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Unit 6 Human Body Systems Regents Living Environment Levels of Organization The levels of organization in a multicellular organism start with the individual cell. A group of similar cells that do the same function (job) are tissues. Similar tissues form organs that do a complex function for example the kidneys filter urea from the blood. Organs work together in organ systems. The circulatory and respiratory systems work together to perform gas exchange (oxygen and carbon dioxide) in the body. Regents diagram of the Levels of Organization Human Organ Systems Human Body Systems Integumentary System – skin, hair, nails, sweat and oil glands. Function – barrier against infection & injury; helps regulate body temperature; protects against UV radiation from the sun. Nervous System – brain, spinal cord, peripheral nerves. Function – recognizes & coordinates the body’s response to changes in its internal & external environments. (i.e.touching a hot stove) Human Organ Systems Skeletal System – bones, cartilage, ligaments & tendons Function – supports the body; protects internal organs; allows movement; stores mineral reserves; site of blood formation. Human Organ Systems Endocrine System – hypothalamus, pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries (females), testes (males). Function – controls growth, development, metabolism & maintains homeostasis. Hormones - chemical released by cell in one part of the body, that sends out messages that affect cells in other parts of the organism. Circulatory System – heart, blood vessels (veins, arteries, & capillaries), blood. Function – brings oxygen, nutrients & hormones to cells; fights infection; remove cell wastes; regulate body temperature Human Organ System Lymphatic/Immune System – White blood cells, thymus, spleen, lymph nodes, lymph vessels. Function – helps protect the body from disease; collects fluid lost from blood vessels & returns the fluid to the circulatory system. Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. Autoimmune Diseases Crohns Disease: Crohns disease is a disorder of the intestine. Diabetes Type 1: the body's immune system, attacks the insulin producing cells in the pancreas Multiple sclerosis (MS): the body's immune system attacks its own central nervous system. Rheumatoid Arthritis: leads to the destruction of all the cartilages at the joints HIV stands for Human Immunodeficiency Virus. A person is said to be HIV positive if that person is infected with HIV virus. Testing positive for HIV virus does not become AIDS until immune system is compromised which usually takes ten years. A person who has been diagnosed with AIDS is always at risk of getting life-threatening diseases, called opportunistic infections 32.9 million people were living with HIV/AIDS worldwide as of end of 2007 Respiratory System – Nose, trachea, bronchi, bronchioles, & lungs. Function – provides oxygen needed for cellular respiration & removes carbon dioxide from the body. Human Organ Systems Digestive System – mouth, esophagus, stomach, small & large intestine, rectum. Function – Breaks down food into simpler molecules (starch is too large to move through membranes) using enzymes that can be used by the body cells; absorbs food; eliminates wastes. Waste (Feces or solid waste) is not excretion of metabolic waste but simply the end products of digestion Digestive System Remember that the appendix is a vestigial organ Excretory System – skin, lungs, kidneys, ureter, bladder, urethra. Function – eliminates waste products of metabolism and helps maintain homeostasis. People with Kidney disease may be treated with kidney dialysis Human Organ System Reproductive System –The reproductive system or genital system is a system of organs within an organism which work together for the purpose of reproduction Function – produces reproductive cells (gametes). Male gamete is sperm, Female gamete is ovum/egg. . Males Males – testes, epididymis, vas deferens, urethra, penis. Sperm are produced by the cell division process of Meiosis Females Females – ovaries, fallopian tubes, uterus, vagina. Eggs are produced by the cell division process of Meiosis Sexual Development For the first six weeks of life male & female embryos are identical in appearance. (Pigs, birds and reptiles also look very similar) During the seventh week the primary reproductive organs testes in males, ovaries in females begin to develop. The testes begin to produce testosterone and the male reproductive organs are formed. If it’s a female, the ovaries produce estrogen, which produces the female reproductive organs. Puberty The reproductive organs are not capable to produce active gametes (sex cells) prior to puberty. (The genes involved have not “turned on “ yet) Puberty is a period of rapid growth and sexual maturity where the reproductive organs become fully functional. Puberty usually starts between the ages of 9 & 15 years. The hypothalamus signals the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH) The Male Reproductive System The main function of the male reproductive system is to produce & deliver the male gametes (sperm). The primary male reproductive organs, the testes develop in the abdomen. Before birth the testes descend into the scrotum. The testes remain in the scrotum, outside the body, where the temperature is one to three degrees lower than normal body temperature. The lower temperature is important for proper sperm (gamete) development. Sperm Development Sperm cells are haploid which means they have 23 chromosomes. The sperm cells have many mitochondrion. Why? Sperm Development Sperm produced in the testes are moved into the epididymis, where sperm mature & are stored. The sperm move into the vas deferens. The vas deferens merges with the urethra the tube that leads to the outside of the body through the penis. The glands lining the reproductive tract including the seminal vesicles & prostate gland produce a nutrient rich seminal fluid. The combination of sperm & seminal fluid is known as semen. 50 – 130 MILLION sperm are present in 1 ml of semen. Male Reproductive System Female Reproductive System The ovaries are the primary reproductive organ for females. This is where the eggs/ovum are stored. The main function of the female reproductive system is to produce ova (eggs). The female reproduce system also prepares the females body to nourish a developing embryo. The ovaries usually produce only one mature ovum (egg) each month. Females are born with thousands of immature eggs (follicles) only about 400 eggs will actually mature & be released Egg Release Approximately every 28 days, when a follicle has matured, the egg is released during ovulation. The egg is released from the ovary and floats through one of the two fallopian tubes. As it moves through the fallopian tube the egg may be fertilized. The egg moves from the fallopian tube into the uterus. The lining of the uterus is ready for a fertilized egg. If an unfertilized egg comes into the uterus, the uterine lining will shed resulting in menstruation. Female Reproductive System Menstrual Cycle The menstrual cycle is controlled by hormones made by the hypothalamus, pituitary gland & ovaries. This cycle is controlled by a feedback system. The menstrual cycle begins at puberty and continues until the mid-forties. The production of estrogen drops and ovulation & menstruation stop. The permanent stopping of the menstrual cycle is called menopause. The average age of menopause for women is 51. Menopause can happen earlier or later depending on the individual female. Sexually Transmitted Diseases (STDs) Sexually transmitted diseases are spread from one person to another during sexual contact. Chlamydia is an STD caused by bacteria. Females between the ages of 15 – 18 have the highest rate of Chlamydia infection. This infection can cause infertility (inability to have children). Other STDs include syphilis, gonorrhea, Viral STDs hepatitis B, genital herpes & warts, & AIDs. STDs can be avoided by abstaining from sex or using condoms to help protect from you from STDs. Fertilization Fertilization of an egg usually happens in the fallopian tube. Hundreds of millions of sperm swim through the cervix, uterus and into the fallopian tubes, if an egg is present it may be fertilized. The egg is surrounded by a protective layer that has binding sites where sperm can attach. Fertilization of the egg restores the chromosome number to 46 (23 egg plus 23 sperm= 46) Once the single sperm enters the egg, the egg releases a barrier to the outside of the cell that prevents any other sperm from entering. The fertilized egg is called a Zygote. Fertilization While the zygote is still in the fallopian tube it beings to divide through Mitosis (2N cells). About six days after fertilization the fertilized cell implants into the uterus. After implantation, the cell starts to specialize into different tissues in the body. This process of cell differentiation creates the different tissues types and systems of the body. Membrane Development As the embryo develops, membranes form to protect and nourish it. Two of the membranes are the amnion and the chorion. The amnion becomes the fluid-filled amniotic sac that cushions & protects the developing embryo in the uterus. The chorion has small finger-like projections called chorionic villi form on the outer layer of the chorion and plant themselves in the uterine lining. Placenta The chorionic villi & uterine lining form the placenta. The placenta is the connection between mother and baby. The developing embryo needs nutrients & oxygen. It also needs to eliminate carbon dioxide & metabolic wastes. Nutrients & oxygen in the mother’s blood diffuse into the embryo’s blood in the chorionic villi. Waste diffuse from the embryo to the mother. The mother & baby’s blood flow past each other but DON’T MIX. They are SEPARATED by the placenta. Placenta after Birth Fetal Development The first weeks of pregnancy are very important because many external factors can disrupt or harm the embryo’s growth & development. The placenta helps to protect the baby but some substances can cross the placenta and affect the baby. This includes German measles, drugs like alcohol, cocaine, heroin, and medications.