The Digestive System and Excretory System By: Kay Foos, Amanda Smith, Joanna Dare, Lilli Blumkin Kay
Digestive System The function of this system is to break down the food particles into materials the body can use The digestive system includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine Some other important structures are the salivary glands, the pancreas, and the liver Kay
The Mouth The mouth is where mechanical and chemical digestion begins The main parts of the mouth are the teeth and the saliva Teeth: do most of the mechanical work in the mouth Saliva: do most of the chemical work; contains an enzyme called amylase that breaks the chemical bonds and releases sugars from starch Kay
The Esophagus This is the food tube to the stomach Bolus is the clump of chewed food Peristalsis works to contract the esophagus to push the bolus down into the stomach A ring of muscle called the cardiac sphincter closes the esophagus and prevents the contents of the stomach from moving back up Kay
The Stomach It continues the mechanical and chemical breakdown of bolus on its journey through the digestive system Alternating contractions of the stomach s three smooth muscle layers thoroughly churn and mix the food you swallow Kay
Joanna
The Stomachs Mechanical and Chemical Digestion Mechanical: stomach muscles contract to churn and mix stomach fluids and food producing chyme; the pyloric valve opens and chyme flows into the small intestine Chemical Mucus protects the stomach wall from all the strong acids like hydrochloric acid; pepsin digests proteins Kay
Small Intestine This is where almost all of digestive enzymes enter The duodenum is the first of three parts; it mixes enzymes and digestive fluids from the pancreas and liver into chyme Pancreas: an organ just behind the stomach; a gland that regulates blood sugar levels, produces enzymes, and produces sodium bicarbonate Liver: an organ above the stomach; produces bile which disolves and disperses the droplets of fat in fatty foods Gallbladder: where bile is stored Joanna
Absorption The small surfaces of the small intestine are covered with little projections called villi Nutrient molecules are constantly absorbed into the cells lining the small intestine By the time food is ready to leave the small intestine, its is nearly nutrient free Joanna
Large Intestine a.k.a. the COLON The primary function is to remove water from the undigested material that is left Colonies of bacteria present in the large intestine produce compounds that the body uses the concentrated waste remains after the water has been removed passes through the rectum Joanna
Joanna
Fun Facts of Digestive System When large doses of antibiotics are given to fight an infection they can destroy bacteria that make Vitamin K The powerful acids released into the stomach sometimes damage the organs own lining producing a hole in the stomach wall known as a peptic ulcer If not enough water is absorbed during digestion, diarrhea occurs Joanna
Excretory System The four organs used for excretion: - skin - lungs - liver - kidneys The process by which metabolic wastes are eliminated is called excretion. Lilli
Homeostasis The process of maintaining a controlled, stable internal environment The kidneys help maintain homeostasis by: Removing waste products from blood Maintaining blood ph Regulating the water content of the blood Amanda
Kidneys Main organs of the excretory system Located on either side of the spinal column The components that make up the kidneys are the ureter, urinary bladder, renal medulla, renal cortex, and nephron Amanda
Functions of Components of Kidneys Ureter: the tube that carries urine from the kidney to the urinary bladder Urinary bladder: a saclike organ where urine is stored Renal medulla: inner part of the kidney Renal cortex: outer part of the kidney Nephron: functional part of the kidney Amanda
Blood Purification The kidney removes waste from blood that enters the kidney through the renal artery The kidney removes urea, a toxic compound, excess water, and other waste products and passes them through the ureter The clean, filtered blood leaves the kidney through the renal vein and returns to circulation Amanda
Filtration Passing a liquid or gas through a filter to remove waste, and takes place in the glomerulus The glomerulus is a small network of capillaries The materials that are filtered from the blood are collectively called the filtrate The filtrate contains water, urea, glucose, salts, amino acids, and some vitamins Bowman s capsule is a hollow, cup-shaped structure Lilli
Reabsorption The process of which liquid is taken back into a vessel Not all the filtrate is excreted; most of the materials removed from the blood makes its way back into the blood Materials including amino acids, fats, and glucose are removed from the filtrate by active transport and reabsorbed by the capillaries When the filtrate drains in the collecting ducts, most of the water and nutrients have been reabsorbed into the blood Lilli
Urine >;D The material that remains, emptied into a collecting duct The tube that releases the urine from the body is called the urethra Concentrated in the loop of Henle Amanda
Kidney Function As the amount of water in the blood increases, the rate of water reabsorption in the kidneys decreases The kidneys are controlled by the composition of blood itself Regulatory hormones are released in response to the composition of blood Lilli
What if the kidney doesn t work? There are two options: - the first way is to transplant a healthy kidney from a compatible donor to the person in need of the kidney - the second way is a kidney dialysis machine, which literally mimics the functions of the kidney Lilli
Lilli
Fun Facts of Excretory System Kidney stones is when substances such as calcium, magnesium, or uric acid salts in the urine>;d crystallize and form kidney stones; when they block the ureter, they cause great pain Humans can survive with one kidney Amanda