Respiratory System Exchange between air and blood capillaries takes place in the alveoli filled with alveolus Alveolus surrounded by capillaries for CO2 O2 exchange o CO2 from cells into capillaries alveolus outside o O2 from air capillaries cells simple diffusion Conducting zone has NO alveoli therefore no gas exchange Bronchi Respiratory zone has alveoli and gas exchange by simple diffusion Bronchioles Respiratory membrane is where gas exchange occurs o Wall of alveolus epithelial cells o Wall of capillaries endothelial cells o Extracellular interstitial fluid is between the two walls Diaphragm relaxes during expiration and contracts during inspiration As the diaphragm goes down thoracic cavity size increases and pressure decreases contraction When diaphragm goes up thoracic cavity size decreases and pressure increases relaxation Atmospheric pressure is 760mm Hg o Alveolar pressure must be greater than 760mm Hg for expiration gas to exit lungs expiration inspiration o Alveolar pressure must be less than 760mm Hg for inspiration gas into lungs F air flow P change in pressure R resistance to airflow If R resistance increases then F air flow will decrease Tidal volume is 500mL volume of air moving in and out during normal breathing Anatomical dead space is 150mL volume of conducting respiratory passages Alveolar air space is 350mL 500 150 350 or what reaches alveoli Most important gases nitrogen more abundant and oxygen more important Partial pressure of oxygen in venous blood is 40mm Hg Partial pressure in alveoli is 104mm Hg or answer closest to 100mm Hg he said Since CO2 has a lower partial pressure gradient it is easier for CO2 to diffuse and move because it requires a lower pressure to get the amount of diffusion o Change in pressure of oxygen is 60mm Hg and change in pressure for carbon dioxide is 5mm Hg 20 times more soluble membranes than oxygen Equilibrium is at 104mm Hg when the blood leaving the capillaries has the same pressure of the alveoli or previous tissue slide titled partial pressure gradients with picture CO2 H2O H2CO3 H HCO3 o If more H more acidic reaction goes to the left o If more CO2 reaction goes to the right o CO2 most important stimulus for breathing o CO2 mainly travels to the lung in the form of bicarbonate bicarbonate is main form of transporting in the plasma Respiratory center medulla oblongata o Inspiratory innervated by diaphragm expiratory is abdomen Blood pH regulated by H2CO3 HCO3 buffer system Peripheral chemoreceptors stimulated by increase in CO2 Central chemoreceptors stimulated by increase in H Renal Physiology Blood pH long term depends on H and bicarbonate Nephron is the functional unit of the kidney Two main types of nephrons cortical 85 and juxtamedullary 15 Flow through cortical o Glomerular Bowman s capsule proximal convoluted tubule descending limb of the loop of Henle LOH ascending limb of LOH distal convoluted tubule DCT collecting ducts Flow through juxtamedullary o Glomerular Bowman s capsule proximal convoluted tubule descending LOH thin ascending tubule collecting ducts Glomerulus is the vascular part of nephron Convoluted is tightly coiled tube not straight Proximal convoluted tubule has most mitochondria helping with primary active transport of solutes water main absorb reabsorption Distal convoluted tube is the second chance for reabsorption Filtrate contains plasma NOT red blood cells because they are too big Amino acids secondary active transport Glucose secondary active transport Electrolytes primary active transport Na If Net Filtration Pressure NFP is less than 10 reduced filtrate less urine Low BP is stimulus for secretion of renin helps convert angiotensinogen from liver to angiotensin I becomes angiotensin II with ACE angiotensin converting enzyme stimulates ADH secretion ADH and aldosterone are synergistic Aldosterone causes epithelial cells of kidney to reabsorb sodium leads to water retention and increase in BP Bladder is made of smooth muscle Detrusor muscle is the stronger muscle in the bladder Gastrointestinal Physiology Mucus secretes into the lumen and reduces friction Increased parasympathetic Increased secretion of enzymes increased movement Muscularis externa external longitudinal muscle contracts and pushes stuff through and the circular muscle will cause the lumen to get smaller if it contracts Plexus is a group of nerves Myenteric nerve pleux major nerve supply that controls GI tract mobility Chemical digestion begins in mouth with salivary amylase Stomach has 3 muscle layers Other GI has 2 smooth muscle layers Chief cells produce pepsinogen inactive and HCl converts to pepsin in stomach because HCl lowers the pH in stomach Pepsin starts digestion of proteins Parietal cells secrete HCl G Cells enteroendocrine cells secrete gastrin in stomach Gastric phases o Cephalic food not in stomach yet but we smell or think of food which causes secretion of saliva o Gastric ingesting food into stomach gastric secretion increased o Inhibitory Enterogastric Reflex emptying the stomach sphincter relaxes gastric secretion is decreased Bile is produced from some cholesterols CCK and secretin go to blood to stomach to decrease parietal and chief cell activity this will decrease gastric secretion CCK also stimulates the release of bile in gallbladder Secretin also tells pancreas to release pancreatic juices contains bicarbonate Trypin becomes trypsinogen from enteropepitdase Carb absorption glucose is secondary active transport on apical border and facilitated on nasal border Perstalsis is stimulated by parasympathetic activity Digestion of fats is in the duodenum Bile is made in liver and stored in gallbladder Bile is made mostly of cholesterol and water
View Full Document
Unlocking...