Chapter: The Human Body Table of Contents Section 1: Body Systems Section 2: Human ReproductionHuman...

Chapter: The Human Body

Table of ContentsTable of Contents

Section 1: Body Systems

Section 2: Human Reproduction

• Your body has a framework, your bones.

• Bones are covered by skin and muscle.

Structure and Movement

Body SystemsBody Systems

11

• All the bones in your body make up your skeletal system.

• Your skeletal system gives shape and support to your body.

The Skeletal System11

• Without bones, your body would be a formless mass of tissue.

• Bones also protect your internal organs.


• Bones are made of living cells.

• Like all the other cells in your body they need nutrients and use energy.

The Skeletal System11

• Bones are hard because of the calcium and phosphorus that are deposited in them.


• Your bones can move.

• The place where two or more bones come together is called a joint.

Joints11

• Muscles can move your bones by moving your joints.


• The largest human body organ is the skin.

• Skin forms a protective covering for your body.

The Skin11

• Unbroken skin can protect your body fromdisease-causing organisms.


The Skin11

• The pigments, or coloring, in your skin protects it from damage by ultraviolet light.

• This pigment is called melanin (MEH luh nun).


• Skin is a sense organ.

• Because of special nerve cells in the skin, you can sense heat or cold, and you can feel the sharp prick of a pin or the smoothness of a polished rock.

The Skin11Body SystemsBody Systems

• Skin helps control your body temperature.

• Sweat glands in your skin produce sweat that help cool your body.

The Skin11

• As sweat evaporates from your skin, heat is lost and your skin is cooled.


• Skin helps provide a nutrient for your body.

• Vitamin D, which is important for good health, formed in your skin when your skin receives ultraviolet light from the Sun.

The Skin11Body SystemsBody Systems

• A muscle is an organ that can relax, contract, and provide force to move you and your body parts.

• Even when you are sitting in a chair, your muscles are still working.

The Muscular System11

• Some muscles are always moving, such as the muscles that help you breathe and your heart muscles.


• Your body has some muscles that you can choose to move, called voluntary muscles.

• Other muscles, such as your heart and muscles in your digestive organs, are not controlled consciously.


• These are called involuntary muscles.


• To lift a weight, one muscle in your arm contracts while another relaxes.


Click image to view movie.


• Food enters your body's digestive system though your mouth.

Digestion and Excretion11

• As food moves through each organ of your digestive system, some of it is broken down into smaller molecules.



• These smaller molecules are absorbed from your digestive system and enter your blood.


• From the blood, these molecules move into your cells where the food molecules are needed.


• Undigested food is eliminated from your digestive system.


• Your digestive system is designed to take in food and break it down so that the nutrients can be absorbed by your body.

Organs of the Digestive System11Body SystemsBody Systems

• Nutrients (NEW tree unts) are the substances in food that provide for cell development, growth, and repair.

Nutrients11

• There are six kinds of nutrients that are available in food—proteins, carbohydrates (kar boh HI drayts), lipids, vitamins, minerals, and water.


• Proteins, carbohydrates, lipids, and vitamins are called organic nutrients.

Nutrients11

• Minerals and water are called inorganic nutrients.


• Your body uses vitamins for many important functions, such as growth, regulating body functions, and preventing some diseases.

Inorganic Nutrients11

• Vitamins are classified into two groups.


• Vitamins that dissolve easily in water are called water-soluble vitamins.


• They are not stored in your body.

• Fat-soluble vitamins dissolve only in fat and can be stored by your body.


• Your body uses minerals to control many chemical reactions.


• Calcium and phosphorus are two minerals that are used in the largest amounts by your body.

• One of their uses is in making and maintaining bone.


• You cannot live for more than a few days without water.


• Most of the other nutrients can’t be used by your body unless they are carried in water.

• Your cells need water to carry out the chemical reactions that are needed for you to live.


• Wastes produced by cells are removed from the blood through the urinary system.

The Urinary System11

• Your kidneys are the main organs of the urinary system.


• The kidneys remove excess water, salts, and other wastes from your blood.

The Urinary System11

• The bladder holds the urine until it is excreted from the body.


• The wastewater, called urine, then passesthrough tubes called ureters (YOO ruh turz) into the bladder.


• Your respiratory system removes waste gases, such as carbon dioxide and water vapor.

Other Organs of the Excretory System

11

• Salt and some other wastes are lost through the skin.


• Besides food and water, you need a constant supply of air.

Respiration and Circulation

Body SystemBody System

11

• Your body’s cells need oxygen, a gas that is found in the air.

• Your body’s cells produce carbon dioxide, a waste gas, that must be removed from the body.

• The respiratory system is made up of structures and organs that help move oxygen into the body and waste gases out of the body.

The Respiratory System11Body SystemsBody Systems

• When you breathe in, or inhale, air enters through the mouth or nose and then travels though a series of passageways—the pharynx (FER ingks), larynx (LER ingks), and trachea (TRAY kee uh). Bronchi (BRAHN ki) then carry air into your lungs.

The Respiratory System11

• In the lungs, bronchi branch into smaller and smaller tubes.


• The smallest tubes are called bronchioles (BRAHN kee ohlz).

The Respiratory System11

• Grapelike clusters of air sacs called alveoli (al VEE uh li) (singular, alveolus) are at the end of each bronchiole.

• Microscopic blood vessels called capillaries (KAP uh ler eez) surround each alveolus.


• Oxygen leaves alveolus and enters capillaries.The Respiratory System11

• Then oxygen is carried to every cell in your body through the bloodstream.

• Waste gases leave capillaries and enter alveoli.

• These gases are removed from your body when you exhale.



• Your circulatory system is made up of your heart, blood vessels, and blood.

The Circulatory System11Body SystemsBody Systems

• Your heart is the pump of your circulatory system that pumps blood to all the cells of the body.

The Circulatory System11

• Then blood moves back to the heart.

• Blood moves throughout your body in a network of blood vessels.



• Without blood, your body's cells would die because they could not get the oxygen and nutrients necessary for life.

Blood11

• Your blood is tissue that is made up of liquid and cells.


Blood11

• Oxygen is carried by red blood cells.

• Your blood also has cells, called white blood cells, that fight infections and heal wounds.


• When you cut yourself, special chemicals and cell fragments, called platelets (PLAYT luts), in blood form a clot.

Blood11

• This clot plugs the wounded blood vessels and acts somewhat like a bandage.

• Blood clots stop bleeding in minor wounds.


• Humans can donate blood to one another because of the similarities in human blood.

Blood11

• However, the blood must be typed to be sure that the right kind is given.

• If the wrong type is given, the person may die.


• People can inherit one of four major blood types: A, B, AB, or O.

Blood Types11

• Each blood type is different because of chemical identification tags, or antigens (AN tih junz), on red blood cells.


• Each blood type also has specific antibodies in the liquid part of the blood.

Blood Types11

• Because of these antibodies, certain blood types cannot be mixed.

• Only certain blood types can be given to certain other blood types in blood transfusions.


• Rh factor is another identification tag of red blood cells.

Blood Types11

• If the Rh factor is present on the red blood cells, the person has Rh-positive (Rh +) blood. • If the factor is absent, the person has Rh-negative (Rh –) blood.

• An Rh – person cannot receive Rh + blood in a blood transfusion.


• Between cells, there is tissue fluid.

The Lymphatic System11

• This tissue fluid is collected and returned to the blood through the lymphatic (lihm FA thik) system.


• The lymphatic system does not have a heartlike organ that pumps the fluid.


• The movement of fluid depends on the contraction of muscles in the walls of the lymph vessel and skeletal muscles.


• Lymphatic vessels also contain cells called lymphocytes.


• Lymphocytes help defend your body against disease-causing organisms.


• First-line defenses are your skin and your respiratory, digestive, and circulatory system.

Immunity11

• Most disease-causing organisms cannot get through unbroken skin.


• A second-line of defense, called specific immunity, attacks disease organisms that get past these first-line defenses.

Immunity11

• In specific immunity, your body makes antibodies that can destroy disease-causing organisms.


• You also can develop antibodies to fight off diseases when you receive vaccinations.

Immunity11

• Vaccinations can prevent diseases.

• Your body formed antibodies against these diseases after you received the vaccinations.


• Your nervous system and endocrine system are the control systems of the body.

Control and Coordination11

• They coordinate your body functions.


• Your brain, spinal cord, nerves, and nerve receptors make up your nervous system.

The Nervous System11

• The basic unit of the nervous system is the neuron (NOO rahn), or nerve cell.


• The neuron has a cell body and branches called dendrites and axons (AK sahns).


• Dendrites receive messages from other neurons and send them to the cell body.

• Axons carry messages away from the cell body. Click image to view movie.


• A reflex is an involuntary, automatic response to a stimulus.


• You can’t control reflexes.

• Reflexes help protect your body by allowing your body to respond without you having to think about what to do.


• The other control system in your body is the endocrine (EN duh krun) system.

The Endocrine System11

• In the endocrine system, chemicals called hormones (HOR mohnz) carry messages throughout the body.


• Hormones are released by endocrine glands directly into your bloodstream.


• Hormones travel through the blood to reach target tissues.

• The thyroid gland secretes a hormone that helps increase the rate of chemical reactions in your body.


• Some endocrine glands are found in the brain—the pineal and pituitary glands.


• Other endocrine glands include the pancreas and adrenal glands, which are found in the abdomen.


11Section CheckSection Check

Question 1

What is the largest human body organ?

The skin is the largest organ. Skin helps your body in many ways including protection, as a sense organ, control of body temperature, and production of Vitamin D.

Answer

IN: 6.4.11


Question 2

What two systems are shown working together in this diagram?

IN: 6.4.11


A. muscular system and digestive system B. muscular system and skeletal systemC. nervous system and skeletal systemD. skeletal system and respiratory system

IN: 6.4.11


The correct answer is B. When muscles attached to bones contract they move your bones by moving your joints.

Answer

IN: 6.4.11


Question 3

Would your body respond more quickly to a message from hormones in your pancreas, to change the amount of sugar in your blood, or to a message from a skin nerve to pull your hand away from something hot?

IN: 6.4.11


Your body would respond more quickly to a message from the skin nerve. Glands in the endocrine system, like the pancreas, use hormones to send chemical messages. Your body does not respond as quickly to messages from hormones.

Answer

IN: 6.4.11

Male Reproductive System

• The male reproductive system is made up of several organs and structures.

• The scrotum contains two testes (TES teez) that produce the male hormone testosterone and sperm, the male reproductive cells.

Human ReproductionHuman Reproduction

22


• Each sperm has a head and a tail.

• The head contains genetic information in the nucleus and the tail moves the sperm.


22

• After sperm are produced in the testes, they travel through the sperm ducts.


• Fluid from the seminal vesicles, organs behind the bladder, is mixed with the sperm.


22

• This mixture of fluid and sperm is called semen (SEE mun).

• Semen leaves the body through the urethra—the same tube that carries urine from the body.

Female Reproductive System• Ovaries are the female sex organs that

produce eggs and the female sex hormones, estrogen (ES truh jun) and progesterone (proh JES tuh rohn), when a female matures sexually.


22

Female Reproductive System• The ovaries contain certain cells that

eventually develop into eggs.


22

• The female sex hormones control the development and release of egg from the ovaries.

• Every 28 days on average, an egg is released from one of the ovaries. This process is called ovulation (ahv yuh LAY shun).

The Menstrual Cycle

• The monthly cycle of changes in a sexually mature female’s reproductive system is the menstrual cycle.


22

• The average length of a menstrual cycle is 28 days. However, the cycle can vary in length from 20 to 40 days.

The Menstrual Cycle• The menstrual cycle is divided into three

phases.


22

• Phase one is the phase of menstrual flow, ormenstruation (men STRAY shun).

The Menstrual Cycle• In phase two, an egg develops in the ovary

and the lining of the uterus thickens.


22

• The lining of the uterus continues to thicken.

• The last phase, phase three, is the phasebetween ovulation and menstruation.

The Menstrual Cycle

• If the egg is fertilized, it can attach to the wall of the uterus and begin to develop while hormones continue to be produced.


22

• If the egg is not fertilized, the hormone levels decrease, the lining of the uterus breaks down, and menstruation begins.

Life Stages• Human

development begins when an egg from the female is united with a sperm from the male.


22

• This process is called fertilization. Click image to view movie.

Life Stages• The nucleus of the sperm and the nucleus of

the egg join together creating a fertilized cell called the zygote.


22

• If the zygote successfully attaches to the wall of the uterus, the zygote will develop into a baby in about nine months.

• This period of development from fertilized egg to birth is called pregnancy.

Development Before Birth• After attachment to the wall of the uterus,

the zygote is called an embryo.


22

• During the embryo period, which is the first two months of pregnancy, the major organs develop and the heart begins to beat.

Development Before Birth

• After the first two month of pregnancy, the developing embryo is called a fetus.


22

• The fetus continues to grow and develop during the pregnancy.

• At nine months, the fetus weighs about 2.5 kg to 3.5 kg and measures about 50 cm.

Birth

• The process of childbirth begins with labor, the muscular contractions of the uterus.


22

• As these contractions increase in strength and frequency, the opening to the uterus widens, and the baby is pushed out through the vagina.

Stages After Birth• Infancy is the time from

birth to around 18 months of age.


22

• The infant’s nervous and muscular systems develop rapidly and the infant interacts with the world.

Stages After Birth• Childhood lasts from 18

months of age until around 12 years of age.


22

• During childhood, growth is rapid but not as rapid as it was during infancy.

Stages After Birth


22

• The child learns many new skills including control of the bladder and bowels between the ages of two and three, and dressing and undressing by about age four.

Stages After Birth• Adolescence begins around age 12 to 13

years.


22

• Puberty occurs during adolescence. • During puberty the human body matures

sexually.• Some of the changes in girls include breast

development and the growth of pubic and underarm hair.

• In boys, the voice deepens, muscles increase in size, and facial, pubic, and underarm hair grow.

Stages After Birth

• Adulthood is the final stage of human development.


22

• It begins at the end of adolescence and continues through the rest of the human’s life.

• During this time, the muscular and skeletal systems stop growing.


Question 1

Where are sperm produced in the male reproductive system?

A. penisB. prostate gland C. seminal vesicleD. testis

IN: 6.4.11, 6.4.12


Answer

The correct answer is D. After they are produced in the testis, sperm are mixed with fluid from the seminal vesicles to produce semen.

IN: 6.4.11, 6.4.12


Question 2

In the menstrual cycle, what happens if the egg produced as a result of ovulation is not fertilized?

AnswerHormone levels decrease, the lining of the uterus breaks down and menstruation begins. Menstrual flow is made of tissue cells from the thickened lining of the uterus and blood.

IN: 6.4.12


Question 3

What are the four stages of human development following birth?

Answer

The four stages, in order, are: infancy, childhood, adolescence, and adulthood.

IN: 6.4.12

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