Unit Eleven - The Endocrine System

I. Introduction

A. Overview: the endocrine system and nervous system work to control homeostasis within the body. The endocrine system operates at a much ____________ pace but the results are more widespread and longer lasting. The endocrine system releases chemicals called _______________ into the ___________________. Hormones enable the system to spread its control wherever blood goes and controls processes like growth, development, reproduction, blood pressure & metabolism.

B. Structure of endocrine system

1. Made up of ____________ throughout the body that make chemicals (hormones) which carry messages.

2. Uses the __________ __________ for the transport of these chemicals.

C. Function of endocrine system 1. Messages carried by hormones travel to different _______________

throughout the body looking for receptors to ____________ to. 2. Hormones will alter the metabolism of a target organ.

D. Definitions 1. Endocrinology (endo=within, crin=to secrete, ology=study of) the study of

the endocrine system. 2. Hormones: ________________ (hormone=set in motion) released into

the bloodstream by the glands. Hormones can be divided into three groups: amino acid, peptide and protein, and steroid (lipid based).

3. Endocrine glands: glands that release their hormones into the space

surrounding the producing cells. The hormones are then picked up by ________________ and spread throughout the body.

Diagram comparing exocrine and endocrine glands:

II. Overview of the Endocrine System:

Hypothalamus Pituitary gland Ovary (2) Testes (2) Thyroid gland Adrenal glands (2) Parathyroid gland Pancreas Thymus gland

III. Pituitary gland (hypophysis)

A. Located at the bottom of the brain and controlled by the _________________. Actually connected to the hypothalamus (a part of the brain) by a stalk called the _________________.

B. Only the size of a ___________ but controls many organs and body functions and

therefore is often called the “___________ ___________”.

C. Diagram of the pituitary gland:

D. There are two parts to the pituitary gland: the anterior lobe and the posterior

lobe.

1. Anterior lobe of the pituitary gland

a. Responsible for the release of _______ types of hormones. The release of these hormones is controlled by the ___________________. The hypothalamus will release chemical hormones that travel a short distance to the anterior pituitary causing the anterior pituitary to either release more or less of particular hormones.

B. The seven hormones released by the anterior pituitary will regulate different processes taking place in the body.

(1) Growth hormone (GH): affects cause cells of ___________ and

muscles to grow and divide. (2) Prolactin (PRL): (pro=for, lact=milk) after childbirth it stimulates the

____________ ______________ by the mother’s breasts.

(3) Melanocyte stimulating hormone (MSH): stimulates the production of

melanin in the skin to increase in _________________.

(4) Thyroid stimulating hormone (TSH): influences the growth and activity of the ____________ ____________.

(5) Adrenocorticotropic hormone (ACTH): controls the production and

secretion of hormones released by the adrenal gland.

(6) Follicle stimulating hormone (FSH): stimulates the development of ___________ in the ovaries and ___________ in the testes.

(7) Luteinizing hormone (LH) causes the ovary to actually

______________ the egg (ovulation) and prepares the uterus to accept the implantation of a fertilized egg. Stimulates the production of testosterone in the testes.

Diagram of the female ovulation cycle:

1. Posterior lobe of the pituitary gland

a. Not really an endocrine gland because it ___________ _________ produce the hormones it releases. The hormones are made by the cell bodies of neurons found in the ________________. After production, the hormones travel down the axons and are stored in the posterior pituitary until the time of their release. Because these neurons can secrete hormones they have the special name of _________________________ ____________.

b. Diagram of hypothalamus and posterior pituitary:

c. The two hormones released by the posterior pituitary will then regulate different processes taking place in the body.

(1) _________________ (OT) (oxy=swift, tokes=birth): released in

significant amounts only during childbirth and in nursing women. Causes ________________ of uterus during childbirth and milk ejection in a nursing mother.

(2) Antiduretic hormone (ADH) (anti=against, diuretic=passing of

urine): regulates fluid balance in the body by controlling the amount of ____________ produced.

IV. Thyroid gland

A. Description: the thyroid gland is located just below the thyroid cartilage (Adam’s apple) of the larynx (voice box) and in front of the trachea (windpipe). It consists of _______ lobes lateral to the trachea, which are connected by a narrow band of the gland called the ________________.

B. Diagram of the thyroid gland:

C. Structure of the thyroid gland

1. The thyroid gland is made up of an outer capsule and an inner area made up of secreting cells.

2. The thyroid produces ______ hormones:

a. Thyroxine (T4) and triiodothyronine (T3) both contain

______________ and increase the rate of metabolism. Thyroxine T4 has ______ iodine atoms, T3 has ______ iodine atoms.

b. Thyroxine (T4) and triiodothyronine (T3) are very important

hormones because they influence nearly every __________in the body. These hormones increase the rate at that glucose is broken down for energy, during ______________ _______________.

c. The third hormone produced by the thyroid gland is calcitonin (CT).

Its main function is to ______________ the amount of calcium and phosphate in the blood. It inhibits the breakdown of bone.

d. What might occur if the thyroid did not receive enough iodine to form proper thyroxine (T4) and triiodothyronine (T3)?

e. What might happen in older age when glands tend to become less productive?

V. Parathyroid glands

A. Description: ______ total glands; two located on the posterior side of each lobe of the thyroid gland. B. Structure of the parathyroid glands

1. Each gland has an outer capsule and an inner area made up of ________________ cells. 2. The glands produce only one hormone.

C. Function of the parathyroid glands

1. Produces parathyroid hormone (PTH) that is important in maintaining the calcium and phosphate levels in the blood. It ______________ the amount of calcium and lowers the level of phosphate. 2. Low levels of calcium in the blood will stimulate the release of the hormone.

3. Parathyroid hormone regulates the calcium level in the blood by:

A. Increases the breakdown of bone.

B. Increases the uptake of calcium from the digestive track. C. Diagram of the parathyroid glands:

VI. Adrenal glands

A. Description: there are ______ adrenal glands. Each one located on the top of a ___________. B. Structure of the adrenal glands

1. Each adrenal gland is divided into _______ parts the cortex and medulla. 2. The adrenal medulla produces _______ principle types of hormones.

C. Diagram of the adrenal gland:

D. Function of the adrenal glands

1. The functions of the adrenal glands can be divided into those of the adrenal cortex and the adrenal medulla.

A. Functions of the adrenal ____________

(1) Outer zone: responsible for the secretion of aldosterone. Basically, aldosterone acts upon the kidneys causing them to ___________ more sodium (Na+), which causes the retention of _____________. Water follows sodium by the process of osmosis, so if more sodium is retained by the body then body fluid levels would increase.

(2) Middle zone: responsible for the release of the glucocorticoids. The most

important of these are cortisol and cortisone. When the body comes under ______________ these hormones will increase the levels of _________ available by increasing the amount of glucose available to the cells of the body. This additional ATP will help the body combat stresses such as fright, temperature extremes and also inhibit allergic reactions and reduce inflammation.

(3) Inner zone: responsible for the production and release of gonadocorticoids

(adrenal sex hormones). These are _______________ (male sex hormones) and _______________(female sex hormones).

B. Functions of the adrenal ________________

(1) It secretes two hormones called ________________ (adrenaline) and _____________________ (noradrenaline). Both hormones function to act upon the body like the sympathetic nervous system does during the fight or flight response. Both hormones increase heart rate, raise blood pressure, accelerate breathing, dilates respiratory passages, increases glucose blood levels and other responses that will help the body deal with anything that might be causing stress.

VII. Pancreas

A. Description: the pancreas is located behind and below the stomach. It is a mixed gland because it produces enzymes for ______________, as well as two important hormones. B. Structure of the pancreas

1. Located in clusters are cells designated the _____________ ___

________________.

2. There are mainly two different types of cells: _________ cells and ___________ cells.

3. Each type of cell produces a different type of hormone, each causing an

opposite effect (but both helping to regulate the amount of sugar [glucose] in the blood).

C. Function of the islets of langerhans

4. The alpha cells produce ______________, a hormone responsible for _______________ the blood level of glucose. Basically, it does this by stimulating the liver to breakdown stores of glycogen (animal starch).

5. The beta cells produce _____________, a hormone responsible for

________________ the blood level of glucose. It does this by increasing the transport of glucose into cells to be used for energy.

VIII. Gonads

A. Description: there are two types of gonads. The female gonads, called the _____________ are paired and located in the pelvic cavity. The male gonads, called ______________ are paired and lie in a sac outside the pelvic cavity. B. The ovaries

1. Produce the hormones _____________ and ________________, which are responsible for the development of the female sex characteristics. Ovaries are stimulated to release their hormones in a cycle by the anterior gonadotropic hormones (FSH and LH).

C. The testes

1. Produce the hormone _________________, which is responsible for the development of adult male characteristics. Testosterone production is stimulated by luteinizing hormone (LH) from the anterior pituitary.