlargement of thyroid gland, causing swelling in

neck; deficiency of iodine in diet

Graves’ disease Hyperthyroidism; antibodies attach to thyroid

gland, causing it to produce too much thyroid hormone

Myxedema Thyroid gland produces inadequate amounts of

thyroid hormone; common in females over 50

Apply Your Knowledge

True or False:

_ Acromegaly develops as a result of too much growth hormone in a

child.

_ In diabetes insipidus, the kidneys fail to reabsorb water.

_ Too little growth hormone in childhood results in dwarfism.

_ Myxedema is the result of hyperthyroidism.

_ Addison’s disease is the result of too little corticosteroid.

_ Cushing’s disease is the result of too little ACTH.

_ Cretinism is an extreme form of hyperthyroidism present at birth.F

In Summary

30.1 Endocrine glands are ductless glands,

releasing hormones directly into the bloodstream and tissues

30.2 The organs of the endocrine system produce

hormones that regulate the chemical reactions within cells, controlling the functions of

organs, tissues, and other cells

30.3 Hormones are chemicals released by cells

that affect the functioning of other cells

In Summary (cont.)

30.4 In a negative feedback loop, a stimulus

causes a body reaction, which is detected by another area of the body, which stops the

reaction The rise in blood sugar causing the pancreas to release insulin to lower blood

sugar is an example In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the

suckling releases milk from the mother’s breast until the suckling stops

In Summary (cont.)

30.5 The hypothalamus, pituitary, and pineal

glands are located within the brain The thyroid and parathyroid glands are located in the neck The thymus is found in the

mediastinum The adrenal glands are located above each kidney, and the pancreas is

located behind the stomach In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac

In Summary (cont.)

30.6 The pituitary gland releases the following

hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT Each hormone’s specific function may be found in Table 30-1

30.7 The thyroid gland releases calcitonin, T3, and

T4 which are important in growth and protein synthesis The parathyroid releases PTH which balances the action of calcitonin

In Summary (cont.)

30.8 The adrenal medulla secretes epinephrine

and norepinephrine, which work with the sympathetic nervous system The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP

maintenance and cortisol, which decreases inflammation

30.9 The endocrine cells of the pancreas are

known as the Islets of Langerhans The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release

insulin

In Summary (cont.)

30.10The pineal body releases melatonin to

regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone

30.11The kidneys produce erythropoietin, affecting

the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP

In Summary (cont.)

30.12Stressors are defined as stimuli that produce

a stress response, a physiologic response to the stimulus that changes the body’s

functioning in some way

30.13 The diseases and disorders of the

endocrine system are as varied as the organs and hormone dysfunctions that cause them An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter

End of Chapter 30

I t s not st re ss

t hat kills us, it

is our re act ion

t o it

~ Hans S e lye