Module 1 Flashcards
What does the foregut consist of?
mouth, pharynx, oesophagus, stomach and small intestine
what does the hindgut consist of?
caecum, large colon, small colon, rectum and anus
lips
upper lip strong, used to sort and grasp
incisors
cutting teeth, used to bite
molars
grinding teeth, located at the back of the jaw
Where is saliva produced?
mandibular, parotid and sublingual glands
What does saliva do?
aid movement of food, also is slightly alkaline which helps buffer acid in stomach
How much saliva is produced daily?
production of saliva is proportional to the number of chews. Approx 10-12l produced daily
Tongue
forms food bolus and passes to the back of the mouth
Pharynx
cavity behind the mouth where food passes over tracheal opening
Epiglottis
small cartilage over trachea, depressed during swallowing
oesophagus
tube that passes through the chest, diaphragm into the abdominal cavity and to the stomach. Located on the left side of the neck
How long is the oesophagus?
approx 1.2m-1.5m
stomach
size of a rugby ball but can expand to 9-18l
what is the cardiac sphincter?
It allows food into the stomach and prevents food from going backwards
What are the 4 regions of the stomach?
oesophageal, cardiac, fundic and pyloric
oesophageal region
acts as a holding area, no glands and food matter is neutral
cardiac region
glands produce mucus to protect stomach from HCl
fundic region
main body of stomach, food is highly acidic in this region
what are the three type of cells in the fundic region?
parietal/border, neck chief, body chief
what do parietal/border cells secrete?
HCl
what do neck chief cells secrete?
mucus
what do body chief cells secrete?
enzymes
pyloric region
secretes mucus and small amount of protein digesting enzymes
what does food stimulate?
the release of gastric juice and HCl
How much gastric juice is produced daily?
10-13l
What is the purpose of pepsin?
breaks down peptones and protoeses
what does HCl do to pepsinogen?
converts to pepsin
what is pepsin secreted as and where?
pepsinogen in gastric juices
Roles of HCl
acidifies food, anti-bacterial action and converts pepsinogen to pepsin
how long can food remain in the stomach for?
2 hours
pyloric sphincter
ring muscle that regulates food leaving the stomach
what foods do the small intestine breakdown?
starch, lipids and protein
function of small intestine
breakdown of concentration foods and absorption of nutrients
structure of small intestine
coils close to small colon, moves relatively freely in the abdomen and lining covered with villi
what does villi aid?
it gives a larger surface area to aid absorption
what are the 3 types of glands in the small intestine?
intestinal glands, duodenal glands, peyer’s patches
where are intestinal glands located and what do they secrete?
throughout the small intestine, secrete large number of enzymes
where are duodenal glands located and what do they secrete?
in duodenum, secrete alkaline solution
where are peyer’s patches located and what is their function?
throughout small intestines, accumulations of lymphoid tissue. Produce antibodies and control bacterial population
Peristalsis
involuntary muscle contractions to push food through intestines
how does peristalsis work?
layer of longitudinal muscle and layer of circular muscle work antagonistically to push food in one direction
what is the length and formation of duodenum?
approx 1m long, forms an S shape
what is absorbed into the bloodstream in the jejunum?
amino acids, vitamins, minerals and glucose
how are triglycerides formed in the jejunum?
lipids are digested and re-assimilated within epithelial cells into triglycerides, they are packaged together with protein and cholesterol
how long is the jejunum?
approx 20m long
how long is the ileum?
approx 2m long
what is the function of ileum?
mesentery tissue supports intestines and supplies blood vessels, lymphatics and nerves
what is the collective volume capacity if duodenum, jejunum and ileum?
approx 50l
Liver
- metabolic centre
- situated behind the diaphragm, in front of the stomach
- weighs 5-9kg
functions of the liver
- breaks dow excess amino acids
- detoxifies waste products and pathogens
- Old haemoglobin is broken down by liver cells
- Important source of body heat
- Bile emulsifies lipids aiding the action of lipase
- production of cholesterol and maintenance of lipid levels
- storage iron and vitamins A, D and B12
- synthesis of blood plasma proteins
- large veins serve of blood reservoir
what is the function of bile?
renders the acidic stomach contents alkaline before reaching digestive tract; prevents acid attaching to walls and provides correct pH
How has the horse adapted to having no gall bladder
this causes bile to trickle continuously into the duodenum because the bile cannot be stored
how are glucose levels maintained?
- glucose is either utilised or stored in liver
- insulin secreted in response to increase in glucose after food and encourages storage of glucose either as fat or glycogen
- glucagon increases blood glucose by stimulating enzyme breakdown of liver glycogen and adipose tissue (counteracts insulin)
where is the pancreas located?
gland that lies behind stomach, alongside duodenum
functions of pancreas
- produces insulin and glucagon
- produces pancreatic juice
what are the islets of langerhans?
small masses of special cells interspersed throughout the pancreas
function of pancreatic juice
- increases when food is present
- reduces acidity of food
- breaks down protein into smaller fragments
- converts protein fragments into amino acids
- breaks starch down into maltose
crypts of lieberkuhn glands secrete
amino peptidases, sucrase, lactase, maltase and intestinal lipase
large intestine functions
- provide optimum environment
- digest remaining soluble carbohydrates or starch
- absorb water and vitamins
caecum
- food reaches here later
- holds 35l
- valve controls food coming in
- held here before being passed on to large colon on a top up basis
digestion of fibre through fermentation process
- starts in caecum and is activated by bacteria, yeasts, fungi and protozoa
- population continually changing to adjust to diet
- cellulose, hemicellulose and pectin broken down to release volatile fatty acids. Used as energy source by tissues
- microorganisms synthesise essential vitamins
what can high roughage cause?
horses will have large bellies due to bulk within caecum
structure of large colon
- right ventral colon
- sternal flexure, diameter narrows, turns back
- left ventral colon, along left side to pelvic region
- turns into pelvic flexure, diameter reduced 9cm
- expands towards diaphragm, left dorsal colon
- turn at diaphragmatic flexure, form right dorsal colon
- narrows and become small colon
what happens in the large colon?
bacteria ferment cellulose
why is the small colon susceptible to twisting?
lies intermingled with jejunum and moves freely
how much can the small colon hold?
14l
what is extracted through the walls of the small colon?
water and nutrients
foregut
deals with small quantities of concentrate feed
hindgut
deals with large quantities of fibre-containing roughage
what energy sources are stored?
carbohydrates, lipids and proteins
what is balance of carbohydrates and fat affected by?
state of feeding, exercise level and intensity, state of training, feed type and time of feeding
what happens to excess dietary protein?
either re-processed or used as immediate energy supply
when can tissue protein be used?
only in extreme circumstances
where are carbohydrates stored?
as glycogen in muscle cells and liver
how does glucose remain constant?
insulin and glucagon secreted by the pancreas , travel to the liver which prompts the release of glucose
composition of fat
one molecule of glycerol to three molecules of fatty acids
subcutaneous fat/adipose tissue
fat under the skin
what high energy compounds are within every cell?
adenosine triphosphate (ATP)
composition of ATP
adenosine attached to a chain of 3 phosphates
how is energy released from ATP?
one phosphate group is broken off in the presence of an enzyme
what does released energy become?
ADP (has 2 phosphate)
how is rate of reformation of ATP calculated?
reformation corresponds to the rate original ATP is broken down
what happens during tissue respiration?
sugars are broken down to provide energy for regeneration ATP, this occurs when a phosphate group is attached to ADP
what does the rate of sugar broken down depend on?
amount of ATP being used
why is anaerobic respiration less efficient?
sugars are only partially broken down, less energy production and lactic acid end product
anaerobic threshold/onset of blood lactate accumulation (OBLA)
point where lactate is produced faster than it can be removed by blood and lactic acid is retained
how is lactate removed?
lactate is diffused out of muscle cells entering the blood, which transports it to the liver. Lactate is converted back to pyruvate, which can be used to produce glucose
what does a build up of lactic acid cause?
can reduce of pH of cells and cause a deficiency in production of ATP. Causes fatigue as muscle fibres cannot contract properly and normal functioning is impaired
