Grade 8 Science: Human Digestive System PDF

GRADE 8 SCIENCE TOPIC 2.1 HUMAN DIGESTIVE SYSTEM MR. MARK CHRISTIAN AQUINO  LEARNING OBJECTIVE/S At the end of the session, you are expected to: 1.identify the parts and function of each part...

GRADE 8 SCIENCE TOPIC 2.1 HUMAN DIGESTIVE SYSTEM MR. MARK CHRISTIAN AQUINO  LEARNING OBJECTIVE/S At the end of the session, you are expected to: 1.identify the parts and function of each part of the digestive system; 2.describe the function of enzymes in digestive system; and 3.explain what happens to a piece of food as it goes through the digestive system.  DIGESTIVE SYSTEM It includes structures and organs that form the alimentary canal, or digestive tract. It also includes those structures or organs that do not directly act upon the food but secrete or store substances that aid in chemical digestion. The functions of the digestive system are: to ingest food to digest food to small nutrients molecules that can pass through membranes to absorb nutrient molecules to eliminate indigestible remains HUMAN DIGESTIVE SYSTEM PHASES OF DIGESTION Digestion Ingestion Elimination Assimilation Absorption  PHASES OF DIGESTION Digestion Ingestion Elimination Assimilation Absorption Ingestion Digestion Absorption Assimilation Elimination taking food breaking down moving food making food secretion of into the body and dissolving into cells part of cell unused food in food a form of feces ENGAGE BREAD IN A BAG Materials needed: Plastic bags or cups Crackers or bread Water Vinegar Baking soda Spoons  BREAD IN A BAG 1. Place a cracker or bread in a plastic bag, use a spoon to crush and mash the food, and observe the changes. What changes did you observe in the food as it was crushed? What do you think is happening during this step? MECHANICAL DIGESTION 2. Add water, vinegar, and baking soda to the crushed food and observe the changes. What happens when water, vinegar, and baking soda are added? What do you think these represent in the digestive system? CHEMICAL DIGESTION  TWO STAGES OF DIGESTION Mechanical Digestion Chemical Digestion  TWO STAGES OF DIGESTION Chemical Digestion  TWO STAGES OF DIGESTION Chemical Digestion CARBOHYDRATES PROTEINS CARBOHYDRATES PROTEINS FATS CARBOHYDRATES PROTEINS EXPLORE/ EXPLAIN DECODE YOUR BODY’S BUSY HIGHWAY Type the words in the block to label the picture.  PARTS OF THE DIGESTIVE SYSTEM Upon entering mouth, the food is physically broken into pieces by teeth. Mucus secreted by the cells lining mouth Mouth moistens the food and facilitates swallowing of the broken pieces. Saliva lubricates the food and secrets ptyalin (salivary amylase) – an enzyme that converts starch to maltose. Bolus is the food that has been chewed and mixed in the mouth with saliva.  PARTS OF THE DIGESTIVE SYSTEM After chewing and mixed the food inside the mouth, it goes down to alimentary canal. Pharynx Esophagus The food passes first in pharynx (throat) which also conducts air to trachea. From the pharynx, swallowed food pass to esophagus.  PARTS OF THE DIGESTIVE SYSTEM Epiglottis a flap of cartilage closes trachea when swallowing to prevent from entering the respiratory tract Peristalsis a rhythmic, wavelike muscular action that pushes the food down  PARTS OF THE DIGESTIVE SYSTEM Peristalsis A recall on structure of pharynx, epiglottis and esophagus:  PARTS OF THE DIGESTIVE SYSTEM A large, J-shaped organ found at the end of esophagus, on the upper left side of the body. It’s lining is a thick, wrinkled membrane in which numerous gastric glands are embedded. Common enzymes produced is protease (i.e., pepsin) – break down proteins into Stomach polypeptides. Hydrochloric acid produced is a strong acid that helps break down food. It also destroys most of the bacteria that may be present. The partially digested food that is retained before transferred to small intestine is called chyme.  PARTS OF THE DIGESTIVE SYSTEM Liver Gallbladder Pancreas PARTS OF THE DIGESTIVE SYSTEM Pancreas It secretes a pancreatic juice which neutralizes the acidic stomach contents (chyme) before passing into small intestine. It also produces digestive enzymes that act on all three major foods – carbohydrates, fats and proteins. Pancreatic juice contains enzyme: a) lipase – breaks down fats b) pancreatic amylase – digests starch c) trypsin and chymotrypsin – break polypeptides into amino acids PARTS OF THE DIGESTIVE SYSTEM Liver produces bile – a greenish-yellow consisting of waste products, cholesterol, and bile salts that is secreted by the liver cells to perform 2 primary functions:. 1) to carry away waste and; 2) to break down fats during digestion. PARTS OF THE DIGESTIVE SYSTEM Gallbladder A small pouch that stores bile until chyme triggers its release into the small intestine. It releases bile into the duodenum of small intestine through a bile duct. The cholesterol in bile can crystallize forming gallstones that partially block the duct to the small intestines.  PARTS OF THE DIGESTIVE SYSTEM Remember: It is in the small intestine that final digestion and absorption of food take Villi place. small finger-like projections found inside the inner walls of the small intestine Small intestines A tubular organ that completes digestion and absorbs nutrients and water. PARTS OF THE DIGESTIVE SYSTEM tiny extensions that mainly occur on the cell membrane of different organs Microvilli on the surface of epithelial cell adds to the surface of the small intestine. PARTS OF THE DIGESTIVE SYSTEM Three parts of small intestine: first part; short, descending chute (about 10 inches long) that curves around the pancreas in a “C” shape before connecting to the rest of the coiled intestines middle section; characterized by many blood vessels, which give it a deep red color last and longest section; where food spends the most time; it is where the most water and nutrients are absorbed.  PARTS OF THE DIGESTIVE SYSTEM It is also known as colon. It absorb water from the undigested food materials Large intestines that it receives from small intestines. It is bigger in diameter compared to small intestines. At the junction between small and large intestines is a small fingerlike outgrowth called the appendix – a vestigial organ, no specific function. However, a food and bacteria can be trapped in the appendix and cause Appendix inflammation (appendicitis). PARTS OF THE DIGESTIVE SYSTEM The remaining food materials, which then become more solid are called feces. Feces pass into rectum, a muscular cavity where they are temporarily stored and eventually eliminated through an opening called anus as waste.  ELABORATE GUT FEELINGS: CASE STUDY ABOUT DIGESTIVE SYSTEM DISORDER Read the case studies and identify what digestive system disorder is presented. Lactose Intolerance GERD Acute Appendicitis Irritable Bowel Movement  CASE STUDY 1 Lactose Intolerance Patient Profile: A 24-year-old male presents with abdominal pain, nausea, and fever. GERD Acute Appendicitis Details: Symptoms began with mild discomfort around the belly button, Irritable Bowel Movement progressing to severe pain in the lower right abdomen. Physical examination reveals tenderness in the right lower quadrant, along with rebound tenderness.  CASE STUDY 2 Lactose Intolerance Patient Profile: A 35-year-old female reports recurrent abdominal pain, bloating, and changes in bowel habits (diarrhea and GERD constipation). Acute Appendicitis Details: Irritable Bowel Movement Symptoms have been ongoing for over six months, triggered by stress and certain foods. She has no signs of structural abnormalities in her gastrointestinal tract.  CASE STUDY 3 Lactose Intolerance Patient Profile: A 30-year-old woman experiences bloating, gas, and diarrhea after consuming dairy products. GERD Acute Appendicitis Details: She has noticed these symptoms consistently after meals containing Irritable Bowel Movement lactose but has no history of gastrointestinal diseases.  CASE STUDY 4 Lactose Intolerance Patient Profile: A 45-year-old female complains of heartburn and regurgitation, particularly after meals. GERD Acute Appendicitis Details: Symptoms worsen when lying down or after consuming fatty Irritable Bowel Movement foods. He has tried over-the-counter antacids with minimal relief. Gastroesophageal reflux disease (GERD)  SDG 3 GOOD HEALTH AND WELL-BEING Sheila has been experiencing frequent heartburn and indigestion. Her diet includes the following below. What dietary adjustments can she make to reduce these symptoms, and why? LARGE MEALS ACIDIC FOODS FATTY FOODS CAFFEINE AND ALCOHOL ELABORATE MY PODIUM Share your insight on the illustrations in the next slides SDG 2 ZERO HUNGER AND SDG 3 GOOD HEALTH AND WELL-BEING Explain the saying, “You are what you eat” A DOSE OF REMINDER…  THE MALADY OF FOOD WASTE INQUIRER.net / 04:02 PM October 22, 2021 SDG 12 RESPONSIBLE CONSUMPTION AND PRODUCTION A reminder: Regulate the kind and amount of food you eat and Prevent food waste.  LESSON SYNTHESIS Today, you learned that… 1.The alimentary tract is composed of the mouth, pharynx, esophagus, stomach, small intestines, large intestine, and anus whereas salivary glands, pancreas, liver and gallbladder are the accessory organs. Both parts act upon the food for digestion. 2.The body generally cannot utilize food in its most complex form. There is a need to be broken down with help of several enzymes such as salivary amylase, pepsin, etc. 3.The flow of food: mouth – esophagus – stomach – (liver, pancreas and gallbladder) small intestine – large intestine – rectum – anus. LEARNING ACTIVITY 2.1: HUMAN DIGESTIVE SYSTEM Due Date: Day 5 of Week 2  REFERENCES Hoefnagels, Marielle (2019). Second Edition: General Biology (Books I and II). McGrawHill Education pages 557-571 Rogers, Kara (2011). The Human Body: The Digestive System (e-book/lib)