Biology (Nutrition in Humans) Flashcards
(24 cards)
Why do people choke when they eat while talking?
The glottis is a slit located at the larynx. The epiglottis closes over the glottis to prevent food
from reaching the larynx and trachea when swallowing. People tend to choke when they talk while swallowing, as the epiglottis cannot fully close.
Structure of oesophagus
Circular muscles = inner layer
Longitudinal muscles = outer layer
What is peristalsis?
It refers to the rhythmic, wave-like muscular contractions in the wall of the alimentary canal. It enables food to be mixed with digestive juices and helps to push or propel the food along the gut.
How does peristalsis occur?
When the circular muscles contract, the longitudinal muscles relax. As a result, the gut becomes narrower and longer (constricts). The food is squeezed or pushed forward.
When the longitudinal muscles contract, the circler muscles relax. The gut becomes wider and shorter (dilates), allowing food to enter the lumen.
What is the optimum pH for salivary amylase?
pH 7
What is the function of hydrochloric acid in gastric juice?
-stops the action of salivary amylase by denaturing it
– provides a low pH environment in the stomach for protease to digest proteins
– kills microorganisms in food.
What does pancreatic juice contain?
pancreatic amylase, protease and pancreatic lipase
What is the function of bile?
As bile does not contain enzymes, it cannot digest food. Bile speeds up the digestion of fats by breaking up large fat molecules into smaller fat molecules. (emulsification)
How are carbs digested
Starch is broken down into maltose by amylase in the mouth and small intestine.
Maltose is broken down into glucose by maltase in the small intestine.
How are proteins digested
Protein digestion starts in the stomach, where stomach protease digests proteins to
polypeptides. The undigested proteins that enter the small intestine are digested by intestinal protease to
polypeptides. The polypeptides produced are further digested to amino acids by intestinal protease.
How are fats digested?
Bile is released into the duodenum, and the bile salts emulsify fats by lowering the
surface tension of the fats. Thus, the fats break into tiny fat droplets, increasing the surface area-to-volume ratio
for enzyme action.
How does absorption takes place in the small intestine?
Glucose and amino acids are absorbed by diffusion into the blood capillaries of the villi. Glycerol and fatty acids diffuse into the epithelium. Here they combine to form minute fat globules that enter the lacteals.
What is assimilation?
The process whereby some of the absorbed nutrients are converted into new cytoplasm of used to provide energy
What is the function of the hepatic portal vein?
transports nutrients
from the small intestine to the liver.
What happens to glucose after absorption?
In the liver, most absorbed sugars are converted into glycogen and stored. Some glucose is transported by the blood leaving the liver, and is distributed around the body to be used for energy during cell respiration. Excess glucose is transported back to the liver and stored as glycogen for use
in the future.
What happens to amino acids after absorption?
Amino acids that enter the cells are converted into new cytoplasm that is used
for growth and repair of worn-out parts of the body. Amino acids are also used to form enzymes and hormones. In the liver, excess amino acids have their amino groups are removed and converted into urea. This is known as deamination. Urea is removed from the body in the urine. The remains of the deaminated amino acids are converted into glucose in the liver.
What happens to fats after absorption?
Fats are absorbed into the lymphatic capillaries, which join to form larger lymphatic
vessels. These discharge fats into the bloodstream. When there is enough glucose, fats are not broken down and are used to build protoplasm like cell membranes. When glucose is in short supply, fats are broken down to provide the energy needed for vital activities in the body. Excess fat is stored in adipose tissues beneath the skin and around the heart and
kidneys. Adipose tissues protect organs by acting as shock absorbers.
What is assimilation?
Process whereby some of the absorbed nutrients are converted into new cytoplasm or used to provide energy
What is the function of HPV
the HPV transports nutrients from the small intestine to the liver
What happens to glucose after assimilation?
Most absorbed sugars are converted into glycogen and stored. Some glucose is used for energy during cell respiration, excess glucose is transported back to the liver and stored as glycogen
What happens to amino acids after assimilation?
Converted into new cytoplasm that is used for growth and repair. used to form enzymes and hormones. In the liver, excess amino acids are converted into urea. Remainig deaminated amino acids are converted in to glucose.
Functions of the liver?
-Produces bile
-Deamination of amino acids
-Regulation of blood glucose concentration
-Breakdown of hormones
-Detoxification
What happens when there is high blood glucose concentration in the liver?
the pancreas produces insulin to make cell membranes more permeable to glucose, allowing more glucose to diffuse into the liver and muscle cells. Stimulates liver and muscle cells to convert excess glucose into glycogen.
What happens when there is low blood glucose concentration in the liver?
the pancreas produces glucagon, which increases blood glucose concentration by stimulating the conversion of glycogen into glucose
