Nutrition Flashcards
What is Assimilation?
Assimilation is the incorporation of absorbed nutrients into the cells of the body. The body cells absorb the required nutrients which are necessary for the building and maintenance of compounds. For example, muscle cells will absorb amino acids to be converted to proteins and glucose will be absorbed by cells to provide energy.
Bile
Bile emulsifies large water insoluble fat globules into small fat droplets which aids chemical digestion. Lipids are broken down by bile into tiny droplets which provide a larger surface area on which enzymes can act to break them down. T
It neutralises the acidic fluid (chyme) which comes from the stomach so that the intestinal enzymes can function at their optimal pH (= 8).
It promotes peristalsis in the small intestine
It acts as an antiseptic which prevents decay of food particles in the small intestine
Why is the small intestine good for absorption
The small intestine is approximately 6 m long.
The walls of the small intestine contain transverse folds.
The inner wall of the small intestine has millions of finger-like projections called villi.
Each villus contains microvilli to further increase the surface area.
Villus
The epithelium is only one-cell layer thick allowing nutrients to pass through quickly.
Goblet cells secrete mucus to ensure the absorptive surface is moist and to allow nutrients to be dissolved and then to be absorbed.
The epithelium contains many mitochondria to supply energy for active absorption of nutrients.
Microvilli further increase the surface area.
There is a lymph vessel called a lacteal in each villus which absorbs and transports lipids.
The villus is richly supplied with blood capillaries to transport glucose and amino acids.
Glands
xocrine glands: secretions are carried by ducts to where they are needed.
Endocrine glands: secretions are released into the blood stream and carried to the rest of the body.
Pancreas
The pancreatic juice is secreted via the pancreatic duct and goes to the duodenum of the small intestines.
The hormones are secreted into the blood stream and carried to the rest of the body.
Hormones
Hormones
Hormones are your body’s chemical messengers. They travel in your bloodstream to target specific tissues or organs. They can sometimes work slowly, over time, and affect many different processes, including:
Growth and development.
Metabolism - how your body gets energy from the foods you eat.
Homeostasis glucose
The amount of glucose in the blood (blood-sugar level) must be kept constant:
Too high = hyperglycemia
Too low = hypoglycemia
Hyperglycemia causes kidney & heart failure. Hypoglycemia causes headaches, shakiness, weakness, seizures, coma, and even death.
Hormones regulating blood glucose levels
The pancreas releases two hormones from cells called the Islets of Langerhans.
Insulin: decreases blood glucose levels
Glucagon: increases blood glucose levels
Insulin causes the cells of the body (particularly muscle and liver cells) to take in more glucose from the blood stream. Insulin is produced by cells called beta cells of the Islets of Langerhans. The excess glucose is stored in these cells as glycogen (similar to how plants store carbohydrates as starch).
Glucagon causes the cells storing glycogen to break down this carbohydrate and release glucose into the blood stream. Glucagon is released by alpha cells of the Islets of Langerhans.
Type 1 diabetes mellitus
This type of diabetes occurs when the beta cells of the Islets of Langerhans are damaged and they do not produce insulin. This damage is typically caused by the bodies immune system attacking the beta cells.
Type 2 diabetes mellitus
This type of diabetes occurs when the body cells do not respond to insulin. It is caused by various factors including obesity, inactivity and age.
If Diabetes is left untreated
Body cells don’t get enough glucose
Cells lose water due to osmosis causing dehydration
Organs damaged
Blindness, kidney failure and cardiovascular disease
Coma
Symptoms of Diabetes
Frequent urination
Increased thirst and hunger
weight loss
infections
wounds that are slow to heal
impaired vision
exhaustion and dizziness
Malnutriton
Malnutrition occurs when a person does not follow a balanced diet. It can result in under-nourishment (eating too little food) or over-nourishment (eating too much food).
Examples of under-nourishment disorders:
kwashiorkor
marasmus
anorexia nervosa
bulimia
