Human Endocrine System

Human Endocrine System

The endocrine system consists of ductless glands that produce hormones Hypothalamus, pituitary, pineal, thyroid,

parathyroid, thymus, adrenal, pancreas, ovary, testes

Hormones are chemical messengers that travel through the blood stream and affect activities throughout the body. Steroid hormones Nonsteroid hormones

Hormones Hormones are chemical messengers that

bind to target cells and affect cell activities Nonsteroid hormones are made from amino

acids and generally cannot pass through the cell membrane. These hormones bind to a receptor site on the outside of a cell in order to initiate chemical reactions inside the cell.

Steroid hormones are produced from the lipid, cholesterol and are able to pass through cell membranes and bind to receptor proteins.

Steroid hormones – can go through cell membrane to reach receptors inside the cell

Nonsteroid hormones – cannot go through cell membrane, must activate proteins in the cell membrane

Hormones have specific shapes that fit receptors or the surface of the target organ or structure they are going to influence

Bind with cell receptors

If incorrect receptor the particular hormone has no effect

Pons

Pituitary gland

Hypothalamus

Cerebrum

Medulla oblongata Spinal cord

Cerebellum

Pineal gland

Thalamus

Section 35-3

The BrainPituitary gland biology AnimationEndocrine Glands biology Animation

HypothalamusThe hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland.

Pituitary glandThe pituitary gland produces hormones that regulate many of the other endocrine glands.Parathyroid glandsThese four glands release parathyroid hormone, which regulate the level of calcium in the blood.ThymusDuring childhood, the thymus releases thymosin, which stimulates Tcell development.Adrenal glandsThe adrenal glands release epinephrine and nonepinephrine, which help the body deal with stress.

Pineal glandThe pineal gland releases melatonin, which is involved in rhythmic activities, such as daily sleep-wake cycles.

ThyroidThe thyroid produces thyroxine, which regulates metabolism.

PancreasThe pancreas produces insulin and glucagon, which regulate the level of glucose in the blood.OvaryThe ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg.

Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics

Section 39-1 The Endocrine Glands

Glands I

Hypothalamus – coordinates activities of the nervous and endocrine systems and produces hormones to regulate the pituitary gland

Pituitary – produces hormones that direct the activities of other endocrine glands

Pineal – releases melatonin which is involved in rhythmic or cyclic activities

Thyroid – produces hormones that regulate metabolism and development

Parathyroid – helps maintain appropriate calcium levels

Glands II Thymus – involved with immune development during childhood Adrenal – regulates the body’s stress response (epinephrine,

norepinephrine, cortisol, aldosterone) Pancreas – controls glucose levels in the blood (insulin,

glucagon)

Ovary – secretes estrogen and progesterone to regulate reproduction

Testes – produces testosterone to control formation of sperm and sexual behavior

Negative Feedback

The level of one hormone in the blood inhibits or stimulates the production of another hormone or substance

Homeostasis biology Animation

CONTROL OF THE ENDOCRINE SYSTEMCONTROL OF THE ENDOCRINE SYSTEM

REGULATED BY FEEDBACK MECHANISMSFEEDBACK MECHANISMS EX: HEATING SYSTEMS

ROOM COOLS DOWN

ROOM WARMS

UP

FURNACE KICKS

OFF

FURNACE KICKS

ON

Negative Feedback

The release of hormones is controlled through a negative feedback system

Negative feedback systems are control mechanisms that operate by inhibiting a process or activity that originally led to starting the process or activity For example, as glucose levels in the body

increase, sensors in the pancreas signal the release of the hormone insulin

Insulin promotes the entry of glucose into cells, lowering glucose levels

As the glucose levels in the blood decrease, the pancreas stops secreting insulin.

Beta cells release insulin into the blood

Body cells absorb glucose

Blood glucose level decreases

Homeostasis: Normal blood glucose level

Blood glucose level decreases

Alpha cells release glucagon into blood

Liver converts glycogen to glucose

Blood glucose level increases

Blood glucose level increases

Liver converts glycogen to glucose

 Actions of Insulin and GlucagonSection 39-2

Disorders Goiter

Enlargement of the thyroid gland due to the inability to manufacture thyroxin (hypothyroidism)

Grave’s Disease Hyperthyroidism- over secretion of thyroxin

Diabetes Insulin deficiency which results in elevated

blood sugar level

Symptoms of Diabetes Excessive thirst Frequent urination Extreme hunger Unexplained weight loss Glucose in urine Fatigue Vision problems Numbness tingling in extremities High infection rate

regulates

Concept MapSection 39-2

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

GrowthWater

balanceReproduction Metabolism

Calciumand glucose

levels

Responseto stress

The Endocrine System

Pituitary

Ovaries

Testes Thyroid Pancreas Adrenals

Parathyroids