Living Environment - Chapter 1: Similarities and Differences Among Living Things

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that take place when smaller molecules join together to form larger molecules. 6. Regulation: control and coordination of all life activities by nerves and chemicals in the blood (hormones) in order to maintain homeostasis. Homeostasis means a stable or balanced internal environment (same or constant amounts of sugar, salt, and water in the organism). 7. Growth: increase in size and number of cells in the organism. 8. Reproduction: producing new individuals (babies, offspring) which is not needed for each individual's survival. 9. Locomotion: moving from place to place. All of these life functions together are called metabolism. Life processes require energy (in the form of ATP). Wastes produced by these life processes are called metabolic wastes. All living things carry on these life processes but different living things (ex: plants and animals) carry on these life processes in a different way: (plants make their own food and animals take in food). Chemical composition All living things have the same chemical composition. All living things are made of these four main elements carbon, hydrogen, oxygen, and nitrogen, and many other elements in small amounts. Elements (ex: carbon, hydrogen, oxygen) combine to form molecules (example: sugar). Organic molecules have both carbon and hydrogen. Examples of organic molecules are sugar, starch, protein, fats, enzymes, and DNA. • Carbon, hydrogen, and oxygen combine to form sugar and starch. • Carbon, hydrogen, oxygen, and nitrogen combine to form protein and parts of living things (ex: cell wall and cell membrane). • Carbon, hydrogen, oxygen, and nitrogen also combine to form enzymes, needed for chemical reactions in living things, and to form DNA, which is used for heredity (example: how children, grandchildren, great-grandchildren look-eye color, height, etc.). Inorganic molecules do not have carbon and hydrogen together but can have any element combined with other elements to form inorganic molecules (examples: salts, minerals, water). Living things are mostly made of water. In short, all living things are similar; living things are made of cells, carry on life processes, and have the same chemical composition. Organization All living things (organisms) are made of one or more cells. The cell is the basic unit of structure and function of living things. Simple organisms (ex: ameba) have one cell; complex organisms (ex: human beings, dogs, trees) can have billions of cells. You will learn later that inside a cell have specialized structures called organelles that carry out different functions. A cell is the basic unit of structure and function of all living things. A group of similar cells (similar in structure and similar in function) forms a tissue (which is more complex than cells). Examples of the uses of tissues: Millions of skin cells make up skin tissue, which covers and protects the body. ● Cells in the body (similar cells) that clean the air before it gets into the lungs form a tissue. • Millions of muscle cells make up muscle tissue. One muscle cell cannot pick up a piece of paper, but a muscle tissue (made of millions of muscle cells) can pick up a baseball, basketball, soccer ball, etc. Different types of tissues combine to form an organ (even more complex than tissues) which carries out a life function. Epithelial (skin) tissue, muscle tissue, nerve tissue, blood tissue, etc. combine to form the stomach, an organ that digests food. Different organs work together to form a system (even much more complex than organs) which also carries out life functions. For example: • The digestive system is made up of these organs: mouth, esophagus, stomach, small intestine, which carries out the life function of nutrition (taking in food, digesting food, and eliminating undigested wastes). • The respiratory system is made of the following organs: nose, trachea, bronchial tubes, and lungs, which carry out breathing, taking in air, bringing oxygen to the blood, and taking away carbon dioxide. In short, similar cells combine (join together) to form tissues, tissues combine to form organs, organs combine to form organ systems (digestive system, respiratory system, etc.), and organ systems combine to make up the organism. Cells Tissues Organ Organ System Organism Cells Living things are made up of one or more cells. You can see cells using a compound light microscope. Each cell carries out the life processes and all the cells work together in a coordinated manner. Look at the picture of the cell. The cytoplasm is the jelly-like substance inside the cell, surrounded by the cell membrane. The cytoplasm transports material through the cell. Many chemical reactions take place in the cytoplasm. PLANT VS. ANIMAL CELLS CELL MEMBRANE NUCLEUS NUCLEOLUS SMOOTH ENDOPLASMIC RETICULUM ROUGH ENDOPLASMIC RETICULUM RIBOSOMES VACUOLE MITOCHONDRIA -GOLGI APPARATUS CHLOROPLASTS CENTRIOLES LYSOSOMES CELL WALL CENTROSOMES -PLASMODESMATA Organelles Organelles are structures (ex: nucleus, ribosomes, vacuoles) that are inside the cell. Each organelle carries out a specific life function (see below). All organelles work together to do all life functions; all life functions (ex: respiration, synthesis, nutrition) together are called metabolism. Cell membrane surrounds the cell. The cell membrane is made mostly of fats (lipids) and some proteins. The cell membrane controls which materials (or how much of a material) enters or leaves the cell. The cell membrane lets digested food (ex: simple sugar) enter the cell and lets wastes leave the cell (waste disposal). Nucleus is the control center; it controls all life processes (metabolism). The nucleus stores genetic information; information in the nucleus directs protein synthesis (joining together of smaller molecules to form proteins (large molecules)). Vacuoles storage sacs that are inside the cytoplasm. Some vacuoles store food and digest food; other vacuoles store water and get rid of excess water and other vacuoles store wastes. Vacuoles can store different materials, such as food, water, or waste. Mitochondria are called the powerhouse of the cell. Mitochondria are the place where cellular respiration takes place. Mitochondria contain enzymes that take the energy out of food and produce energy in the form of ATP. Cells that need more energy (ex: muscle cells) have more mitochondria to produce more energy. Ribosomes are where protein synthesis (the place where protein is made) occurs. Some ribosomes are attached to membranes; other ribosomes are floating in the cytoplasm. Chloroplasts are only in plants (and some one-celled organisms) but not in animals. Plants have chloroplasts and can make their own food in the presence of light. When plants make their own food (glucose) in the presence of light, it is called photosynthesis. Cell walls are found in plant cells but not in animal cells. Cell walls are outside the cell membrane and made of cellulose, a hard, nonliving material. Cell walls support the plant. Organelles work together: Organelles are structures inside the cell. These organelles interact to maintain a balanced internal environment (homeostasis). Examples: • The nucleus and ribosomes are interrelated. The nucleus is the control center; it directs the cell on what to do and tells the ribosome what protein to make. Ribosome makes proteins by joining together amino acids to form proteins. • Mitochondria and ribosomes interact. Mitochondria contain enzymes that take the energy out of food and produce energy in the form of ATP. Ribosomes use energy in the form of ATP to make protein. . Cell membrane and ribosomes interact. Cell membrane lets amino acids enter the cell. Ribosomes use amino acids as building blocks to make proteins. Organelles, cells, tissues, organs, and organ systems work together to maintain homeostasis (constant internal environment). Cell Membrane The cell membrane surrounds the cell and is made mainly of fats (lipids) and some protein. Proteins in the cell membrane (called receptors) recognize and respond to chemical signals (ex: insulin). The chemical signals attach to the proteins (receptors) on the membrane, causing the cell to respond. You learned the cell membrane controls which materials, or how much of a material, enters the cell or leaves the cell. Only small, soluble molecules such as glucose (simple sugar) and dissolved gases such as oxygen can pass through the cell membrane; large molecules (ex: starch) cannot pass through the cell membrane. Starch, fats, and proteins must first be digested (broken down into simple substances), then they can go through the cell membrane. The cell membrane lets wastes leave the cell (waste disposal). Diffusion and active transport are important in moving material into and out of the cell. Diffusion If there is more concentration of a dissolved substance (ex: dissolved sugar) outside the cell and a lower concentration of the dissolved substance inside the cell, some dissolved sugar will go across the membrane into (inside) the cell so that there is the same concentration (amount) of sugar inside and outside the cell. If there is more concentration of a dissolved substance inside the cell and a lower concentration (less) of dissolved substance outside the cell, some of the dissolved sugar will go across the membrane out of the cell so that there is the same concentration (amount) of dissolved sugar inside and outside the cell. Diffusion: molecules go from an area of higher concentration across a membrane to an area of lower concentration. The diffusion of water is called osmosis. When water goes from a higher concentration of water across a membrane to a lower concentration of water it is called osmosis. less sugar more sugar more sugar less sugar Examples of osmosis: 1. A cell has 94% water, the surrounding area has 96% water. Water goes from a higher concentration of water across a membrane to a lower concentration of water, therefore, water will enter the cell until the concentration of water inside and outside the cell is the same. 2. A cell has 97% water, the surrounding area has 92% water. Water goes from a higher concentration of water (97% in the cell) to outside the cell (92%) until the concentration of water inside and outside the cell are the same. Note: A 3% solution (salt in water) means that it has 3% salt and 97% water. Percent of salt (3%) and percent of water (97%) must equal 100%. An 8% sugar solution (sugar in water) means that it has 8% sugar and 92% water. Percent of sugar (8%) and percent of water (92%) must equal 100%. Diffusion and osmosis (diffusion of water) are called passive transport because no energy is required for diffusion. Active Transport Some cells can use cellular energy (energy from ATP) to force materials to go across a membrane from areas of lower concentration to areas of higher concentration. This is the opposite of diffusion; diffusion is from higher concentration to lower concentration. Since energy is required, it is called active transport. Desert plants use active transport to take water into their roots from desert soil which has very little water. Receptor Molecules: Cellular Communication The nervous system (ex: brain, nerve cells) and the endocrine system (ex: pancreas) produce chemicals that help in cellular communication (communication between cells). The endocrine system produces chemicals in the blood called hormones that regulate how the body works. For example, the pancreas produces the hormone insulin, which regulates the amount of sugar in the blood. When the hormone (chemical signal) in the blood moves toward the cell membrane with its receptor, the hormone attaches itself to the receptor on the cell membrane. The receptor is a protein on the cell membrane. Each receptor is specific and can only recognize and respond to a specific hormone (the shape of the receptor matches only the shape of the specific hormone). The receptor is on the cell membrane; the receptor molecule with the hormone sends a signal to that cell, telling the cell what to do (how to respond). For example: When there is too much glucose (sugar) in the blood, the pancreas produces insulin. The hormone insulin in the blood attaches to a receptor on liver cells, telling the liver cells to remove glucose (sugar) from the blood and store it in the liver. Now the blood has the right amount of glucose. As you can see, there is communication between cells. The pancreas tells the liver cells what to do. The pancreas produces the hormone insulin; the insulin goes to the liver and tells the liver "Take glucose out of the blood." In the nervous system, nerve cells produce chemicals called neurotransmitters (ex: acetylcholine) that regulate how the body responds to the environment (ex: hand jumps away when it touches a hot pot). The chemical at the end of the first nerve cell moves toward the receptors which are at the beginning of the next nerve cell. The chemical attaches itself (like a lock and a key) to the receptors. Each receptor is specific and can only recognize and respond to a specific chemical (nerve signal) which fits into the receptor. The receptor with the chemical (acetylcholine) sends a message through its nerve cell to a muscle, gland, or to another nerve cell telling the muscle, gland, or another nerve cell what to do. If the nerve cell dies or the chemical (neurotransmitter) does not work, the nerve cell cannot send a message to the muscle (or another nerve cell); then the muscle cannot respond. In short, nerve cells can communicate with glands, muscles, or nerve cells on what to do. There is communication between nerve cells and other cells (gland cell or muscle cell or nerve cell). In short, receptor molecules on the cell membrane recognize and respond only to specific chemicals (chemical signals, nerve signals, hormones, hormone signals) which have the exact shape that fits into the receptor. The chemical must have the exact shape that fits into the receptor so the hormone or nerve signal can work. Example of chemicals having the exact shape that fits into the receptor do the hormone or nerve signal can work: • A drug is given to block substance A. The drug must have a shape that fits into substance A (lock and key), therefore the shape of a drug must be receptive to it. The result of the drug attached to substance A would look like two puzzle pieces. • Some cells in a female body respond to reproductive hormones while other cells do not. Only cells with receptors for these reproductive hormones respond. SYSTEMS OF THE HUMAN BODY Let's understand the systems of our body in more detail. These systems are interrelated. Digestive System THE DIGESTIVE SYSTEM When you eat a sandwich, the food goes from your mouth to the esophagus, to the stomach and small intestine, where the digested food goes (diffuses) into the blood and then goes (diffuses) into the cells of your body. The function of the digestive system is to digest food (break down food) into smaller pieces (mechanical digestion) and into simpler substances (chemical digestion) so it can be used by the cells of the body. Starch, protein, and fat are large molecules, which need to be broken down to simpler (smaller) substances because only the simpler substances can diffuse from digestive system (small intestine) into the blood and be used by the body. Starch is digested into simple sugars, protein is digested into amino acids, and fat is digested to fatty acids and glycerol. Enzymes help to break down the food chemically, forming simpler substances (ex: amino acids, fatty acids), which can be used by the body. Starch, protein, fats, sugars, amino acids, fatty acids, glycerol, and vitamins are nutrients that are used by the body to help in life processes (ex: respiration, nutrition, synthesis (such as amino acids joining together to form protein), and growth). Starch (nutrient) is found in bread, cereal, pasta, and rice, sugar (nutrient) is found in fruit, and protein (nutrient) is found in meat, fish, chicken, eggs, and milk. When you eat bread or pasta, you get starch, which is digested into simple sugars used for energy. When you eat meat, fish, eggs, or milk, you get protein, which your body uses for growth and repair and making enzymes, hormones, etc. When you eat fruit, you get sugar, which your body uses for energy; the energy is available right away. Food is moved down the digestive tract by muscular contraction called peristalsis. PHARYNX at the beginning of the throat, both food and our travel through it. EPIGLOTTIS: flap of muscle that closes over the larynx to direct food into the esophagus ESOPHAGUS tube leading from pharynx to stomach -bolus (food blob) is pushed down by muscle contractions. called per CAL eristalsis type of -protected by trachea LIVER: has >200 jobs - - produces bile, which is stored in the gall bladder -filters blood and breaks down used red blood cells -regulates amount of glycogen (stored excess blood sugar)" GALLBLADDER stores bill gall stones are formed due to too much cholesterol in the bile it hardens (when blocking exit causes pain) -caused by diet, weight, alcohol, combo -treated. drink fluids (wash out) 1. break up crystals 3. Surgically remove PANCREAS enzyme creation location -produces NaHCO₂ which neutralizes acids MOUTH where food is ingested. teeth ~ MECHANICAL digestion saliva CHEMICAL digestion. Lamylase (enzyme) breaks down starches into sugar STOMACH where food is (mainly) digested smooth muscle ~ MECHANICAL stomach and~ CHEMICAL Lopepsin (entyme) breaks down protems into amuno ands LHCl (aced) kills bad bacteria in/on our food muc protects stomach lining from acids Lble (a digestive juice) breaks down lipids NaHCO₂ neutralizes gastric acid (HCA) Lolipase (enzyme) breaks down lynds chyme~ mixture of raw materials SMALL INTESTINE where absorption occurs. trypsin (enzyme) catalyzes the hydralisis of polypeptide bonds ville and microville ~ increase surface area in order to absorb max. nutrients LARGE INTESTINE where absorbtion and elimination occur LH₂O absorbed (key nutrient) RECTUM/ANUS APPENDIX an filter where elumnation occurs. if it gets bactena multiply and if may explode, causing infection Lappendicitis blockary L must remove (appendectomy) Digestive System 1. In the mouth a. the teeth break the food mechanically (ex: a sandwich broken into smaller pieces) b. the enzyme (ptyalin) in saliva begins the digestion of starch, breaking down starch chemically into a type of sugar (which is a simpler substance) 2. Food goes down the esophagus 3. Food goes to the stomach. The stomach has gastric juice that has enzymes that begin protein digestion. The stomach has hydrochloric acid. 4. Partially digested food goes into the small intestine. The small intestine is a long coiled tube. The enzymes in the small intestine help more to break down chemically the partially digested protein and sugar into smaller substances that the body can use. The liver produces bile (not an enzyme) which goes through a duct into the small intestine. Bile helps mechanically to break down fat into smaller pieces. The pancreas produces pancreatic juice, which goes into the small intestine. Pancreatic juice contains enzymes that digest fats and continue the digestion of starch and proteins. Digestion of food is finished in the small intestine. Starch is changed to simple sugar, fat is changed to fatty acids and glycerol, and protein is changed to amino acids. The end products of digestion are simple sugar, fatty acids and glycerol, and amino acids. The digested food goes (diffuses) from the small intestine into the blood. The lining of the small intestine has villi which increase the surface area so more digested food can go into the blood. Digested food (ex: simple sugars, amino acids, and fatty acids) goes through the villi and goes into the bloodstream (which is part of the circulatory system) and then goes by diffusion to the cells of the body and even into parts of the cell such as the mitochondria. Some of the small molecules of simple sugar, amino acids and fatty acids combine together (synthesis) to form larger molecules of starch, proteins, fat, and DNA (or, you can say, sugar, amino acids and fatty acids are used as building blocks forming starch, protein and fat). Sugar molecules are the building blocks which combine together forming starch. Amino acids are the building blocks that combine together forming protein (example of a protein is an enzyme; enzymes are proteins). Fatty acids and glycerol are the building blocks forming fats. 5. Undigested food goes from the small intestine to the large intestine. The large intestine absorbs excess water from the undigested food and the water goes into the blood (bloodstream) by diffusion and then goes by diffusion to the cells of the body. Undigested food (wastes) go into the rectum (lower part of the large intestine) and the undigested food leave the body (egestion, elimination) through the anus. Circulatory System The circulatory system consists of the heart, blood vessels, (blood vessels that go away from the heart are called arteries; blood vessels that go to the heart are called veins), and blood (which has plasma (the liquid part of the blood), red blood cells, white blood cells and platelets). Red blood cells Plasma Platelets Blood vessel White blood cell The function of the circulatory system, or you can say the blood, is to transport (carry) dissolved material (ex: glucose, oxygen, amino acids) to all parts of the body and carry and take away wastes and carbon dioxide. The blood also carries hormones and antibodies (which fight disease). Blood from the lungs which has a lot of oxygen (oxygenated blood) goes to the left atrium of the heart, then goes to the left ventricle of the heart. The left ventricle pumps the oxygenated blood through the arteries (blood vessels that go away from the heart). Then the blood goes to capillaries (very thin-walled blood vessels) where oxygen and glucose go from the blood to the cells of the body (by diffusion) and wastes and carbon dioxide go from the cells of the body to the blood (by diffusion). The blood (which has a lot of carbon dioxide and wastes) goes through blood vessels called veins back to the right atrium of the heart, then the right ventricle, then the blood goes to the pulmonary arteries to the lungs. In the lungs, carbon dioxide goes out and then leaves the body; oxygen is taken in. Right- atrium Valves Right- ventrice Blood from body Blood to body Aorta Blood to lung Blood from lung Left atrium Valves Left ventricle Septum The heart beats (contracts and relaxes) to pump blood. Every time the heart contracts, blood is forced into the arteries, making the arteries bulge (get a little wider). When an artery is close under the skin, we feel these bulges as a pulse. Your heart rate (ex: 72 or 76 beats per minute) is equal to the pulse (ex: 72 or 76 per minute.) People have different pulse rates: A person's pulse rate depends on the person's weight, whether they are male or female, how physically fit they are, how fast their body uses food (faster or slower metabolism) and differences in genes, therefore people have different pulse rates (ex: 60, 72, 80 per minute) even when resting, sitting. During exercise, heart rate and pulse increase. When sitting your pulse might be 72 per minute, when walking, your pulse might increase to 92 per minute and when running your pulse might even increase more to 108 per minute. Note: The heart beats at a rate causing the blood to flow, bringing enough oxygen and glucose to the cells and taking away carbon dioxide. During exercise, the heart beats faster (heart rate increases, pulse increases), therefore the blood moves faster and brings more oxygen and glucose to the cells of the body and removes more wastes. Respiratory System Air goes from the nose to the trachea, to the bronchi (bronchial tubes), and then to the lungs. The oxygen in the air goes from the alveoli in the lungs (by diffusion) to the blood, which goes to all parts of the body. Carbon dioxide from the cells of the body goes into the blood, then the carbon dioxide from the blood goes into the alveoli in the lungs, and then the carbon dioxide goes to the bronchi, and the trachea and out the nose. In short, the function of the respiratory system is breathing, also called gas exchange (to take oxygen into the body and remove carbon dioxide). Nasal cavity Trachea Lungs Bronchi Pharynx Larynx Bronchioles Alveoli Diaphragm Excretory System The excretory system consists of the lungs, kidneys (also ureters, urinary bladder, urethra), and sweat glands in the skin. The function of the excretory system is to remove wastes produced by the cells of the body. Vena Cava The kidneys remove wastes from the blood. The wastes (urine) go from the kidney to the ureter, to the urinary bladder, and then to the urethra and the Renal Vein. urine goes out of the body. Blood enters the kidneys through renal arteries and leaves through renal veins. Tubes called ureters carry waste products from the kidneys to the urinary bladder for storage or for release. In short, the excretory system eliminates non-solid wastes through sweat, exhalation, and urine. This helps the body maintain homeostasis. Main organs of the excretory system are the kidneys, ureters, urinary bladder, urethra, skin, and lungs. Ureter Endocrine System The endocrine system is made of endocrine glands (ex: pancreas, thyroid), that produce hormones (chemicals in the blood), which tell other organs (ex: liver) what to do. Like, regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things. The endocrine system also helps in cellular communication. The endocrine system regulates the body. For example, the pancreas produces the hormone insulin, which regulates the amount of glucose (sugar) in the blood. sto Endocrine system Pineal gland- Thymus -Aorta Nervous System The nervous system is made of the brain, spinal cord, and nerves. The nervous system helps in cellular communication. Nerves carry messages from the body. from your hands, feet, etc. (ex: you are touching a very hot spoon, you are stepping on a sharp object, a person is stepping on your foot, etc.) to the brain or spinal cord; the brain or spinal cord sends instructions to different parts of the body, telling the body how to respond. Ovary (in female) Testicle (in male) Renal Artery Kidney Bladder Urethra Hypothalamus Pituitary gland Thyroid and parathyroid glands -Pancreas Adrenal glands Placenta (during pregnancy) Reproductive System The function of the reproductive system is to produce more organisms of the same type. Male Reproductive System: The testes produce the sperm (make gamete). The sperm go from the testes to the sperm duct and then to the urethra, which is in the penis. Hormone: The testes produce testosterone, male sex hormone which influences (regulates) the development of secondary sexual characterists (ex: facial hair (beard) and a deep voice). Note: As you can see, the urethra is used in both the excretory system and the reproductive system. Vas Deferens Prostate Gland Urethra Epididymis Female Reproductive System: The ovaries produce eggs (female gamete). The egg goes from the ovary to the oviduct (fallopian tube) and then to the uterus. If sperm are present, the egg unites with a sperm (fertilization) in the oviduct. The fertilized egg then goes down to the uterus. Hormones: Ovaries produce estrogen (a female sex hormone) which influences the development of the secondary sex characteristics (developing mammary glands) and regulates the reproductive cycle. Penis Fimbriae Endometrium - Vagina Bladder Uterus 1 Cervix Ovary Ovaries produce progesterone (a female sex hormone), which regulates the menstrual cycle and prepares the uterus for a pregnancy. The hormone progesterone goes and attaches itself to the receptor on the uterus and tells the uterus to make a thick lining, which prepares the uterus for a pregnancy. In short, the male reproductive system produces the sperm; the female reproductive system produces the egg. The sperm and egg unite to form a new individual. Ureter Seminal Vesicle Erectile Tissue Scrotum Testis Fallopian Tube (Oviduct) Regulation The environment outside the body (such as a very loud noise or very high temperature) and inside the body (such as too much or too little sugar in the blood) keep changing. The nervous system (brain, spinal cord, and nerves) and the endocrine system (glands; ex: pancreas, ovaries) help to regulate, control how our bodies should react to the changing environment, and what our bodies should do. Our reactions to the changing environment should be coordinated. The nervous and endocrine system carry out the life process of regulation (control and coordination of life activities). Some of the responses of the nervous and endocrine systems are needed for homeostasis. You learned, the nervous system (ex: nerve cells) and the endocrine system (ex: pancreas) produce chemicals that help in cellular communication. The nervous system sends signals through the nerves. The endocrine system consists of glands that produce hormones that are carried by the blood. The nerves produce chemicals (neurotransmitters) and the endocrine system (glands) produce chemicals (hormones) to help in cellular communication. Movement The skeletal system (bones) supports the body. The muscular system (muscles) helps the animal move. Immunity The immune system fights organisms (ex: viruses, bacteria) that cause disease, protecting the body against disease. The immune system has white blood cells and antibodies that kill organisms that cause disease. On the surface of the pathogens (organisms that cause disease; ex: bacteria) are antigens. The white blood cells recognize the antigen and surround and engulf the pathogen (ex: bacteria, viruses) which has the antigen on it. Other white blood cells produce antibodies. Antibodies help white blood cells to fight pathogens. Antibodies and white blood cells together kill pathogens. Interaction Among Systems (Body Systems Work Together) Different body systems work together to carry out life functions. Examples of systems working together: 1. Digestive and circulatory systems: The digestive system digests food (breaks down food into simpler substances). Digested food is carried all over the body by the blood, which is part of the circulatory system. You can also say life functions (life processes) of digestion and transport (or circulation) work together. 2. Respiratory and circulatory systems: The respiratory system (nose, trachea, lungs) takes in oxygen, which goes into the blood (circulatory system)). The blood carries the oxygen to all cells of the body. The respiratory and circulatory systems work together. The blood (circulatory system) carries the oxygen to the cells of the body. In cellular respiration (also called respiration), glucose (simple sugar) unites with oxygen, producing energy, water, and carbon dioxide. The life function of transport works together with the life function of respiration (cellular respiration). 3. Digestive and respiratory systems: The digestive system breaks down food into simpler substances (ex: starch is broken into glucose). The respiratory system brings in oxygen. The glucose and oxygen combine in cells to give off energy (ATP). You can also say the life functions (life processes) of digestion and respiration work together. 4. Excretory and circulatory systems: Wastes produced in the cells go into the blood (part of the circulatory system). The blood brings the wastes to the kidneys (part of the excretory system) where the wastes are removed from the blood and leave the body. You can say life functions (life processes) of excretion and transport work together. 5. Endocrine and reproductive systems: The female reproductive system has ovaries which produce eggs. An egg and sperm unites together to form a child. Hormones from the endocrine system are needed to produce eggs and to prepare the uterus for a pregnancy. You can say life functions (life processes) of regulation (hormones) and reproduction work together. 6. Skeletal and muscle systems: the skeletal system (bones) supports the body. The muscular system (muscles) helps the animal move. When a person moves, it involves both the muscles and the bones, carrying on the life function (life process) of locomotion (moving from place to place). 7. Nervous system (brain, spinal cord, and nerves) and muscular system (muscles): when temperature drops, messages from the brain (part of the nervous system) signal the muscles to shiver, which produces heat and warms the body, The temperature of the animal is kept constant (humans have a constant temperature of about Muscular System Nervous System 98.60 F). The nervous system carries out the life function of regulation. When a person runs, the nervous system sends a message to the leg muscles (muscular system) to move quickly. 8. Endocrine system and circulatory system: The pancreas (part of the endocrine system) and blood (part of the circulatory System) work together. If the blood has too much sugar, the pancreas produces the hormone insulin, which attaches itself to receptors on the liver cells and tells the liver to remove sugar from the blood and store the sugar. Now the blood has the right amount of sugar. If the blood has too little sugar, a different hormone attaches itself to a specific receptor on the liver cells and tells the liver release the stored sugar, which goes into the blood. Now the blood has the right amount of sugar. The endocrine system carries out the life function of regulation (helps the body adjust to changes in the environment (in this case inside the body, too much or too little sugar in the blood)). You can say life functions of regulation (hormones) and transport (or circulation) work together. As you can see from the eight examples above, the systems of the body work together to carry out life functions (life processes). Examples of Homeostasis (Maintaining a Constant Internal Environment) The body (which has systems, organs, tissues, cells, and organelles) must work properly in order to maintain homeostasis. Homeostasis is a stable or balanced internal environment (same or constant amount of sugar, salt, water) in the cells of the organism. 1. You learned hormones from the pancreas (part of the endocrine system) keep the amount of sugar constant in the blood. 2. The kidneys (part of the excretory system) also regulate the amount of water and salts (ex: sodium) in the body and keep them constant. 3. White blood cells and antibodies help the body to stay healthy by fighting disease and maintaining homeostasis (a healthy constant environment inside the body). 4. The heart pumps blood to all parts of the body; the blood carries oxygen and food (glucose) to the cells and takes away carbon dioxide and wastes. In short, homeostasis means constant internal environment, constant amount of sugar, salt, water, etc, which is needed for the animal to be alive. Homeostasis is not maintained: (when systems, organs, tissues, cells, or organelles are not working properly): If a system (ex: circulatory system, excretory system) is not working properly (you can say, a disruption in the system), homeostasis is not maintained. 1. If the pancreas (part of the endocrine system) is not working properly, then obviously the sugar in the blood would not be constant and homeostasis would not be maintained (imbalance in homeostasis). If the pancreas produces too little insulin, there is too much sugar in the blood, Diabetes is a disease where there is too much sugar in the blood because the pancreas produces too little insulin. 2. If the kidneys (part of the excretory system) are not working properly, then the amount of water and salts would not be constant and homeostasis would not be maintained (imbalance in homeostasis). It is dangerous if there is too little sodium (salt) in the blood; it can be fatal. If there is too much salt in the body and the body cannot keep it at a good constant level, it can cause high blood pressure or too much fluid in the body. Note: other causes of high blood pressure are stress, genetics, and cigarette smoking. High blood pressure damages blood vessels and causes heart attacks, strokes, and kidney damage. 3. If there are too few white blood cells, the body cannot fight diseases. Note: Blood cells are part of the circulatory system. 4. In a heart attack, the heart muscle (the heart is part of the circulatory system) is damaged; the heart cannot pump enough blood to all parts of the body. In short, if any system, organ, tissue, cell, or organelle does not work properly, homeostasis would not be maintained (imbalance in homeostasis). Homeostasis is also not maintained if there is too much or too little of a needed chemical (ex: insulin, estrogen) Maintaining Homeostasis While Doing Very Strenuous Exercise During strenuous exercise, such as running a marathon, the runner sweats and the body loses salt and water. The body may lose too much salt, that the body cannot replace. The runner can drink sports drinks, which contain salt, (or eat salty foods) to make up the sale the runner lost by sweating. This helps the runner to maintain homeostasis. Diseases Caused by Organ Malfunctions Disrupt Homeostasis Diseases caused by organ malfunctions (organs such as the heart, kidney, or brain not working properly) are explained in the chart below. Organ Part of System Heart part of circulatory system Pancreas part of endocrine system Brai part of the nervous system Stomach part of digestive system Bronchi (bronchial tubes) part of respiratory system Disease: Organ Malfunction Heart attack Diabetes: too much sugar in the blood (high blood sugar) Stroke Ulcers: painful sores in the stomach wall Bronchitis: inflammation of the membrane of the bronchi Causes Blood clot (blockage) in artery that brings blood to heart muscle; therefore, blood cannot go to the heart muscle. Also, heart attacks can be caused by a high-fat diet, which narrows the arteries of the heart, causing blood clots in the heart. Too little insulin (undersecretion of insulin) Blood clot in blood vessel in brain. Too much stomach acid damages the stomach wall. Infection or other irritant (such as cigarette smoke) Effect Damaged heart muscle; cannot pump enough blood containing oxygen to body organs (ex: brain; part of nervous system). Too much sugar in the blood; causes poor circulation and damage to eyes. Causes brain damage: affects organs or systems; can harm movement, speech, breathing, etc. Painful sores in the stomach wall; causes bleeding. Difficulty breathing; not enough oxygen goes to cells (ex: brain cells). Kidney part of excretory system Kidney disease: kidney not working properly High blood pressure, diabetes Wastes not removed from blood; wastes can enter other systems and poison them. Kidneys not working properly can cause a dangerous amount of sodium in blood, which can cause death. In the next chapter, you will learn that diseases caused by viruses, bacteria, fungi, and parasites also disrupt homeostasis and hurt the body. All living things carry on Life Functions You learned that all living things (organisms that have one or more cells; ex: human) carry on life processes. You learned all life processes together (ex: transport, excretion, respiration) are called metabolism. In any cell (in a one-celled organism or a many-celled organism) the functions of the nucleus, cytoplasm, cell membrane, etc., is similar. Examples of one-celled organisms are the ameba and paramecium. One-celled organisms are also called single celled organisms or unicellular organisms. One-Celled Organisms Digestion: In a single-celled organism like an ameba or paramecium, food is digested in the food vacuole. In a multi-cellular animal (many-celled animal, example human), food is digested in the organs (mouth, stomach, small intestine) of the digestive system. Transport: The liquid inside the organism carries oxygen, carbon dioxide, and digested food throughout the organism: In a single-celled (one-celled) organism like the ameba or paramecium, the cytoplasm carries (transports) the digested food and oxygen throughout the organism. In the multicellular (many-celled) organism, the circulatory system (blood) carries digested food, oxygen, etc., throughout the organism. Taking in oxygen, giving off carbon dioxide: Look again at the diagram above and the chart below. In the one-celled organism, oxygen is taken in and carbon dioxide is given off through the cell membrane. In a multicellular (many-celled) organism, the organs (nose, trachea, lungs) of the respiratory system take in oxygen and give off carbon dioxide. Excretion: In a single-celled organism (example ameba or paramecium) wastes go through the cell membrane. In a multi-cellular organism, wastes go out through the organs (kidneys, urethra, etc.) of the excretory system (see chart below). food is digested in the food vacuole. In a multicellular animal (many-celled animal, example human), food is digested in the organs (mouth, stomach, small intestine) of the digestive system. Transport: The liquid inside the organism carries oxygen, carbon dioxide, and digested food throughout the organism: In a single-celled organism, the cytoplasm carries the digested food and oxygen throughout the organism. In the multicellular organism, the circulatory system (blood) carries digested food, oxygen, etc., throughout the organism. Taking in oxygen, giving off carbon dioxide: In the one-celled organism, oxygen is taken in and carbon dioxide is given off through the cell membrane. In a multicellular organism, the organs (nose, trachea, lungs) of the respiratory system take in oxygen and give off carbon dioxide. Excretion: In a single-celled organism (ex: ameba or paramecium) wastes go through the cell membrane. In a multicellular organism, wastes go out through the organs (kidneys, urethra, etc.) of the excretory system. Life Functions in a Single-Celled and Multicellular Organism Single Cell food vacuole Life Function Nutrition (included digestion of food) Liquid inside cell; carries food, oxygen, etc. Taking in oxygen, giving off carbon dioxide Excretion (getting rid of wastes) cytoplasm cell membrane cell membrane Multicellular Organism digestive system circulatory system respiratory system excretory system As you can see, the organelles inside the one-celled organism do the same function as the organ systems in a multicellular organism like the human body. You learned in a multicellular organism, the systems of the body must work properly in order to maintain homeostasis. Similarly, in a unicellular organism, the organelles must work properly in order to maintain homeostasis. You realize one-celled organisms and many-celled organisms carry out the same life functions (life processes).