Download Chapt 18 Other Systems - Spokane Public Schools

Chapter 18
Skin, Digestion, Excretion, Endocrine
Name ________________________
Life Science
Period ______
1. Homeostasis – When your organs work together to maintain a stable environment in the body
this is called homeostasis.
2. Integumentary System – The body system that consists of the skin, hair, and nails is called
the integumentary system. It protects all the tissues that lie beneath it. The skin is the first line
of defense against moisture and invading organisms like bacteria. Because skin covers the
entire body it is considered the largest organ of the body. (394)
3. Sweat Glands – Glands in the skin produce a salty fluid called sweat. These glands are called
sweat glands. Sweating helps regulate body temperature and excretes (gets rid) of wastes.
There are about 3 million sweat glands in the skin. Sweat contains water, salt and a waste
called urea. When sweat evaporates off the skin it cools the skin, as well as the blood
underneath. As stated before this helps us control body temperature. (394)
4. Epidermis & Dermis – The thin outer layer of the skin is called the epidermis. Hair follicles
are found in the epidermis of your skin, as well as muscle fibers that help the hairs stand
up. This helps regulate body temperature. The dermis layer lies underneath and is made from
connective tissue and protein fibers. The dermis contains the sweat glands and the nerve
endings. The dermis also contains the oil glands that produce oils to waterproof your skin.
Underneath the skin is a third subcutaneous fat layer that functions as insulation for the
body. (394)
Note: Small amounts of vitamin D are produced in the epidermis when it is exposed to
sunlight. This is important to our overall health. Also, there are many dead cells on the surface
of the epidermis. Many of these dead cells are continually rubbing off, causing the flaking and
renewal of your skin.
5. Melanin – Pigment cells in the epidermis produce a chemical called melanin that darkens
the skin (tan). Melanin protects the skin from the harmful ultraviolet light of the sun.
6. Endocrine System & Hormones – A group of ductless glands produce chemicals called
hormones and release them into the blood. These glands are called endocrine glands and they
make up the endocrine system. A hormone is a chemical that regulates body functions such as
cell processes, reproduction, or response to stress. (395)
7. Pituitary Gland – The master gland of the endocrine system is called the pituitary gland. It is
found at the base of the cerebrum (brain) and it produces hormones that control all the other
glands. It is the gland that also controls body growth. (395)
8. Adrenal Glands – The adrenal glands produce a hormone called epinephrine, which is
sometimes referred to as adrenaline. Epinephrine (adrenaline) prepares several of your organs
for stress. It is your “fight or flight” hormone. It increases heart rate, breathing rate, and the
release of additional blood sugar for extra energy. The adrenal glands also help control blood
sugar, salt and water balance, and cell metabolism. (395)
9. Thyroid & Parathyroid Gland – The thyroid gland in the throat makes a hormone which controls
how quickly energy is produced in the body. It does this by controlling the use of carbohydrates
(sugar) and, therefore, the level of cellular energy. The parathyroid glands in the throat control the
level of calcium in the blood.
10. Pancreas – The pancreas releases a hormone called insulin. Insulin helps regulate the
amount of dissolved sugar in the blood. Insulin works with the liver in the storage and release
of blood sugar (glucose). The pancreas also produces enzymes that help the digestive system
digest carbohydrates, proteins, and fats. (395)
11. Testes & Ovaries – Endocrine glands that produce sex cells, and hormones to regulate the
development of male and female traits, are called the testes (male, produce the hormone
testosterone), and the ovaries (female, produce hormones progesterone and estrogen). (395)
12. Feedback Control Systems – Systems that control the level of endocrine hormones in the
blood are called feedback control systems. Example: The pancreas releases insulin to control
high levels of blood sugar that enter from the digestive system. Insulin tells the liver to store
the extra blood sugar. This brings sugar levels back to normal and the pancreas then stops
producing insulin. When the pancreas does not produce insulin properly this causes a
malfunction to the feedback system called diabetes. (396)
13. Digestive System – A groups of organs that take in food, digest it so that it can be absorbed
into the blood, and then eliminate the solid waste that is left over is called the digestive
system. Digestion starts in the mouth. (chewing, saliva). It then moves down the esophagus
to the stomach. There gastric juice (acid) is added for digestion. It liquefies the food. Mucous
is also added to protect the stomach from the acid . Next food moves into the small intestine.
Here bile from the liver is added (to break up fat) and digestive enzymes from the pancreas
are added. The pancreas also adds bicarbonate to neutralize the stomach acid. Most of the
digestion and absorption of food into the blood occurs through the villi (finger-like
projections) in the small intestine. Water and undigested wastes then move into the large
intestine. The water and vitamins are absorbed there. Solid waste is then eliminated through
the rectum and out the anus. (397)
Note: The liver often produces extra bile. This is stored in an organ called the gall bladder.
14. Excretory System – A group of organs that excrete (remove) chemical wastes are called the
excretory system. The liver breaks down waste compounds into urea. Urea is a by-product
left over after protein reactions in the body. The kidneys and sweat glands in your skin
excrete the urea, water, & salts. The lungs excrete carbon dioxide, which is a waste product
left over after your cells break down sugar for energy. (397)
15. Testes – The male reproductive glands are called the testes. They produce sperm and the
hormone called testosterone. This regulates the development of male traits and the
production of sperm. (398)
16. Ovaries – The ovaries are the female glands of the reproductive system. They produce
female hormones called estrogen and progesterone. They regulate the development of female
traits, and the production and release of eggs. (398)