BIOL 252 1st Edition Lecture 24 Outline of Last Lecture I PCT Tubular Reabsorption II Tubular Secretion III Loop of Henle IV Distal Convoluted Tubule and Collecting Duct V What about the loop VI Urine Storage and Elimination VII Digestive System VIII Saliva and Salivary Glands IX Layers of Digestive Tract X Peristalsis XI Stomach Outline of Current Lecture I Digestive System II Reproductive System Current Lecture I Digestive System a Gastric Motility i Stomach controls its own motility but may be influenced by vagus nerve ii Emetic center of medulla can cause reverse peristalsis via vagus nerve b Liver i Hepatocytes 1 Absorb from the blood a Glucose amino acids iron vitamins other nutrients for metabolism or storage b What do we do with glucose Make glycogen c Vein carrying deoxygenated blood has already exchanged w digestive tract cannot deliver O2 to liver so we must have an artery vein and artery in same direction 2 Degrade from blood a Hormones toxins bile pigments drugs 3 Secrete into blood These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute c d e f g a Glucose albumin lipoproteins clotting factors angiotensinogen other products 4 Excrete bile a Bile pigments bile salts Circulatory Routes i Portal system where left capillary bed liver right capillary bed ii Middle vessel hepatic portal vein Gallbladder i Bile salts mix w fats and emulsify makes them water soluble ii Liver secretes about 500 1000 mL of bile daily 80 of bile salts are reabsorbed in small intestine iii Gall bladder stores and concentrates bile 1 Bilirubin excretory product 2 Bile salts acids steroids synthesized from cholesterol Pancreas i Stomach s chyme is acidic pancreatic juice neutralizes contains HCO3 ii Proteases trypsinogen and carboxypeptidase iii Lipase iv Amylase v Ribonuclease and deoxyribonuclease vi Pancreatic zymogens proenzymes are converted to active enzymes in duodenum vii Nervous system stimulates enzyme release 1 ACh from vagus and enteric nerves stimulates enzymatic secretion 2 Increased enzymes viii CCK stimulates enzyme release and gall bladder contraction 1 CCK secreted by duodenum in response to fats ix Secretin stimulates bicarbonate release 1 Secretin secreted by duodenum in response to acidic chyme Small Intestine duodenum i Receives stomach contents pancreatic juice bile ii Stomach acid is neutralized here iii Fats are physically broken up by bile acids iv Pancreatic enzymes take over job of chemical digestion Jejunum i First 40 of small intestines ii Thick muscular wall iii Internal ridges of mucosa plica 1 Villi 2 Microvilli 3 Expand amount of surface area present iv If inside were smooth far less surface area v Why care about surface area Absorption II h Ileum i Thinner less muscular less vascular than ilium ii Peyer patches prominent lymphatic nodules i Microscopic Anatomy i Blue vein to liver ii Brush border completes chemical digestion in intestines iii Lacteal where fats go large molecules j Intestinal Motility i Peristalsis gradual movement of contents towards colon ii Segmentation pinching off of segment followed by churning w in segment k Large Intestines i Most of digestion complete ii Water being pulled out of what s left iii What s in feces 1 Water solids bacteria undigested fiber fat remaining mucus sloughed epithelial cells a What is fiber Indigestible iv Large intestine reabsorbs water and electrolytes compaction v Bacterial flora 1 Huge colonies of bacteria 2 Benefit from our indigestibles metabolize them and make by products a Ferment undigested carbs helps in synthesis of vitamins B and K 3 About 800 species of bacteria populate large intestine l Defecation Reflex i Stimulus rectal wall stretching ii Involuntary response contraction of smooth muscle in wall iii Sense of urgency internal anal sphincter relaxes involuntary iv Brain tells spinal cord to relax not relax external anal sphincter voluntary v Steps 1 3 happen automatically Reproductive System a How do two cells form 1 cell with 23 pairs of chromosomes b Meiosis i Reduces chromosomes number by half ii Maintains chromosome number for species at fertilization iii Provides genetic diversity through independent assortment and crossing over c Spermatogenesis i Events of meiosis that are male specific ii Diploid cell 2n haploid n iii 23 pairs of chromosomes 23 unpaired chromosomes iv Where do cells come from 1 Primordial germ cells from yolk sac migrate to colonize gonads and become spermatogonia or oogonia 2 Gonia means seed v Mitosis Spermatogonium primary spermatocyte Spermatogonium 1 Constantly spinning off daughter cells vi Meiosis I primary spermatocyte secondary spermatocyte 1 Replicate DNA before we divide 2 Start out diploid before dividing duplicate then divide 3 Replication and first division meiosis I vii Meiosis II second division 1 Secondary spermatocyte 2 spermatids contain 23 unpaired chromosomes 2 2 secondary spermatocytes 4 spermatids viii Spermiogenesis 1 To make sperm cell must differentiate the cell 2 Spermatogenesis contains spermiogenesis ix Where does this happen 1 Inside testes groups of tubules called seminiferous tubules 2 Cells that are spermatogonium are on top as become sperm go toward lumen bottom x Spermiogenesis 1 Round looking cell sperm cell 2 Appearance of acrosomal vesicle and flagellum in spermatid 3 Growth of acrosome and flagellum 4 Shedding of excess cytoplasm 5 Mature sperm a Midpiece mitochondria produce ATP to move flagellum b Nucleus c Acrosome specialization internal membrane that produced in differentiation process that produces enzymes that helps sperm break barriers to egg 6 Spermatozoon a Axoneme s 9 2 arrangement of microtubules d What determines sex i SRY gene carried on Y chromosome determines male sex without it a female will develop e Semen i Typical ejaculation is 2 5 mL semen containing 1 10 sperm and spermatic duct secretions 2 30 prostatic fluid 3 60 seminal vesicle fluid ii Sperm count of 50 120 million sperm mL is typical iii Seminal fluid fructose prostaglandins prosemenogelin iv Prostatic fluid citrate buffer enzymes f Male Hormonal Control i GnRH from hypothalamus responds to environmental stimulus ii FSH and LH from anterior pituitary 1 Target testes in male ovaries females 2 FSH inhibin and ABP androgen binding protein enhancing effect on testosterone a Inhibin inhibits FSH feeds back negatively 3 LH produces testosterone a Testosterone levels do