TEAS 7

• Enteric nervous system (ENS)


  Controls the digestive system, stimulated by the parasympathetic nervous system (PNS), inhibited by the sympathetic nervous system (SNS)
• Digestive system pathway


  1. Mechanical digestion starts in mouth (mastication)

  2. Swallowing (deglutition)

  3. Muscularis externa of digestive tract is 2 layers (3 in stomach)

  4. Peristalsis: contract and relax to squeeze food from pharynx to esophagus to stomach, extra layer helps to churn and mix food

  5. Segmentation: non-adjacent portions contact and relax to move chyme (partially digested) back and forth

  6. Mass peristalsis: movements that occur 2-4 times a day to push large amounts of chyme toward rectum
• Ingestion


  Food ingested is moistened by saliva secreted by salivary glands
• Saliva


  Contains enzymes, antimicrobial agents, bicarbonate ions to maintain pH
• Salivary amylase


  Breaks down polysaccharides into simple sugars
• Lingual lipase


  Breaks down fats
• Stomach


  Stretches to accommodate volume of food, mainly serves as storage, churns and pummels food for 3-4 hours, mixes with gastric juices to create chyme
• Stomach glands


  Produce digestive enzymes, endocrine cells release hormone gastrin, parietal cells absorb vitamin B and produce HCl, chief cells produce pepsin to digest proteins, mucous cells secrete bicarbonate mucus to protect stomach
• Liver


  Produces bile, metabolises nutrients, detoxifies
• Bile


  Yellow-green solution of bile salts, breaks down hemoglobin, cholesterol, and electrolytes, emulsifies fats into micelles that can be broken down by lipases in small intestine, enhances absorption of fat-soluble vitamins
• Gallbladder


  Stores bile, releases bile into duodenum when food enters small intestine
• Liver's role in blood glucose regulation

  Regulates blood glucose concentration, stores excess glucose as glycogen, breaks down glycogen to release glucose when blood sugar is low, can also produce glucose from proteins and fats (gluconeogenesis)
• Liver's detoxification


  Converts ammonia to urea which is sent to kidneys
• Pancreas


  Releases insulin, glucagon, and somatostatin, produces and secretes digestive juices that are released into duodenum, raises pH of chyme
• Small intestine


  Pancreatic enzymes digest food so nutrients can be absorbed, microvilli and villi increase surface area for absorption, duodenum neutralizes digestive juices, amino acids and sugars absorbed by active transport, lipids and water absorbed by diffusion
• Large intestine


  Absorbs water from indigestible food, waste, and bacteria, bacterial flora release gases and waste products
• Gonads


  Produce gametes (sex cells) and secrete hormones
• Female reproductive cycle


  LH triggers ovulation, follicular phase FSH stimulates follicle maturation and estrogen secretion, ovulation releases secondary oocyte, luteal phase corpus luteum forms, uterine lining proliferates then becomes secretory, menstruation sheds uterine lining
• Epidermal cell types


  Keratinocytes produce keratin, melanocytes produce melanin, Langerhans cells are immune cells, Merkel cells detect light touch
• Skin functions


  Sensory receptors, physical barrier, UV protection, thermoregulation, sweat glands, physical protection (nails, calluses, hair)
• Cardiovascular system functions


  Transport oxygen, nutrients, hormones, ions, fluids, remove metabolic wastes, bring wastes to kidneys
• Cellular respiration


  Glucose + oxygen = carbon dioxide + water, oxygen moves from air to blood to alveolar capillaries and binds to red blood cells
• Thermoregulation


  Thermoreceptors detect temperature changes, vasodilation and sweating cool the body, vasoconstriction and arrector pili warm the body
• Endothelial cells


  Line blood vessels, semi-permeable, allow vasoconstriction
• Blood pressure


  Systolic pressure is maximum during systole when vessels contract, diastolic pressure is during diastole when vessels relax
• Circulatory circuits


  Systemic circuit carries blood from left ventricle to aorta and other tissues, pulmonary circuit carries deoxygenated blood from right ventricle to lungs for gas exchange
• Cardiac arrhythmias


  Bradyarrhythmias are abnormally slow heart rates, tachyarrhythmias are abnormally fast heart rates, conduction irregularities are irregular pulses
• Capillary beds


  Groups of connected capillaries that exchange gases and solutes, can be continuous, fenestrated, or sinusoidal
• Peripheral resistance


  Resistance of vessels to blood flow, higher resistance decreases blood flow rate
• Blood composition


  55% plasma, 45% blood cells (RBCs, WBCs, platelets), plasma is mostly water, proteins, and other chemicals
• Erythropoiesis


  Production of RBCs in red bone marrow, stimulated by erythropoietin when oxygen is low, old RBCs broken down and recycled
• Leukocytes


  B cells, T cells, monocytes, granulocytes
• Blood types


  A, B, O, AB based on presence of A and B antigens on RBCs
• Blood clotting


  Vessel constriction, platelet adhesion, extrinsic and intrinsic coagulation pathways
• Oxygen transport


  Hemoglobin in RBCs transports oxygen and carbon dioxide
• Cardiovascular regulation


  Heart rate and blood pressure influenced by sympathetic, parasympathetic, and endocrine systems
• Nervous system functions


  Voluntary and involuntary control of body functions

  
• Autonomic nervous system


  Sympathetic and parasympathetic divisions control involuntary functions

  
• 1. What are the three types of salivary glands and where are they located in the mouth?

  - Parotid, sublingual, and submandibular glands located in the roof of the mouth, cheeks, and under the jawbone, respectively.
• 1. Which of the following substances is excreted by the kidneys to regulate blood pressure?

  - Renin