Energy And Nutrients Flashcards
What are essential nutients
One’s your body can’t produce
What is the role of essential nutrients
Energy, metabolism, promotion of growth and development, maintenance of good health
How much of your daily energy expenditure is made up from the GI tract
10-20%
What does the GI tract do
Breakdown, absorption, excretion
What happens in the oesophagus
Peristalsis begins, moving food automatically to the stomach
What is peristalsis and how does it work
Propelling food down the GI tract
- contraction of longitudinal muscles
Explain what happens in the stomach (GI tract)
Food is mixed with digestive juices forming chyme
What is chyme
A thick, semifluid substance consisting of food and gastric juices.
What happens in the small intestine (GI tract)
Digestion continues, nutrients and water are absorbed
What happens I the large intestine (GI tract)
Absorbs water, forms and moves stool to rectum
What are the elements of the alimentary canal or GI tracts
- moth
- Oesophagus
- stomach
- small intestine
- Large intestine
- anus
What are the accessory organs of the GI tract
Salivary glands
Liver
Pancreas
Gall bladder
What is the role of the salivary glands
Produce saliva to moisten food aiding easy movement to the stomach
What is the role of the pancreas
Produce enzymes that break down carbohydrates, fats and proteins
What is the role of the liver in GI tract
Produces bile which helps in the breakdown of fats
What is the role of the gallbladder in the GI tracts
Stores bile from the liver and releases it into the small intestine when needed
What is digestion and what are the two types
Breaking down food small enough to be absorbed by the body
- mechanical
- chemical
What is absorption
Transporting these digested molecules across the walls of the GI tract and into the bloodstream
What are the stages of mechanical digestion
Chewing
Peristalsis
Segmentation
What stage of digestion happens before food intake
The cephalic stage
The anticipatory physiological response to sensing or expecting food
- vagus nerve activated
Increase production of saliva
Prep for processing
20% of acid secretion before food enters stomach
Bile + enzymes
Explain what peristalsis is and where it takes place
Propelling using longitudinal muscles, wave like contractions
Oesophagus
Stomach
Small intestine
(Mainly)
Smooth muscle
Stomach rumbling
What is segmentation and where does it occur
Mixes chyme
Mainly smalintestine
Alternating movements, circular muscles
What is chemical digestion and what are the elements
Dietary components
(Macronutrients broke down into smaller molecules)
Enzymatic hydrolysis
What are enzymes and what is enzymatic hydrolysis
Protein molecules with active sites which speed up chemical reactions
• enzymes break down the chemical bonds holding food molecules together, transforming them into their constituent building blocks which can then be absorbed and utilised by he body.
What are carbohydrates broken down into
Monosaccharides
What are lipids broken down into
Fatty aids and monoglycerides
What are proteins broken down into
Amino acids
What is the fundus
Reservoir for food received from the osophogus
What is the GI sphincter
Acts as a gateway to prevent backflow
Between oesophagus and stomach
What is the pyloric sphincter
Release chyme into small intestine
Located at bottom of stomach before the duodenum
What are the features of the small intestine
Villi and micrrovilli
Duodenum, fist part, c shaped
Jujeum, middle
Ilium, last
Absorption of nutrients occurs mainly here
Explain the breakdown of carbohydrates
Mouth: salivary amylase - into shorter polysaccharides and disaccharides
Duodenum of small intestine: pancreatic amylase - into disaccharides
Epithelium of small intestine: disaccharidases - di to mono
Explain the breakdown of lipids
Bile salts from liver
Lipase from pancreas
(Both break down in the duodenum)
Into fatty acids and monoglycerides in small intestine
Explain the breakdown of protein
Stomach: pepsin breaks it down to polypeptides
Duodenum: trypsin, chymotrypsin, carboxypeptidase (from pancreas) - peptides
Small intestine: peptidases - amino acids
What is the definition of gastric emptying
The process by which the contents of the stomach are transfers to the duodenum
What are the methods for measuring gastric emptying
GE scintigraphy - drink radioactive liquid with short half life
Breath test
How is GE regulated
The coordinated motor activity of the stomach and proximal intestine
Involves smooth muscle, neural and hormonal factors
Why is GE important
Nutrient passage: Appropriate passage of nutrients and indigestible particles through the GI tract
Enables the absorption of digested food into the blood stream
What are the hormones which control gastric emptying
Gherkin
Gastric inhibitory polypeptide (GIP)
Glucagon like peptide (GLP)
Peptide tyrosine-tyrosine (PYY)
Where is gherkin produced and what does it do
Stomach
Stimulate appetite and accelerate gastric emptying
Where is GIP produced
Intestinal k cells
Where are GLP and PYY produced
Intestinal L cells
What do GIP, GLP1 AND PYY do
Delay gastric emptying and reduce appetite
What is the difference between solid and liquid GE
Solid food has a lag (30 mins) before volume of the meal decreases in a linear manner
What factors effect GE rates
- solid v liquid
- fat content, delays
- acidity, more acidic = delay
- Digest-ability and fibre content
- energy density
- volume and particulate size
What was found on the influence of nutrients to GE
Increased specific exposure can alter GE in response to increased dietary load
FINISH GE ON NOTABILITY + TEXT BOOK
D
How is energy maintained
The oxidisation of macronutrients
The brain is the most energy demanding organ
What is the estimated average requirement for energy (EAR)
-Represents the level of energy intake needed to maintain energy balance and a healthy BMI.
•Applies to otherwise healthy individuals at existing population levels of physical activity.
•To support overall health and prevent nutrition-related diseases.
50 carb
35 fat
15 protein
How does EAR vary
- infants need proportionally more for their size
- climate, activity, body size and muscle mass
- less for older adults
- +200cal women final trimester
What is one cal in kj
4.184
What is tdee
Total daily energy expenditure
Bmr
Tef
Activity
How much is bmr in sedentary individuals
70%
What is tef
Energy required to digest absorb metabolise and store food
About 10% of tdee
Protein 20-30% as atp harder to break and store
What are the two types of adipose tissue
Subcutaneous adipose tissue
- just under skin, neutral protective
Visceral
- deep in abdominal cavity
- risk cardiometabolic disease
What is bmi
Measures excess weight, not fat
Weight in kg/height
