Chapter 5 – Nutrition in Humans (Vocabulary Review)

These vocabulary cards cover the major structures, processes, enzymes, physiological adaptations, hormonal controls and health implications discussed in Chapter 5 – Nutrition in Humans. Review each term–definition pair to reinforce key concepts for your exam.

Nutrition

Process by which organisms obtain food and energy for growth, repair and maintenance, encompassing ingestion, digestion, absorption, assimilation and egestion.

Ingestion

The taking in of food into the body through the mouth.

Digestion

Breakdown of large, insoluble food molecules into smaller, soluble molecules that can be absorbed.

Absorption

Movement of digested nutrients from the small intestine into the bloodstream or lacteals.

Assimilation

Utilisation of absorbed nutrients by body cells for energy, growth or repair.

Egestion

Elimination of undigested and unabsorbed matter from the body as faeces.

Peristalsis

Rhythmic, wave-like contractions of circular and longitudinal muscles that mix and propel food along the alimentary canal.

Buccal Cavity

The mouth cavity where food is chewed, mixed with saliva and formed into a bolus.

Pharynx

Muscular throat cavity linking buccal cavity to oesophagus and trachea; site where epiglottis prevents food entering windpipe.

Epiglottis

Flap-like cartilage that closes over the glottis during swallowing to prevent choking.

Oesophagus

Narrow muscular tube connecting mouth to stomach; transports food by peristalsis.

Stomach

Muscular organ that stores food, churns it with gastric juice and starts protein digestion.

Gastric Juice

Secretion containing hydrochloric acid, mucus and protease that initiates protein digestion in the stomach.

Chyme

Partly-digested, acidic food mixture leaving the stomach for the duodenum.

Small Intestine

Long, coiled tube (duodenum + ileum) where most digestion and nutrient absorption occur.

Duodenum

First section of small intestine receiving chyme, bile and pancreatic juice.

Ileum

Longest part of small intestine specialised for absorption, lined with villi.

Large Intestine

Section comprising colon, rectum and anus; absorbs remaining water and stores faeces.

Colon

Major part of large intestine that absorbs water and mineral salts from undigested food.

Rectum

Terminal portion of large intestine for temporary storage of faeces.

Anus

Opening through which faeces leave the body.

Liver

Largest gland; produces bile, stores glycogen, detoxifies substances and regulates blood glucose.

Bile

Alkaline fluid containing bile salts that emulsify fats and neutralise stomach acid in the duodenum.

Gall Bladder

Small sac beneath liver that stores and concentrates bile, releasing it via the bile duct.

Pancreas

Gland that secretes pancreatic juice (digestive enzymes) into duodenum and hormones insulin & glucagon into blood.

Peristaltic Constriction

Narrowing of gut lumen when circular muscles contract and longitudinal muscles relax.

Peristaltic Dilation

Widening of gut lumen when longitudinal muscles contract and circular muscles relax.

Physical Digestion

Mechanical breakdown of food (chewing, churning, emulsification) increasing surface area for enzymes.

Chemical Digestion

Enzymatic hydrolysis of macromolecules into absorbable monomers.

Salivary Amylase

Enzyme in saliva that converts starch to maltose at pH 7.

Protease

Enzyme group that hydrolyses proteins to polypeptides and amino acids (e.g., pepsin, trypsin).

Lipase

Enzyme that hydrolyses fats into fatty acids and glycerol.

Maltase

Intestinal enzyme that converts maltose into glucose.

Emulsification

Break-up of large fat globules into tiny droplets by bile salts, increasing surface area for lipase action.

Villus

Finger-like projection of small-intestinal lining that increases surface area for absorption.

Microvilli

Microscopic folds on epithelial cells of villi that further enlarge absorptive surface.

Lacteal

Lymphatic capillary inside each villus that absorbs glycerol and fatty acids (as minute fat globules).

Hepatic Portal Vein

Blood vessel transporting nutrient-rich blood from small intestine to liver.

Glycogen

Storage polysaccharide formed in liver and muscles from excess glucose.

Insulin

Pancreatic hormone that lowers blood glucose by promoting uptake and conversion to glycogen.

Glucagon

Pancreatic hormone that raises blood glucose by stimulating glycogen breakdown in liver.

Deamination

Liver process that removes amino groups from excess amino acids, forming urea and glucose.

Detoxification

Liver conversion of harmful substances (e.g., alcohol, drugs) into harmless compounds.

Cirrhosis

Chronic liver disease where cells are replaced by fibrous tissue, often due to excessive alcohol.

Wet Brain (Wernicke–Korsakoff)

Alcohol-related dementia caused by vitamin B1 deficiency and brain damage.

Peristaltic Wave

Sequential contraction pattern propelling bolus through gastrointestinal tract.

Capsule Endoscopy

Diagnostic technique where a swallowed camera capsule photographs the gastrointestinal tract.