BIO 156 Chapter 13 Powerpoint

8/14/2019 BIO 156 Chapter 13 Powerpoint

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BIO 156

Chapter 13


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The Endocrine System


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The endocrine system produces hormonesthat are transported in the blood to distantsites where they influence many functions.

Hormones affect five vital aspects of ourlives:

HomeostasisGrowth and development

ReproductionEnergy production, storage, and use

Behavior

Principles of Endocrinology


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The Human

Endocrine System


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Target cells contain receptors for

specific hormones.

Hormones stimulate the synthesis and

release of other hormones or activatecellular processes.

Three types of hormones are produced in

the body:

Steroids

Proteins and polypeptides

Amines


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Hormone secretion is often controlled by

negative feedback mechanisms.

Most hormones undergo periodic

fluctuations in their release.

The chemical nature of a hormone

determines how it is transported in the

blood and how it acts on cells.


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The pituitary is a pea-sized gland suspended fromthe hypothalamus by a thin stalk.

It consists of two parts:

The anterior pituitaryThe posterior pituitary

The Pituitary and Hypothalamus


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Hormones of the Pituitary Gland


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Growth Hormone Secretion in Adults


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Acromegaly

Dwarfism Giantism


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Thyroid Stimulating

Hormone (TSH)

Main function isstimulating the

breakdown of glucose.


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Adrenocorticotropic Hormone

(ACTH)


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Prolactin Secretion


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The posterior pituitary

secretes two

hormones.1. Antidiuretic

hormone increases

the water

absorption in thekidney.

Oxytocin facilitates

birth and stimulatesmilk let-down.


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The thyroid gland locatedin the neckon either side of thetrachea near its junctionwith the larynx.

The thyroid producesthree hormones:

Thyroxine (T4)

TriiodothyronineCalcitonin

The Thyroid Gland


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Thyroxine and triiodothyronine accelerate the

breakdown of glucose and stimulate growth and

development.

Calcitonin decreases blood levels of calcium.


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The Parathyroid Glands

The parathyroid glands produce the hormone

parathomone (PTH). PTH increases blood calcium levels.


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The pancreas produces two hormones, insulin andglucagon, from the islets of Langerhans.

The Pancreas


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Insulin is a glucose-

storage hormone and isproduced by the betacells. Insulin causesblood sugar levels todecline rapidly after a

meal.

Glucagon increasesblood levels of glucose,

thus opposing theactions of insulin.


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Diabetes mellitus is a disease resulting

from an insulin deficiency or a decrease

in tissue sensitivity to insulin.

Diabetes has two principal forms:

Type I, or early-onset diabetes, may be

caused by an autoimmune reaction thatdestroys the beta cells of the pancreas. It can

be treated by insulin injections.

Type II, or late-onset diabetes, results from a

reduction in the number of insulin receptors ontarget cells. It is caused by obesity and genetic

factors and can often be treated successfully by

dietary management.


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The adrenal glandslie atop the kidneysand consist of aninner and outerregions, both of whichproduce hormones:

The adrenal medulla

The adrenal cortex

The Adrenal Glands


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The adrenal medulla produces stresshormones.

Adrenalin and noradrenalin stimulate heart rate

and breathing, elevate blood glucose levels,constrict blood vessels in the intestine, and dilate

blood vessels in the muscles.


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The adrenal cortex produces three

types of hormones with markedly

different functions. Glucocorticoids, mineralocorticoids, and

sex steroids.

Glucocorticoids affect carbohydrate metabolismand tend to raise blood glucose levels. The

principal glucocorticoid is cortisol.

The chief mineralocorticoid is aldosterone. It

acts on the kidneys, sweat glands, and salivary

glands causing sodium and water retention and

potassium excretion.

The sex steroids are identical to those

produced by the ovaries and testes


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Health and Homeostasis

The endocrine system is sensitive to

outside factors.

Stress can lead to an imbalance in theadrenal hormones.

Toxic pollutants can affect hormonal

balance.


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End of Chapter 13

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BIO 156 Chapter 13 Powerpoint