Systems

Nutrients & Digestion Key Concepts

• Food contains the nutrients we need for energy and growth

• A balanced diet provides fuel and building materials

• You must process food in your digestive system in order to use the nutrients effectively

• Food processing occurs in 4 stages

Nutrients:

• All living things need essential nutrients to:

  • Build and maintain body structures

  • Perform life functions

  • Obtain energy for survival

• Essential nutrients are the basic chemical building blocks required by organisms.

• There are 6 essential nutrients.

The 6 Essential nutrients

Divided into 2 groups:

• Macronutrients (Body needs in larger amounts)

  • Carbohydrates

  • Proteins

  • Fats

  • Water

• Micronutrients (Body needs in smaller amounts)

  • Vitamins

  • Minerals

Processing molecules

• Food contains molecules that are too large and complex for cells to use directly

• Digestive system breaks food into smaller molecules

  • Smaller molecules→ Can be used by cells for energy and are converted into macromolecules.

  • Macromolecules→ Help build cell structures and maintain cell structure/function.

Carbohydrates

• Made of Carbon, hydrogen, and oxygen atoms

• Provide a quick source of energy

• The fast energy released can cause a “sugar rush”

• Simple sugars are the most basic unit of carbohydrates

• The most basic fundamental building blocks of simple sugars are monosaccharides

Monosaccharides (Carbohydrates)

• “one sugar”

• Cannot be broken down into simpler compounds

• Combine chemically to form disaccharides and polysaccharides

Disaccharides (Carbohydrates)

• “double sugar”

• Form when 2 simple sugars combine

Polysaccharides (Carbohydrates)

• Complex carbohydrates made of many linked sugar units

• Starch(plants) and glycogen (animals) are glucose based Polysaccharides that store energy

• Cellulose (Polysaccharides) provides structural support in plants

• Glycogen is stored in liver and broken down into glucose when energy is needed

Fiber (Carbohydrate)

• Made of cellulose found in veggies, whole grain, etc.

• Also called “roughage” → not completely digestible

• Helps clean the digestive system and moves food and waste through the guts.

Lipids (fats)

• Provide energy and are used to build cell membranes and hormones

• They help insulate the body, protect organs, absorb vitamins, and conduct nerve impulses

• Are made of a glycerol backbone with 3 fatty acid tails

• Dietary fats come from nuts, cheese, oil, etc.

• There are 3 types of fats.

3 types of fats

• Saturated fats (straight chains) → made from animals, recommended to consume

• Unsaturated fats (double bond) → lower calories

• Trans fats (hydrogenated → hydrogen extends the shelf life, not recommended to consume

Proteins

• Made of a amino acid subunits linked by peptide bonds into polypeptide chains

• Antibodies, many enzymes, and some hormones are proteins.

• Proteins help build and repair muscles and cell membranes

• Humans cannot produce 9 amino acids called essential amino acids

  • Complete proteins contain all 9 essential amino acids.

Minerals

• Are inorganic compounds needed in small amounts

• They help chemical reactions and build bones

• Don’t contain carbon and are easily absorbed into bloodstream

• Important parts of hemoglobin, hormones, enzymes, and vitamins

Vitamins

• Are only needed in small amounts but are essential

• Act as co-enzymes for enzyme function

• support tissue growth, development, and immune defense

• Vitamin D is made in the skin from sunlight, Vitamin K and some B are made by gut bacteria

• Vitamin A and D are stored in body

• VItamins are fat or water soluble

DIfference of Vitamins and Minerals

• Vitamins→ found in plants/animals, can be lost during food prep, all are beneficial

• Minerals→ come from the earth, not easily lost during food prep, not all are beneficial

Water

• Makes up 2/3 of body weight and is essential for all body functions

  • Transports nutrients, removes waste, lubricates tissues, and forms body fluids

  • Regulates body temperature and helps eliminate waste through urine and sweat

  • Maintains fluid balance by replacing lost fluids

    • Is lost through breathing, sweating, urine, and bowel movements

Structure and Function of the digestive system

• Cellular respiration releases energy for food

• Glucose reacts with oxygen to produce energy, CO2, H2O

• About 40% of the energy is used by cells, 60% becomes heat to maintain body temperature

Calories

• A calorie is the energy needed to raise 1 gram of water by 1 degree celsius

• A dietary calorie equals 1000 calories

• Carbohydrates, proteins, and fats provide energy through cellular respiration

• Fats contain more energy per gram than carbohydrates

• THe body needs daily calories to sustain life

Foods that may fight diseases

• Nutraceuticals→ foods derived substances taken like medicine for health benefits

• Functional foods → provide extra health benefits beyond basic nutrition

Probiotics

• They all beneficial bacteria that support health

• Antibiotics can kill helpful bacteria

• Probiotics foods like yogurt can help restore them

Invertebrate DIgestive system

1. Gastrovascular Cavity→ one opening used for both eating and waste removal

2. Alimentary Canal → has 2 openings (mouth for eating, anus for waste removal)

Human gastrointestinal track

• Passageway extending from the mouth to anus (7-9 meters long)

• Inside the digestive track is technically outside the body

• 4 stages to food processing

  • Ingestion→ taking in food

  • Digestion → Breaking down food into nutrients

  • Absorption→ taking in nutrients by cell

  • Elimination/egestion→ Removing ant leftover waste

Organs

• Organs food and liquid pass through the gastrointestinal tract

• Accessory organs help digestion by producing/storing substances

  • Together they form the digestive system

The human digestive system(mouth to Esophagus)

• DIgestion begins in the mouth

• Teeth physically break down food

• salivary amylase starts chemical digestion by breaking down carbohydrates

• Tongue forms food into a ball called a bolus

• Bolus moves to the pharynx (throat)

• Epiglottis directs the bolus into into the esophagus, preventing it from entering the trachea (closes it off)

• Bolus moves through the esophagus by peristalsis

Movement and Control

• Peristalsis → wave-like muscle contractions that push food to stomach

• Sphincters → ring shaped muscles that open and close to control the movement of food and waste through digestive system

• Accessory glands → glands that secrete substances(like enzymes and fluids) to help with digestion

Mouth (Ingestion)

• Mechanical digestion (teeth breaking food)

• Chemical Digestion (Saliva)

  • Amylase (enzymes that digest starch)

  • Mucin (Mucus helps make swallowing easier)

  • Buffers (Neutralizes acid to prevent tooth decay)

  • Anti-Bacterial chemicals (kills bacteria)

The human digestive system(Lower esophageal sphincter to Start of small intestines)

• Bolus enters stomach through lower esophageal sphincter(muscle that blocks stomach acid from going back into the esophagus)

• Stomach has folds called rugae

  • Muscular pouch that churns food and mixes bolus with gastric juices( acid, mucus, enzymes)

    • Acid→ Kills off bacteria/viruses

    • Mucus → protects the lining of stomach from being eaten away from acid

    • Enzymes → Helps break down proteins and lipids through chemical digestion

• Stomach does some absorption

• Digested food becomes chyme, chyme leaves the stomach through pyloric sphincter

• Chyme enters the small intestine (Most absorption happens here→ Liver and pancreas help)

Small intestine is broken into 3 parts

1. Duodenum

2. Jejunum

3. Ileum

Duodenum

• Bile from the liver/gallbladder enters through the bile duct to break down fats

• Pancreas secretes pancreatic juice to reduce chyme acidity

Jejunum

• Main site of absorption that is lined with villi that increase surface area for nutrient absorption

  • Villi have microvilli that increase the surface area even more

  • Villi contain blood(where sugar and amino acid enter) and lymph vessels(where fats enter)

  • Glucose and amino acid are absorbed by active transport, fructose absorbed by passive transport.

    • All travels through intestinal epithelial cells to capillaries to portal vein to the liver.

    • Nutrient rich blood goes to the liver for processing and detoxifying. Blood then travels to the heart and rest of body.

Ileum

• Compacts leftovers before passing them to the large intestine through the caecum

• Large intestine absorbs water and produces vitamin K and some B vitamins with help from bacteria.

• Water is stored in rectum (end of large intestine)

• When full, the anal sphincter relaxes

• feces leaves the body through the anus

Pancreas

• Digestive enzymes

  • Peptidases (breaks down protein)

    • Trypsin (Trypsinogen)

    • Chymotrypsin (Chymotrypsinogen)

    • Carboxypeptidase(procarboxypeptidase)

  • Pancreatic amylase (breaks down carbohydrate)

  • Buffers (reduces acidity)

Liver

• Bile is made in liver and stored in gallbladder

  • Enters small intestines via bile duct

  • Emulsifies fats (breaks into smaller droplets to increase surface area)

Appendix

• Small pouch at the caecum (start of large intestine)

• Supports immunity and stores good bacteria

• Can become infected (appendicitis)

• Removed by appendectomy

Mensentary

• Folded membrane

• Holds/suspends intestines in abdominal cavity

• supplies blood vessels

• Carries nerve and lymph vessels

Digestion and homeostasis

• Body system coordinates digestion

• smell triggers saliva and gastrin release

• Gastrin increases stomach acid

• Large meals speed up stomach emptying

• High fats slow digestion, fat keeps you feeling full longer.

Structures of the Circulatory system

• Blood vessels, blood, and the heart work together to transport substances that are vital to health.

• Blood contains useful substances and cellular wastes. The substances are exchanged between the blood and other tissues.

• Lymphatic system→ a transport system that recycles fluid needed in the circulatory system

Key functions of the circulatory system

1. transport gases, nutrient molecules, and waste materials

2. Regulates internal temperature and chemical substances

3. protects against blood loss and disease causing microbes or toxic substances

Blood

• circulates through the body delivering nutrients and removing waste materials

• Blood is made up of red blood cells,white blood cells, platelets that are all mixed in plasma

Plasma

• 55% of human blood is made up of plasma

• A liquid made up of proteins, minerals, dissolved salts, and water.

Red Blood cells

• Makes up 45% of blood

• Body produces 2 million every second

• Responsible for carrying oxygen from your lungs to your cells and carrying carbon dioxide from your cells to your lungs

• One blood drop contains 5 million red blood cells that contain 250 million molecules of hemoglobin.

Hemoglobin

• Protein that binds oxygen in the lungs and releases it through the body

• Also binds carbon dioxide, removing it from cells and bringing it to lungs.

• Also known as “erythrocytes” → red-hallow, red colour and ability to carry oxygen comes from a special iron rich protein inside of hemoglobin.

White Blood cells

• Also called “leukocytes”

• Defends the body against bacteria/viruses

• Forms antibodies that protect the body from future attacks

• Makes up round 1% of blood (can double when body is fighting)

• Phagocytosis→ process of engulfing and destroying pathogens

5 main types of white blood cells:

1. Lymphocytes

• Produce antibodies that prevent pathogens from harming the body and can be easily detected then destroyed

2. Monocytes

• Circulates in the bloodstream for only a few days before specializing into macrophages

3. Neutrophils

• Most abundant, found in the body tissues and blood

4. Eosinophils

• Found in mucus lining of digestive and respiratory tracts

5. Basophils

• Help immunity by secreting substances that attract phagocytes to destroy pathogens

Platelets

• Contains enzymes that trigger a chemical reaction that converts liquid clotting proteins into a tough, sticky mesh of firin fibers that heal wounds.

• Collect around the edges of a wound, breaks themselves open and release the enzymes

• Also known as “thrombocytes”

Blood vessels

• the body’s transportation system is like roads that all go one way

• 3 types of blood vessels:

  • Arteries

  • Veins

  • capillaries

Arteries

• Carry blood away from the heart

• Have muscular walls that send the blood throughout the body

• Everytime the heart contracts, it sends out a gush of blood under high pressure, leading to the artery walls expanding

• Between every contraction (heart beat) the pressure decreases, leading to arteries going to their normal shape.

• Each time the artery expands/contracts the blood moves along→ this rhythm is called the pulse

• Much thicker than veins and most located deep in body → because its much high pressure so if cut blood with gush out

Veins

• Carry blood towards the heart

• Have valves (folds/flaps that prevent blood from backing up)

• Since blood in veins is lower pressure, they are located closer to bodies surface

• Clotting can easily be stopped if cut

Varicose veins

• Swollen/twisted veins that are usually just not aesthetic, but can sometimes lead to serious issues. Ex, blood clots.

Capillaries

• Tiny blood vessels that join arteries to veins

• Usually walls are no more than 1 cell thick

• Nutrients and gases diffuse into the cells through the capillary walls

• Wastes diffuse from the cells to the capillaries

Heart

• 4 chamber pump that moves blood

• adjust its heartbeat to match bodies needs

• When exercising, heart beat speeds up, increases the volume of blood pumped to meet your increased needs for nutrients/oxygen

Anatomy of heart

• Made of a special kind of muscle (only found in heart)

• The muscles are connected so they expand and contract at the same time

• Made of→ left atrium, right atrium, left ventricle, right ventricle

• The atria are smaller than the ventricles and their walls are thinner since they only need to pump blood to ventricles

• The ventricles have to pump blood to the lungs and around whole body

• Left ventricle is the strongest

• Each atrium is separated from its ventricle by a valve → act as a one way door

Valves of the heart

• The atria and ventricles are separated from each other by 2 valves called atrioventricular valves

  • Right side called tricuspid valve (made of 3 flaps)

  • Left side is called bicuspid or mitral valve (made of 2 flaps

• Other 2 valves are called semilunar valves

  • Right side→ pulmonary valve

  • Left side→ aortic valve

Lymphatic system

• Network of vessels, nodes, and organs

• Collects the fluid that leaves the capillaries and detects any micro-organisms

• Releases lymphocytes to kill any disease causing bacteria

• Maintains fluid balance (collects excess fluid and transfer back to bloodstream)

• Fluid collected is called lymph

• Blood