Chapter 12 Review

Carbohydrates are the main source of energy e.g. grains such as rice

fruit and vegetables give the body vitamins and minerals

dairy contains calcium for bones

protein helps muscles to grow and repair

fat helps insulate the body and protect organs

There are 4 types of macromolecule: carbohydrate, protein, lipid and nucleic acids

They are broken down into smaller units by special proteins called enzymes

Carbohydrates are broken down into glucose by amylase

Proteins are broken down into amino acids by pepsin

Lipids are broken down into fatty acids by lipase

ingestion: eating or taking the food into the mouth

digestion: breaking larger molecules down into smaller molecules

absorption: the body taking in the nutrients from the food

elimination: the body removing the left over waste products

A - the esophagus. A muscular tube connecting the mouth and stomach. It contracts to move the food through peristalsis.

B - the stomach. A muscular sac filled with stomach acid and digestive enzymes, where the food is digested.

C - the small intestine. Some chemical digestion, and most nutrient absorption happens here through the finger-like projections called villi.

D - the large intestine. Water is absorbed into the body here. The solid that is left becomes waste called feces and is eliminated from the body.

The liver produces bile, which helps with the digestion of lipids

Bile is stored in the gallbladder until it is needed

The pancreas produces digestive enzymes and substances that help neutralise stomach acid, to help with chemical digestion

The excretory system functions to remove wastes

It includes 4 body systems, each removing different wastes

The urinary system filters blood to remove waste as liquid urine

The integumentary system removes waste and excess salt through sweating

The digestive system removes solid waste from food

The respiratory system removes carbon dioxide and water vapour through breathing

The kidneys filter the blood, removing waste to produce urine

The ureters carry urine to the bladder

The bladder is a muscular sac that holds the urine

Sphincter muscles allow us to control the bladder

The urethra carries urine from the bladder, out of the body, when it is eliminated

Homeostasis is maintaining a stable internal environment

This means keeping everything in the body, at the level it needs to be

The nervous system and urinary system work together to do this

The hypothalamus in the brain releases hormones (chemical messengers) into the blood

The hormones tell the kidneys how much water to reabsorb into the blood, and how much to eliminate as urine

This maintains the correct level of water in the body