Animal Nutrition Flashcards
What is the importance of food
- Supply energy
- Provision of materials for growth and repair of damaged tissue
- Maintaing body processes
Incisors
For cutting and biting
Canines
For tearing
Premolars
For chewing and grinding
Molars
For chewing and grinding
Characteristics of the dentition of an omnivore
- chisel-shaped incisors
- pointed canine for tearing meat
- fairly flattened pre-molars and molars to chew both meat and plant material effectively
What is the function of the accessory organs in the digestive system
To secret substances into the alimentary canal to facilitate digestion
Ingestion
The intake of food through the mouth
Digestion
The mechanical and chemical break down of food
Absorption
The diffusion of simple food molecules through the intestine walls and into the blood
Assimilation
Intake of nutrients into the cells
Egestion
The removal of undigested food particles and waste from the body through the anus
The mouth
The mouth is bounded by two lips that keep the food in the mouth
Structures in the mouth
- Teeth
- Tongue
- Salivary glands
Function of teeth
To chew food into smaller pieces. This will increase the surface area of the food that is exposed so that enzymes can break it down further
Mastication
The process of chewing
Tongue
A strong muscular organ that has taste buds that are sensitive to chemicals in food
Function of the tongue
Helps to force food between teeth for chewing and rolls it into a ball
Bolus
A ball of chewed up food
Function of Salivary glands
Secretes saliva which contains an enzyme called salivary amylase that breaks down cooked starch. Saliva keeps the pH of the mouth at 7.2 for optimal enzyme functioning
The three types of salivary glands
1.parotid
2.submadibular
3. Sublingual
Position of the parotid gland
Just below and in front of the ear
Position of the submandibular gland
Lies in the lower jaw
Position of the sublingual gland
Lies below the tongue
Pharynx
The point at which the nasal and mouth cavity meet
Epiglottis
A structure that prevents entry of food or liquid particles into the air passages when we swallow
The oesophagus
A long tube extending from the pharynx to the stomach.
The structure of the oesophagus
It consists of smooth muscle and is lined with columnar epithelial that contains goblet cells
What is the function of the goblet cells in the oesophagus ?
The goblet cells secrete mucous that lubricates the oesophagus for ease of passage
Peristalsis
Waves of contractions
How does food move from the oesophagus into the stomach?
As food passes down the oesophagus, waves of contractions follow the food bolus, pushing the food into the stomach
The stomach
An organ that follows on the oesophagus and is bounded by circular muscles called the cardiac sphincter and the pyloric sphincter
What is the function of the cardiac sphincter?
Stops the food from moving back into the oesophagus
What is the function of the pyloric sphincter?
Prevents food from moving into the small intestines until it is ready to do so.
What hormone does the stomach wall secret?
Gastrin
What is the function of gastrin?
It stimulates glands in the wall of the stomach to secrete gastric juice that helps to digest food
What substances does gastric juice contain?
- Hydrochloric acid (HCl)
- Enzymes
- Mucus
Function of hydrochloric acid in the stomach
1.Keeps the pH acidic (pH 2) for enzymes to break down substances such as proteins.
2. It kills micro-organisms ingested with food
Function of enzymes in the stomach
Chemically breaks down various molecules. Examples include pepsin that breaks down proteins and lipase that breaks down fats (lipids)
Function of mucus in the stomach
Protects stomach wall against the digestive actions of enzymes and HCl
Chyme
When the bolus has been churned and liquefied in the stomach
What are the three parts of the small intestine
The duodenum, the jejunum, the ileum
What happens in the stomach intestine?
The process of digestion finishes in the duodenum and the products of digestion is absorbed along the length of the intestine
What is the function of the crypts of Lieberkuhn
To secrete the hormone secretin in the duodenum
What is the function of secretin?
To stimulate the pancreas to release pancreatic juice, and the gall bladder to release stored bile (from the liver) into the duodenum
Succus entericus
All the secretions of the small intestine
What is the function of the succus entericus?
To neutralise the acidic chyme
how do pancreatic juice and bile aid with digestion?
Pancreatic juice contains trypsin, which will break down long polypeptide chains (i.e. protein digestion), amylase which breaks down starch, and lipase which breaks down lipids. The bile will emulsify lipids aiding in lipid digestion.
What is the jejunum and what is its functions?
It is the midsection of the small intestine. The products of digestion are absorbed in the jejunum. It contains numerous villi and micro-villi to increase the surface area for absorption.
what are the three parts of the large intestine (colon)
- ascending colon
- transverse colon
- descending colon
What is the ileum and what does it do?
It is the last section of the small intestine. It also contains villi and absorption of nutrients continue here.
what is the first part of the colon called?
the caecum
what is the valve between the small intestine and the large intestine?
the ileo-caecal valve
Where is the appendix found and what does it do?
Its found below the caecum and its believed to repopulate our stomachs with bacteria after a bout of diarrhea.
what is the main function of the colon
the absorption of water to solidify waste
what is the function of the rectum and the anus?
the rectum stores solid undigested waste, the waste is then expelled from the body via the anus.
name the accessory glands?
- salivary glands
- liver and gall bladder
- pancreas
what is the liver?
The liver is the largest organ in the digestive system and lies just below the diaphragm.
what are the functions of the liver?
- Produces bile
- Stores glucose in the form of glycogen
- Surplus amino acids are broken down to form urea and glucose in a process called deamination
- Converts glycerol (from fat) into glucose
- Converts excess carbohydrates into fatty acids (fats)
- Synthesises Vitamin A
- Stores Vitamin D and iron
What is bile, were produced and stored?
Bile is a yellowing-green substance, it is produced in the liver and stored in the gallbladder
what are the functions of bile?
- nuetralises the acidic chyme from the stomach as it enters the small intestine.
- emulsifies large fat globules into small fat droplets which aids digestion.
- promotes peristalsis in the small intestine.
- acts as an antiseptic which prevents decay of food particles in the small.
what is the pancreas and where is it found?
It is a soft, pink, tad-pole shaped gland which extends across the abdomen just below the stomach
what is the function of the pancreas?
It produces pancreatic juice which contains:
1. enzymes which digest food
2. bicarbonate ions which neutralise acidic chyme in the small intestine 3
It also produces hormones that control blood sugar levels- insulin and glucagon
The pancreas acts as both an endocrine and exocrine gland, explain?
endocrine- it releases hormones (insulin and glucagon) directly into the blood (ductless)
exocrine- it releases pancreatic juice, through a duct, into the duodenum.
what are the functions of glucagon and insulin?
They control blood sugar levels
1. insulin- help decrease blood sugar levels
2. glucagon- help increase blood sugar levels
What is mechanical digestion?
The physical breakdown of large food particles into smaller particles. It occurs during mastication (chewing), churning int the stomach and during peristalsis.
What is peristalsis and what is it triggered by?
Peristalsis is when the food is moved through the digestive system by the rhythmic contraction and relaxation of circular muscles along the alimentary canal. Peristalsis is a reflex action and it triggered by the presence of food in the alimentary canal.
How does mechanical digestion assist with chemical digestion?
Physical digestion does not alter the chemical structure of the compounds, but it increases the surface area for enzyme action.
What is chemical digestion and how does it occur?
The breaking down of large, insoluble molecules into smaller soluble molecules, which can be absorbed by the blood. It occurs when water is added to the food to break the molecular bonds in a process called hydrolysis.
What is responsible for chemical digestion
Enzymes are mainly responsible for chemical digestion. Enzymes are very sensitive to changes in temperature and pH and only work in optimal temperatures and pH ranges.
metabolism
all the chemical reaction in your body
anabolism
chemical reaction that builds (synthesise) molecules
catabolism
chemical reaction that breaks molecules down
how many amino acids do you need to make:
1. polypeptide chain
2. protein
- less then 50
- 50 to 1000
what breaks down:
1. protein molecules
2. carbohydrate molecules
3. fat molecules
- protease
- carbohydrase
- lipase
Why can a fat not be called a polymer
it is made up of two different TYPES of monomers
what is an enzyme
An enzyme is protein which acts as a chemical catalyst which increases the rate of metabolic action in an organism.
What are the steps in the catalytic cycle of an enzyme ?
- The enzyme is available with an empty active site.
- The substrate enters the active site, which enfolds the substrate with an induced fit.
(water is added) - The substate is converted to products
- The products are released.
How does an increase of temperature affect enzymatic action?
As temperature increases, the reaction rate increases. If the temperature continues to increase, the shape of the active site changes ∴ we say its denatured. The substrate can then no longer fit into the active site ∴ the enzyme cannot function.
How does a decrease of temperature affect enzymatic action?
If the temperature is below the optimum temperature, the rate of the reaction becomes slower, but the enzyme is not denatured.
How does a change in pH levels affect enzymatic action?
When an enzyme is exposed to conditions above or below the optimum, the enzyme will denature
Where does most of the absorption take place in the body and why?
Most absorption takes place in the small intestine (mainly the ileum) because most of the digestion has taken place by the time the food reaches the small intestine. (i.e. the food is small enough to absorb)
Name the adaptations of the small intestine for absorption
- Contain villi and microvilli to increase surface area
- Villi have thin walls (one cell layer) to promote absorption of nutrients
- Capillary network in the villi ensure efficient transport of nutrients
- Transverse folds increase surface area
- Very long to provide enough time for absorption of nutrients
Name the adaptation of the villi for absorption
- Epithelium is one cell layer thick allowing nutrients to pass through quickly
- Goblet cells secrete mucus to ensure the absorption surface is moist and to allow nutrients to be dissolved and then be absorbed.
- Epithelium contains many mitochondria to supply energy for active absorption of nutrients
- Microvilli further increase surface area
- There is a lymph vessel called the lacteal in each villus which absorbs and transports lipids
- The villi are richly supplied with blood capillaries to transport glucose and amino acids
Name all the steps that take place for protein and carbohydrate absorption
- Carbohydrates are digested into glucose fructose and galactose. Proteins are digested into amino acids
- The monosaccharides and amino acids combine with the protein carries and are actively carried across the cell membranes.
- Amino acids and monosaccharides are absorbed into the blood capillaries of the villi in the small intestine.
- Capillaries join together to form large venules to form the hepatic portal vein transports amino acids and glucose in the liver.
- Glucose and amino acids flow through hepatic vein to the heart
- The liver converts excess glucose t glycogen and stores it.
- Excess amin acids are deaminated by the liver to form urea (waste product) and removed from the body
Name all the steps that take place for fat absorption
- Fats are digested into glycerol and fatty
- Glycerol is water- soluble and is absorbed by the villus.
- Fatty acids are water-insoluble, and need to combine with bile-salts to make them water-soluble
- The glycerol and fatty acids combine again to form fats, which are too big to enter the capillary blood.
- They enter the lacteals and join with lymph, this substance is known as chyle
what is assimilation?
The process where absorbed nutrients are transported to the cells and incorporated into the cells
Name the ways in which the liver plays a role in assimilation
- Converts glucose into glycogen for storage
- Glucose production from glycogen and other molecules
- Deamination of amino acids
- Metabolises lipids
- Produces various proteins (albumin, clotting proteins/ factor)
- Secretes bile
What is the function of the hepatic portal vein?
It transports substances from the small intestine to the liver so the liver can perform its function.
What causes diarrhoea and constipation
Diarrhoea: The waste moves too fast through the colon and not enough water is reabsorbed.
Constipation: The waste moves to slow through the colon and too much water is reabsorbed
