Nutrition for sport, exercise and health (IB)

Trypsinogen

the inactive form of trypsin

gallbladder

is a small, pear-shaped organ located beneath the liver

Bile

plays a crucial role in the digestion and absorption of fats.

Bile salts

emulsify large fat globules into smaller droplets, increasing the surface area for enzymes (such as lipase) to efficiently break down fats into fatty acids and glycerol.

Peptidases

enzymes present on the brush border of the small intestine's epithelial cells (enterocytes), further break down peptides into individual amino acids.

Amino acids

are absorbed across the apical membrane of the enterocytes (the side facing the intestinal lumen) through various transporter proteins.

enterocytes

amino acids are processed and may undergo various modifications before being transported to the basolateral membrane (the side facing the bloodstream).

liver

plays a role in regulating amino acid levels, as well as in amino acid metabolism.

slightly acidic to neutral

typical pH range found in the mouth

Saliva

which is produced by the salivary glands and presen

Enzymes

play a crucial role in digestion by facilitating the breakdown of complex food molecules into smaller, absorbable units.

Digestion

involves the conversion of large macromolecules, such as carbohydrates, proteins, and fats, into smaller components like sugars, amino acids, and fatty acids.

Amylase

Breaks down complex carbohydrates (starches) into simpler sugars (such as maltose and glucose).

Pepsin (in the stomach), trypsin, chymotrypsin, and peptidases (in the small intestine)

Breaks down proteins into peptides and amino acids.

Lipase

 Hydrolyzes triglycerides (fats) into fatty acids and glycerol, allowing for their absorption.

Nucleases

Breaks down nucleic acids (DNA and RNA) into nucleotides.

Brush Border Enzymes

Located on the surface of intestinal epithelial cells, these enzymes further break down disaccharides into monosaccharides for absorption.

Enterokinase

Activates trypsinogen into trypsin in the small intestine.

6 to 7

The pH in the duodenum

7 to 8

The pH in the jejunum

Pepsin

is an enzyme produced by the chief cells in the stomach lining.

Trypsin

is produced by the pancreas and released into the duodenum of the small intestine.

Coenzymes

are essential for the activity of various enzymes involved in metabolic pathways.

thiamine (vitamin B1)

is a coenzyme that participates in reactions related to energy metabolism.

 B vitamins

function as coenzymes

vitamins C and E

function as antioxidants.

Mechanical digestion

involves the physical breakdown of food into smaller particles. 

Chewing or Mastication

The process in Mechanical Digestion

Chemical digestion

involves the breakdown of complex molecules into simpler ones through the action of enzymes.

Salivary digestion by enzymes

The process in Chemical Digestion

large macromolecules

Most dietary nutrients come in the form of

Salivary amylase

is produced by the salivary glands and released into the mouth. 

Pancreatic amylase

is produced by the pancreas and released into the duodenum of the small intestine.

Gastric lipase

is produced in the stomach.

Trypsin and chymotrypsin

further break down peptides into smaller fragments, and peptidases on the brush border of the small intestine complete the process by breaking down peptides into individual amino acids.

Extracellular fluid (ECF)

This fluid is found outside cells and includes interstitial fluid (between cells) and plasma (within blood vessels).

Homeostasis

is the maintenance of stable internal conditions. 

Negative feedback mechanisms

work to counteract changes and return the system to a set point.

Loop of Henle

This structure in the kidney creates an osmotic gradient, allowing for the concentration of urine.

Medulla

assists in concentrating urine by reabsorbing water.

ADH (Antidiuretic Hormone)

is released by the pituitary gland and increases water reabsorption in the kidneys, reducing urine volume and helping maintain water balance.

Dark urine

This color of urine may indicate dehydration.

Basal Metabolic Rate (BMR)

is the amount of energy expended by the body at rest to maintain basic physiological functions such as breathing, circulation, and cell production.

Energy Intake - Energy Expenditure = Energy Balance.

what is the Energy Balance Equation?

Energy Balance

The relationship between energy intake and expenditure determines whether an individual is in a state of energy balance, surplus, or deficit.

Type I (Slow-Twitch) Fibers

About 10-15 grams of glycogen per 100 grams of muscle tissue.

Type II (Fast-Twitch) Fibers

About 3-5 grams of glycogen per 100 grams of muscle tissue.

Low-Intensity Exercise

Type I fibers predominantly use glycogen for energy.

High-Intensity Exercise

Both Type I and Type II fibers utilize glycogen, with Type II fibers relying more heavily on anaerobic glycolysis.

glycemic index (GI)

is a measure of how quickly a carbohydrate-containing food raises blood glucose levels.

Sodium

Helps maintain electrolyte balance, preventing hyponatremia during prolonged exercise.

Carbohydrate

Provides a source of energy to delay fatigue during endurance events.

Central Nervous System (CNS) Depression

Alcohol acts as a depressant, impairing cognitive function, coordination, and reaction time.

Dehydration

Alcohol is a diuretic, leading to increased urine production and potential dehydration.

Metabolic Effects

Alcohol can interfere with nutrient

Antioxidants

are substances that neutralize free radicals, protecting cells from oxidative damage.