ch9apptendocrinesystem

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PowerPointLecture Slide Presentation

by Patty Bostwick-Taylor,

Florence-Darlington Technical College

Copyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART B9

The Endocrine

System


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The Endocrine System

Second-messenger system of the body

Uses chemical messengers (hormones) that are

released into the blood

Hormones control several major processes

Reproduction

Growth and development

Mobilization of body defenses

Maintenance of much of homeostasis

Regulation of metabolism


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Hormone Overview

Hormones are produced by specialized cells

Cells secrete hormones into extracellular fluids

Blood transfers hormones to target sites

These hormones regulate the activity of other

cells


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Major Endocrine Organs

Pituitary gland

Thyroid gland

Parathyroid glands

Adrenal glands

Pineal gland

Thymus gland

Pancreas

Gonads (Ovaries and Testes)

Hypothalamus


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Location of Major Endrocrine Organs

Figure 9.3


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Pituitary Gland

Size of a pea

Hangs by a stalk from the hypothalamus in the

brain

Protected by the sphenoid bone

Has two functional lobes

Anterior pituitaryglandular tissue

Posterior pituitarynervous tissue

Often called the master endocrine gland


7/38Copyright 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Hormones of the Anterior Pituitary

Six anterior pituitary hormones

Two affect non-endocrine targets

Growth hormone

Prolactin

Four stimulate other endocrine glands (tropic

hormones)

Thyroid-stimulating hormone (thyrotropic

hormone)

Adrenocorticotropic hormone

Two gonadotropic hormones




Figure 9.4




Growth hormone

General metabolic hormone

Major effects are directed to growth of skeletal

muscles and long bones

Plays a role in determining final body size

Causes amino acids to be built into proteins

Causes fats to be broken down for a source of

energy




Growth hormone (GH) disorders

Pituitary dwarfism results from hyposecretion

of GH during childhood

Gigantism results from hypersecretion of GH

during childhood Acromegaly results from hypersecretion of GH

during adulthood




Gigantism

Figure 9.5a




Dwarfism

Figure 9.5b




Prolactin (PRL)

Stimulates and maintains milk production

following childbirth

Function in males is unknown

Adrenocorticotropic hormone (ACTH)

Regulates endocrine activity of the adrenal

cortex

Thyroid-stimulating hormone (TSH)

Influences growth and activity of the thyroid

gland




Gonadotropic hormones

Regulate hormonal activity of the gonads

Follicle-stimulating hormone (FSH)

Stimulates follicle development in

ovaries Stimulates sperm development in

testes

Luteinizing hormone (LH)

Triggers ovulation of an egg in females

Stimulates testosterone production inmales



PituitaryHypothalamus Relationship

Hormonal release is regulated by releasing and

inhibiting hormones produced by thehypothalamus

Hypothalamus produces two hormones

These hormones are transported toneurosecretory cells of the posterior pituitary

Oxytocin

Antidiuretic hormone

The posterior pituitary is not strictly an endocrine

gland, but does release hormones



Hormones of the Posterior Pituitary

Oxytocin

Stimulates contractions of the uterus during

labor, sexual relations, and breastfeeding

Causes milk ejection in a nursing woman




Antidiuretic hormone (ADH)

Inhibits urine production by promoting water

reabsorption by the kidneys

In large amounts, causes vasoconstriction

leading to increased blood pressure Also known as vasopressin




Figure 9.6



Thyroid Gland

Found at the base of the throat

Consists of two lobes and a connecting isthmus

Produces two hormones

Thyroid hormone

Calcitonin



Thyroid Gland

Figure 9.7a


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Thyroid Gland

Thyroid hormone

Major metabolic hormone

Composed of two active iodine-containing

hormones

Thyroxine (T4)

Triiodothyronine (T3)


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Thyroid Gland

Figure 9.8


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Thyroid Gland

Thyroid hormone disorders (continued)

Myxedema

Caused by hypothyroidism in adults

Results in physical and mental

slugishness Graves disease

Caused by hyperthyroidism

Results in increased metabolism, heatintolerance, rapid heartbeat, weight loss,and exophthalmos


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Thyroid Gland

Figure 9.9


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Thyroid Gland

Calcitonin

Decreases blood calcium levels by causing its

deposition on bone


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Parathyroid Glands

Tiny masses on the posterior of the thyroid

Secrete parathyroid hormone (PTH)

Stimulate osteoclasts to remove calcium from

bone

Stimulate the kidneys and intestine to absorbmore calcium

Raise calcium levels in the blood


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Pancreatic Islets

The pancreas is a mixed gland and has both

endocrine (secrete directly into blood) andexocrine (secrete via duct) functions

The pancreatic islets produce hormones

Insulinallows glucose to cross plasmamembranes into cells from beta cells

Glucagonallows glucose to enter the blood

from alpha cells

These hormones are antagonists that maintainblood sugar homeostasis


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Pancreatic Islets

Figure 9.14ab


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Figure 9.15

Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood

Elevatedblood sugarlevels

Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)

Rising blood

glucose levelsreturn blood sugarto homeostatic setpoint; stimulus forglucagon releasediminishes

Blood glucoselevels declineto set point;stimulus forinsulin releasediminishes

Stimulus:

declining bloodglucose levels(e.g., afterskipping a meal)

Low bloodsugar levels

Glucagon-releasingcells of pancreasactivated;release glucagoninto blood; targetis the liver

Uptake of glucosefrom blood is en-hanced in mostbody cells

Liver breaks downglycogen stores andreleases glucose tothe blood

Liver takes upglucose and storesit as glycogen

Homeostasis: Normal blood glucose

levels (90 mg/100ml)


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Pineal Gland

Found on the third ventricle of the brain

Secretes melatonin

Helps establish the bodys wake and sleep

cycles

Believed to coordinate the hormones offertility in humans


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Thymus Gland

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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Gonads Ovaries

Produce two groups of steroid hormone

Estrogens (Stimulate the development of

secondary female characteristics)

Progesterone (Helps in the implantation of an

embryo in the uterus; Helps prepare breasts

for lactation)

Testes

Produce androgens, such as testosterone(Responsible for adult male secondary sex

characteristics; Required for sperm cell

production)


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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 estrogenare common

Growth hormone production declines with age

Many endocrine glands decrease output with

age


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Major Endocrine Glands and Hormones

Table 9.1 (1 of 4)


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Table 9.1 (2 of 4)


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Table 9.1 (3 of 4)



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Table 9.1 (4 of 4)


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