The Digestive and Excretory Systems Nutrition • Nutrition is the science or study of how our bodies obtain energy, build tissue, and control body functions using materials supplied in the food we eat • Food contains nutrients (molecules that provide energy and material for growth and repair) • Humans are heterotrophs-obtain their food • Autotrophs (i.e. Plants) are capable of producing their own food Types of Nutrients • Organic nutrients include carbohydrates, proteins, lipids , and vitamins • Inorganic nutrients include water and minerals • Scientists refer to the energy stored in food as dietary calories • Adolescent females require about 2200 calories per day and males require about 2800 per day • A balanced diet includes foods from the four basic food groups: vegetables and fruit, grain products, dairy products, and protein-rich foods Nutrients Continued Carbohydrates- most of the energy made up of Carbon, Hydrogen, and Oxygen (1:2:1 ratio) sugars and starches monosaccharides, disaccharides, and polysaccharides Nutrients Continued Proteins- Provides the body with material necessary for growth and repair Made up of amino acids Lipids or Fats Your body does need a certain amount of fat in order to be healthy Three fatty acids joined to a Glycerol molecule Saturated fats or Unsaturated fats Nutrients continued Vitamins- Do not contain energy Water -soluble and fat- soluble Needed by the body in very small amounts that serve as coenzymes Play a role in cellular reactions When the body does not receive a sufficient supply , it can develop a vitamin deficiency Minerals – Inorganic substances required by the body for normal functions Nutrients continued A balanced diet usually provides all the necessary minerals Water- Essential nutrient and most important Most of our bodies weight is water Solvent We lose between 3-5 L of water through sweat, urine, and exhaled air Dehydration Digestion • The Digestive System includes: the mouth, the pharynx, esophagus, stomach, small intestines, and large intestines • Several major accessory structures include salivary glands , the Pancreas, and the Liver all add secretions to the digestive system • The function of each organ of the digestive system is to help convert foods into simpler molecules that can be absorbed and used by the cells of the body Path of Digestion Food is ingested through the mouth. It is here where food is broken down into chewable and swallow able chunks by the teeth and the tongue (mechanical digestion). The teeth do much of the mechanical digestion by cutting, tearing, and crushing food into smaller fragments. The salivary glands secrete saliva, which helps to moisten food and make it easier to chew. Amylase is an enzyme that breaks down chemical bonds between the sugar monomers and the starches. • Pharynx-the food then passes from the mouth or oral cavity into the pharynx. As the tongue moves food into the pharynx, it presses down on a small flap of cartilage called the Epiglottis. Once in the Pharynx swallowing becomes involuntary and the medulla is the part of the Brain the controls swallowing. • Esophagus-food is then passed through the food tube or esophagus and into the stomach. The food moves down the esophagus by involuntary muscle contractions known as peristalsis. Path of Digestion • The sphincter closes the esophagus after food passes into the stomach and prevents contents from moving back up. • Reverse peristalsis • Stomach-food enters the stomach from the esophagus. The stomach contains microscopic gastric glands that release mucus, hydrochloric acid, and gastric juices. Pepsin is also produced , especially useful for protein digestion. • Ulcers are lesions of the digestive tract lining Path of Digestion • The semi-liquid mass of partially digested food known as Chyme enters the duodenum and into the small intestines. • Pancreas-the presence of chyme in the duodenum causes the release of pancreatic fluid from the pancreas. The pancreas is a gland that formed by the duodenum and under the surface of the stomach. The pancreas produced hormones that regulate blood sugar levels, produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acid. Path of Digestion • Liver- assists the pancreas and produces bile. Bile helps to neutralize the chyme from the stomach and emulsifying fats. Bile is stored in the gall bladder. • Small Intestines- made up of the duodenum, jejunum, and the ileum, specially adapted to absorb nutrients because it is covered with villi. • The Large Intestines-main job is to reabsorb water and electrolytes. Diarrhea occurs when there is interference with water absorption. Today’s Agenda • Aim: What is the job of the excretory system? • Do Now • Class Discussion • Group work • Closing The Excretory System DO NOW How is the process of preparing a pot of coffee using a coffee filter, ground coffee, and boiling water similar to the processes involved in human excretion? The Human Excretory System The excretory system plays a major role in maintaining homeostasis The organs of excretion are the skin, lungs, and kidneys The liver may also be considered an organ of excretion Carbon dioxide, urea, water, and salts are all metabolic wastes produced by humans The Skin Epidermis (outer layer) protects dermis Dermis (inner layer) Sebaceous glands-produce oils Sweat glands-produce sweat that is released through holes called pores Helps to remove excess heat because evaporation of sweat cools the body The Lungs • Upon exhaling the lungs rid the body of carbon dioxide and water vapor The Kidneys • Main organ of the excretory system • 2 kidney’s located on either side of the spinal column near the lower back • Play a role in maintaining homeostasis by regulating the water content of the blood, and, therefore, blood volume, maintains blood pH, and removes waste products from the blood • Urine (urea, water, salts, and other waste products) • Filtration and reabsorbtion The Urinary System • The kidneys, ureters, the bladder, and the urethra • Urine passes from each kidney through the ureter to the urinary bladder where it is stored • During urination, the urine travels from the bladder to the outside of the body through the urethra during urination Structure of the Kidney • 3 main parts of the kidney: cortex ( the outer part), the medulla ( the middle part) , and the pelvis ( inner region) • Renal artery and renal vein supply kidneys with blood • Over 1 million nephrons • Each nephron is made up of a glomerulus, Bowman’s capsule, and a renal tubule • The glomerulus is a network of capillaries • Bowman’s capsule is a double walled chamber that surrounds the glomerulus Structure of Kidney • Proximal tubule is a segment of the nephron tubule where water, sodium ions, glucose, and amino acids are absorbed • Loop of Henle is where the proximal tubule leads, and it is here that sodium ions are actively transported out • Distal tubule is where additional sodium and water can be reabsorbed • Collecting tubule receives urine from smaller tubules The Liver • Detoxification –removes harmful waste from the blood • Overloading the liver with alcohol can lead to cirrhosis and the liver becomes overgrown with extra tissue • Cirrhosis limits the function of the liver and can lead to death Interference • Kidney stones- substances in urine crystallize in the urinary tract or kidney • Gout is a disorder where uric acid builds up and is stored in the body, usually the joints or big toe • Humans can survive with one kidney , but if both are damaged by disease or injury there are two ways to keep the person alive 1. Kidney transplant from a compatible donor 2. Dialysis Partner Discussion • What is the purpose of a urine test? • What can a urine test possibly detect?