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BIOL 1051H Lecture Notes - Lecture 4: Lingual Lipase, Gastric Acid, Gastric Glands

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bluebadger978
3 May 2018
School
Trent University
Department
Biology
Course
BIOL 1051H
Professor
Holly Bates

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Digestion and Metabolism
Stages of Digestion
1. Ingestion: selective intake of food
2. Digestion: mechanical and chemical breakdown of food into a form usable by the body
3. Absorption: uptake of nutrient molecules into the epithelial cells of the digestive tract
and then into the blood and lymph
4. Compaction: absorbing water and consolidating the indigestible residue into feces
5. Defecation: elimination of feces
Digestion and Absorption
●Salivary and gastric enzymes partially digest protein and lesser amounts of starch and fat
in the stomach
●Most digestion and nearly all absorption occur after the chyme has passed into the small
intestine
Types of Digestive Function
●Mechanical Digestion
○The physical breakdown of food into smaller particles
■Cutting and grinding action of the teeth
■Churning action of stomach and small intestines
■Exposes more food surface to digestive enzymes
●Chemical Digestion
○Hydrolysis reactions that break dietary macromolecules into monomers
■Carried out by digestive enzymes produced by salivary glands, stomach,
pancreas, and small intestine
○Results
■Polysaccharides → monosaccharides
■Proteins → amino acids
■Fats → monoglycerides and fatty acids
■Nucleic acids → nucleotides
The mouth- First Phase of Ingestion
●Functions
○Ingestion (food intake)
○Taste and other sensory response to food
○Chewing (mastication)
○First phase of chemical digestion (starch)
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●Saliva is mostly water and the following solutes:
○Salivary amylase: enzyme that begins starch digestion in mouth
○Lingual Lipase: enzyme activated by stomach acid and digests fat after food is
swallowed
○Mucus: binds and lubricates a mass of food and aids in swallowing
○Lysozyme: enzyme that kills bacteria
○Immunoglobulin A (lgA): antibody that inhibits bacterial growth
○Electrolytes: Na, K, Cl, phosphate, and bicarbonate
Gastric Gland: Release gastric juice
1. Mucous Cells
○Secrete mucus
2. Regenerative (stem) cells
○Found in base of pit and in neck of gland
○Divide rapidly and produce continual supply of new cells to replace cells that die
3. Parietal cells
○Secrete HCL, intrinsic factor, and a hunger hormone called ghrelin
4. Chief cells
○Most numerous
○Secrete gastric lipase and pepsinogen (enzymes)
5. Enteroendocrine cells
○Concentrated in lower end of gland
○Secrete hormones and paracrine messengers that regulate digestion (ie Gastrin
from G cells)
Hydrochloric Acid (HCI)
●Gastric juice has high HCI
○pH as low as 0.8
●Produced by Parietal cells
Pepsin
●Zymogens
○Digestive enzymes secreted as inactive proteins
■Converted to active enzymes by removing some of their amino acids
●Pepsinogen
○Zymogen secreted by chief cells
■Activated to pepsin by HCI (removes AA)
■Autocatalytic effect
●Pepsin converts more pepsinogen into more pepsin
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Document Summary

Salivary and gastric enzymes partially digest protein and lesser amounts of starch and fat in the stomach. Most digestion and nearly all absorption occur after the chyme has passed into the small intestine. The physical breakdown of food into smaller particles. Cutting and grinding action of the teeth. Churning action of stomach and small intestines. Exposes more food surface to digestive enzymes. Hydrolysis reactions that break dietary macromolecules into monomers. Carried out by digestive enzymes produced by salivary glands, stomach, pancreas, and small intestine. Taste and other sensory response to food. Saliva is mostly water and the following solutes: swallowed. Salivary amylase: enzyme that begins starch digestion in mouth. Lingual lipase: enzyme activated by stomach acid and digests fat after food is. Mucus: binds and lubricates a mass of food and aids in swallowing. Immunoglobulin a (lga): antibody that inhibits bacterial growth. Electrolytes: na, k, cl, phosphate, and bicarbonate. Gastric gland: release gastric juice: mucous cells.

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Related Questions

EAP HW 22 – The Digestive System

Define digestive tract

Define accessory organs

Provide the 6 functions of the digestive system

Define ingestion

Define mechanical processing

Define digestion

Define secretion

Define absorption

Define excretion

Provide the 4 layers of the digestive tract AND what types of tissue they are composed of

Define peristalsis

Provide the 3 functions of the tongue

Describe how the ingredients of saliva help breakdown food

Define salivary amylase

Provide the 4 types of teeth found in the human mouth AND their functions

Provide the 4 steps of the swallowing process

Define esophagitis

Provide the 2 types of cells found in gastric glands AND their functions

Define pepsin

Define cephalic phase

Define gastric phase

Define intestinal phase

Does absorption occur in the stomach? Explain.

Define circular folds

Define villi

Define microvilli

Define brush border

What organ is the above picture from?

Most of the important digestive processes are completed in the _________________________.

Define carbohydrases

Define lipases

Define nucleases

Define proteases

Provide the 3 general functional roles of the liver

Provide the function of bile salts

Define emulsification

Provide the function of the gall bladder

Define gallstones

Provide the standard screening test for colorectal cancer

Define diverticulosis

Define diarrhea and what causes it?

Define constipation, what causes it, and how do you prevent it?

Where does carbohydrate digestion begin?

Where does lipid digestion begin?

Where does protein digestion begin?

Define lactose intolerance

10. The organs associated with the Alimentary Canal share which similarity/similarities? They all belong to the lymphatic system They all belong to the gastrointestinal system Food does not pass directly through them during the process of digestion Food does pass directly through them during the process of digestion Both B and D \

11. Of the five basic functions of the digestive system, which one occurs first? Excretion Absorption Ingestion Peristalsis Digestion

12. The elimination of indigestible material from the body is called _______________. Peristalsis Absorption Defecation Ingestion

13. The pancreas helps to regulate metabolism and blood sugar levels through the release of insulin. Insulin tells the liver to stop sugar production to keep levels regulated within the blood stream. If a person’s pancreas does not function properly, they have a condition called diabetes, a metabolic disease that often requires monitoring of one’s diet. People with Type 1 Diabetes have a pancreas with damaged islet cells, meaning no insulin is produced. People with Type 2 Diabetes have a pancreas that produces insulin properly, but their cells are resistant to this insulin due to various factors that often include but are not limited to obesity, lack of exercise, or poor diet choices. Certain foods, specifically starches and sugars, affect diabetics in different ways. Type 1 diabetics must limit their consumption of sugars in order to keep their blood sugar levels stable. Type 1 diabetics often achieve regulation of blood sugars through injections of insulin. Type 2 diabetics must still pay attention to their diets, but not all of them are dependent on manual injections of insulin. Because Type 2 Diabetes is often brought on through a poor diet, Type 2 diabetics are advised to monitor their food choices to prevent weight gain and achieve a more balanced diet overall. Approximately 90% of Americans with diabetes have Type 2. Which are contributing factors to developing Type 1 Diabetes? Poor liver function Poor pancreatic function Sedentary lifestyle All of the above

14. There are five activities that occur within the gastrointestinal system: • Ingestion – the taking in of food or drink • Peristalsis – the movement of food along the digestive tract • Digestion – the breakdown of food and drink by both mechanical and chemical mechanisms • Absorption – the passage of food into the cardiovascular and lymphatic systems • Defecation – the elimination of substances the body can’t use Many digestive disorders and diseases can be tied to an activity within the gastrointestinal system. For example, inflammation of the digestive tract, commonly known as inflammatory bowel disease, is an example of a gastrointestinal activity breakdown. An inflamed digestive tract means digestion is painful and hindered in some way, affecting the rest of the gastrointestinal activities coming after it. An inability to break down lactose, or “lactose intolerance,” is another example of a breakdown that can occur within the gastrointestinal system. Another example of a breakdown in gastrointestinal activities is an eating disorder, where food is either withheld or ingested at a fast rate. Some disorders include the elimination of food through vomit, in essence reversing some of the activities of the gastrointestinal system. A final example of a breakdown in gastrointestinal activities is constipation, which can often lead to further problems such as bowel impaction if not corrected immediately. A balanced diet is recommended to keep the gastrointestinal system functioning properly, and many over the counter medications can help to correct some breakdowns if caught early enough. Foodborne illness, or food poisoning, happens when spoiled or contaminated food is consumed. A common symptom of food poisoning is vomiting. Though microbes can move from the stomach and into the intestines after vomiting occurs, the food itself gets thrown up, stopping its travel through the gastrointestinal system. During which activity is the food thrown up? Peristalsis Absorption Ingestion Digestion

15. The skin is a vital organ that covers the entire outside of the body, forming a protective barrier against pathogens and injuries from the environment. The skin is the body's largest organ; covering the entire outside of the body, it is about 2 mm thick and weighs approximately six pounds. It shields the body against heat, light, injury, and infection. The skin also helps regulate body temperature, gathers sensory information from the environment, stores water, fat, and vitamin D, and plays a role in the immune system protecting us from disease. The color, thickness and texture of skin vary over the body. There are two general types of skin; thin and hairy, which is more prevalent on the body, and thick and hairless, which is found on parts of the body that are used heavily and endure a large amount of friction, like the palms of the hands or the soles of the feet. Basically, the skin is comprised of two layers that cover a third fatty layer. These three layers differ in function, thickness, and strength. The outer layer is called the epidermis; it is a tough protective layer that contains the melanin-producing melanocytes. The second layer (located under the epidermis) is called the dermis; it contains nerve endings, sweat glands, oil glands, and hair follicles. Under these two skin layers is a fatty layer of subcutaneous tissue, known as the subcutis or hypodermis. The skin contains many specialized cells and structures: • Basket Cells: Basket cells surround the base of hair follicles and can sense pressure. They are evaluated when assessing overall nerve health and condition. • Blood Vessels: Blood vessels carry nutrients and oxygen-rich blood to the cells that make up the layers of skin and carry away waste products. • Hair Erector Muscle (Arrector Pili Muscle): The arrector pili muscle is a tiny muscle connected to each hair follicle and the skin. When it contracts it causes the hair to stand erect, and a "goosebump" forms on the skin. • Hair Follicle: The hair follicle is a tube-shaped sheath that surrounds the part of the hair that is under the skin and nourishes the hair. It is located in the epidermis and the dermis. • Hair Shaft: The hair shaft is the part of the hair that is above the skin. • Langerhans Cells: These cells attach themselves to antigens that invade damaged skin and alert the immune system to their presence. • Melanocyte: A melanocyte is a cell that produces melanin, and is located in the basal layer of the epidermis. • Merkel Cells: Merkel cells are tactile cells of neuroectodermal origin located in the basal layer of the epidermis. • Pacinian Corpuscle: A pacinian corpuscle is a nerve receptor located in the subcutaneous fatty tissue that responds to pressure and vibration. • Sebaceous Gland: Sebaceous glands are small, sack-shaped glands which release an oily substance onto the hair follicle that coats and protects the hair shaft from becoming brittle. These glands are located in the dermis. • Sensory Nerves: The epidermis is innervated with sensory nerves. These nerves sense and transmit heat, pain, and other noxious sensations. When they are not functioning properly sensations such as numbness, pins-and-needles, pain, tingling, or burning may be felt. When evaluating a skin biopsy, total number, contiguity, diameter, branching, swelling, and overall health of the sensory nerves are assessed. • Stratum Corneum: The stratum corneum is outermost layer of the epidermis, and is comprised of dead skin cells. It protects the living cells beneath it by providing a tough barrier between the environment and the lower layers of the skin. The stratum corneum is useful for diagnosis because in some conditions it will become thinner than normal. • Sweat Gland (Sudoriferous Gland): These glands are located in the epidermis and produce moisture (sweat) that is secreted through tiny ducts onto the surface of the skin (stratum corneum). When sweat evaporates, skin temperature is lowered. If you use a product to moisturize your hair, which part of the integumentary system are you targeting? Hair follicle Hair shaft Blood vessels Melanocyte

Food that we consume is composed of very complex molecules. During the digestive process these compounds are broken down into smaller and smaller subunits in preparation for use by the body as building blocks needed for the many components of the human body.

The digestion process begins at the mouth. Food enters and then accessory digestive organs like the tongue, teeth, and salivary glands break down the substance. It then travels through the pharynx and esophagus into the stomach, where the stomach acid further breaks down the food (UXL Complete Health Resource). After that, the food travels through the small and large intestines where a majority of its nutrients are absorbed. The waste then exits through the end of the large intestine which is made up of the rectum and anus. After the teeth assist in chewing, food rolls over the tongue and reaches stomach through the esophagus within 8 seconds. General Tso’s Chicken and Rice consist of carbohydrates, fats and proteins. However, carbohydrates are digested easily than the fats and proteins. After broken down in the stomach, most of the nutrients are absorbed from the small intestine, and it takes 6 to 8 hours to pass through small intestine. The remaining unabsorbed material, “moves very slowly through the large intestine where the final absorption of water and other nutrients take place” (UXL Complete Health Resource). The parasympathetic nervous system encourages the food to move through the digestive tract and motivates digestion process. The sympathetic nervous system works against the parasympathetic nervous system by decreasing the contraction and relaxation of the digestive tract (Taylor). Mouth produces saliva, which contains amylase. Amylase is key in digesting carbohydrates. The stomach produces hydrochloric acid, pepsinogen, intrinsic factor, and mucus (Taylor). Hydrochloric acid kills the bacteria and other organisms that enter the stomach, and then continues to activate pepsinogen. Pepsinogen then changes into pepsin, which digests protein peptides. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases. Trypsin, chymotrypsin, and carboxypeptidases digest proteins, whereas lipases, phospholipases digest lipid molecules. Small intestine produces lactase, sucrase, maltase, lipases, and peptidases. Lactase, sucrase, and maltase digest carbohydrates (UXL Complete Health Resource). Saliva glands, pancreas, liver, and gallbladder are the accessory organs of the digestive process. Saliva glands produce mucus and amylase which digests starch into simple sugars and binds food particles together, while lubricating the palette when one swallows. The pancreas produces amylase, lipases, and proteinases etc. These digestive juices are responsible for breaking down carbohydrates, proteins, and fats. The liver is the largest gland in the body, “It produces bile salts to emulsify lipids. It detoxifies metabolic end products to protect the body” (UXL Complete Health Resource). Gallbladder stores bile juice. The chicken in the General Tso’s contains proteins. Proteins cannot be digested in mouth. However, the mouth can physically digest chicken into smaller pieces. These partially digested chicken pieces travel to stomach, where it is digested by pepsin. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases (UXL Complete Health Resource). The chicken is then digested by trypsin, chymotrypsin, and carboxypeptidases in the duodenum of the small intestine. After the complete digestion, the chicken’s proteins change into amino acids, which are then absorbed into blood. The rice of the General Tso’s is a carbohydrate. Carbohydrates are partially digested inside the mouth by amylase. The rest of the rice travels to the stomach where it is digested by pancreatic juices and enzymes that are produced by small intestine. The digestion of the rice produces monosaccharides that absorb into the blood stream. The left over, and undigested parts of the chicken and rice that are useless to the body are excreted by large intestine through rectum.

1) Based on your finding in the Module 3 Report, begin the Module 4 Report by identifying which metabolites are being absorbed and specifically which vessels of the cardiovascular or lymphatic system are the initial vessel of transport from the digestive system. 2) From the point that the specific metabolites are absorbed from the GI tract, trace the path of the resulting metabolites to the following locations in the body for incorporation into the body structure: Metabolites of protein for use in the Gastrocnemius muscle for muscle maintenance. Metabolites of the carbohydrates for energy to contract the cardiac muscle cells. Metabolites of fat to incorporate into the myelin sheaths of the Schwann cells of the Trigeminal nerve that innervates the Masseter muscle. Water for incorporation into the synovial fluid of the hip joint. Iron for incorporation into red blood cells in the bone marrow of the sternum.