animal nutrition Flashcards
what is the purpose of mastication
It increases the surface area that comes into contact with the enzymes
Food is mixed with saliva to allow for easy swallowing and passage through the oesophagus.
What is mechanical digestion
It is a physical process also known as mastication where food is crushed and grinded by the teeth
what happens during mechanical digestion
large pieces of food is broken dowwn into smaller pieces of food
what is ingestion
the intake of food in large complex substances
What is assimilation?
the transportation to and the use of absorbed nutrients in various cells for repair , growth and energy
what is chemical digestion
the chemical breakdown of food where large insoluble nutrients are broken down into smaller soluble nutrients through the process of hydrolysis
define hydrolysis
the process whereby large insoluble nutrients are broken down into smaller soluble nutrients with the chemical addition of water.
importance of food
1) brings about growth by providing substances required by cells
2) serves as a energy source
3) it is a source of regulating substances that are required for functioning of the body. E.g minerals and vitamins
herbivores
organisms that eat plants only
carnivores
organisms that eat meat only ( other animals)
omnivores
organisms that eat both plants and animals
type of teeth that herbivores have
incisors- broad and flattened for clipping of blades of grass
premolars and molars- large and flattened for grinding grass
cliastema(a gap)- occurs between incisors and premolars to enable tongue to move around during chewing.
the role of water in digestion
1) makes food more liquid so it can move around more freely around the alimentary canal
2) keeps surrounding tissues of the alimentary canal soft and pliable.This also allows free movement
Peristalsis
the rythmical contraction and relaxation of the muscles of the oesophagus
describe the process of peristalsis
the circular muscles above the bolus contracts and this narrows the oesophageal tube
the circular muscles below the oesophagus relax, this causes the oesophagus to widen and the bolus is moved forward
What substances are absorbed by the small intestine
glucose ,amino acids, fatty acids and glycerol, vitamins , minerals, water , undigested and indigestable material
what is the difference between undigested and indigestable material
undigested material is food that can be digested by the body but was not digested because it was not needed whereas indigested material is food that cannot be digested because the body does not have the ability to do so
peristalsis in the stomach
food enters stomach through cardiac sphincter , cardiac sphincter controls movement of bolus in the stomach, in the stomach peristalsis occurs in many different ways, this ensures that food is broken down into smaller pieces and it is thoroughly mixed with digestive juices
The food is then moved into the large intestine through peristalsis
importance of saliva
contains water to soften food and helps with chewing
contains mucous to lubricate food and helps with chewing
creates a slightly alkaline medium for the enzymes that are found in the mouth
The enzyme carbohydrase is part of the saliva. Plays a role in digesting carbohydrates
what enzymes are required for hydrolysis
proteases - breakdown[hydrolyse] proteins into amino acids
carbohydrases- hydrolyse carbohydrates into simple sugars
lipases - hydrolyse fats [lipids] into fatty acids and glycerol [produced in the pancreas]
need for digestion
food contain large amounts of energy so that food must be broken down , absorbed and transported so that the energy can be released so the food we eat is made up of large complex molecules that are insoluble in water, digestion must occur so that the large molecules can be broken down into small soluble substances so that these smaller substances can be absorbed and transported
how are gastric juices formed
when the stomach detects protein it secretes a hormone called gastin through the stomach walls into the blood vessels , the blood passes the stomach lining and the gastin stimulate the stomach cells to secrete gastric juices
How do gastric juices assist in digestion
1) contain enzyme protease, which plays a role in the digestion of protein
2) contains water to keep food fluid to allow for easy movement along alimentary canal
3) contains mucin ,mucin combines with water to form a protective lining inside the stomach that protects the stomach from the action of enzymes
4) hydrochloric acid is present to provide an acid medium for the enzymes found the stomach and it acts as an antiseptic as well , it destroys germs that may come in with the food
digestive juices in the small intestine
pancreatic juices
formation of pancreatic juices
when food from stomach enters the duodenum the hormone secretin is secreted by the duodenal walls into the blood stream,
the blood passes through the pancreas and the secretin stimulates pancreatic cells to secrete pancreatic juices
role of pancreatic juices in digestion
1) contains water to keep food fluid to enable easy movement along the alimentary canal
2) Chyme coming from stomach is acidic, enzymes that make up part of the pancreatic juices cannot work with the acid so pancreatic juices contain sodium bicarbonate , it neutralizes the acid chyme so that the enzymes of the pancreas can function
enzymes found in pancreatic juices
carbohydrases, proteases, and lipases
secretions of the small intestine
intestinal juices
where does final hydrolysis occur
cell membranes of small intenstine
what protects the small intestine
the walls of the small intestine contains glands ,these glands secrete mucus
The mucus forms a protective layer, protecting the lining of the small against the acid chyme from the stomach
bile
found in small intestine, secreted by liver cells, stored in gall bladder , contains no digestive juices
what happens bile is needed for digestion
it is carried by the cystic duct , the cystic duct joins the common bile duct, the common bile duct joins the pancreatic duct to form the hepato-pancreatic duct
The hepato-pancreatic duct carries the bile to the small intestine
functions of bile
water present to keep food fluid to enable easy movement
2) alkaline bile salts neutralize the acid chyme from the stomach
3) bile salts emulsify fats [breaks fats up into droplets], this increases the surface area for enzyme action
4) bile assists in absorption of fats and fat soluble vitamins [ A , E,D &K]
5) bile salts are slightly antiseptic , preventind the decomposition of food in the small intestine
villi
tiny finger like projections which increase the surface area for absorption of digested foods ,found in the inner surface of the small intestine
absorption
when food is absorbed into the cells and then the bloodstream
egestion
the removal of undigested and indigestable food from the body
what happens in the small intestine
- proteins, carbohydrates and lipids are digested
- nutrient and excess water absorption occurs here
- site of fructose malabsorption and coelliac disease
what happens in the liver
- produces bile to emulsify fats
- emulsified fats are then mixed with juices the small intestine
- food is changed into energy ,alcohol and poison are cleared from bloodstream
- stores vitamins and irons
the large intestine
-water from chyme and water and electrolytes from stool are absorbed and moves into the blood
-forms and stores solid wastes (faeces)
contains beneficial bacteria which help produce certain vitamins
rectum
stores and expels faeces
pancreas
a gland that makes enzymes for digestion & sodium bicarbonate to neutralize acid chyme
-makes insulin (a hormone) which helps the body turn food into energy & regulates blood sugar levels
stomach
- secretes gastric juices and hydrochloric acid
- activates enzymes to digest food[ protein] and kill pathogens
- liquifies food into chyme
describe the digestion ,absorption and assimilation of food that contain only carbohydrates
Digestion:
- food in the mouth is mixed with saliva and chewed to break it up, saliva contains the enzyme carbohydrases and it helps in the digestion of carbohydrates in the mouth into polyssacharides
- in the stomach the food is then turned into chyme
- the chyme coming from the stomach is acidic so the alkaline bile salts in the small intestine neutralize the acid chyme , the pancreatic juices then contain the enzyme carbohydases that breakdown the polyssacharides into dissacharides
- the intestinal juices then eventually break down the dissacharides into monossacharides like glucose
Absorption
- glucose is actively absorbed by the villi
- carrier molecules are used to carry the glucose across the concentration gradient
- glucose then enters the blood capillaries of the villi
Transport:
- glucose enters the blood capillaries of the villi, the capillaries join to form venules then larger veins the larger veins then open into the hepatic portal vein and the glucose in the hepatic portal vein is carried into the liver where it is converted into glycogen by insulin and then stored.
- the the blood rich in glucose is also the carried out by the liver into the hepatic vein
- the hepatic vein joins the inferior vena cava, the inferior vena cover then carries the blood rich nutrients to the heart
- the heart then pumps this blood to the lungs , in the lungs the blood is oxygenated
- it is then pumped back into the heart and the heart it to the rest of the body via the aorta
absorption of amino acids
amino acids are actively absorbed against a concentration gradient
-they then enter the blood capillaries of the villi
absorption of fatty acids and glycerol
bile salts emulsify fatty acids and glycerol so they are soluble in water
-they enter the villi by diffusion, the fatty acids and glycerol are absorbed by the lacteal
absorption of water
absorbed by villi through osmosis
adaptations of the alimentary canal for efficient absorption
- alimentary canal is very long to ensure that food stays in the small intestine for a long period of time this is too ensure that maximum absorption occurs
- the millions of villi found in the small intestine increase the surface area for absorption
- walls of villi are thin since they are made up of a single layer of epithelial cells this allows easy absorption
- lacteals and blood capillaries are present to quickly transport absorbed food away
- columnar epithelial cells of villi have micro-villi to further increase the surface area for maximum absorption
- columnar epithelial cells have a large number of mitochondria to provide energy needed for active transport
hepatic portal system
consists of the hepatic portal vein and other small veins that carry blood with absorbed nutrients from the alimentary canal to the liver
assimilation of fatty acids and glycerol
- fatty acids and glycerol enter the lacteal of the villi(absorbed by villi)
- the lymph vessel transports(drains) the fatty acids and glycerol from the lacteal to the left thoracic duct
- the left thoracic duct then opens into the blood system
assimilation of glucose, amino acids ,water , vitamins and mineral ions
they enter the blood capillaries of the villi ,these capillaries join to form venules then larger veins
-the larger veins pour into the hepatic portal system and the the hepatic portal system carries the nutrients into the liver
role of liver
- excess glucose is converted into glycogen by insulin and then stored
- excess amino acids are de-aminated to form urea which is excreted via kidneys
- it detoxifies harmful substances like, alcohol ,poisons and drugs
- it inactivates certain hormones after they have been used
- changes food into energy
deamination
the removal of the amino (NH2) group from the amino acids
importance of rough
- adds bulk to the material in the colon so that it stretches and peristalsis can occur, thus moving faeces towards the rectum
- cellulose in roughage enable faeces to retain & absorb water, preventing drying out of faeces
homeostasis
the natural tendency of the body to maintain a constant internal environment irrespective of the external environment
how does the body return the blood sugar levels back to normal when it is too high
- the hormone insulin is secreted by the pancreas
- the insulin then increases the rate at which glucose is absorbed by the cells
- it then stimulates the liver and muscles to convert glucose into glycogen and fat
how does the body return the blood sugar levels back to normal when it is too low
- the pancreas secretes a hormone glucagon
- glucagon stimulates the conversion of glycogen back into glucose and this glucose is returned back into the bloodstream
negative feedback
when something changes in the internal environment the opposite is produced to keep the internal environment constant
role of insulin in homeostasis
the insulin helps in decreasing the high glucose levels in the blood
role of glucagon in homeostasis
the glucagon secreted increases the blood sugar levels when it is too low
give an example of negative feedback
when the glucose level is too high ,the pancreas secretes more insulin and less glucagon ,and the processes of decreasing the sugar levels are set in motion .
