On Exam 3 you will be presented with an essay question. The essay topic is enzymes and
(chemical and physical) processes involved in chemical digestion
You will be asked to compose an essay about digestion.
A discussion should include the structures (specialized organs and cells) involved. Your
essay should describe the enzymes, how they work and where they are produced.
There are many different organs and cells within the body. Each of these different organs work together to
contribute to an organized pathway of delivering to the needs of the body. The main organs that work for
this are the, stomach, pancreas, liver, and the intestines.
Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking
down the food into simpler nutrients that can be used by the cells. Chemical digestion begins in the mouth
when food mixes with saliva. Saliva contains an enzyme (amylase) that begins the breakdown of
carbohydrates. The stomach contains gastric glands which release digestive acids to create a low pH
environment. The acidic environment functions to denature proteins and other macromolecules, aiding in
their overall digestion. There are CHIEF cells which secrete pepsinogen. Then the Parietal cells,
simultaneously secrete hydrochloric acid (HCl) and intrinsic factor, which is needed to activate the B12.
The first pepsinogen molecules they release are activated by HCl. The stomach epithelium contains a
mucous membrane which prevents the acids from damaging the gastric lining. Hydrochloric acid is a
component of gastric juice that helps create the environment that pepsin needs to break down protein in
the stomach which is Secreted into stomach.
Sucrase Is an enzyme secreted into the small intestine which breaks down sucrose (carbohydrate). maltase
secreted into the small intestine which breaks down maltose (carbohydrate).
Brush border enzymes which can be found within the small intestine, cover the microvilli allowing the
breakdown of disaccharides and starches; examples are sucrase, isomaltase, and lactase. The small
intestine is the major site of chemical digestion, which is carried out by enzymes released from the
pancreas and liver. The small intestine is the main site of nutrient absorption; molecules like sugars and
amino acids are taken up by cells and transported into the bloodstream for use.The pancreas releases
alkaline compounds (e.g. bicarbonate ions), which neutralise the acids as they enter the intestine.
Pancreatic amylase comes from the pancreas and is the enzyme made in the pancreas into the small
intestine that digests any remaining starch. The liver produces bile, which is stored in the gall bladder
before entering the bile duct into the duodenum. Bile emulsifies fats, facilitating their breakdown into
progressively smaller fat globules until they can be acted upon by lipases. Bile contains cholesterol,
phospholipids, bilirubin, and a mix of salts. Fats are completely digested in the small intestine, unlike
carbohydrates and proteins. Nuclease is secreted in the small intestines that breaks down DNA or RNA
into its component nucleotides.
Enzymes are important. Enzymes are biological catalysts which speed up the rate of a chemical reaction
(i.e. digestion) by lowering the activation energy. Enzymes allow digestive processes to therefore occur at
body temperatures and at sufficient speeds for survival requirements. Enzymes are specific for a substrate
and so can allow digestion of certain molecules to occur independently in distinct locations. They are vital
for life and serve a wide range of important functions in the body, such as aiding in digestion and
metabolism.
,I can apply this to me because as a human in general it is very important to understand the processes that
go on within your own body. When I become a Pharmacist, it will be very important to understand how
the body breaks down enzymes. Different medications can have a severely different effect on how the
body will react, or even digest certain foods. For example, since I am interested within this field,
understanding that the brand name Pepto-Bismol, is an antacid medication used to treat temporary
discomforts of the stomach and gastrointestinal tract, such as diarrhea, indigestion, heartburn and nausea.
This will be important, since Pharmacists are the ones who counsel and help patients with the medications
that would help them the most.
1. Differentiate between organs of the alimentary canal and the accessory digestive organs.
Alimentary canal (GI tract) is the muscular tube that winds through the body, its
organs include: the mouth, pharynx, esophagus, stomach, small intestine, and
large intestine. Accessory organs aid in digestion physically and produce
secretions that break down food in the GI tract, they are teeth, tongue,
gallbladder, salivary glands, liver, spleen
2. Relate the structure of each organ and accessory organ of the alimentary canal to its
function.
3. Describe the tissue composition and the general function of each of the four layers of the
alimentary canal.
mucosa: the innermost layer; is a moist epithelial membrane that lines the
alimentary canal from the mouth to anus. Its major functions are 1) secretion of
mucus, digestive enzymes, & hormones 2) absorption of end products of
digestion into blood 3) protection against infectious disease
The mucosa consists of 3 sublayers:
lining epithelium: simple columnar epithelium rich in mucus-secreting goblet cells
lamina propia: underlies the epithelium & is loose areolar connective tissue.
Capillaries nourish the epithelium & absorb digested nutrients. The isolated
lymphoid follicles are part of MALT, the mucosa-associated lymphatic tissue that
protect us against bacteria/pathogens.
muscularis mucosae: scant layer of smooth muscle cells that produce local
movements of the mucosa. In the small intestine, the mucosa has a series of
small folds that increase its surface area.
Submucosa is external to the mucosa. It's moderately dense connective tissue
containing blood & lymphatic vessels, lymphoid follicles, & nerve fibers.
The rich supply of of elastic fibers allow the stomach to recoil after holding a
meal, and the vascular network supplies surrounding tissues of the GI wall.
Muscularis externa is deep to the submucosa & it's responsible for segmentation
& peristalsis. It has an inner circular layer & an outer longitudinal layer of smooth
, muscle cells.
Sphincters: areas along tract where circular layer thickens and acts valves to
prevent back flow; control food passage from organ to organ
Serosa is the protective outermost layer of the intraperitoneal organs (visceral
peritoneum). It's formed of areolar connective tissue covered w/ mesothelium
(single layer of squamous epithelial cells).
Adventitia: ordinary fibrous connective tissue that binds the esophagus to
surrounding structures .
Retroperitoneal organs have serosa (side facing peritoneal cavity) & adventitia
(side abutting dorsal body wall)
4. Explain the dental formula.
It is a shorthand way of indicating the numbers & relative positions of different
types of teeth in the mouth. It is written as a ration (uppers over lowers for 1/2 of
the mouth). The dental formula is multiplied by 2 since the other half of the
mouth mirrors the first half.
Primary Dentition: 2 incisors (I), one canine (C), & 2 molars (M) on each side of
the jaw.
2I, 1C, 2M (UJ) / 2I, 1C, 2M (LJ) x 2 = 20 teeth
Permanent Dentition: 2 incisors (I), one canine (C), 2 premolars (PM) & 3 molars
(M) on each side of the jaw.
2I, 1C, 2PM, 3M / 2I, 1C, 2PM, 3M x 2 = 32 teeth
5. Describe the functions of saliva and explain how salivation is regulated.
Function: cleans the mouth, dissolves food chemicals (for tasting) & moistens
food & aids in compacting it into a bolus, and contains enzymes that begin the
chemical breakdown of starchy food.
Saliva is produced by extrinsic salivary glands that lie outside the oral cavity &
empty their secretions into it. Output is augmented by intrinsic salivary glands
(buccal glands) scattered throughout the oral cavity mucosa.
Regulation: The intrinsic salivary glands secrete saliva continuously to keep the
mouth moist. When food enters the mouth, the extrinsic glands are activated &
copious amounts of saliva pour out (1000-1500 ml daily).
Salivation is controlled by parasympathetic division of ANS. Chemoreceptors &
mechanoreceptors in the mouth send signals to the salivary nuclei in the pons &
medulla --> the PNS activity increases & impulses sent via motor fibers in the
(chemical and physical) processes involved in chemical digestion
You will be asked to compose an essay about digestion.
A discussion should include the structures (specialized organs and cells) involved. Your
essay should describe the enzymes, how they work and where they are produced.
There are many different organs and cells within the body. Each of these different organs work together to
contribute to an organized pathway of delivering to the needs of the body. The main organs that work for
this are the, stomach, pancreas, liver, and the intestines.
Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking
down the food into simpler nutrients that can be used by the cells. Chemical digestion begins in the mouth
when food mixes with saliva. Saliva contains an enzyme (amylase) that begins the breakdown of
carbohydrates. The stomach contains gastric glands which release digestive acids to create a low pH
environment. The acidic environment functions to denature proteins and other macromolecules, aiding in
their overall digestion. There are CHIEF cells which secrete pepsinogen. Then the Parietal cells,
simultaneously secrete hydrochloric acid (HCl) and intrinsic factor, which is needed to activate the B12.
The first pepsinogen molecules they release are activated by HCl. The stomach epithelium contains a
mucous membrane which prevents the acids from damaging the gastric lining. Hydrochloric acid is a
component of gastric juice that helps create the environment that pepsin needs to break down protein in
the stomach which is Secreted into stomach.
Sucrase Is an enzyme secreted into the small intestine which breaks down sucrose (carbohydrate). maltase
secreted into the small intestine which breaks down maltose (carbohydrate).
Brush border enzymes which can be found within the small intestine, cover the microvilli allowing the
breakdown of disaccharides and starches; examples are sucrase, isomaltase, and lactase. The small
intestine is the major site of chemical digestion, which is carried out by enzymes released from the
pancreas and liver. The small intestine is the main site of nutrient absorption; molecules like sugars and
amino acids are taken up by cells and transported into the bloodstream for use.The pancreas releases
alkaline compounds (e.g. bicarbonate ions), which neutralise the acids as they enter the intestine.
Pancreatic amylase comes from the pancreas and is the enzyme made in the pancreas into the small
intestine that digests any remaining starch. The liver produces bile, which is stored in the gall bladder
before entering the bile duct into the duodenum. Bile emulsifies fats, facilitating their breakdown into
progressively smaller fat globules until they can be acted upon by lipases. Bile contains cholesterol,
phospholipids, bilirubin, and a mix of salts. Fats are completely digested in the small intestine, unlike
carbohydrates and proteins. Nuclease is secreted in the small intestines that breaks down DNA or RNA
into its component nucleotides.
Enzymes are important. Enzymes are biological catalysts which speed up the rate of a chemical reaction
(i.e. digestion) by lowering the activation energy. Enzymes allow digestive processes to therefore occur at
body temperatures and at sufficient speeds for survival requirements. Enzymes are specific for a substrate
and so can allow digestion of certain molecules to occur independently in distinct locations. They are vital
for life and serve a wide range of important functions in the body, such as aiding in digestion and
metabolism.
,I can apply this to me because as a human in general it is very important to understand the processes that
go on within your own body. When I become a Pharmacist, it will be very important to understand how
the body breaks down enzymes. Different medications can have a severely different effect on how the
body will react, or even digest certain foods. For example, since I am interested within this field,
understanding that the brand name Pepto-Bismol, is an antacid medication used to treat temporary
discomforts of the stomach and gastrointestinal tract, such as diarrhea, indigestion, heartburn and nausea.
This will be important, since Pharmacists are the ones who counsel and help patients with the medications
that would help them the most.
1. Differentiate between organs of the alimentary canal and the accessory digestive organs.
Alimentary canal (GI tract) is the muscular tube that winds through the body, its
organs include: the mouth, pharynx, esophagus, stomach, small intestine, and
large intestine. Accessory organs aid in digestion physically and produce
secretions that break down food in the GI tract, they are teeth, tongue,
gallbladder, salivary glands, liver, spleen
2. Relate the structure of each organ and accessory organ of the alimentary canal to its
function.
3. Describe the tissue composition and the general function of each of the four layers of the
alimentary canal.
mucosa: the innermost layer; is a moist epithelial membrane that lines the
alimentary canal from the mouth to anus. Its major functions are 1) secretion of
mucus, digestive enzymes, & hormones 2) absorption of end products of
digestion into blood 3) protection against infectious disease
The mucosa consists of 3 sublayers:
lining epithelium: simple columnar epithelium rich in mucus-secreting goblet cells
lamina propia: underlies the epithelium & is loose areolar connective tissue.
Capillaries nourish the epithelium & absorb digested nutrients. The isolated
lymphoid follicles are part of MALT, the mucosa-associated lymphatic tissue that
protect us against bacteria/pathogens.
muscularis mucosae: scant layer of smooth muscle cells that produce local
movements of the mucosa. In the small intestine, the mucosa has a series of
small folds that increase its surface area.
Submucosa is external to the mucosa. It's moderately dense connective tissue
containing blood & lymphatic vessels, lymphoid follicles, & nerve fibers.
The rich supply of of elastic fibers allow the stomach to recoil after holding a
meal, and the vascular network supplies surrounding tissues of the GI wall.
Muscularis externa is deep to the submucosa & it's responsible for segmentation
& peristalsis. It has an inner circular layer & an outer longitudinal layer of smooth
, muscle cells.
Sphincters: areas along tract where circular layer thickens and acts valves to
prevent back flow; control food passage from organ to organ
Serosa is the protective outermost layer of the intraperitoneal organs (visceral
peritoneum). It's formed of areolar connective tissue covered w/ mesothelium
(single layer of squamous epithelial cells).
Adventitia: ordinary fibrous connective tissue that binds the esophagus to
surrounding structures .
Retroperitoneal organs have serosa (side facing peritoneal cavity) & adventitia
(side abutting dorsal body wall)
4. Explain the dental formula.
It is a shorthand way of indicating the numbers & relative positions of different
types of teeth in the mouth. It is written as a ration (uppers over lowers for 1/2 of
the mouth). The dental formula is multiplied by 2 since the other half of the
mouth mirrors the first half.
Primary Dentition: 2 incisors (I), one canine (C), & 2 molars (M) on each side of
the jaw.
2I, 1C, 2M (UJ) / 2I, 1C, 2M (LJ) x 2 = 20 teeth
Permanent Dentition: 2 incisors (I), one canine (C), 2 premolars (PM) & 3 molars
(M) on each side of the jaw.
2I, 1C, 2PM, 3M / 2I, 1C, 2PM, 3M x 2 = 32 teeth
5. Describe the functions of saliva and explain how salivation is regulated.
Function: cleans the mouth, dissolves food chemicals (for tasting) & moistens
food & aids in compacting it into a bolus, and contains enzymes that begin the
chemical breakdown of starchy food.
Saliva is produced by extrinsic salivary glands that lie outside the oral cavity &
empty their secretions into it. Output is augmented by intrinsic salivary glands
(buccal glands) scattered throughout the oral cavity mucosa.
Regulation: The intrinsic salivary glands secrete saliva continuously to keep the
mouth moist. When food enters the mouth, the extrinsic glands are activated &
copious amounts of saliva pour out (1000-1500 ml daily).
Salivation is controlled by parasympathetic division of ANS. Chemoreceptors &
mechanoreceptors in the mouth send signals to the salivary nuclei in the pons &
medulla --> the PNS activity increases & impulses sent via motor fibers in the
