Nutrition Digestion Excretion Science in Our Lives II

Nutrition Digestion Excretion Science in Our Lives II Unit 1

Nutrition Definition Process of taking materials from environment and changing it to a usable form Essential nutrients for life include lipids (fats), proteins and carbohydrates Also important are vitamins, minerals, fiber and water Functions: growth, repair, regulatory molecules (enzymes, hormones), energy

Nutrient Composition What makes up a nutrient? Water is made up of hydrogen and oxygen molecules Vitamins and minerals are made up from numerous elements from the periodic table such as iron and calcium The main building blocks of nutrition include: Proteins (which are made by connecting amino acids together) Lipids or fats (which are made by connecting 3 fatty acids together with 1 glycerol molecule) Carbohydrates/starches (which are made by connecting simple sugars together

Nutrient Composition Protein Example - Notice that this protein (the entire purple strand) is made up of individual amino acids Ex. Enzymes, hormones, connective tissue, chlorophyll, hemoglobin Function: structure, function

Nutrient Composition Fat (or Lipid) Example - Notice the 1 glycerol molecule and the 3 fatty acids that make up a fat molecule Ex. Oils, waxes, etc. Function: energy

Nutrient Composition Carbohydrate Example - Notice how simple sugars (like glucose) join to form a carbohydrate Glucose (a simple sugar) Ex. Simple sugar = glucose Complex sugar = starch Function: energy Maltose (a carbohydrate)

Two types of Nutrition Autotrophic Nutrition The organism MAKES its own nutrients using a process called photosynthesis Ultimate nutrient produced is glucose (a simple sugar) Organisms who make their own food are called AUTOTROPHS or PRODUCERS Example: All green plants ODDITY: HETEROTROPHIC PLANTS! Heterotrophic Nutrition The organism must obtain nutrients from its environment by grazing plants or eating other organisms Photosynthesis is NOT possible by these organisms Organisms who must find nutrients because they cannot make their own are called HETEROTROPHS or CONSUMERS Example: All animals

Autotrophic Nutrition Photosynthesis -Chemical reaction where plants make glucose from sun’s energy - produces O 2 for the planet Reactants - Materials that interact with each other in a reaction Photosynthesis Song Products - Materials that are created from the reactants interacting with one another

Where does photosynthesis occur? Most photosynthesis occurs in the palisade layer of the leaf because that is where most of the plant’s CHLOROPLASTS are located -Cholor 0 plasts (tiny green organelles in plants) trap the sun’s light which is needed for photosynthesis to take place -Remove the leaves from a green plant and the amount of food (glucose) they produce is reduced dramatically -Hmm… Do plants make food in winter then?

Basic Leaf Parts 6. Cuticle 1. Palisade Layer 2. Spongy Layer 7. Upper Epidermis 8. vein 3. Air spaces 4. Guard Cells 9. Lower Epidermis 5. Stoma

Leaf Part Definitions Cuticle: waxy layer of leaf that prevents excess water loss Upper/Lower Epidermis: “skin” of the leaf Palisade layer: part of leaf where most chloroplasts are; glucose production abundant in this layer Spongy layer: area of leaf that contains “air spaces” for gas transport Vein: tube that runs through leaf to deliver water and nutrients

Leaf Part Definitions Guard cells: cells on underside of leaf that swell or deflate in order to allow gas exchange through the stoma Guard cells swell or “puff up” to close off the stoma They will deflate to allow air through the stoma Stomata: stoma, singular; small openings on the underside of the leaf that allow the exchange of oxygen and carbon dioxide between the leaf and the outside environment STOMATA VIDEO CLIP

Feedback Mechanism in Stomata Sometimes the stomata must be open to allow water and gases in for photosynthesis; other times the stomata must be closed as protection This is called a feedback mechanism -If it is really hot and dry outside, the stomata will be closed to lower water loss -If it is cooler and humid outside, the stomata will be open to increase water content -This allows the plant to maintain homeostasis or equilibrium -More or less of either water or gas will affect the rate of photosynthesis Cooler weather Hot, dry weather

Photosynthesis Feedback Mechanism What can affect the rate of photosynthesis? Low CO 2 levels means low photosynthesis rates High CO 2 levels means higher photosynthesis rates Low sunlight levels means low photosynthesis rates High sunlight levels means high photosynthesis rates Low temperature levels means low photosynthesis rates High temperature levels means high photosynthesis rates

Autotrophic Nutrition Once a plant makes glucose from photosynthesis, the plant still needs to perform another process to change that glucose into usable energy called ATP This conversion of basic nutrients like glucose into energy is called RESPIRATION This occurs in the mitochondria of the plant Respiration will be discussed in detail later on in the year

Heterotrophic Nutrition If an organism is a HETEROTROPH, then they must obtain food from their environment Heterotrophs perform three main processes as part of nutrition: • Ingestion: act of putting the food source in the oral cavity of the organism (usually the mouth) • Digestion: act of internal organs breaking the food source down in smaller, simpler molecules • Egestion: the removal of the indigestible food product in the form of feces

Digestion In-Depth Definition The breakdown of nutrient molecules (lipids, proteins, carbohydrates/starches) for use by the cells of the organism’s body Allows these large, complex nutrient molecules to be broken down into simpler, smaller molecules Performed by heterotrophic organisms such as dogs, cats, humans, pigs, lizards Involves two types: mechanical and chemical digestion

Types of Digestion Mechanical Digestion Breakdown of food into smaller pieces using force Involves the use of muscles and teeth Does not change the nutrient molecules Occurs in the mouth and stomach only Increases the surface area of food Ex. Chewing a piece of steak with your teeth Chemical Digestion Breakdown of food into its most simple, molecular form The nutrient is no longer the original nutrient but rather its building blocks Involves the use of enzymes and chemicals Occurs in the mouth, stomach and small intestine Ex. Protein pieces of steak breakdown into amino acids

Enzymes How can we speed up digestion? Use an enzyme!!! Enzyme: a catalyst (a material that speeds up a reaction) of a specific shape; it remains unchanged • Ex. A Lock and Key • The key opens the door (door changes; now open) but the key does not change • Each key is unique to each lock; a specific shape

Enzymes – A specific shape!

Enzymes – A specific shape! Want to break down a protein into amino acids? - Must have an enzyme that matches SHAPE with a protein Want to break down a carbohydrate or starch into simple sugars? - Must have an enzyme that matches SHAPE with a carbohydrate or starch Want to break down a lipid (fat) into fatty acids and glycerol? - Must have an enzyme that matches SHAPE with a lipid (fat)

What affects the rate of enzymes? p. H The p. H (level of acidity or basicity) can either slow a reaction down or speed it up Each enzyme functions (works) best at a particular p. H can also denature (change shape) of enzymes that causes the enzyme not to work anymore; shapes no longer fit together

What affects the rate of enzymes? Temperature Enzymes work best at a particular temperature, depending on the enzyme If the temperature is too low, an enzyme will either be too slow to start or not work at all If the temperature is too high, the enzyme will denature (change shape) and the enzyme will no longer fit onto the molecule

What affects the rate of a reaction? Concentration of enzyme The amount of enzyme and substrate (what’s being acted upon by the enzyme) can affect the rate of an enzyme Too little enzyme or too little substrate slows the reaction down The reaction reaches a point where it cannot happen any faster because the enzymes run out of substrates to pair with

Human Digestive System Order Food Passes Through: 1. Mouth 2. Esophagus 3. Stomach 4. Small intestine 5. Large intestine 6. Rectum 7. Anus **Notice: Liver, gall bladder and pancreas not included in the order because food does not pass through them

So how does digestion in humans begin? Mechanical digestion begins with teeth chewing the food Chemical digestion Starts in the mouth with the Chyme: the soupy mixture (gastric juice) created in the stomach from the mixture of the enzymes, acids and food nutrients enzyme amylase (in saliva)breaking down starches/carbohydrates into simple sugars Proteins begin digesting chemically Peristalsis: muscular in the stomach; pepsin (an enzyme contractions that push food specific to protein) starts to break along the gastrointestinal tract the protein down into amino acids Muscular contractions in the GASTRIC JUICE VIDEO CLIP stomach continue mechanical digestion PERISTALSIS VIDEO CLIP

Digestion in Humans Chemical digestion continues in the small intestine The pancreas releases 3 enzymes into the small intestine that continue to help breakdown nutrients As the nutrients travel through the small intestine, these enzymes continue to break the food down into a form that can be absorbed Remember, each pancreatic enzyme can only work with a specific nutrient of matching shape

Bile – An emulsifier At the same area that the pancreas secretes enzymes into the small intestine, the gall bladder secretes BILE into the small intestine The liver makes the bile; gall bladder stores it Bile “chops up” the fat molecules into smaller, more digestible pieces Bile breakdown is NOT chemical digestion

Absorption What happens to these nutrients that have been broken down by enzymes? Villi of the small intestine “soak up” or Villi: fingerlike projections within the small intestine that increase the surface area so more nutrients can be absorbed absorb these nutrients The nutrients diffuse (pass through) into the blood stream Once on the “blood bus”, the nutrients are transported to all the cells of the body The cells use these nutrients to do chemical processes

Egestion Solid nutrient materials that cannot be absorbed by the villi of the small intestine pass into the large intestine (colon) The large intestine (colon) absorbs excess water surrounding these larger, indigestible food nutrients, creating feces Feces then passes through the rectum and out the anus This is called egestion

Digestive Disorders Ulcer: a sore/hole in the stomach mucus lining due to excessive acid production; caused by bacterial infection, stress, aspirin, ibuprofen and smoking Indigestion: painful or uncomfortable feeling in the stomach typically after eating; usually an indication of an underlying problem Tooth decay: bacterial infection in the mouth; caused frequently by a lack of brushing and flossing; triggers the development of cavities

Digestive Disorders Anorexia: eating disorder where one refuses to eat or eats very little; body begins to starve to death from lack of nutrients Bulimia: eating disorder where one consumes food (often in large amounts) and then vomits the food up to avoid gaining weight; can include the use of laxatives; causes severe damage to the esophagus and teeth

Digestive Disorders Constipation: difficulty moving food product through the digestive track due to a lack of fiber and water in the diet; feces has difficulty exiting the body; can cause intestinal cramping as well Diarrhea: typically caused by a bacterial infection, condition where feces is extremely loose and runny; excessive water retained within the stool

Excretion When nutrients are digested, and when cells use the nutrients that are delivered to them by the “blood bus”, waste products form Ex. Think of eating an egg; what is the waste product from cracking an egg open? These waste products must be removed from the body, otherwise they can become toxic The removal of the cell’s wastes is known as excretion

Which waste products must be removed from the body? Carbon dioxide: CO 2 is a by-product of making ATP (energy) during respiration; this gas must be removed from the body Water: excess water is a by-product of making ATP (energy) during respiration and synthesis; this is removed to maintain water balance Urea and salt: these are both by-products from protein digestion and must filtered out of the blood stream

Organs of Excretion Lungs The lungs remove carbon dioxide from the blood stream The carbon dioxide comes from all the cells of the body after they make energy (ATP) The “blood bus” carries this carbon dioxide away from every cell and drops off the CO 2 at the lungs where it is exhaled Excess heat and water also are excreted at the lungs as well

Organs of Excretion Liver The liver filters the blood of certain toxins such as those associated with drugs, alcohol and chemical by-products of various reactions within the body Once the liver filters these by products, they can then be transported to the kidneys for complete excretion from the body

Organs of Excretion Skin The skin helps regulate (control) body balance or homeostasis by keeping the body cool To maintain body temperature, the skin excretes excess heat, water, salt and a little urea The large surface area of the human body allows the skin to release excess heat very effectively

Organs of Excretion Kidneys The two kidneys filter urea, salt and other chemicals from the body Tiny filtering units in the kidneys called nephrons remove these toxins The toxins then flow out of the kidney through tubes called ureters The ureters deposit the toxins, now in the form of urine, into the bladder, where they exit out through the urethra

Homeostasis in the Kidneys How does our body maintain water balance if our kidney’s remove it from our body? On hot days, because your body sweats to cool it down, expect to produce less urine to make up for that loss On days where you consume lots of water, expect to urinate more to maintain proper water levels When your body is dehydrated, your body reabsorbs more water through the kidney, instead of releasing it in the form of urine, so expect less urine production on those days as well

Excretion Disorders Dialysis: this is a PROCEDURE that involves a machine which filters one’s blood if the kidneys are no longer able to do so efficiently Typically the person goes to the hospital a few times a week Blood leaves the body and enters a machine that filters the toxins out, and then the blood returns to the body Jaundice: yellowing of the skin typically caused when bilirubin, a by-product of broken down red blood cells that is not properly removed; may be an indication the liver is not functioning correctly

Excretion Disorders Cirrhosis of the liver Heavy scarring of the liver due to repeated damage or disease The cell tissue scars over and can no longer filter the blood Jaundice may be a side effect since the toxins are not being removed from the blood efficiently Common causes: alcohol and drug use