Digestion, Nutrition & Animal Diets

Digestion and Nutrition

• Digestion and nutrition are essential processes for obtaining energy and nutrients from food.

Consumers

• Heterotrophs cannot produce their own food and must consume other organisms.
• Autotrophs, like plants, make their own food using sunlight through photosynthesis.
• Heterotrophs consume food made by autotrophs.

Digestive Systems

• The human digestive system resembles that of a carnivore more than that of a herbivore.
• Humans have a longer small intestine to absorb more nutrients.
• A small cecum is for breaking down fibrous material.

Carbohydrates

• Carbohydrates are excellent sources of energy and can be broken down into glucose.
• Glucose is used to produce ATP, the cell's energy currency.

Respiration

• Humans and other animals obtain oxygen through breathing.
• Oxygen breaks down nutrients from food to make ATP.
• Carbon dioxide and water are generated as waste products.

Animal Diets

• Animals have different ways of obtaining and eating food due to differences in diets.
• Herbivores primarily consume plants and algae.
• Examples of herbivores include cattle, snails, sea urchins, and gorillas.
• Carnivores primarily consume other animals.
• Examples of carnivores include lions, dogs, whales, and spiders.
• Omnivores eat both plants and animals, ,like humans, cockroaches and rats.

Feeding Mechanisms

• Aquatic animals like clams and oysters are suspension feeders that filter small organisms or food particles from water.
• Maggots and earthworms are substrate feeders eating their way through their food source.
• Maggots feed on animal carcasses.
• Earthworms feed on decaying material in the soil, helping to fertilize and aerate it..
• Female mosquitos, ticks, and aphids are fluid feeders that get their food from blood or sap, while male mosquitos feed on nectar.
• Most animals that eat large pieces of food are bulk feeders.
• Snakes are bulk feeders, that eat their prey whole.

Food Processing

• Digestion starts by taking food into the mouth through ingestion
• Ingested food is broken down through digestion.
• Digestion breaks carbohydrates, fats, proteins, and nucleic acids down for nutrient absorption.
• Undigested materials exit the digestive system through elimination.

Ingestion

• Ingestion is the process of taking food into the mouth.
• Teeth, saliva, and the tongue play important roles in mastication to prepare food into a bolus.
• Salivary amylase in saliva starts to chemically process food.

Digestion Processes

• Animals use enzymes to break down food.
• Compartmentalization in digestion prevents body cells from being digested by enzymes.
• Digestion occurs in compartments surrounded by body cells, avoiding self-digestion.

Stomach Regions

• The four main regions of the stomach are the cardia, fundus, body, and pylorus.
• The cardia is where the esophagus connects to the stomach.
• The fundus is located inferior to the diaphragm, above and to the left of the cardia.
• The body is the main part of the stomach.
• The pylorus connects the stomach to the duodenum.
• The wider end of the pylorus is called the pyloric antrum.
• The narrower end of the pylorus is called the pyloric canal.
• The pyloric sphincter controls stomach emptying.
• A ruga is a large fold formed by the mucosa and submucosa when the stomach deflates.

Food Vacuoles

• Single-celled protists and sponges digest food inside food vacuoles.. Food vacuoles contain hydrolytic enzymes for food breakdown.

Gastrovascular Cavity

• Cnidarians and flatworms use a gastrovascular cavity as a compartment with only one opening, the mouth.
• Food is ingested through the mouth.

Alimentary Canal

• The alimentary canal is a digestive tract with two openings.
• Most animals have an alimentary canal.
• It allows digestion to proceed in one direction, enabling specialization in different parts of the tract.

Esophagus

• Different species have different names for the structure after the esophagus.
• Some species have a crop, which is used to make food softer and to store it.
• Other species have a gizzard or a stomach, both of which can store food and mechanically break it down.

Human Digestive System

• Digestion starts in the oral cavity with mechanical digestion.
• The teeth chew, cut, tear, and grind food.
• Salivary glands produce almost 1 liter of saliva, important for lubrication, buffering, and antibacterial effects.
• Saliva contains salivary amylase, which starts to break down starch.
• The tongue aids in the digestion process; it also shapes digested food into a bolus.
• The bolus is pushed to the pharynx by the tongue.
• The pharynx (throat) leads to the larynx, the adam's apple that connects to the lungs, and the esophagus connecting to the stomach.
• The epiglottis is a flap of cartilage which prevents the bolus from going to the lungs.

Esophagus Function

• The esophageal sphincter opens when food moves from the pharynx to the esophagus.
• Sphincters help move food in one direction only.
• Peristalsis, or involuntary muscular contractions, is responsible for food movement towards the stomach.

Stomach Functions

• The stomach stores up to almost 2 liters of food and fluid.
• It secretes gastric juice, which is composed of enzymes, mucus, and hydrochloric acid (HCl).
• Enzymes partially break down proteins.
• Mucus protects the cell lining of the stomach from being digested.
• Acid, at pH 2, kills most bacteria and other pathogens.

Absorption

• Digested food from the stomach is called chyme, and travels to the small intestine.
• The small intestine averages 3m (9ft) in length, with a diameter of 2.5 cm which is smaller compared to the large intestine 5cm diameter.
• The nutrients are absorbed into blood from the small intestine.

Small Intestines

• The three parts of the small intestine are the duodenum, jejunum and ileum
• The duodenum works as a mixing bowl for acid neutralization.
• The jejunum is where chemical digestion and nutrient absorption take place
• The 'bowel' consists of the small and large intestines.

Duodenum

• The duodenum receives the section of the liver and pancreas
• Bile from the liver breaks down fats in emulsification
• Pancreatic juice contains a basic component which helps neutralize the acidity of chyme..
• The pancreatic juice is responsible for complete digestion of food molecules.

Jejunum

• The main function of the jejunum is the absorption of important nutrients.
• The jejunum absorbs nutrients such as sugars, fatty acids, and amino acids.
• Peristalsis, the smooth muscle contractions, is vigorous and quick here.

Ileum

• The ileum is the final portion of the small intestine measuring around 3 meters.
• The ileum absorbs final nutrients like vitamin B12 and bile acids.
• It also absorbs other nutrients such as vitamins, minerals, carbohydrates, fats, and proteins. The ileum absorbs water so it can be used by the body.

Nutrient Digestion and Absorption

• Mechanical digestion of carbohydrates occurs in the mouth.
• Mechanical digestion of proteins occurs in the mouth and esophagus
• Mechanical digestion of fats occurs in the mouth, esophagus, and small intestine.
• Chemical digestion of carbohydrates occurs in the mouth and small intestine.
• Chemical digestion of proteins occurs in the stomach and small intestine.
• Chemical digestion of fats occurs in the small intestine.
• Absorption of all occurs in the small intestine and partly in the stomach
• Water is absorbed mainly in the stomach

Liver Functions

• The liver maintains homeostasis.
• Nutrients from the blood and lymph vessels are sent to the liver for processing.
• Excess glucose is converted to glycogen and stored in the liver and muscle cells.
• Excess calories are converted to fats.
• Liver synthesizes plasma proteins and lipoproteins to distribute cholesterol and fats.
• The liver regulates blood cholesterol levels.
• It detoxifies toxins from alcohol and drugs.
• The liver eliminates waste in the urine.
• Kupffer cells digest and destroy cellular debris and invading bacteria.
• The liver detoxifies exogenous substances such as drugs and alcohol.

Large Intestine Structure

• The name of the large intestine reflects its larger diameter
• The large intestine is much shorter than the small intestine.
• Its parts include the cecum, appendix, colon, rectum, and anus.
• The cecum is a pouch where the small and large intestines meet.
• The appendix is a finger-like projection of the that contributes minimally to immune system function by storing white blood cells.

Appendicitis

• Appendicitis happens when the inside the appendix is blocked caused by infections or stool

Large Intestine Function

• The main function of the large intestine: reabsorption of water.
• 90% of the 7 L of water that goes through the digestive tract is reabsorbed.
• Reabsorption occurs during the movement of wastes through the colon.
• Feces are mainly undigested bacteria, fiber, and other wastes.
• Bacteria in the large intestine help break down digestible material and produce vitamins B and K.

Elimination

• The rectum stores feces that are eliminated through the anus.
• The urge to defecate occurs when muscles of the colon contact.
• Two sphincters control the opening of the anus.
• The inner sphincter prevents the rectum from opening while sleeping and is made up of smooth muscles.

Colon Cancer

• Colorectal cancer affects the colon (large intestine) or rectum.
• It is one of the most common types of cancer worldwide.
• The risk of colorectal cancer increases with age especially over 50 years old.
• Common symptoms include diarrhea, constipation, blood in the stool, abdominal pain, weight loss, fatigue, and low iron levels.

Macronutrients

• Their components synthesize new molecules The body needs

Raw Materials

• Aside from raw materials, the food that we eat, specifically carbohydrates, supply the energy needed for all cellular processes.

Micronutrients

• Vitamins and minerals in small quantities are important for our metabolic needs.
• Our diet must supply with three basic needs:
• Sources of raw materials
• Energy
• Vitamins and minerals

Vitamin C

• Vitamin C, also called ascorbic acid, is an antioxidant that protects the body's cells against free radical exposure.
• Vitamin C helps the body produce collagen, improves iron absorption, and helps immune system function.
• Adult women typically need 75 milligrams (mg); adult men need 90 mg of Vitamin C.
• citrus fruits, kiwis, red and green peppers, strawberries, and broccoli are good sources of Vitamin C.
• Cooking can reduce a food's vitamin C content.

Vitamin B1

• Vitamin B1, also known as Thiamine, helps the body use carbohydrates for energy.
• Vitamin B1/Thiamine plays a critical role in nerve function, skin, hair, and muscle health.
• Adult women typically need 1.1 mg, while adult men typically need 1.2 mg of Vitamin B1.
• Whole grains, meat (especially pork), fish, legumes, seeds, nuts, and fortified bread, cereal, pasta, and rice are good sources of Vitamin B1/Thiamine.

Vitamin B2

• Vitamin B2, also called Riboflavin helps convert food into energy.
• Vitamin B2/Riboflavin is important in the growth and function of body's cells and plays a key role in metabolism, especially fats, drugs, and steroids.
• Adult women typically need 1.1 mg, adult men typically need 1.3 mg of Vitamin B2/Riboflavin.
• Good sources of Vitamin B2/Riboflavin include animal products like eggs, organ meat, low-fat milk, and green vegetables like broccoli and spinach.

Vitamin B3

• Vitamin B3, also known as Niacin, helps convert food into energy and is important in the development and function of body's cells.
• Adult women typically need 14 mg; adult men need 16 mg of Vitamin B3/Niacin.
• Poultry, beef, pork, fish, nuts, legumes, grains, and many enriched and fortified breads and cereals are good sources of Vitamin B3/Niacin.

Vitamin B5

• Pantothenic acid or Vitmain B5, helps convert food into energy and helps your body produce and break down fats.
• Adults typically need 5 mg per day of Vitamin B5
• Patothenic acid is naturally present in most foods.
• Good sources of Vitamin B5 are beef, poultry, seafood, mushrooms, avocados, potatoes, broccoli, whole grain, peanuts, chickpeas, and sunflower seeds.

Vitamin B6

• Vitamin B6/Pyridoxine is used in over 100 different enzyme reactions involved in aiding the body's metabolism.
• It also plays a key role in brain development during pregnancy.
• Adults typically need 1.3 mg of of Vitamin B6.
• Good sources of Vitamin B6 include fish, organ meat, potatoes and other starchy vegetables, and non-citrus fruits.

Vitamin B7

• Good sources of Vitamin B7 are like whole grains, fish, egg yolks, seeds, nuts and certain vegetables like spinach, broccoli, and sweet potatoes.
• Helpful for healthy bones and hair

Vitamin B9

• Plays an important role in cell division and the creation of DNA and other genetic materials/ Asparagus, brussels sprouts, dark green leafy vegetables

Vitamin B12

• Can aids the body in production of red blood cells and protects nerve cells.

Other Vitamins

• Essential nutrients are molecules our bodies cannot make even with raw meterials
• Essential B9/Folate plays an important role in cell division and creaton of genetic materials and DNA.
• Essential B12 are need for vegetarian because of their diets

Protein Importance

• Proteins are built from 20 Amino acids and can be consumed through meat in the body.

Solutions for Obesity

• Balanced diets in correct portions and exercise are key to obesity for better health..

Risks of certain diets

• Can lead to cardiovascular diseases