Name: Date: Class: Unit 7 Outline: The Digestive System and Nutrition

Transcription

1 Name: Date: Class: Unit 7 Outline: The Digestive System and Nutrition The Digestive System: Mouth and Pharynx The Digestive System and Body Metabolism Breakdown of ingested Absorption of nutrients into the Production of cellular Constructive and degradative Organs of the Digestive System Two main groups coiled hollow tube (ATP) activities canal- continuous digestive organs - form the lateral walls Hard palate- forms the Soft palate- forms the roof roof - fleshy projection of the soft palate - space between lips externally and teeth and gums internally Oral cavity- area contained by the teeth - attached at hyoid and styloid processes of the skull, and by the lingual frenulum Tonsils tonsils tonsil Organs of the Alimentary Canal Mouth Stomach intestine intestine Mouth (Oral Cavity) Anatomy Lips ( anterior opening )- protect the Processes of the Mouth (chewing) of food Mixing masticated food with Initiation of Allowing for the sense of Pharynx Anatomy by the tongue - not part of the digestive system - posterior to oral cavity - below the oropharynx and connected to the esophagus Pharynx Function Serves as a air and food Food is propelled to the esophagus by Alternating contraction of two muscle layers Unit 7: The Digestive System and Nutrition 11 for

2 * inner layer * outer layer Digestive System: Esophagus and Stomach Esophagus Runs from pharynx to through the diaphragm Conducts food by peristalsis (slow rhythmic squeezing) Passageway for only (respiratory system branches off after the pharynx) Layers of Alimentary Canal Organs Innermost layer * Surface * Small amount of tissue (lamina propria) membrane * Small muscle layer Just beneath the mucosa Soft tissue with blood vessels, nerve endings, and lymphatics Muscularis Inner Outer Outermost layerperitoneum Layer of cells - smooth muscle layer layer fluid-producing Food enters at the sphincter Regions of the stomach Body region- near the heart - funnel-shaped terminal end Food empties into the small intestine at the - internal folds of the mucosa External regions curvature curvature Layers of peritoneum attached to the stomach Lesser liver to the lesser curvature - attaches the omentum- attaches the greater curvature to the posterior body wall Contains fat to insulate, cushion, and protect abdominal organs Stomach Anatomy On the cavity side of the abdominal Stomach Functions for food Site of food Chemical breakdown of begins Delivers (processed food) to the small intestine Specialized Mucosa of the Stomach Simple Mucous neck cells- produce a sticky Gastric glands- secrete epithelium mucus juice Unit 7: The Digestive System and Nutrition 12

3 Chief cells- produce enzymes (pepsinogens) Parietal cells- produce acid Endocrine cells- produce Structure of the Stomach Mucosa -digesting pits formed by folded mucosa and specialized cells are in the gastric gland region Digestive System: Small and Large Intestine Small Intestine Body s Site of the blood digestive organ absorption into Muscular tube extending from sphincter to the ileocecal valve Suspended from the posterior abdominal wall by the Subdivisions of the Small Intestine Attached to the Curves around the head of the Attaches anteriorly to the duodenum Extends from jejunum to Chemical Digestion in the Small Intestine Source of with chyme Intestinal cells that are mixed enters from the gall bladder Folds of the Small Intestine folds called plicae circulares Deep folds of Do not disappear when Submucosa has patches (lymphatic tissue) Villi of the Small Intestine Fingerlike structures formed by the Give the small intestine more Microvilli of the Small Intestine Small projections of the membrane Found on Nutrient Absorption Structures and submucosa with food cells cells Blood Lacteals ( capillaries) Unit 7: The Digestive System and Nutrition 13

4 Large Intestine Larger in diameter, but than the small intestine the internal abdomen Functions of the Large Intestine Absorption of Eliminates undigested food from body as participate in food digestion Goblet cells produce (lubricant) Structures of the Large Intestine - saclike first part Accumulation of lymphatic tissue; can become inflamed (appendicitis) Hangs from the Colon S-shaped - external body opening Large Intestine Muscularis Externa Smooth muscle is reduced to bands (teniae coli) Muscle bands have some degree of tone Walls are formed into (pocket-like sacs) Accessory Organs of the Digestive System Accessory Digestive Organs glands Salivary Glands and Saliva Saliva-producing glands Saliva anterior to ears Mixture of serous fluids Helps form food bolus glands- located glands glands and Contains salivary (begin starch digestion) Dissolves chemicals so they can be tasted Teeth Purpose- Humans- 2 sets of teeth (chew) food (baby or milk) teeth * 20 teeth fully formed by age 2 teeth * Replace baby teeth between the ages of 6-12 * Full set is teeth (some people have no wisdom teeth) Classification of Teeth Unit 7: The Digestive System and Nutrition 14

5 Produces a wide spectrum of digestive enzymes that break down all categories of food Enzymes secreted into the fluid introduced with enzymes neutralizes acidic chyme Endocrine products of Glucagons Liver gland in the body side of the body under the diaphragm lobes suspended from the diaphragm and abdominal wall by falciform ligament Connected to the via the common hepatic duct Regions of a Tooth - exposed part Outer Region in contact with gum Connects crown to root Attached to the Root canal contains and nerves cavity Bile Produced by cells in the Composition Bile Bile pigment (mostly from breakdown of hemoglobin) Cholesterol Gall Bladder Found in fossa of the Stores from the liver introduced into the duodenum in the presence of fatty food can cause blockages Pancreas Unit 7: The Digestive System and Nutrition 15

6 Digestive System Processes Processes of the Digestive System - getting food into the mouth - moving foods through the digestive system waves of contraction - alternating - moving materials back and forth to aid in mixing * are broken to fatty acids and alcohols End products of digestion are absorbed in the blood or Food must enter and then into blood or lymph capillaries Elimination of substances as feces cells Peristalsis Segmentation digestion by the tongue Segmentation in the intestine of food in the mouth of food in the stomach Digestion Enzymes break down food molecules into their building blocks Each major food group uses different enzymes * are broken to simple sugars * Proteins are broken to Control of Digestive Activity Controlled by (parasympathetic) Chemical and mechanical receptors located in organ walls trigger reflexes Stimuli include: Presence of products Reflexes include: Activation or inhibition of glandular Digestive Activities of the Mouth Mechanical breakdown of the organ of the contents muscle activity Unit 7: The Digestive System and Nutrition 16

7 Physical breakdown of food by Chemical digestion Food is mixed with Breaking of starch into by salivary amylase Deglutition (Swallowing) phase Occurs in the Food is formed into a Bolus is forced into the pharynx by the Only and absorption occurs in the stomach Propulsion in the Stomach Food must first be well mixed Rippling in the lower stomach - digesting milk protein Pylorus meters out into the small intestine (30 ml at a time) Stomach empties in occurs hours Pharyngeal-esophageal phase transport of the bolus All passageways except to the stomach are blocked * blocks off the mouth * Soft palate (uvula) blocks the * blocks the larynx toward the stomach opens when food presses against it Food Breakdown in the Stomach Gastric juice is regulated by and hormonal factors Presence of food or falling release of gastrin moves the bolus sphincter causes the causes stomach glands to produce protein-digesting enzymes acid makes stomach contents very acidic Stomach Digestion and Absorption Protein digestion enzymes enzyme - active protein digesting Digestion in the Small Intestine Enzymes from the brush border Break double simple sugars Complete some into digestion enzymes- major digestive functions Pancreatic amylase completes digestion Carry out about (trypsin) Responsible for Digest Alkaline content acidic chyme Absorption in the Small Intestine of all protein digestion digestion (lipase) acids (nucleases) is absorbed along the length of the small intestine End products of digestion Most substances are absorbed by transport through cell membranes Substances are transported to the by the hepatic portal vein or lymph Propulsion in the Small Intestine are absorbed by diffusion - major means of moving food Segmental movements Mix with digestive juices Unit 7: The Digestive System and Nutrition 17

8 Aid in propelling food Absorption in the Large Intestine No digestive Resident remaining nutrients Produce some vitamin Release are produced digest and vitamins K and B are absorbed Remaining materials are eliminated via Propulsion in the Large Intestine Sluggish Mass movements Occur Presence of feces in the causes a defecation reflex Nutrition Nutrition, powerful movements times per day anal sphincter is relaxed Defecation occurs with relaxation of the (voluntary) anal sphincter - substance used by the body for growth, maintenance, and repair Categories Lipids Mineral Dietary Sources of Major Nutrients Mostly from Except: lactose ( glycogens (meats) Saturated fats- Unsaturated fatsvegetable oils Cholesterol- egg yolk, products ) and products, seeds,, milk Complete- contain amino acids essential * Most from products Legumes and proteins - incomplete Unit 7: The Digestive System and Nutrition 18 Most are used as act with enzymes Found in all major Play many roles in the body and Mineral-rich foods-, legumes, milk, some meats Metabolism Chemical reactions necessary to maintain life - substances broken down to simpler substances from smaller ones Energy is released during Carbohydrate Metabolism Body s preferred source to produce - larger molecules built (blood sugar)- major breakdown product and fuel to make ATP Fat Metabolism Handled mostly by the Use some fats to make ATP * Must be broken down to * In, acetic acid is oxidized to produce H 2 O, CO 2, and ATP Synthesize cholesterol Release to the blood Cells remove fat and cholesterol to build Protein Metabolism and products and steroid hormones Proteins are body cells (used for most cellular structures) by

9 Ingested proteins are broken down to Cells remove build proteins proteins are actively transported across cell membranes Amino acids are used to make only if proteins are overabundant or if other sources are low Cholesterol Metabolism and Transport Functions of cholesterol Form hormones and vitamin D Major building block of plasma membranes produces most cholesterol (not diet) Cholesterol and fatty acids freely circulate in the bloodstream Transported by lipoproteins Low-density lipoproteins ( body cells to ) to High-density lipoproteins ( ) from body cells to the liver Cellular Respiration Cellular Respiration Oxygen-using events take place within the cell to create from ADP leaves cells as CO 2 atoms combine with Oxygen to form water Energy produced by these reactions adds a to ADP to produce ATP ATP is broken down to energy for cellular use Metabolic Pathways Involved in Cellular Respiration - energizes a glucose molecule so that it can be split into two pyruvic acid molecules and yield ATP cycle Produces most of the H 2 O from cell respiration Yields a and amount of ATP transport chain removed during glycolysis and the Krebs cycle are delivered to protein carriers H is split into H + mitochondria and e - in give off energy in a series of steps to enable ATP production Production of ATP from Protein groups are removed from proteins as ammonia Rest of the protein molecule enters the cycle in mitochondria Liver converts ammonia to in urine Metabolic Role of the Liver Role of the Liver in Metabolism - eliminated drugs and alcohol Degrades Produce cholesterol, blood (albumin and clotting proteins) Central role in Metabolic Functions of the Liver to glycogen Glycogen molecules molecules converted in the liver Unit 7: The Digestive System and Nutrition 19

10 Glucose released from the after conversion from glycogen Glucose produced from and proteins and fatty acids are picked up by the liver Some for energy for liver cells Rest are broken down into simpler compounds and released into the Metabolism and Digestive Homeostasis Body Energy Balance Energy = total energy output (heat + work + energy storage) Energy intake- released during food Energy output * Heat is usually about % * Storage energy is in the form of or glycogen Regulation of Food Intake Body weight is usually stable Energy intake and output remain about Mechanisms that regulate food intake Levels of the blood Body in factors Metabolic Rate and Body Heat Production Basic metabolic rate ( )- amount of heat produced by the body per unit of time at rest Factors that influence BMR higher BMR have a higher BMR area- small body has - males have higher BMR - children and adolescents Amount of produced is the most important control factor * More thyroxine means metabolic rate Total Metabolic Rate (TMR) Total amount of the body must consume to fuel ongoing activities TMR increases with an increase in body TMR must calories consumed to maintain homeostasis and maintain a constant weight Body Temperature Regulation Most energy is released as are oxidized Most energy escapes as The body has a narrow range of homeostatic temperature Must remain between to F (35.6 to 37.8 C) Body s thermostat is in the * Initiates heat-loss or heat-promoting mechanisms Heat Promoting Mechanisms of blood vessels Blood sent to deeper, more vital organs - contraction of muscles produces heat Heat Loss Mechanisms Heat loss from the skin via and evaporation Capillaries in skin Evaporation of cools the skin with warm blood Unit 7: The Digestive System and Nutrition 20

11 Digestive System Development Alimentary canal is a continuous tube by the week Digestive glands bud from the mucosa of the tube Developing fetus receives all nutrients through the Newborn- frequent feeding, inefficient peristalsis, and vomiting is common Teething begins around age Metabolism Middle age digestive problems Activity of digestive tract in old age Fewer digestive months with old age problems slows and cancer more common Unit 7: The Digestive System and Nutrition 21