Life Maintenance Systems: Nutrition and Excretion Notes

Autotrophs

Organisms that produce their own food from inorganic materials; also known as producers.

Heterotrophs

Organisms that cannot produce their own food and obtain energy by feeding on other organisms.

Herbivores

Animals that consume only plants.

Carnivores

Animals that consume only meat.

Omnivores

Animals that eat both plants and meat.

Detritivores

Organisms that feed on dead organic materials.

Carbohydrates

Sugars that serve as a main source of energy for organisms.

Proteins

Nutrients made of amino acids that are essential for growth, repair, and various functions in the body.

Amino Acids

Building blocks of proteins; some are essential and cannot be synthesized by the body.

Fats

Nutrients that provide energy and are essential for various body functions; offer twice the energy per gram as carbohydrates.

Digestion

The process of breaking down food into nutrients, which can then be absorbed by the body.

Intracellular Digestion

Digestion taking place within cells, involving phagocytosis.

Extracellular Digestion

Digestion occurring outside of cells, often in specialized digestive compartments.

Gastrovascular Cavity

An incomplete digestive system with only one opening.

Complete Digestive Tract

A digestive system with separate mouth and anus.

Endocytosis

Process by which cells take in substances by engulfing them in a vesicle.

Phagocytosis

Cell eating; a form of endocytosis where cells engulf large particles.

Pinocytosis

Cell drinking; a form of endocytosis where cells engulf fluids.

Basal Metabolism

The amount of energy needed for vital activities while at complete rest.

Metabolism

All the chemical reactions occurring within an organism's body.

Vitamins

Complex organic molecules needed in small amounts; cannot be synthesized by the body except for Vitamin D.

Minerals

Inorganic substances essential for various functions in the body.

Fiber

Indigestible materials found in fruits and vegetables that aid in digestion.

Assimilation

The process of transporting and absorbing digested food into body cells.

Kidney

An organ that filters blood, removes waste, and regulates water and electrolyte balance.

Nephron

The functional filtering unit of the kidney.

Urea

A less toxic nitrogenous waste that is produced from ammonia and excreted by the kidneys.

Egestion

The process of expelling undigested material from the body.

Filtrate

The waste fluid resulting from filtration in the kidneys.

Gastric Juice

Digestive fluid produced in the stomach that changes food into chyme.

Villi

Small finger-like projections in the intestines that aid nutrient absorption.

Peristalsis

The rhythmic contraction of muscles to move food through the digestive tract.

Insulin

A hormone produced by the pancreas that facilitates the uptake of glucose by cells.

Glucagon

A hormone that prompts the conversion of stored glycogen back into glucose when needed.

Epithelial Cells

Cells that line the surfaces of the body and are involved in absorption processes.

Electrolytes

Minerals that carry an electric charge and are vital for many body functions.

Protease

An enzyme that breaks down protein molecules into amino acids.

Carbohydrase

An enzyme that breaks down carbohydrate molecules into sugars.

Lipase

An enzyme that breaks down fats into fatty acids and glycerol.

Salivary Amylase

An enzyme in saliva that begins the chemical digestion of carbohydrates.

Chyme

The semi-fluid mass of partially digested food found in the stomach.

Pancreatic Juice

A mixture of digestive enzymes produced by the pancreas.

Bile

An alkaline fluid produced by the liver that aids in the emulsification of fats.

Gallbladder

An organ that stores bile before it is released into the small intestine.

Rectum

The final section of the large intestine where feces are stored before elimination.

Anus

The opening at the end of the digestive tract through which feces are expelled.

Dehydration

A condition that occurs when the body loses more fluids than it takes in.

Excretion

The removal of waste products from the body.

Transpiration

The process of water loss in the form of vapor from the surfaces of plant leaves.

Blood Pressure

The force of circulating blood against the walls of blood vessels.

Glomerulus

A cluster of capillaries in the kidney involved in filtration.

Renal Tubules

Parts of the nephron where reabsorption and secretion occur.

Collecting Ducts

The final part of the nephron where urine is collected before being excreted.

Ureter

The duct through which urine is conveyed from the kidney to the urinary bladder.

Urinary Bladder

A muscular sac that stores urine before it is expelled from the body.

Urinate

The act of expelling urine from the body.

Chronic Kidney Disease

A condition characterized by gradual loss of kidney function over time.

Dialysis

A medical treatment to filter wastes from the blood using a machine.

Kidney Stones

Solid crystalline masses formed in the kidneys that can cause pain during excretion.

Essential Amino Acids

Amino acids that cannot be synthesized by the body and must be obtained through diet.

Deficiency Disease

Health problems caused by the lack of essential nutrients.

Chlorine

An essential mineral needed by the body in relatively large amounts.

Potassium

A mineral important for function of nerve and muscle cells, including heart function.