Class Notes, week of 02/29
Class Notes, week of 02/29 BSC 2023
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This 7 page Class Notes was uploaded by Eleonora Sacks on Friday March 4, 2016. The Class Notes belongs to BSC 2023 at Florida International University taught by Paul Sharp in Spring 2016. Since its upload, it has received 19 views. For similar materials see Human Biology in Biology at Florida International University.
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Date Created: 03/04/16
Class Notes: week of 02/29 3/5/16 12:08 AM Cont.: Cardiovascular system: • Diastole is more stable, it doesn't change if we are anxious or not. • Normal blood pressure reading: below 120/below80 • • Cardiac conduction system: • SA (sinoatrial) node: o Specialized myocardial cells in the wall of the right atrium o Like the pacemaker of the heart, 70 beats per minute o Initiates the heartbeat, sends the information to the heart o If this node is damaged, you will only have 50 beats per min • AV (atrioventricular) node: specialized mass of conducting cells located at the atrioventricular junction in the heart. If this node is damaged, you will only have 30 beats per min • There's a space between the two nodes so that there's time between electrical impulses. So that the atria contract before the ventricles. • Nodes create the information that makes the parts of the heart contract, like the brain sends signals to the body for it to move via neurons, the nodes are like the brain and send the signals through the atrioventricular bundle and the Purkinje fibers. • If there's a problem with the • Atrioventricular bundle: bundle of specialized fibers that conduct impulses from the AV node to the right and left ventricles. (they carry the information that the nodes send: it tells them to contract or not) • Purkinje fibers: modified cardiac muscle fibers of the cardiac conduction system • ECG (Electrocardiogram): recording of electrical activity associated with the heartbeat. • • P wave: atria about to contract • QRS wave: ventricles about to contract • T wave: ventricular muscle fiber recovery • Ventricular fibrillation: the heart is not pumping properly. o When this happens, the person needs to be defibrillated using the 2 shock things that are put on people's chest in movies, and the doctors say "clear". What this does is apply a strong electrical current for short time so that all heart cells discharge electricity at once. Digestive System: • Gastrointestinal tract: a continuous hollow tube extending from the mouth to the anus. AKA: alimentary tract • It's made up of the: o Oral cavity: the mouth ▯ Hard palate: bony anterior part of the roof of the mouth ▯ Soft palate: only muscular portion at the back roof of the mouth ▯ Uvula: tissue tag hanging from the soft palate ▯ Salivary glands: glands associated with the mouth, they secrete saliva. Saliva isn't secreted under the tongue ▯ Saliva: solution of water, mucus, salivary amylase, lysozyme, and bicarbonate. (salivary amylase is the first enzyme that begins the digestion of starch--carbs) ▯ Tongue: occupies the floor of the mouth. Has 4 functions: 1. Grips food 2. Repositions food between teeth 3. Mixes food with saliva (because the saliva has salivary amylase- an enzyme that starts to break down the carbohydrates in food we eat) 4. Movements form the bolus (the mush of the food we are chewing that goes down when we swallow) ▯ Pharynx: the back of the throat ▯ o Esophagus o Stomach o Small intestine: absorbs nutrients o Large intestine: absorbs water • About 30 feet long in humans • Accesory organs: the ones that aren't part of the tubing (tract) • 5 processes necessary so that the digestive process happens: 1. Ingestion: taking of food or liquid into the body through the mouth 2. Digestion: breaking down of large nutrient molecules into smaller molecules that can be absorbed o Mechanical digestion: cutting and mastication of food, peristalsis o Chemical digestion: digestive enzymes hydrolyze macromolecules 3. Movement (mixing): food is passed from one organ to the next via peristalsis 4. Absorption: taking in of subunit molecules (like sugars, etc) by cells or membranes. Happens in the small intestine 5. Elimination: process of expelling substances from the body via defecation (pooping) • Peristalsis: we don't have to think about our body digesting to make it happen, it happens on its own. • Reverse peristalsis: when there's something wrong with the food and makes us vomit or expel it. • Smooth muscles have peristalsis, except the bladder which is a smooth muscle but we have control over it (if we didn't we would pee our pants all the time) • Class notes: week of 02/29 3/5/16 12:08 AM Cont.: Digestive System (Parts of the mouth) • Teeth: • lie in sockets in the gum covered margins of the maxilla and mandible • 2 main divisions: crown and root • 32 teeth in adults • Composed of: o Enamel: hard material composed of calcium compounds that cover the crown (the part of the tooth that is above the gum) o Dentin: thick layer of bone-like material beneath enamel o Pulp: inner tissue containing blood vessels and nerves • • Problems: o Dental caries (cavity): hole in the tooth that results from acids produced by bacteria metabolizing sugar, the hole is close to the pulp when it starts to hurt the person. o Periodontitis: inflammation of the periodontal membrane that lines tooth sockets, this causes loss of bone and loosening of tooth • Pharynx: • Fancy word for throat • Portion of the GI tract between the mouth and esophagus • Serves as a passageway for food and also air on its way to trachea (the trachea is parallel and in front of the esophagus) • Esophagus: muscular tube for moving swallowed food from the pharynx to stomach • Swallowing: composed of a voluntary phase and involuntary phase (reflex action): • Soft palate moves back to close off nasal passage via uvula. This is so that food doesn't get into the nasal passage. • Epiglottis covers the glottis, which is the opening to the larynx (voice box). The epiglottis is like a lid on the glottis, it opens up either the path to the trachea or the esophagus. The epiglottis doesn't work when we are swallowing and laughing at the same time. • • Peristalsis: wavelike contractions that propel the bolus along the esophagus (smooth muscles in the GI tract) • • Sphincters: muscle that surrounds a tube to open or close by relaxing or contracting. • Lower gastroesophageal sphincter: marks the entrance of the esophagus to stomach. It contracts to prevent the stomach acids from going up the esophagus (although, when this happens it's called heartburn) • Heartburn: lower gastroesophageal sphincter fails to open and allow food to go into the stomach or it fails to close and the stomach acids go up the esophagus. • Stomach: a muscular sac that mixes food with gastric juices to form chyme which enters the small intestine: • 1L capacity, has a pH of 2 (same as a car battery) • Stores food, doesn't absorb nutrients. It empties 2-6 hours • Initiates digestion of proteins with enzyme pepsin • Controls the movement of food into the small intestine • Gastric juice: produced by gastric glands of the stomach, includes pepsin mucus and hydrochloric acid (HCl) o The HCl destroys bad bacteria that enter in the food • Chyme: thick semi-fluid food material that passes from stomach to the small intestine • Pyloric sphincter: regulates chyme entry into the small intestine • The first place that chemical digestion happens is in the mouth, then in the stomach. • Pancreatic juice joins with the bile • Small intestine: • Long tube-like chamber of GI tract between stomach and large intestine • Contains enzymes secreted by pancreas and enters via duct in duodenum to digest carbs, fats and proteins • Receives bile produced by the liver and is stored by the gallbladder that is released into the duodenum. The bile breaks things down into small globules • Parts: 1. Duodenum: first 10 inches of the small intestine 2. Jejunum: 2nd part of the small intestine, 8 feet long 3. Ileum: 3rd part of the small intestine, 12 feet long • Nutrients are absorbed by the small intestine • Villus: small fingerlike projections of the inner small intestine wall (mucosa) o Outer layer has cells that have microvilli (brush border) o Blood capillaries and small lymphatic capillaries (lacteal) are present. • • Lactose intolerance: inability to digest lactose because of an enzyme deficiency o These people do not have brush border enzyme lactase o Symptoms: ▯ Diarrhea (due to fluid retention) ▯ Gas, bloating and cramps when bacteria break ▯ Down lactose anaerobically o People that aren't lactose intolerant are mutants, what is supposed to happen is that the only time that people are supposed to break down lactose was when they were a baby so they could break down the mother's milk. But after a mutation, the gene that stopped the breakdown of lactose after being a baby was changed in some people so that people can breakdown lactose their whole lives. • • Accessory organs: • Pancreas: internal organ that produces digestive enzymes, it also produces hormones insulin (helps lower sugar levels) and glucagon (helps elevate sugar levels). Produces pancreatic juice that contains: o Pancreatic amylase: enzyme in the pancreas that digests starch to maltose o Trypsin: protein-digesting enzyme o Lipase: fat-digesting enzyme secreted by the pancreas •
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