BIOL 2420 Lecture Notes - Lecture 1: Extracellular Fluid, Intestinal Epithelium, Enteric Nervous System

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

2. General questions about the digestive tract A. Mechanical digestion of all foods begins in the oral cavity. Describe how food is digested mechanically in the oral cavity. B. What is the scientific name for swallowing? Which portions of the pharynx does food pass through when swallowing? What is the function of the esophagus? C. Cells lining the stomach release hydrochloric acid (HCl). How does HCl assist in food digestion? How are the cells lining the stomach protected from being auto-digested by HCl? D. Carbohydrates, fats, and proteins must be broken down into their smallest subunits (AKA building blocks) in order to be absorbed through the epithelial lining of the small intestine. Name the building blocks of each of the major classes of nutrients: complex carbohydrates (AKA polysaccharides), fats, and proteins. E. About 99% of all nutrients are absorbed in the small intestine. Name the 3 portions of the small intestine. In which of these 3 portions does the greatest amount of nutrient absorption occur (think about the location and length of each segment)? Which type(s) of nutrient(s) is/are absorbed into blood capillaries? Which type(s) of nutrient(s) is/are absorbed into lymphatic capillaries? F. The last portions of the digestive tract are the rectum, anal canal and anus. Name the 2 muscular sphincters located at the anus. When the rectum fills, the defecation reflex is initiated. Describe the events that occur during the defecation reflex. Name the 2 sphincters located at the anus. Which sphincter undergoes involuntary relaxation during the defecation reflex? Which division of the autonomic nervous system causes this sphincter to relax and open? Name the sphincter that you control consciously to stop or initiate defecation.

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