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GI

rebekahwallace94 Englisch 202 Karten

The electrolyte composition of the primary secretion is produced by the acinar cells and this is modified by the duct cells…

Karten in diesem Stapel (202)

1What are the 4 digestive processes?Motility, Secretion, Digestion and absorption
2What does motility mean?Muscular contractions of muscle that mix and move the food along the GI tract
3What type of muscle is present within the GI tract (apart from the sphincters)Smooth muscle
4What is the function of the smooth muscle in the GI tract?It maintains a low level of tonic contraction known as tone which is important for maintaining a steady pressure and to prevent the walls from remaining stretching following distension
5What are the two types of tone?This is propulsive and mixing movements
6What are propulsive movements?They push the contents of the GI tract along at differing speeds though specific locations
7What are mixing movements?The food mixes with the digestive juices and facilitates absorption by exposing all sides of the food to the absorptive surfaces
8What is important to remember about the types of muscle in the GI tract?There is mainly smooth muscle along the tract except at the ends of the tract where skeletal muscle is required for chewing, swallowing and defecation
9What glands secrete the digestive juices in secretion?Exocrine glands
10How is tone derived in the GI tract?It is achieved by the action potential induced bursts of contraction
11What does digestive secretions consist of?They are mainly made up of water, electrolytes and specific contents
12Where are the materials for the enzymes gathered from?The plasma
13Why does secretion require energy?Active transport of some of the raw materials and the synthesis of the secretory products from the endoplasmic reticulum
14When does secretion occur?It occurs by hormonal and neural innervation
15Apart from digestion, what is another important role for secretion?Protection
16Name three monosaccharides?Glucose, Galatose and fructose
17Name two polysaccharidesCellulose and starch
18Name two disaccharides?Sucrose and lactose
19What are proteins broken down into?They are broken down into amino acids and some small polypeptides
20What are triglycerides broken into?3 fatty acids and one molecule of glycerol
21How does digestion occur?It occurs by hydrolysis
22What is absorption?This is the transfer of absorbable products of digestion with water, electrolytes and vitamins from the digestive tract to the blood or lymph
23What are the accessory digestive organs?These include the salivary glands the exocrine pancreas and the biliary system, which is composed of the liver and the gall bladder.
24What important about protease?Once these enzymes are synthesised in the inactive form, they are not activated until they reach the site of action as this enzyme could destroy the body's own cells.
25What are the four layers of the GI tract?The mucosa, submucosa, muscularis externa and the serosa
26What are the 3 layers of the mucosa?The mucous membrane, the lamina propia and the muscularis mucosa
27What is the function of the mucous membrane?It is an inner epithelial layer that protects the surface and contains endocrine glands and epithelial cells for digestion and absorption
28What is the function of the lamina propia?This is the middle layer of connective tissue which contains the gut-associated lymphoid tissue
29What is the function of the muscularis mucosa?Smooth muscle which forms the outermost mucosa layer
30What is important about the shape of the mucosal surface and how can this be modified?It is highly folded with many folds and the amount of folding depends on the location. The pattern of this folding can be altered by the muscularis mucosa
31What is the function of the submucosa?This is a thick layer of connective tissue that provides the digestive system with distensibility and elasticity which contains larger blood and lymph vessels and also contains the submucosal plexus
32What is the function of the musclaris externa?This contains two types of muscle- the inner circular muscle and the outer longitudinal muscle.
33What is the function of the inner circular muscle?Contraction results in a decrease of the diameter of the lumen
34What is the function of the outer longitudinal muscle?This shortens the tube
35What is the combined effect of these muscles?They produce the propulsive and mixing movements
36Where does the myenteric plexus lie?It lies between the circular and longitudinal muscle layers
37What does the serosa do?This is the outer connective tissue covering the digestive tract which secrete serous fluid that lubricates and prevents friction between the digestive system and the surrounding viscera.
38What is the mesentery?This suspends the digestive organs from the inner wall of the abdominal cavity and provides support and movement from the propulsive and mixing movements
39What is the function of the palate?This is the nasal cavities from the oral cavity and it allow breathing and chewing occurring simultaneously
40What is the function of the uvula?This is the dangling projection which is important in sealing off nasal passages during swallowing
41What is the function of the tongue?Forms the floor of the oral cavity and the movements are important in guiding the food during chewing and swallowing. It also contains the taste buds
42What is the role of the pharynx?This acts as a common passageway for food and air. Within the walls of the pharynx, are the tonsils which are lymphoid tissues
43What is mastication?The motility of the mouth that involves splicing, tearing, grinding and mixing of ingested food by the teeth
44What are the function of teeth?They are for chewing which is mediated by the masseteric and diagastric reflexes which breaks food down and mixes it with saliva, stimulates the tastes buds and by reflexes following the stimulation of the taste buds, increase salivary, gastric and pancreatic secretions.
45Where is saliva secreted?It is secreted by the parotid, submandibular and the sublingual glands
46What are the functions of saliva?Lubrication- salivary water and mucus are important in speech and swallowing
Solvent- important for taste
Antibacterial- contains lysozyme, lactoferrin and immunoglobins which is important in the preventation of dental carries
Digestion- contains amylase
Neutralisation of acid- contains bicarbonate
Facilitates sucking in infants- fluid seal
47What is the function of salivary amylase?It is to break down polysaccharides into maltose
48What is the function of mucus in the mouth?Moistens food particles, holding them together and providing lubrication through mucus
49What is the function of lysozyme?It destroys certain bacteria by breaking down their cell wall
50What is the function of lactoferrin?Binds to iron needed for bacterial multiplication
51What is xerostomia?This is a condition with diminished salivary secretion, making chewing and swallowing difficult and affecting speech as well as rapid dental carries.
52How is saliva always constant in the mouth?The continuous basal secretion of saliva is maintained by the parasympathetic nerve allowing a low-level of secretion.
53What is the simple salivary reflex?This occurs when chemoreceptors initiate impulses in nerves that carry the information to salivary centre which is located in the medulla of the brainstem which controls digestive activities.
54What does the salivary centre do?It sends impulses via the extrinsic autonomic nerves to the salivary glands to increase secretion.
55What is conditioned salivary reflex?This occurs without stimulation, just thinking of food intiates salivary secretion. This process stimulates the medullary salivary centre
56What does the salivary centre do?This controls the degree of salivary output by the autonomic nerves system where both sympathetic and parasympathetic stimulation increase salivary secretion.
57What is the role of parasympathetic stimulation?This exerts a dominant role of the salivary secretion which produces a prompt and abundant flow of watery salivary that is rich in enzymes
58What is the role of sympathetic stimulation?This produces a much smaller volume of saliva with the mouth feeling more dry than usual when the sympathetic stimulation is in control.
59Does absorption occur in the mouth?No
60Can drugs be absorbed in the mouth?Yes, some drugs such as nitroglycerin which is a vasodilator used in angina which can be absorbed by the oral mucosa
61The formation of saliva occurs in two stages..what are these?Primary secretion by the acinus and the secondary by the duct cells
62What is the role of the acinus?These cells produce primary secretion with sodium, potassium, chloride and bicarbonate content which is similar to plasma
63What is the role of duct cellsThese cells modify secretion by removing Na and Cl and to a lesser extent adding K and HCO3 with no movement of water
64NB Sympathetic stimulation of saliva is to promote respiration and the saliva produced is thickerParasympathetic stimulation is related to digestion as
65What receptor does the Ach in parasympathetic stimulation activate?M3 receptor which causes an increase in the intracellular concentration of calcium which induces secretion
66What receptors does sympathetic nerves activate during saliva secretion?The noradrenaline release activates the alpha adrenoceptors
67—The electrolyte composition of the primary secretion is produced by the acinar cells and this is modified by the duct cells which reduces the concentration of sodium and chloride with more potassium and bicarbonate in the saliva than the plasma.
68What is significant about the flow of secretion in relation to its composition?As the secretion rate increases, the electrolyte composition of saliva reaches the ionic composition of plasma however in low flow, there is more time for modification and reduces the osmolality of the primary secretion and so the saliva has a lower osmolality than the plasma
69What increases the rate of formation?The simple and conditional reflex
70What happens to the HCO3 content in high secretion rate?It increases and decreases with low flow
71What happens to the concentration of NaCl?It is lower than in plasma
72What happens in the simple reflex?Chemoreceptors/pressure receptors are activated by food- the impulses are sent to the salivary centre in the medulla and the impulses then travel to the salivary glands via the extrinsic autonomic nervous system
73What happens in conditioned reflex?Thinking about taste or smell, activates the cerebral cortex which then activates the salivary center in the medulla.
74What happens during parasympathetic stimulation?The dominant role in normal saliva production which is stimulates the glossopharygneal and the facial nerves producing a large volume of watery enzyme rich saliva which is mediated by M3 receptors
75What causes a dry mouth?Muscarinic receptors antagonists e.g. atropine and antidepressants that block these receptors
76What is the role of the sympathetic stimulation?Dominant in stressful times and is stimulated by the postganglioninc fibers of the superior cervical ganglia which produces small volume of thick, mucus rich saliva which is mediated by B1 adrenoceptors
77Describe the action of swallowing?1. The bolus is formed in the mouth by the action of the teeth and the tongue
2. The tongue forces the bolus into the pharynx at the rear of the mouth
3. The pressure stimulates pharyngeal pressure receptors
4. Afferent impulses to swallowing centre of the medulla
5. Efferents initiate all-or-nothing reflex sequences of muscle movement
4. The upper oesophageal sphincter opens
5. Food passes through the pharynx into the oesophagus
78What are the stages of swallowing?There is the oropharyngeal stage which typically lasts one second and moves the bolus from the mouth through the pharynx and into the oesophagus and the oesophageal stage.
79—LEARN
80Name the two sphincters of the oesophagus?The pharyngoesophageal and the gastroesophageal sphincter.
81When does the pharyngoesophagus open?It opens when during swallowing however most of the time it remains closed due to the neurally induced contraction of the skeletal muscle and this helps to prevent large volumes of air from entering the oesophagus ad stomach during breathing
82What is eructation?Burping
83What is the oesophageal stage?This typically lasts between 4-10 seconds. The swallowing center triggers a primary persistaltic wave that sweeps from the begining to the end, forcing the bolus ahead of it, pushing it into the relaxed area ahead of the contraction. Progression of the wave is controlled by the swallowing centre with the vagus innervertion.
84What is the second peristaltic wave?This is activated if the bolus gets stuck in the oesophagus and so stimulates the pressure receptors within the walls and so a more forceful peristaltic wave is activated which mediated by the intrinsic nerve plexus.
85What is important to remember about the secondary peristaltic wave?It does not involve the swallowing centre of the medulla and the distension of the oesophagus increases the saliva secretion.
86The swallowing centre during the oesophageal stage closes the upper oesophageal sphincterThe peristaltic wave is mediated by skeletal muscle in the upper oesophagus and the smooth muscle in the distal regions.
87What co-ordinates the peristaltic wave?The enteric nervous system- cholinergic nerves
88What is the role of the circular and longitudinal muscles?The circular fibres behind the bolus squeeze the bolus down the stomach and the longitudinal fibers in front shorten the distance of travel
89What nerve supply controls the gastroesophageal sphincter?The myenteric plexus
90What is the difference between the gastro and pharyno-oesophageal sphincter?The gastro is smooth muscle and the pharyno- is smooth muscle
91How is mucus protective in the oesophagus?The oesophageal secretion is entirely mucus as this reduces the likelihood of the oesophagus being damaged by any sharp edges and it protects the oesophagus from the acid and enzymes in the gastric juice
92What are the three sections of the stomach?The fundus which is the part of the stomach that lies above the oesphageal opening
The body- the middle part of the stomach
The antrum- much more smooth muscle
The terminal end of the stomach is the pyloric sphincter.
93What are the main functions of the stomach?Store ingested food until it can be emptied into the duodenum. It is important that the store of food and meter it into the duodenum that does not exceed the small intestine capacities.
The secretion of HCl and enzymes to begin digestion
The mixing movements of the stomach allow the production of chyme
94What is receptive relaxation?The folds of the stomach get smaller and nearly flatten out as the stomach relaxes with each mouthful.
95What is the role of the receptive relaxation?This is to enhance the stomach's ability to accommodate the extra volume with little rise in stomach pressure
96What nerve is responsible for the receptive relaxation?The vagus nerve
97What is the name given to the group of pacemaker cells located in the upper fundusThe interstital cells of Cajal
98What is the role of the interstital cells of Cajal?These generate a slow-wave potential that sweep down the length of the stomach towards the pyloric sphincter. This creates a basic electrical rhythm of the stomach which occurs continuously.
99How are peristaltic waves generated?This basic electrical rhythm - (depending on the excitation of the smooth muscle cells) it may be brought to threshold by this current and generate action potentials which initiate the peristaltic waves at a rate of 3 per minute.
100What does the peristaltic wave do?It spreads over the fundus and body to the antrum and pyloric sphincter. As the muscle is so much thinner in the body and the fundus, the contractions are weak. However when they reach the antrum, they become much stronger and more vigerous because of the thicker muscle which is thicker.
101—Diagram
102What produces the chyme?The strong antral peristaltic contractions mix the food with the gastric secretions to produce chyme
103What is mixing mechanism in the stomach?The strong antral peristaltci contrations mix the food with the gastric secretions to produce chyme. Each antral peristaltic wave propels chyme forward towards the pyloric sphincter. The tonic contraction of the pyloric sphincter keeps it mostly closed however the opening is large enough for water and fluid to pass through however not chyme except when a strong peristaltic wave pushes it through. Before more chyme can pass, the peristaltic wave reaches the pyloric sphincter and causes it to contract more forcefully, blocking the entry of chyme into the duodenum. The bulk of the chyme that was propelled forward but failed to enter the duodenum is tumbled back into the antrum, only to be propelled and tumbled back and this cycle mixes the chyme.
104What determines the amount of chyme entering the duodenum?The strength of peristalsis which is influenced by gastric and duodenal factors
105IMPORTANTThe greater the excitability is, the more frequently the BER will generate action potentials, the greater the degree of peristaltic activity in the antrum and the faster the rate of gastric emptying.
106What are the gastric factors that affect the peristaltic wave?The rate of emptying is proportional to the volume of chyme that is present in the stomach and consistency of the chyme.
107How does the volume of chyme affect the emptying of the stomach?The distension of the stomach increases motility due to the stretch of smooth muscle, the stimulation of the intrinsic nerve plexus, increased vagus nerve activity and an increase in the amount of gastrin that is released.
108How does the consistency of chyme affect gastric emptying?The emptying is facilitated by the finely divided, thick liquid chyme
109—
110What is the function of the small intestine?This is the major site of digestion and absorption
111What are the 3 sections of the small intestineThe duodenal, jejunum and the ileum
112What does contents does the small intestine receive?It receives the chyme from the stomach, the pancreatic juice from the pancreas and the bile from the gall bladder
113What does the small intestine secrete?It secretes the intestinal juices
114What type of secretory cells are present within the mucosa of the duodenum?The endocrine cells
115Where is gastrin released?It is released from G cells of the gastric antrum (mainly) and the duodenum
116What is CCK?Cholecystokinin which is secreted from I cells of the duodenum and the jejunum
117What is secretin?This is released from S cells of the duodenum
118What is motilin?This is released from M cells of the duodenum and jejunum
119What is GIP?Glucose-dependent insulinotropic peptide which is an increatin from K cells of the duodenum and jejunum
120What are gliptins?Sitagliptin is a DDP-4 inhibitor which increases increatin levels i.e increased GLP which inhibit glucagon and increases secretion of insulin, decrease gastric emptying and decreases blood glucose levels and so is used in the treatment of type 2 diabetes.
121What is GlucagnonIt is an increatin which is secreted from L cells in the small and large intestine
122What is important to remember the following secretionsThey all act on G-protein coupled receptors
123What produces succus entericus?Exocrine cells in the small intestinal mucosa and its composition varies through the small intestine
124What factors increase the secretion of small intestine?Distension/irritation, gastrin, CCK, secretin, parasympathetic nerve activity increase the secretion of succus entericus
125What factors decrease succus entericus secretion?Sympathetic nerve activity
126What does secretion contain?Mucus- for protection/lubrication from goblet cells
Aqueous salt- for enzymatic digestion (mostly from crypts)
No digestive enzymes
127Where are the enzymes secreted?The enzymes act within the brush-border membrane of the epithelial cells lining the lumen
128What is segmentation?Segmentation consists of oscillating, ring-like contractions of the circular muscle along the length of the small intestine
129What is important to remember about this segmentation?Between the contracted segments, there are relaxed area containing the small bolus of chyme
130After a brief period of time, the contracted segments relax and ring-like contractions appear in the previously relaxed areas.The new contraction forces the chyme in a previously relaxed area to move in both direction into the now relaxed areas. Newly relaxed segments therefore receive chyme from both the contracting segment ahead of it and the one immediately behind it. This allows the chyme to the chopped, churned and thoroughly mixed.
131How is segmentation activated?It is activated by the small intestinal pacemaker cells causing the basic excitatory rhythm. At the threshold, this activates an action potential, causing contraction of the circular muscle
132How can the intensity of the segmentation be influenced?It can influenced by the distension by the hormone gastrin and extrinsic nervous
133When does segmentation begin?It begins when a meal enters the small intestine- however the duodenum starts to segment primarily to the presence of chyme which causes distension
134What causes segmentation in the empty ileum?This is called the gastoileal reflex
135Apart from gastrin, what else can effect segmentationThe extrinsic nerve activity
136What effect does the parasympathetic activity have on segmentation?It enhances segmentation
137The pacemaker cells depolarise quicker in the duodenum than those further down the tract and this allows more chyme to be pushed forward than the pushed back.The slow propulsive movement is of benefit as it allows loads of time for digestion and absorption to occur
138What occurs when the meal has been absorbed?Segmentation stops and is replaced by the migration motility complex which consists of weak peristaltic waves that move a short distance down the intestine.
139What is the function of the migrating motility complex?With each contraction, there is sweeping of any remnants of the preceding meal plus mucosal debris and bacterial which is taken to the colon
140What is the name of the hormone which regulates the migrating motility complex?Molitin which is secreted during the unfed state from endocrine cells of the small intestine mucosa
141What factors supress the migrating motilin complex?Gastrin which is released in the fed state and CCK
142Does vagal activity affect this complex?Yes it inhibits the MMC
143Why does erythomycin cause GI disturbances?Macrolide antibiotics minic the action of the motilin
144Where does the MMC occurIt occurs from the stomach to the ileocaecal valve
145What hormones are released by the endocrine cells of the pancreas?Insulin and glucagon which are both secreted into the blood
146What do exocrine glands in the pancreas release?Digestive enzymes (acinar cells) and aqueous NaHCO3 solution from duct cells which are both secreted into the duodenum as pancreatic juice.
147What are the acini of the pancreas?These are primary exocrine cells which consist of secretory cells that form the acini sacs
148What are the endocrine glands of the pancreas?The islets of Langerhans which is dispersed throughout the pancreas
149What is pepsinogen and pancreatic enzymes stored in?Zymogen granules
150What are the 3 types of enzymes that the pancreas can secrete?It can enzyme proteolytic enzymes- protein, pancreatic amylase- carbohydrates and pancreatic lipase- fat
151What are the 3 types of proteolytic enzymes?Trypsinogen, chmotrypsinogen and procarboxypeptidase
152What happens when trypsinogen is released into the lumen?It is converted into the active form and becomes trypsin by the enzyme enteropeptidase
153Where is enteropeptidase found?It is found embedded in the lumen of the duodenal lining
154What is an important property of the trypsin?Trypsin can autocatalyically activates more trypsinogen.
155What is trypsin inhibitor?It is an enzyme that is released from the pancreas that blocks the activity of the trypsin if spontaneous activation of trypsinogen in the pancreatic and so provides protection
156What is chymotrypsinogen and procarboxypeptidaseconverted into?It is converted into the chymotrypsin and carboxylpeptidase both of which are activated by the trypsin
157During this stage, what else is secreted along with the protelytic enzymes?Mucus is also released by the intestinal cells to protect the small intestinal wall
158Is pancreatic amylase released in the active form?Yes because the active amylase does not endanger secretory cells
159Pancreatic lipase is the only enzyme that can digest fat and is released in the active form
160What is a zymogen?This is inactivation of the pancreatic enzymes to prevent the digestion of the pancreas itself
161What is the function of the alkaline secretion?The acidic chyme from the stomach must be neutralised for the pancreatic enzymes to work but also to prevent damage to the duodenal mucosa.
162—carbonic anhydrase is involved and the NaK pump provides the driving energy for secondary active trans- port. According to the current model, under the influence of carbonic anhydrase, CO2 in the pancreatic duct cell combines with OH generated from H2O to produce HCO3, which exits across the luminal membrane to enter the duct lumen via a ClHCO3 antiporter. Sodium diffuses through the “leaky” tight junctions into the lumen. Together these actions accom- plish NaHCO3 secretion. The H generated from H2O within the duct cell enters the blood across the basolateral border either by active transport or a NaH antiporter. Thus the pancreatic duct cells secrete HCO3 and absorb H, whereas the gastric parietal cells secrete H and absorb HCO3, so the acid base status of the body is not altered by digestive secretion.
163What are the 3 phases of pancreatic secretion?Cephalic, gastric and intestinal
164What is the cephalic phase?This is mediated by the vagus nerve of mainly the acinar cells
165What is the gastric phaseGastric distension evokes a vagovagal reflex which results in the parasympathetic stimulation of acinar and duct cells
166What regulates pancreatic exocrine release?Secretin and CCK
167What causes the release of secretin?Acid in the duodenum
168What effect does secretin have on the body?It is carried to the pancreas via the blood where it stimulates the duct cells to increase the secretion of HCO3. The amount of acid that is present within the duodenum is equal to the secretion of HCO3 from the pancreas.
169What effects the release of CCK?The presence of fat and to a lesser extent protein.
170—VERY IMPORTANT
171What makes up the biliary system?The liver, gall bladder and associated duct
172—Anatomy
173What guards the opening of the bile duct?The sphincter of Oddi which prevents bile from entering the duodenum
174When does the sphincter of Oddi open?During digestion of meals
175What happens when the sphincter of Oddi is closed?Most of the bile which is produced by the liver is transported to the gall bladder for storage
176How does bile enter the duodenum?Bile enters the duodenum by the emptying of the gall bladder and the increased bile secretions of the liver
177—IMPORTANT
178—
179Is cholesterol fat?Yeah sure is
180Are vitamins lipids?Yes
181Where do we receive protein from?We receive protein from our diet however we receive protein from endogenous sources such as digestive enzymes and dead cells from the GI tract
182Where does most of the digestion occur in the small intestines?It occurs mainly in the duodenum and the jejunum due to the fact that most of the absorption will have been carried out by those regions
183Why is the removal of the terminal ileum problematic?Vitamin B12 and bile salts are not properly absorbed if this is done as the specialised transport mechanism for these only exists at this terminal
184Why is the small intestine so well adapted for absorption?It has a very large surface area and the epithelial cells in the lining have a variety of specialised transport mechanisms.
185How is the small intestine's surface area increased?It is increased by the number of permanent folds that are present , villi are present and microvilli as well.
186How are carbohydrates digested in the body?The dietary polysaccharide starch and glycogen are converted into maltose by the salivary alpha-amylase
187What type of amylase is present in the stomach?salivary alpha-amylase within the bolus
188How does the digestion of carbohydrates continue in the duodenum?It contains pancreatic alpha-amylase which is secreted into the lumen
It also contains oligosaccharides which are integral to the brush border membrane of the enterocytes and includes isomaltase, sucrase, lactase and maltase
189What is amylase?It is an endoenzyme which attacks the internal but not the terminal alpha 1-4 alpha- glycosidic bonds, producing oligosaccharides
190—Digestion of carbohydrates
191—d
192What is lactose intolerance?This is a deficiency of lactase- when lactose-rich milk or dairy products are consumed, the undigested lactose remains in the lumen which causes the an osmotic gradient which draws water into the intestinal lumen and bacteria within the large intestine have lactose-splitting ability so produce huge quantities of carbon dioxide and methane gas. Distension of the intestines by both fluid and gas produces cramps and diarrhoea.
193How are carbohydrates absorbed?Glucose and galatose are both absorbed by secondary active transport by a sodium and glucose co-transporter (SGLT) on the luminal membrane transport both the monosacharide and Na from the lumen into the interior of the intestinal cell with the entry of 2 sodium ions.
194How does glucose/galactose leave the cell?It leaves the cell down its concentration gradient by facilitated diffusion via the GLUT-2 in the basal border to enter the blood.
195Fructose is absorbed into the blood by facilitates diffusion and enters the epithelial cell by the GLUT-5 co-transporter and then exits these cells to enter the blood through the GLUT-2 transporter.
196What are the 3 sources of endogenous proteins?1. Digestive enzymes which have been secreted into the lumen
2. Proteins within the cells that are pushed off from the villi into the lumen during mucosal turnover and the small amount of plasma proteins that leak from the capillaries.
197How does protein digestion occur in the stomach?The HCl creates the optimum environment for the pepsin which cleaves the proteins into peptides.
198How does protein digestion occur in the duodenum?Pancreatic enzymes spilt the peptide bonds between different amino acids
199What are the brush border enzymes?These are aminopeptidase, carboxypeptidase or dipeptidase) which cleave amino acids at the ends of the molecule and hydrolyse dipeptides.
200After digestion of protein in the stomach and the duodenum, what are the final products?Amino acid , depeptides, tripeptides, oligopeptides and some intact proteins
201How does protein absorption occur?The absorption depends on the type of protein that it is.
202How are amino acids absorbed?They are either absorbed by passive diffusion- hydrophobic amino acids e.g. tryptophan