Health Revision Lecture Notes PDF

Lecture Notes Body Systems One way to increase your awareness of health is to develop a better understanding of how the body works. Understanding the body means being able to identify and describe the different body systems. You should understand the purpose and function of each system, and recogniz...

Lecture Notes Body Systems One way to increase your awareness of health is to develop a better understanding of how the body works. Understanding the body means being able to identify and describe the different body systems. You should understand the purpose and function of each system, and recognize the different organs that are involved. In this lesson, we’ll briefly review each body system and its organs. You’ll find a much more detailed explanation of each body system in Part 2 of this course. The systems of the human body include the following: Integumentary system Muscular system Skeletal system Nervous system Circulatory system Lymphatic system Respiratory system Endocrine system Urinary system Reproductive system Digestive system Integumentary System The integumentary system is an organ system that consists of the skin, hair, subcutaneous (under the skin) fat, and nails. Its function is to protect the body from the environment; it also prevents bacteria and viruses from entering the body. The skin is the body’s largest organ. Its function is to detect temperature, pain, and pressure. The body then responds accordingly. For example, if the temperature is cold outside, your skin will cause you to shiver in response. You’ll need to go inside or add additional clothing layers to restore heat. Similarly, if you touch a hot stove, the perception of pain on the skin will cause you to pull your hand away, preventing further damage. Finally, through perspiration, skin also helps eliminate wastes from the body. FIGURE 1–The body’s largest organ, the skin, protects the internal organs. Muscular System The muscular system is an organ system that permits and manages the body’s movement. The muscular system includes approximately 650 muscles of three types, as follows: Skeletal muscle, which connects to bone Smooth muscle, which is inside organs Cardiac muscle, which is in the heart Muscles aid in movement, help move substances through organs, and pump blood throughout the body. They also produce the body’s heat.  FIGURE 2–The Muscular System Skeletal System The skeletal system includes 206 bones that support the body through connection with joints, cartilage, ligaments, and tendons. Although teeth aren’t considered bones, they’re considered part of the skeletal system. The function of the skeletal system is to provide structural support for the body. It protects internal organs and is involved in calcium storage and the production of blood cells. This system also contains minerals that are needed in physiological processes, such as calcium, phosphorus, and magnesium. The skeletal and muscular systems work together to allow movement.  FIGURE 3–The Skeletal System Nervous System The nervous system includes both the central nervous system—the brain and spinal cord—and the peripheral nervous system. The latter includes the nerves that connect the rest of the body to the central nervous system. The nervous system also includes the sensory organs, or those organs that support vision, hearing, smell, taste, and touch. The nervous system controls how the body responds to internal and external stimuli through voluntary and involuntary actions. For example, breathing is an involuntary movement; throwing a ball is a voluntary movement. The sensory organs support sight, hearing, smell, touch, and taste, and promote balance. The nervous system also regulates moods. It stores and processes memories. Finally, it facilitates your ability to interact and develop socially.  FIGURE 4—The Nervous System Circulatory System The circulatory system includes the heart, arteries, veins, and blood. Its function is to move oxygen and nutrients to organs, tissues, and cells. The circulatory also moves hormones and other substances through the body. It works closely with the lymphatic system.  FIGURE 5—The Circulatory System Lymphatic System The lymphatic system includes lymph nodes, lymph ducts, and lymph vessels. The lymphatic system’s main function is the body’s defense. It moves lymph, a liquid with white blood cells, to places in the body that are fighting infection. It carries immune cells through the body. This system also transports fats that have been absorbed. Respiratory System The respiratory system includes organs necessary for breathing, such as the trachea, diaphragm, and lungs. Its function is to bring oxygen into the body and then to expel carbon dioxide from the body. Oxygen travels through the bloodstream and carbon dioxide is carried away. The respiratory system also supports the functions that allow you to speak.  FIGURE 6—The Respiratory System Endocrine System The endocrine system includes organs known as glands, which produce hormones. Hormones travel through the bloodstream to regulate activities in other organs, such as growth, sexual function, or metabolism. There are many glands in the body, and each serves a special purpose. The list of glands in the human body includes Thyroid Pituitary Pancreas Adrenals Hypothalamus Gonads Pineal  FIGURE 7—The Endocrine System Urinary System The urinary system includes the kidneys, ureters, the bladder, sphincter muscles, and the urethra. The function of this system is to eliminate excess water and metabolic wastes from the body. The kidneys create urine. Urine is a waste product that is broken down from food. It travels down the ureters to the bladder and is excreted through the urethra. The kidneys help to maintain the balance of fluid and minerals in the blood. They also are instrumental in controlling blood pressure and producing vitamin D.  FIGURE 8—The Urinary System Reproductive System The reproductive system is the only body system that differentiates males and females. In males, the reproductive organs include the testes, penis, epididymis, vas deferens, prostate, seminal, and vesicles. In females, the reproductive organs include ovaries, fallopian tubes, uterus, vagina, and the labia, as well as mammary glands. The reproductive system allows humans to reproduce. Males produce and deposit sperm that can fertilize eggs in females. Females then nourish the fertilized egg and protect it as it develops into an infant.  FIGURE 9—The Reproductive System of Males and Females Digestive System The digestive system includes a number of connected organs that allow the body to break down and absorb food in order to absorb nutrients. The liver and pancreas, for example, produce digestive juices that help break down food. Remaining materials are excreted as waste. The digestive system also helps the body to maintain fluids and regulate immune responses. The digestive system includes a number of organs, namely, Lips Teeth Mouth Tongue Salivary glands Pharynx Esophagus Stomach Liver Gallbladder Pancreas Small intestine Large intestine Rectum Anus  FIGURE 10—The Digestive System Life Stages Now that you understand the complexity of the human body, we’ll review the changes in the human body from conception through the end of life. Human development is a term that refers to the changes that occur throughout life. It includes physical, behavioral, emotional, and cognitive changes. As you’ll see, an enormous amount of growth and change occurs from conception onward. The stages of human development include the following: Conception and fetal development Infancy and childhood Puberty and adolescence Adulthood Old age and death Conception and Fetal Development Conception, or fertilization, occurs when a sperm from a male implants into an egg of a female in a fallopian tube. The fertilized egg is then called a zygote. Pregnancy has three stages: Germinal stage Embryonic stage Fetal stage Germinal Stage During the germinal stage, the zygote moves into the uterus. During this journey, which takes about a week, the zygote begins to divide its cells and grow. The zygote begins to form into two separate masses—an embryo and a placenta. The embryo develops into the fetus while the placenta provides a protective layer around the embryo, allowing for nutrients and wastes to pass through. The cells continue to divide and develop into a blastocyst, which has three layers: The ectoderm develops into the integumentary and nervous systems. The endoderm develops into the digestive and respiratory systems. The mesoderm develops into the muscular and skeletal systems. When the blastocyst reaches the uterus, it attaches itself to the uterine wall. This is called implantation. Not every blastocyst properly implants, but when it does, the woman experiences many changes, including her menstrual cycle stopping. This may be one of the first signs of pregnancy. FIGURE 11—The Germinal Stage Embryonic Stage After implantation, the blastocyst is referred to as an embryo, approximately three weeks after conception. The embryo divides into layers that will develop into body systems. The neural tube forms, which later develops into the central nervous system. About one week later, the head begins to form and develop features. The cardiovascular system begins its early stages of development and early limbs begin to grow. After eight weeks, all the basic organs except the sex organs have developed. The embryo is still only about one inch in length.  FIGURE 12—The Embryonic Stage Fetal Stage As the pregnancy continues, the embryo continues to grow rapidly in the uterus. During the period from around nine weeks until birth, the embryo is known as a fetus. This period is the fetal stage. During this stage, body systems continue to develop and the fetus grows. The neural tube develops into the brain and spinal cord and neurons form. Sex organs begin to appear approximately three months after conception. The first trimester of pregnancy lasts until the end of the third month. Months four through six are known as the second trimester. The fetus grows in weight and size, the heart beats stronger, and body systems continue to develop. The brain and central nervous system start to respond. Hair, eyelashes, fingernails, and toenails form. During the third trimester, from months seven until birth, the fetus continues to grow and put on weight. Lungs began to function to prepare for breathing after birth. FIGURE 13—The Fetal Stage Childbirth After about nine months (in actuality, 40 weeks) of pregnancy, a woman typically goes into labor. Labor begins with contractions that help expel the fetus from the womb. A woman’s cervix dilates to approximately 10 centimeters to allow the fetus to pass through the vaginal canal. In the next stage, the woman pushes the fetus down; this stage can take minutes, hours, or even days, and lasts until the fetus emerges. Once the fetus is born, the child is called an infant. Finally, after the infant has emerged, the placenta is delivered from the womb. If there is an issue during labor, physicians may decide to opt for a Caesarean section delivery, which is a surgical procedure in which an incision is made in the mother’s abdomen and the infant is manually removed from the uterus. Infancy and Childhood An infant grows and develops rapidly during the first year. Several milestones occur over this time period. Here are some of the major milestones: Rolling over (four to six months) Sitting up unassisted (by six months) Crawling (by 12 months) – some infants even begin to walk by this time Developing fine motor skills to pick up small objects (by 12 months) Communicating by babbling, squealing, or laughing (by 12 months) Some infants may even say simple words like “mama” and “dada.” They may also understand basic words such as “no” or “ball.”  FIGURE 14—An Infant Toddlers Children between the ages of one and three are known as toddlers. At this stage, children are becoming more independent than they were during infancy. They begin to feed themselves. They also develop the skills to walk and run, kick a ball, walk up and down stairs, and so on. Toddlers begin to express themselves by building with blocks or scribbling designs. One major milestone during the toddler years is communication. By the age of two, most toddlers can speak about 500 words and understand many more than that. However, toddlers have little self-control either socially or emotionally. For example, they may grab toys from other children and declare “mine!” They develop more self-control in the preschool years. FIGURE 15—A Toddler Preschoolers Ages three through five are known as the preschool years. Physically, children learn to move with greater balance and coordination by the age of four. They can hop on one foot and throw a ball with greater aim. By the age of five, they usually can skip, tumble, and climb more skillfully. Brain development and the refinement of fine motor skills help preschoolers draw more recognizable shapes. Most can write letters and numbers at this age. They also become better able to express themselves orally, using words instead of actions. For example, instead of grabbing someone else’s toy, the child may ask for a turn with it. Preschoolers also begin to develop social skills and make friends. They may even develop empathy for others; if they see another child crying, they may try to soothe the child by handing him or her a toy.  FIGURE 16—A Preschooler School-aged Children The period between age six through early adolescence is often known as the school-aged or grade school years. In this period of time, gross motor abilities develop and children may try new, more demanding physical activities, such as soccer or gymnastics. Fine motor skills develop, allowing children to write letters and numbers and draw in more detail. Cognitively, children develop skills such as reading, writing, and mathematics; they begin to understand science and language. Younger children look to parents and caregivers for social and emotional needs. However, as children grow, their friends and peers begin to play a greater role in social and emotional development. This continues until the child reaches the next milestone of development—adolescence. FIGURE 17—A School-aged Child Puberty and Adolescence The teen years are known as adolescence. This time period marks the transition from childhood to adulthood. A great number of developmental changes—physical, emotional, and social—occur during this time. The onset of adolescence is marked by puberty, a developmental period of sexual maturation. The reproductive system matures and sex hormones increase and are released into the body; these changes lead to fertility and the ability to reproduce. Physical changes in puberty include spurts of growth in height and/or weight, a change in body shape, and the growth of body hair. Girls enter puberty earlier now than they did in previous decades. Researchers theorize that contributing factors may be environmental and/or nutritional in nature. Modern girls usually enter puberty between the ages of 10 and 14. For them, the physical changes include the development of breasts and the onset of menstruation, or the periodic discharge of blood and tissue from the inner lining of the uterus. Boys typically enter puberty between the ages of 12 and 16. Some of the physical changes for boys include a deepening of the voice and the growth of body hair, such as facial hair. Adolescents tend to become extremely independent as they try to discover who they are. They typically focus more on relationships with friends or romantic interests over their families. They also start to think about what they’d like to do in the future and may try different afterschool jobs or make plans for the future. Issues Associated with Adolescence While adolescents are searching for their identity, they may face a number of issues, such as Substance abuse Peer pressure Eating disorders Depression, suicide attempts, or suicide Unprotected sex, which may lead to sexually transmitted infections (STIs) or unwanted pregnancies Developing coping and resistance skills can be critical during this period – refer back to Lesson 2 for examples; some FIGURE 18—Adolescence adolescents may need help from a professional. Adulthood A person typically enters adulthood at approximately age 20. Adulthood is the longest period of development. Virtual Field Trip Early Adulthood Read more about the changes during In early adulthood, from approximately age 20 to 40, adults typically seek intimacy through long-term relationships. These puberty in the article relationships may lead to marriage and/or children. Most people are concerned with intimacy and love. During this period, “All About Puberty”: long-term relationships are usually formed. These may lead to cohabitation, marriage, and/or children. This period also marks the time where an adult pursues a career. Career choices can affect many life aspects, including security, All About Puberty satisfaction, socioeconomic status, friends, locations, stress, and more. Middle Adulthood The period of middle adulthood generally lasts from about ages 40 to 65. Adults in this age group may need to make a number of choices or adjustments, such as Adjusting to menopause (females) or other physical changes Caring for aging parents Finding job satisfaction or contemplating career moves Helping children become responsible adults and dealing with the “empty nest” Adults in this age group tend to think more about contributing to the world. They may think about their family’s future more, as well as that of future generations. They may find that their original career choices aren’t as satisfying as they once thought, and may begin to explore the idea of trying something completely different. Career changes are quite common during this time of life. During this time, some people may experience a “midlife crisis.” This is an emotional period of time in which mortality seems to loom large. People who experience midlife crises generally do so in their forties or fifties, as they come to understand that life may be half over. Some individuals make drastic changes that help them to live with more satisfaction; others come to terms with their feelings and continue on the same path.  FIGURE 19—Adults typically reach their physical peak in their twenties. Old Age and Death Late adulthood, also historically known as “old age,” begins around age 65. Adults are typically in peak physical condition in their twenties and then experience a gradually decline over the next several decades. In old age, the systems of the body become less efficient. Adults may lose body mass. Women may lead enough body mass that they develop a condition called osteoporosis. In this condition, the bones become fragile and susceptible to fracture, making daily tasks difficult. During old age, muscles become weaker, especially if they aren’t exercised regularly. The skin becomes more dry and less flexible, and hair loss may occur. Senses may become less sharp, making it more difficult to see, hear, smell, taste, or touch well. Chronic and painful health problems may develop, including arthritis, rheumatism, and hypertension. Cognitive changes also occur in old age. Studies have shown that older adults experience a decline in response time and memory. About 15 percent of older people may experience cognitive changes through a condition called dementia. Dementia is a broad category of brain diseases that cause long-term loss of cognitive abilities, such as the ability to think and reason clearly. Dementia can seriously impact the quality of a person’s life. One very serious type of dementia is known as Alzheimer’s disease, which includes severe and sometimes total memory loss, as well as general confusion. Despite the possibility of these drastic changes, many people in old age are in good physical condition, and lead active, happy, and satisfying lives. Many adults retire from the working world around the age of 65, although this age has been on the rise in recent years. Retirement can be difficult if the person is unready to stop working and/or is not financially secure enough to do so. Gerontology is the Life ends with death; the body systems cease to function and the body is no longer capable of sustaining itself. As people study of the process age, they begin to think more death and may attempt to come to terms with it. of aging. Research may include Women tend to have a five- to seven-year greater lifespan than men. So, women often lose their spouses and end life psychological, with a period of widowhood. This period can be particularly stressful and can be eased through the support of family and biological, friends. sociological, and other areas of interest. A discrimination or prejudice directed at older people is known as ageism. For instance, adults may be pressured into early retirement due to their advancing age.  FIGURE 20—Physical strength and endurance decline in old age. Hands-on Activity In this lesson, you learned about growth and development. But did you know that boys and girls develop at different rates? Read about growth in girls: http://life.familyeducation.com/health/child-development/35899.html Read about growth in boys: http://www.nytimes.com/1999/02/17/health/the-seven-stages-of-man.html Read these articles: “Help! Is this my Body?” http://kidshealth.org/en/teens/help-body.html?ref=search “A Guy’s Guide to Body Image” http://kidshealth.org/en/teens/male-bodyimage.html?ref=search Additionally, take some time to browse through the topics on this site and read the articles that interest you: http://kidshealth.org/teen/ Get out your journal. Think about all of the sites you reviewed as well as the information you covered in this lesson. What did you learn that most surprised you? What did you learn that confirmed your own ideas about human growth and development? Write several paragraphs capturing your response. (Hands-on activities are not for a grade but rather for your own personal enrichment to help you apply what you have learned to your every day life.) Exam After completing the reading assignment, you should complete the Check Your Learning activity. These are designed to test your knowledge of the material in the lesson. You can check your answers and go back to the lesson to review anything that seems confusing. Once you feel comfortable with your knowledge of the material, you’ll take an achievement examination for each lesson. Lesson 3 is now complete! Complete the Check Your Learning for this lesson. When you feel comfortable with your knowledge of the material, take the Lesson Exam.