wk6: Digestion and Energy Lecturure content

This set of flashcards covers the core vocabulary and concepts related to human digestion, the gastrointestinal tract, energy metabolism, Atwater factors, and the classification of obesity as described in the lecture notes.

Digestion

The process of breaking down foods into its constituents for absorption and excretion.

Peristalsis

The process where the circular and longitudinal muscles ringed around the gastro intestinal (GI) tract tighten and relax to push food along the tube.

Gastrointestinal (GI) tract

The hollow, muscular tube that extends from the mouth to the anus.

Intestinal villi

Small hair like protrusions lining the small intestine that increase surface area and absorptive capacity.

Simple diffusion

A method of absorption where nutrients cross intestinal cells freely, such as water and small lipids.

Facilitated diffusion

A method of absorption where nutrients are transported by a specific carrier, such as water soluble vitamins.

Active transport

A method of absorption where nutrients move against a concentration gradient using energy, such as glucose and amino acids.

Lymphatic system

The system through which large fats and fat-soluble vitamins enter the bloodstream, bypassing the liver.

Atwater factors

Standardised values for metabolizable energy used to convert macronutrient values into energy values, expressed in $kJ/g$.

Energy expenditure

The amount of energy an individual requires to sustain life, digest food and perform physical activity.

Energy balance

A state where energy consumed is equal to energy expended, resulting in stable body weight.

Pre-clinical obesity

A state of excess adiposity with preserved function of other tissues and organs but an increased risk of developing clinical obesity and other non-communicable diseases.

Clinical obesity

A chronic, systemic illness characterised by alterations in the function of tissues, organs, or the entire individual due to excess adiposity.

Body mass index (BMI)

A measure of health risk at a population level calculated as $\frac{\text{Weight (kg)}}{\text{Height}^2 (\text{cm})}$, where a healthy range is $18.5$ to $24.9\,kg/m^2$.

Visceral fat

Fat that is stored around the organs of the abdomen, also referred to as central obesity or intra-abdominal fat.

Waist circumference

The most practical indicator of fat distribution and central obesity; high risk is indicated by > $88\,cm$ for women and > $102\,cm$ for men.