Topic 4:Nutrition in humans Flashcards
What is the word equation for the digestion of carbohydrates into its end-products?
Carbohydrates+water+enzymes
->simple sugars+other digestion products
what is the word equation for digestion of proteins into its end-products?
protein+pepsin->amino acids
what is the word equation for digestion of fats into end-products?
fats+lipase->Fatty acids+Glycerol
define assimilation
the conversion of absorbed food by body cells to make new protoplasm or to provide energy
what is the difference between Alimentary Canal and Accessory organs?
Alimentary Canal:Consists of organs in which ingested food passes through
Accessory Organs:consists of organs that HELP in digestion of food and is NOT part of the alimentary canal
Describe the function of teeth
Chews large pieces of food into smaller pieces->This increases surface area to volume ratio so digestive enzymes can act on them more efficiently
what is the function of salivary glands?
Secrete saliva into the mouth->which contains salivary Amylase which digests starch in the mouth
what is the function of tongue?
Mixes the food with the saliva and helps to roll food into bolus/boi
what is the pH of saliva?
pH 7
what is the word equation for chemical digestion in the mouth?
starch is digested by salivary Amylase into maltose
what happens to circular muscles and longitudinal muscles during peristalsis?
Behind the bolus: circular muscles contract and longitudinal muscles relax
At the front: Circular muscles relax and longitudinal muscles contract
what happens to salivary amylase when it reaches the stomach?
it gets denatured by the pH of stomach
what type of acid is in the stomach?
Hydrochloric acid
what does hydrochloric acid in the stomach do?
->kills bacteria in food
->provides optimum pH conditions for pepsin to digest proteins
what is the pH in the stomach?
pH 2-3
what is/are the word equation(s) for chemical digestion in stomach?
protein ,digested by pepsin to give polypeptides(PPP)
what parts of the small intestine are there ?and which one comes first ?
Duodenum and Ileum.The duodenum is the first part
which organ is the pancreatic juice secreted into?which organ produces the pancreatic juice?and what enzymes does the pancreatic juice contain?
.The pancreatic juice is secreted into the Duodenum
.The organ that produces the juice is pancreas
.The enzymes in the juice are Trypsin,pancreatic amylase,pancreatic lipase
what organ produces bile?what organ stores it?and what organ is it secreted into?
.The organ that produces bile is liver
.The organ that stores and secretes it is gall bladder
.The organ that it is secreted into is duodenum
what substance reacts with stomach acid to increase the pH ?and what pH is it increased to?
Bile increases the pH to pH 8
what is the function of bile?
emulsifies fats into emulsified small fat droplets which have increased surface area to volume ratio for lipase to efficiently digest them into fatty acids and glycerol
what is/are the word equation(s) for chemical digestion in the duodenum?
.starch digested by pancreatic Amylase to give maltose
.proteins digested by trypsin to give polypeptides
.Emulsified fats digested by pancreatic Lipase to give fatty acids+glycerol
Is the villi or microvilli in the duodenum or ileum?
ileum
is digestion completed in the Ileum or not?
Yes
what are the word equations for chemical digestion in the ileum?
Polypeptides digested by Trypsin to give: Amino acids
Maltose digested by maltase to give: glucose
fats digested by Lipase to give: fatty acids+glycerol
which part of the small intestine exactly is water from undigested food absorbed?
Colon
what organ are digested nutrients transported to for assimilation ?
liver
what organ is connected to the duodenum via the pancreatic duct?
pancreas
what is the role of pancreas in assimilation?
After glucose is absorbed,pancreas secretes hormone insulin to decrease blood glucose concentration back to normal.It also secretes hormone glucagon when the blood glucose concentration falls below normal rage
Describe the structure of the villus
miunte finger-like projections found on the inner wall of the jejunum and ileum
Where do glucose and amino acids move to during absorption ?
Past the epithelial wall of villus->diffuse into blood capillaries(past the one-cell thick wall of capillaries)in the villus
where do fatty acids and glycerol move to during absorption ?
Past the epithelial wall into the villi->recombine into small fat globules
->diffuse into lacteal in the villus
describe the structure of micro-villus
Even smaller projections from the epithelial cells of each villi
what is the function of villi and microvilli ?
to further increase surface area to volume ratio for absorption of digested food molecules efficiently by diffusion
where do glucose and amino acids go to when absorbed from lumen of Ileum?
Are absorbed from the lumen of Ileum by the villi lining the inner wall into the (plasma) of blood capillaries
where do absorbed fatty acids and glycerol from the lumen of ileum go to ?
are absorbed from lumen of ileum by the villi into the lacteal
what is the name of the tube structure right in the middle of a villus ?
Lacteal
where are absorbed glucose and amino acids transported to?
They are transported away in the blood
where are absorbed fatty acids and glycerol transported to?
They recombine into small fat globules and are transported away in the lymphatic capillaries
Describe 5 structural features of the ileum for absorption and explain how it enables efficient absorption
1.Small intestine is very long
->To allow sufficient time for more digested nutrients to be absorbed
2.Inner surface of ileum wall is highly folded and has numerous minute finger-like projections(i.e. villi),and each villi has microvilli
->This increases the surface area to volume ratio of the inner ileum wall. Hence increasing rate of diffusion of digested food substances
3.Wall of villi is one-cell thick,and membrane of microvilli is very thin
->This reduces distance that digested food diffuses across
.Hence increasing rate of diffusion
4.Each villus contains a lacteal surrounded by a rich network of blood capillaries
->This allows fatty acids and glycerol to be quickly transported away in the lacteal ,and glucose and amino acids to be quickly transported away in the blood capillaries .So as to maintain a low concentration in the villus,and hence,maintains a steep concentration gradient for efficient diffusion of more digested food molecules into the villus
5.The epithelial cells contain many mitochondria
->This provides energy for active transport of nutrients into the villi
What is the name of the blood vessel that transports digested nutrients from ileum to the liver?and what is it for?
Hepatic Portal Vein .It transports digested nutrients to the ileum for assimilation and detoxification
What is the name of the blood vessel that transports a substance from liver to heart ?and what is the name of this substance?
Hepatic Vein.Urea is transported via the Hepatic vein from liver to heart (Urea is produced in the liver)
what is the name of the blood vessel that transports substance from heart to liver ?and what is the name of this substance ?
Hepatic Artery .It transports oxygenated blood from heart to liver
what happens to absorbed digested nutrients in the liver?
the liver is the key organ that carries out assimilation of digested products (glucose, amino acids)before they are transported to all cells throughout the body
what is excess glucose converted to?and where is this excess glucose that has been converted stored ?
excess glucose is converted to glycogen to be stored in the liver(When glucose is needed during times like fasting or when blood sugar is lower than normal,liver converts glycogen back into glucose for respiration)
describe what happens when blood glucose concentration increases to higher than normal
.Insulin hormone is secreted by the Islets of Langerhans in the pancreas
.This stimulates liver to convert excess glycogen absorbed in the blood into glycogen,which is stored
describe what happens when blood glucose concentration decreases to lower than normal
.Glucagon hormone is secreted by the Islets of Langerhans in pancreas
.stimulates liver to conver excess glycogen stored back into glucose
state the role of the pancreas in digestion and what gland it is for this context or case
.pancreas is an exocrine gland which is connected directly to the duodenum by the pancreatic duct
.the pancreas is an accessory organ which produces pancreatic juice containing digestive enzymes such as pancreatic amylase, trypsin,peptidases,pancreatic lipase directly through the pancreatic duct into the duodenum to digest starch,protein,polypeptides and fats
what is the role of pancreas in assimilation ?and state what type of gland it is in this context or case
.pancreas is an endocrine gland which secretes hormones(insulin, glucagon)into the blood to stimulate the liver to regulate the concentration of glucose in the blood.
There are 3 other roles of liver which are probably not mentioned .
1.Describe role of liver in detoxification
2.Describe role of liver in storage of iron from the breakdown of RBCs
3.Describe role in synthesis of plasma proteins
1.Liver contains enzyme alcohol dehydrogenase to break down and detoxify alcohol .Alcohol is eventually converted into sugars and harmless substances
2.Liver breaks down the haemoglobin from RBCs which were destroyed in the spleen and stores the iron from Haemoglobin .Bile pigments are also released from breakdown of haemoglobin
3.Liver synthesises proteins like prothrombin and fibrinogen .They are carried by blood plasma and required for blood clotting
explain and describe the effects of alcohol consumption on digestive system
1.Alcohol stimulates gastric glands in stomach to secrete acid->excessive alcohol consumption causes increased secretion of acid .This leads to increased risk of gastric ulcers and hence,stomach pains and reduced function of stomach
2.Alcohol is detoxified by alcohol dehydrogenase enzymes in the liver.Prolonged excessive breakdown of alcohol by liver can damage liver cells.Healthy liver tissue are replaced with fibrous tissue .Over time,this leads to liver cirrhosis(hardening of the liver) and hence,reduced liver function
explain and describe 2 effects of alcohol consumption of nervous system
1.alcohol is a depressant so some brain functions may slow down as amount of alcohol consumed increases,and the person becomes intoxicated .
->This leads to reduced inhibitions and self-control which may result in undesirable behaviour such as violence
->poorer judgement and slower reaction time.When driving,can lead to accidents
->reduced bodily functions such as blurred vision,poor muscular co-ordination ,slower reflex actions
2.Drinking alcohol frequently can be addictive.This causes increased uncontrollable compulsion to drink alcohol and body will be more dependent on alcohol .The compulsion to continue drinking and the influence of alcohol intoxication can lead to societal problems like neglecting of work and family ,and crimes like theft and violence
