Nutrition Review for Exam III: Body Organization and Digestion

Levels of Body Organization

The levels of structure, hierarchy of life, in living things is: Atom -> molecule -> organelle -> cell -> tissue -> organ -> organ system -> organism.

Cell

The basic unit of life.

Prokaryotic Cell

Simple cells with no nuclear membrane nor membrane-bound organelles, very small in size, probably evolved first.

Eukaryotic Cell

Complex cells with a nuclear membrane and membrane-bound organelles, large in size, probably evolved later.

Nucleus

Brain of the cell.

Nucleolus

Makes ribosomes.

Cell membrane

Outer boundary of cell; transport.

Mitochondria

Power house of the cell.

Rough Endoplasmic Reticulum

Transport and helps make proteins.

Smooth Endoplasmic Reticulum

Lipid synthesis.

Ribosomes

Makes proteins.

Golgi Body

Refines proteins.

Centrioles

Cell division.

Vesicles

Intracellular storage.

Lysosome

Intracellular digestion.

Cytoplasm

Center of metabolism.

Cilia

Move materials across cell surface.

Flagella

Move entire cell.

Microvilli

Increases the surface area of a cell; improves absorption.

Tissue

Two or more cells working together to perform some function.

Epithelium

Linings and coatings.

Connective Tissue

Connects body components.

Muscle Tissue

Support and movement.

Nervous Tissue

Responsiveness and regulation.

Organ

A group of two or more tissues working together to perform some specialized function or form a structure.

Serous Membrane

Lines closed body cavities; serous fluid moistens organs.

Mucous Membrane

Lines open body cavities; mucous is a protective fluid.

Synovial Membrane

Found in joints; synovial fluid lubricates joints.

Organ System

Consists of two or more organs working together to perform some functions.

Integumentary System

Composed of the skin and the organs of the skin; functions in protection and temperature regulation.

Muscular System

Composed of the skeletal muscles of the body and the tendons; functions in support and movement.

Skeletal System

Composed of bones, cartilages, and ligaments; functions in support and movement.

Nervous System

Composed of the brain, spinal cord, cranial nerves, spinal nerves; functions in responsiveness and regulation.

Endocrine System

Composed of the endocrine glands; functions in responsiveness and regulation.

Digestive System

Composed of the stomach, esophagus, teeth; functions in nutrition, the digestion and absorption of food and nutrients.

Respiratory System

Composed of the lungs, the trachea, diaphragm; functions in gas exchange.

Cardiovascular System

Composed of the heart, blood vessels, and the blood; functions in the transport of materials throughout the body.

Lymphatic System

Composed of lymph nodes, tonsils, lymphatic vessels.

Urinary System

Composed of the kidneys, ureters, urinary bladder, etc.

Functions of the Urinary System

Functions in removal of toxic waste from the body and in acid-base, water and electrolyte balance.

Reproductive System

Composed of the ovaries, testes, fallopian tubes, prostate gland, etc.

Functions of the Reproductive System

Functions in the continuation of the species.

Digestive System

Details of the digestive system include components, functions, pre-treatment of food, types of digestion, step by step digestion.

Components of the Digestive System

Oral cavity, Teeth, Tongue, Salivary Glands, Esophagus, Stomach, Small Intestine, Appendix, Large Intestine, Anus, Pancreas, Liver, Gall Bladder.

Ingestion of Food

Taking in of food, occurs in the Mouth (oral cavity).

Digestion of Food

Breaking down of food into nutrients, occurs in the Stomach.

Absorption of Food

Uptake of nutrients by cells and or by blood, occurs in the Stomach, Large intestine, small intestine.

Elimination of Food

Removal of indigestible material from the body in the form of feces and urine.

Digestive System

Some 16 feet in length from mouth to anus.

Mechanical digestion

Refers to digestion by mechanical processes only.

Chemical digestion

Refers to digestion by enzymatic processes.

Salivary amylase (ptyalin)

The major enzyme that converts starch into maltose.

Lingual Lipase

An enzyme used for fat digestion that does not work until it enters the stomach.

Bolus

Food converted by the oral cavity prior to swallowing.

Taste buds

Located primarily on the tongue; responsible for detecting different tastes.

Sweet

Taste detected for carbohydrates.

Sour

Taste detected for acids.

Salty

Taste detected for metal ions.

Bitter

Taste detected for alkaloids/toxics.

Umami

Taste detected for savory beef proteins.

Esophagus

Extends about 10 inches from the mouth to the stomach and functions to transfer food.

Epiglottis

Covers the top of the trachea during swallowing to help prevent choking.

Peristalsis

Involuntary process that moves food down the esophagus.

Gastroesophageal sphincter

Closes behind food to seal off the stomach.

Gastric juice

Composed of enzymes and hydrochloric acid with a pH of 1.5 to 2.

Chyme

Semisolid food converted in the stomach.

Pyloric sphincter

An involuntary ring of smooth muscle that food passes through to leave the stomach.

Small intestine

Small diameter, long in length measuring from 9 to 15 feet long.

Duodenum

About 10 inches long; acidic chyme mixes with alkaline secretions of pancreas and gall bladder.

Jejunum

Middle section of small intestine measuring 3 to 5.5 feet long where most digestion and absorption occurs.

Ileum

Last segment of the small intestine measuring 5-9 feet long.

Intestinal lipase

An enzyme secreted by the cells of the small intestine.

Lactase

An enzyme secreted by the cells of the small intestine.

Small intestine transit time

It takes food about 3 to 5 hours to move through the small intestine.

Ileum digestion

Most food is digested and absorbed completely by the time it reaches the middle of the ileum.

Liver functions

The liver produces and stores many nutrients, makes cholesterol, bile, and metabolizes fats.

Bile function

Bile helps to digest fats and to prepare fats and fat-soluble vitamins for absorption.

Liver detoxification

The liver also detoxifies materials such as alcohol.

Gall bladder function

The gall bladder stores bile until needed.

Gall bladder contraction

When food enters the duodenum of the small intestine, the gall bladder contracts and sends bile to the small intestine to facilitate digestion.

Gall stones

The gall bladder is prone to gall stones which may make its removal necessary.

Pancreas enzyme secretion

The pancreas sends large amounts of enzymes to the duodenum to facilitate digestion.

Pancreatic lipase

An example of an enzyme secreted by the pancreas to aid in digestion.

Bicarbonate ions

The pancreas also secretes bicarbonate ions to help neutralize the acidity in the duodenum.

Small intestine enzyme pH

Small intestine enzymes do not function at acidic pH levels.

Insulin function

The pancreas secretes hormones such as insulin to help with glucose.

Cholecystokinin

The hormone _______ stimulates the pancreas to secrete enzymes and the gallbladder to contract and release bile.

Large intestine length

The large intestine is about 5 feet long.

Large intestine function

Little digestion occurs here; mostly water and mineral absorption occurs and the formation of feces.

Chyme to feces conversion time

Chyme is converted into feces within 18-24 hours.

Food pre-treatment

Foods are processed prior to consumption by removing undesirable parts, cleaning, and cooking.

Nutrient loss

Sometimes nutrient loss can occur due to food pre-treatment.

Bioavailability

The extent to which the digestive tract absorbs a nutrient and how well the body uses it.

Villi function

The interior of the small intestine is lined with villi, where most absorption of nutrients occurs.

Microvilli

The villi are covered in ____

Passive absorption

Absorption can occur passively with diffusion, moving from high to low concentration without energy.

Active absorption processes

Absorption can occur actively by processes such as pinocytosis and phagocytosis.

Capillaries and lymphatic vessels

Materials are absorbed into either capillaries or lymphatic vessels.

Hepatic-portal vein

Materials enter the villus and are transported via the ______ to the liver.

Chylomicrons

Lipids are packaged into chylomicrons and are sent via lymphatic vessels and eventually enter into circulation.