The Endocrine System (11.0)

Endocrine System: A collection of glands of an organism that secrete hormones to regulate your metabolism, chemical reactions, water balance, reproductive functioning, and your body’s growth and development.

Includes all endocrine cells and tissues of the body.

Endocrine System Nervous System

Maintains homeostasis

Uses hormones for regulation

Responds slowly with long lasting effects.

Maintains homeostasis

Uses nerve impulses for regulation

Responds quickly with short lasting effects.

Endocrine and Nervous System (11.4)

Endocrine vs. Exocrine (11.3)

Endocrine: secretes substances directly into the blood stream. Example: hormones

Exocrine: secretes substances into ducts onto epithelial surfaces Examples: sweat and saliva.

Key Terms (11.0/11.1)

Hormones – chemical substances released by endocrine glands into the blood stream.

Target Cells – cells with specific receptors for hormones to act on.

Glands – a group of cells that secrete a product.

Negative Feedback (11.8)

A self regulating system that works to achieve balance in the body. Ex. maintaining proper hormone levels or body

temperature.If hormone levels rise – negative feedback

will inhibit further secretion of that hormone.

If hormone levels fall – negative feedback will begin secreting more of that hormone.

Endocrine Glands (11.10)

PARATHYROID

The “Master” Gland (11.10)

The Endocrine system consists of several glands located in various parts of the body.Pituitary gland: a small stalk hanging from the

base of the brain, controlled by the hypothalamus known as the Master Gland. It’s primary function is to control other glands by

secreting hormones.

The Endocrine System (11.10)

The Pituitary Gland is divided into 2 areas, which differ structurally and functionally Each area has

separate types of hormone production.

Posterior Pituitary (11.10/12)

Oxytocin Stimulates uterus for contractions causes “let down” of milk from the breast.

Antidiuretic hormone (ADH) (vasopressin) causes the kidney to retain water.

Anterior Pituitary (11.10/12)

Thyroid Stimulating Hormone (TSH) stimulates the thyroid gland to release it’s hormones,

thus increasing metabolic rate Growth hormone (GH)

Stimulates bone and cell growth and reproduction

Causes an increase in glucose levels by reducing how much is taken in by tissues.

Robert Wadlow – 8’11.1“

Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to release

glucocorticoids which affect glucose metabolism. Follicle-stimulating hormone (FSH)

stimulates maturation of ovarian follicle and spermatogenesis

Luteinizing hormone (LH) Stimulates release of eggs from ovary, and

production of testosterone.

Anterior Pituitary (11.10/12)

Thyroid Gland (11.10/12)

Located in the anterior neck just below the larynyx and secretes: Thyroxine (T4) Triiodothyronine (T3)

When stimulated (by TSH or by cold), these are released into the circulatory system and the metabolic rate of carbs, lipids, and proteins.

Parathyroid gland (11.10/12)

small, pea-shaped glands, located in the neck near the thyroid

produce parathyroid hormone (PTH) – level of calcium in blood

Hypocalcemia can result if parathyroids are removed or destroyed.

Pancreas (11.10/12)

located in the folds of the duodenum has both endocrine

(hormones) and exocrine (digestive juices) functions

secretes several key digestive enzymes

Islets of Langerhans specialized tissues

in which the endocrine functions of the pancreas occurs

Include 3 types of cells that secrete an important hormone: alpha ( ) beta () delta ()

Pancreas (11.10/12)

Alpha () cells release glucagon, essential for controlling blood glucose levels.

When blood glucose levels fall, cells the amount of glucagon in the blood . Glucagon stimulates the liver to

breakdown glycogen and amino acids into glucose.

Pancreas (11.10/12)

Beta Cells () release insulin (antagonistic to glucagon).

Insulin the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level. Insulin is rapidly broken down by the liver and must be secreted constantly.

Adrenal Glands (11.10/12)

2 small glands that sit atop both kidneys.

Each has 2 divisions, each with different functions. Adrenal Medulla Adrenal Cortex

Adrenal Medulla secretes the hormones norepinephrine and epinephrine (closely related to the

sympathetic component of the autonomic nervous system).

Adrenal (11.10/12)

The Adrenal Cortex secretes steroid hormones: Aldosterone -

Mineralocorticoids Cortisol -

Glucocorticoids

Aldosterone: Works to regulate the

concentration of minerals in the blood.

Conserve sodium and excretes potassium

Cortisol: Works to regulate

glucose levels in the blood.

Released in response to stress or injury.

Ovaries (11.10/12)

Located in the abdominal cavity adjacent to the uterus.

Controlled by the LH and FSH from the anterior pituitary gland.When these hormones reach the ovary, two new

hormones may be stimulated.EstrogenProgesterone

Ovaries (11.10/12)

Estrogen Increases during the early menstrual cycle. Essential for secondary sex characteristics that

appear at puberty.Progesterone

Increases during ovulation (middle of menstrual cycle)

Essential for preparing the uterus for implantation of the egg.

*Other organs also produce these hormones in very small amounts – thus, men have these hormones also

Testis (11.10/12)

Located in the scrotum Also controlled by the LH and FSH hormones from the pituitary gland.

When these hormones reach the testis, a new hormone is stimulated. Testosterone

Essential in sperm production promotes male growth

and masculinization