The Digestive and Excretory Systems

Objectives To list the organs of the digestive and excretory systems To describe the function of the organs of the digestive and excretory system To compare and contrast the digestive and excretory systems To explain how the digestive and excretory systems relate to each other as well as in relation to other body systms

Components Esophagus Stomach Small Intestine Large Intestine Gall bladder Liver Pancreas

Digestive System This system is responsible for breaking down food into a useable form of energy for the body

Alimentary Canal Path food travels through the body (your digestive tract) – From mouth to the anus

Organs of the Digestive system Mouth – Digestion starts here – Mechanically breaks down food by the chewing mechanism Chewing is called mastication – Here there are enzymes (present in saliva) that also aid in the break down of food Enzymes are chemicals that simply break up particles/bacteria/viruses… etc – Words ending in –ase are usually enzymes

Stomach Esophagus

the tube that connects your mouth and your stomach

You have a trap door called the epiglottis to cover your windpipe when you swallow.

Organs of the Digestive System Esophagus- muscular tube through which food travels to the stomach – Food moves along the digestive system by means of a muscular movement called peristalsis Peristalsis is an involuntary contraction (and relaxation) of muscles in the digestive system that moves food along the alimentary canal – At the beginning of the esophagus is a small flap (or gate-like structure) called the epiglottis that closes off the entrance to the trachea when you swallow

11 Peristalsis

Stomach A stretchy bag that holds your food after you eat Helps to break food into smaller pieces so your body can use it for energy and nutrition

Organs Stomach- muscular organ responsible for the further breakdown of nutrients – Mixing chamber and storage chamber Chemical break down through stomach acid Mechanical break down through churning/mixing – No food is absorbed through the stomach wall (which is coated with mucus to prevent the stomach acid from “eating through” itself)

Small Intestine

Tube that is 20 feet long. Continues to digest food Food stays in your small intestine for 4 to 8 hours

Organs Small intestine- chemical digestion continues here; in fact, most of the chemical digestion occurs here along with NUTRIENT ABSORPTION! – From ~15 to 32 feet Average 17 feet – Has 3 sections Duodenum- – ~10 inches – digestive juice are secreted from intestine, pancreas and liver are mixed with the food to further break it down

Small intestine cont Pt 2 – Jejunum- ~4 to 7 ft long Food nutrients are absorbed here Pt 3 – Ileum- ~5 to 7 feet long More food absorption occurs here

Small intestine Food absorption – Villi- small tube structures that cover the wall of the small intestine Used for food/nutrient absorption – Food absorbed in the small intestine enters the blood stream in the capillaries and is transported throughout the body (to where needed)

Liver

Factory for antibodies and bile Stores vitamins and sugars until your body needs them

Food Processors Liver- the largest internal organ – Functions as an aid to the digestive system in 2 ways 1 through production of bile- yellowish-greenish fluid used for digestion of fats in the small intestine 2 to filter toxic substances from the body and it stores excess glucose

Gall Bladder

Storage tank for bile (a greenish-yellow liquid) that helps your body break down and use fats Located under your liver Shaped like a pear

Pancreas Helps you digest food by breaking down sugars

Large Intestine

Tube that is 5 feet long Gets waste from small intestine Waste stays for 10 to 12 hours

Garbage Disposal Large Intestine/Colon – Measures about 5 feet long – This organ absorbs most of the water and some of the remaining nutrients left from the food you ate – After food has finished its trip through the colon it moves to the rectum and then anus to be excreted as fecal matter

Large Intestine/Colon Also aids the immune system in that it contains healthy bacteria to fight off harmful bacteria (or microorganisms) – These bacteria also provide vitamins for the body

Functions of the Digestive System Digest the food we eat Take the nutrients out of your food so your body can use it

Human Excretory System

Excretory System The kidneys regulate the amount of water, salts and other substances in the blood. The kidneys are fist-sized, bean shaped structures that remove nitrogenous wastes (urine) and excess salts from the blood. The ureters are tubes that carry urine from the pelvis of the kidneys to the urinary bladder. The urinary bladder temporarily stores urine until it is released from the body. The urethra is the tube that carries urine from the urinary bladder to the outside of the body. The outer end of the urethra is controlled by a circular muscle called a sphincter.

Kidneys Two reddish organs just above the waist behind the stomach Filter the blood and removes waste

Food Processors Gallbladder- located beneath the liver and stores the bile produced in the liver Pancreas- located behind the stomach and produces pancreatic juices – Pancreatic juices are sent to the small intestine to aid in digestion of carbohydrates, proteins and fats

The Job of the Kidneys They are responsible for cleaning the blood by removing metabolic wastes, excess solutes, and excess water and excreting them as urine Besides removing urea, it also removes excess salts or glucose, the remnants of drugs (reason for urine tests), and excess water.

Function of the Kidney The principal function of the kidney is to filter blood in order to remove cellular waste products from the body. At any given time, 20 % of blood is in the kidneys. Humans can function with one kidney. If one ceases to work, the other increases in size to handle the workload.

NOTE Since the kidneys control what leaves and what remains in the nephrons, they maintain the levels of water, ions and other materials nearly constant and within the limits to maintain homeostasis.

Urinary Bladder Smooth muscle bag Stores waste solution - urine

Urethra Connects bladder to outside of the body Allows urine to pass out of the body

Ureter Connects the kidneys to the urinary bladder

Nephron Filtering unit of the kidney Blood enters full of waste and leaves filtered Blood enters under high pressure and flows into the capillary beds

Regulation of Water Levels If the blood becomes too dilute or too concentrated with solutes, then it can interfere with normal cellular activity. The kidneys are able to regulate water concentration in the blood by removing excess water if the blood is too dilute or conserving water in the blood if it is not dilute enough

Waste Products Carbon dioxide – a waste product of cellular respiration is dumped into the blood stream and eventually removed by the lungs Ammonia (NH 3 ) is removed through water – This waste comes from the cells breakdown of old proteins – It is also what makes bleach smell so in high concentrations it is poisonous to the cells and must be removed

Formation of Urine If there is too much water in the blood, then it is removed and put in urine. If there is not enough water in the blood, the kidneys will not remove it. If there is too much urea or other solutes in the blood, the kidneys will remove these excess solutes. By regulating solute numbers and water volume, the kidneys normally maintain homeostasis in blood solute concentration.

Why is excretion necessary? In order for cells to stay alive, they must continually intake water and other molecules. The cells would continue to get bigger and bigger if they only took in molecules They must also export molecules – These molecules may be important signaling molecules such as hormones, or they may be molecules of glucose on their way to other cells, or they may be waste products of cellular metabolism that cells need to dispose.

Removal of Ammonia Once excreted into the blood stream by cells, it is carried to the liver where it is converted from ammonia into urea which is much less toxic It is then carried from the liver to the kidneys where it is removed

Excretory System Problems Kidney stones – crystalized mineral salts and uric acid salts in the urine. Stones block flow of urine and cause excrutiating pain. Kidney failure - can be caused by long-term diabetes, infections, physical injuries, chemical poisoning. Causes toxic materials to build up to lethal levels. Dialysis or kidney transplant is the treatment.

Describe the functions of a person's urinary system Rids the body of wastes, control blood volume, balances salts & water

Explain how the kidneys remove wastes and keep fluids and salts in balance Kidneys filter the blood to remove extra wastes, sugar, water, and salt. Sugar, water, and salt still needed by the body is returned to the blood.

Describe what happens when the urinary system does not function properly. Wastes are not removed. This causes the destruction of cells. Water not removed causes swellings and too much water around the heart. Slats that are not taken away can cause organ damage.

Compare the excretory system and urinary system The excretory system is made of all body organs that get rid of wastes. The urinary system is made of organs that produce urine as a waste.

How is your urinary system similar to a water-purification system? It serves as a filter to screen out harmful materials and helps get rid of wastes in the blood

When you drink a lot of water, you also need to urinate often. Why? The job of the kidneys is to eliminate excess water and wastes. If you drink more than your body needs, it is eliminated by the urinary system.

Healthy Habits Eat foods that are high in fiber like fruits and vegetables

Drink plenty of water

Chew your food completely before you swallow

Interesting Facts Food is in your digestive system for about 24 hours

Your stomach stretches when you eat like a balloon being filled with air