Unit 4 Digestion and absorption of food

Why do animals need to digest food?

To break nutrients down into smaller parts so they can be absorbed into cells and the bloodstream.

What is mechanical digestion?

The physical breakdown of food into smaller pieces, primarily through chewing and muscular contractions.

What is chemical digestion?

The process by which chemicals such as enzymes and acids break down food molecules into simpler nutrients.

What are the salivary glands?

Organs that secrete saliva to moisten food and provide the enzyme amylase to begin digestion.

What is the function of the esophagus?

A tube connecting the mouth to the stomach that uses peristalsis to move food.

What is the role of the stomach?

To secrete gastric juice containing hydrochloric acid and pepsin for digestion.

What is the function of the small intestine?

To secrete digestive enzymes and absorb digested nutrients into the bloodstream.

What role does the large intestine play?

To absorb water from food and form feces.

What is the purpose of the pyloric sphincter?

To control the release of food into the small intestine.

What is peristalsis?

Muscle contractions that move food through the digestive system in one direction, from the mouth to the anus.

What is the function of bile?

To emulsify fats, breaking them down into smaller particles for chemical digestion.

What is denaturation in the context of enzymes?

The alteration of an enzyme's structure due to extreme temperature or pH changes, leading to loss of function.

Explain why enzymes are specific in their action?

Enzymes are specific because each one's active site only fits a particular substrate, similar to a key fitting into a lock.

What adaptations does the small intestine have for absorption?

The ileum has a large surface area with villi, thin walls for quick absorption, a rich blood supply, and lacteals for fat absorption.

What is the function of the liver in processing absorbed food?

To convert nutrients into usable substances, store excess sugar, and produce bile.

What is the order of energy store usage when deprived of food?

1. Glycogen stores in the liver, 2. Fat stores in fat cells, 3. Muscle protein during starvation.

Why is digestion important?

Breaks nutrients down into smaller parts for absorption into the blood.

Mechanical Digestion

Physically breaking down food into smaller pieces (e.g., chewing).

Chemical Digestion

Breaking down food molecules into simpler nutrients using enzymes, bile, and acids.

Salivary Glands

Secretes saliva, moistening food and initiating digestion with amylase.

Esophagus

Tube connecting the mouth to the stomach; uses peristalsis to move food.

Stomach

Secretes gastric juice (HCl and pepsin) for digestion and killing bacteria.

Small Intestine

Secretes intestinal juice; absorbs digested food into the bloodstream.

Large Intestine

Absorbs water and forms feces.

Pyloric Sphincter

Controls food release into the small intestine.

Anal Sphincter

Controls feces release from the rectum.

Gall Bladder

Stores bile from the liver, which breaks down fats.

Bile Duct

Connects the gall bladder to the small intestine.

Pancreas

Makes digestive enzymes, neutralizes stomach acid, and produces insulin.

Liver

Makes bile, processes amino acids, and stores excess sugar.

Chemical Digestion

Substances like bile, enzymes, and acids that break down food.

Enzymes Role

Speeds up digestion, e.g., amylase breaks down starch into maltose.

Bile

Breaks down fat into smaller balls to increase surface area for lipase.

Enzymes

Proteins that speed up chemical reactions in the body.

Active Site

The part of an enzyme that binds to the substrate molecule.

Lock and Key Model

Substrate fits into a specific enzyme's active site, like a key in a lock.

Extreme Temperatures and pH Levels affect Enzyme activity

Can break bonds and alter the shape of enzymes, reducing their ability to catalyze reactions.

Denaturation

Enzyme's shape changes, losing its ability to bond with the substrate and function.

Peristalsis

Muscles contract and release, pushing food forward through the digestive system.

Small Intestine Adaptations

Villi increase surface area; thin walls allow quick absorption; rich blood supply carries nutrients away.

Gut Microbiome

Collection of microorganisms (bacteria, fungi, viruses) in a specific environment, mainly in the small intestine; helps in producing vitamins, preventing harmful bacteria, and breaking down toxins.

Excess glucose converted into glycogen and stored; excess amino acids broken down; makes bile.