Physio Reinforcing Concepts Pt2 PDF

Liver+colon Liver: Kupffer cells are phagocytes(macrophages) that sample the portal blood, cleansing it of pathogens and debris that escapes the intestinal lumen. Damage to the kupffer cells may lead to sepsis Liver has portal vein blood supply, and arterial blood supply, the blood it receives gets...

Liver+colon Liver: Kupffer cells are phagocytes(macrophages) that sample the portal blood, cleansing it of pathogens and debris that escapes the intestinal lumen. Damage to the kupffer cells may lead to sepsis Liver has portal vein blood supply, and arterial blood supply, the blood it receives gets detoxified, metabolites get processed into excretabile forms, albumin and clotting factors are synthesized, and bile gets made. The liver is the site of gluconeogenesis, and is a glycogen storage area. Because of this, in liver failure, hypoglycemia is common. Drugs we take orally go to the liver and immediately undergo first pass metabolism Cholesterol 7alpha hydroxylase is rate limiting step of cholesterol -> bile Large Intestine: Haustral contractions slowly push chyme through the large colon, where it reabsorbs water(mostly in the right colon) fecal waste is stored in the left colon Large intestine secretes bicarb to neutralize the acids produced by the rich bacterial population, and mucus to protect the lumen from fecal abrasions Mass movements are propulsive movements, intense prolonged peristaltic contractions, forces contents toward the rectum Gastrocolic reflex occurs when the stomach is activated by food, initiating a mass movement in the colon Defecation: caused by relaxation of both internal and external anal sphincters, and increase in abdominal pressure. Internal sphincter is parasympathetically relaxed, external sphincter is voluntarily relaxed Flow ● Gravity ○ Blood flow is greater at the base and less at the apex because gravity pulls blood down to the base of the lungs ○ In addition, the base has less vascular resistance and greater transmural pressure (Pc - Palveoli) ○ Zone 1: Apex of lungs ---> Pressure in alveoli is the greatest (low transmural pressure) and pressure in the pulmonary veins is lowest ■ Flow is more or less 0 here because pressure is alveoli is so great vessels are collapsed ○ Zone 2: Middle of lungs ---> pressure in pulmonary artery is greatest and pressure in pulmonary vein is lowest ■ This is a potentially collapsible state for the vessels where flow is equal to Pa - PA ○ Zone 3: Base of lungs ----> pressure is greatest in the pulmonary arteries and least in the alveoli ■ Flow is equal to Pa - Pv meaning that the pressure in the alveoli is too small to ever collapse the vessels and it is therefore non-collapsible ● Ventilation - Perfusion - Diffusion: An overview ○ Conducting zone = Vt = tidal volume x respiratory rate ■ PO2 = (Patm - 47)FIO2 ■ FIO2 is 0.21 or 21% ○ Respiratory zone = Va = (TV - ADS) x RR ■ ADS is the anatomical dead space = 1mL/lb ■ Average person = 150 mL ● ● Conducting zone = Trachea down to terminal bronchiole ○ No gas exchange ---> “dead space” Respiratory zone = Respiratory bronchioles to alveolar sacs ○ Gas exchange happens here ○ Acinus = region supplied by primary respiratory bronchiole (respiratory zone) ○ Terminal respiratory unit = 3 acini Spirometry ● ● ● ● ● Palveoli = Precoil + Pintrapleural End Expiration: ○ No flow condition bc Palveoli = Patm ○ Volume (RV) is determined by Ptl and lung compliance End Inspiration: ○ Also no flow condition ○ Pintrapleural is now more negative ○ And Recoil pressure is larger, equal and opposite to intrapleural pressure ○ As you increase volume, the recoil force will increase! Dynamic Inspiration: ○ Once the intrapleural pressure decreases the alveoli expand ○ The pressure in the alveoli decreases ○ As air enters, the pressure in the alveoli decreases less and less ○ Once pressure in the alveoli = Patm then inspiration has ended Q = Patm - Palv / Rairway ● Helium Dilution ○ Measures FRC and RV ○ Spirometer is loaded with helium (usually 10%) while valve is closed. At FRC valve is opened for 5 mins until the lungs equilibrate. Then the concentration of He is measured again. ○ VL x FL_start + Vsp x Fsp_start = (VL + Vsp) FL_end with FL_end = FL_start ■ FL_start = 0 ■ VL = 0 ■ Vsp = 3000 mL ■ Fsp_start = 10% ■ Fsp_end 5% ■ (0 x 0) + (.10 x 3000) = 0.05 (FRC + 3000) ● FRC = 3000 ■ From here we can calculate RV using the formula RV = FRC - ERV ● ERV is measured with the spirometry (is the Vp number in this case 3 L) Lung Forces ● ● Compliance of the lung is low until you reach enough pressure to open the alveoli against surface tension ---> then compliance increases with increasing volume until a certain max threshold is met C=V/P ○ Can be reduced by scarring, fibrosis, edema, or decreased surfactant ● ● FRC = point where forces are equal and opposite!! Inspiration: ○ Lung force increases ○ Chest force decreases ● ● Resistance is greatest in upper airways ○ Largest values in the bronchi due to size, and branching Resistance decreases with increasing volume Endocrine System ● ● ● ● ● ● Peptide = hydrophilic and can be stored, travel freely in blood ○ Synthesis is via Gs or Gq Steroid = transported via plasma proteins in blood ○ Synthesis from cholesterol ○ Can affect gene transcription Amines = derived from tyrosine, some are hydrophilic and some hydrophobic ○ Carried by thyroid binding globulin Binding globulins increase the half life and hormones Regulated by Feedback Mechanisms ○ Negative Feedback = directly or indirectly inhibits secretion of hormones ■ Ultra short inhibits its own secretion ■ Short = anterior pituitary inhibits the hypothalamus ■ Long loop = end hormone inhibits the whole hypothalamic - pituitary axis ○ Positive Feedback = stimulates further hormone release ■ Ex: estrogen and oxytocin both increase their own hormone release Pituitary ○ Anterior (adenohypophysis) = glandular, releases hormones ■ Regulates reproduction, growth, energy and stress ■ Somatotrophs ----> Growth hormone ■ Thyrotrophs ----> Thyroid stimulating hormone ■ Corticotrophs ----> Adrenocorticotropic hormone ■ Gonadotrophs ---> Follicle stimulating hormone ■ Gonadotrophs ----> Luteinizing hormone ■ Lactotrophs ----> prolactin ○ Posterior (neurohypophysis) = neural, releases neurotransmitters ■ Oxytocin ■ Antidiuretic hormone (aka: anti-vasopressin hormone) Endocrine System Cont. ● ● ● Steroid hormones come from the cortex ○ GFR = Glomerulosa, fasciculata, reticularis ○ “GFR ---> Salt, sugar, sex” ○ Steroids are synthesized from cholesterol ■ Cholesterol desmolase (CYP 11A1) is the RLS and requires the Star protein! Hypothalamic - Pituitary Axis ○ Hypothalamus releases GnRH which binds gonadotroph receptors on the ant. Pituitary ○ Ant. pituitary releases FSH and LH (glycoproteins) ■ LH is released more heavily in Males ----> testosterone ■ FSH ----> spermatogenesis ■ Inhibin inhibits FSH Hypothalamic - Ovarian Axis ○ Hypothalamus releases GnRH which binds gonadotrophs on the ant. Pituitary ○ Ant. Pituitary releases FSH and LH ■ LH ---> theca cells ■ FSH --> granulosa cells ■ Both help regulate menstrual cycle ● ● Vasopressin (ADH) ○ V2 receptors (Gs) regulate osmolarity by increasing H2O reabsorption ○ V1 receptors (Gq) constrict smooth muscle cells Oxytocin ○ Causes let down of milk from breasts ○ Uterine contractions during birth ○ Up regulated during childbirth ○ Can also be used to control postpartum bleeding Digestion ● ● ● Smell ○ ○ ○ ○ ○ Activates salivary glands which release bicarb, amylase and lipase Activates stomach acid, pancreas and gallbladder All controlled by CNS Bicarb neutralizes the acid Clinical Correlation: ■ Sjogren’s Syndrome = autoimmune destruction of salivary glands ---> dry mouth and eyes Pancreas ○ Release digestive enzymes (lipase) and bicarb ○ Insulin and glucagon ○ Cystic Fibrosis: decreased production of lipase ----> fat malabsorption Regulation ○ Somatostatin from the GI tract inhibits the release of all GI hormones and gastric acid secretion ○ Gastrin from G cells in the stomach ■ Increases H+ secretion ■ Stimulated by distention of the stomach, GRP, tryptophan ■ Inhibited by H+ and somatostatin ■ Zollinger Ellison: endocrine tumor that leads to excess gastrin production ---> excess H+ secretion ---> ulcers and many of them (PUD) ● ● CCK ○ From I cells ○ Contraction of the gallbladder ---> relaxes sphincter of Oddi --> bile secretion ○ Stimulates secretin ---> bicarb ○ Inhibits gastric emptying ○ Stimulated by small peptides and amino acids, fatty acids and monoglycerides GLP 1 ○ Stimulates insulin and decreases glucagon Digestion ● ● ● Salivary Glands ○ Secrete saliva ■ Water, bicarb, mucins, amylase, lysozyme, growth factors ○ Regulation ■ Parasympathetic ---> stimulates watery, abundant saliva production and secretion ■ Sympathetic ---> reduces saliva production and produces thick mucus saliva Achalasia ○ Inability to swallow both solids and liquids bc of denervation of the LES ○ This results in INCREASED tone ---> food can’t pass to stomach ○ Different from cancer which is progressive swallowing problem from liquids to solids ● Esophagitis is inflammation of the esophagus due to acid from stomach refluxing up as a result of little LES tone ○ Pill esophagitis ■ Older people have trouble swallowing large pills ---> they get stuck and cause inflammation ■ Common agents = Potassium tablets GERD ○ Incompetent lower esophageal sphincter ---> acid from stomach backflows into esophagus ○ Heartburn is the main symptom ○ Treat with proton pump inhibitor ---> reduces H+ content in the stomach Digestion ● ● ● Motility ○ Migrating Motor Complex ■ Constant sweeping of contractions that continually move through the stomach to prevent large amounts of indigestible materials from accumulating ■ Initiated by Motilin ● If you have a motility disorder then you are deficient in motilin ■ Gastric secretion, bile flow and pancreatic secretion increase ○ Patterns ■ Propulsive = peristalsis (ring like contractions) that move food forward ■ Mixing = segmentation that helps chop food up Slow Wave ○ Oscillating resting membrane potentials of GI smooth muscle ○ Rhythmic depolarizations initiated by pacemaker cells that move food from mouth to anus Dumping Syndrome ○ After bariatric surgery where the stomach is made smaller, the patient has to eat small frequent meals ○ If large meals are eaten, glucose is absorbed too fast leading to hyperglycemia ○ The hyperglycemia results in a secretion of insulin that leads to hypoglycemic symptoms ■ Weakness, dizziness, and sweating after meals