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BIO 1144 Sec 03 Week of Mar 1 Notes

by: Jaren Davis

BIO 1144 Sec 03 Week of Mar 1 Notes BIO 1144

Marketplace > Mississippi State University > Biology > BIO 1144 > BIO 1144 Sec 03 Week of Mar 1 Notes
Jaren Davis

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Hey guys! These notes are from the week of march 1! I hope they help!
Biology II Thomas Holder
Thomas Holder
Class Notes
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This 7 page Class Notes was uploaded by Jaren Davis on Saturday March 5, 2016. The Class Notes belongs to BIO 1144 at Mississippi State University taught by Thomas Holder in Spring 2016. Since its upload, it has received 29 views. For similar materials see Biology II Thomas Holder in Biology at Mississippi State University.


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Date Created: 03/05/16
Digestive System • Heterotrophic ◦ Ingest feeders ◦ They can't make their own food ‣ Already made food ◦ Need food for: ‣ Survival, maintenance, growth, reproduction • One needs more food/energy than the other • Gut Tract - 2 types ◦ Blind Gut ‣ No cavity between the gut itself and the body wall ‣ One opening ‣ Primitive form ◦ Gut tube ‣ Tube-within-a-tube arrangement • Advanced form ‣ Flow through digestive tube ‣ Fluid filled body cavity (coelom) between gut and cavity (mostly) ‣ Separate openings • Digestive enzymes ◦ Hydrolases - break down by adding water ◦ Carbohydrases - carbohydrate ◦ Proteases - proteins ◦ Lipases - lipids ◦ Nucleases - nucleic acids • Functions of Digestive System ◦ Digestion - chemical (h2o and enzymes) / mechanical ‣ Breakdown of large molecules into smaller form ◦ Absorption ‣ The uptake of digestive food by cells lining the gut tract ◦ Transport ‣ Moving food through the gut tract ◦ Elimination ‣ Formation of fecal matter ‣ Excretion ‣ Removable of undigested and unabsorbed materials • Alimentary Canal - Actual digestive tract or tube ◦ Region of Reception ‣ Buccal cavity • Mouth and accessory structures • Both chemical and mechanical digestion occur within the mouth cavity ‣ Jaws, teeth, tongue (help food move and assist with swallowing) • Salivary glands - empty into the mouth cavity ◦ Amylase (breaks down starch) • Pharynx (back of mouth) - point that digestive system and respiratory system cross paths ◦ Region of Conduction ‣ Conducting food away from the mouth cavity ‣ Esophagus • Lined with simple epithelium • Outside of the wall is different layers of smooth muscle • Peristalsis ◦ Rhythmic wave like contractions pushing food through ◦ Region of Storage and Digestion ‣ Stomach - verts. (mostly) • Crop - insects, birds (enlarged lower portion of esophagus) ‣ Stomach • Stretchable sack • When it's small, the inner lung folds up • Folds are called rugae - lined with simple epithelium • Wall of stomach - smooth muscle (has oval called that form sheets/ sheets get thicker in stomach) ◦ 3 layers Contractions happen in different directions ◦ Churning movements when contracting -mixer ‣ Speeds up digestion • Enzymes ---> chemical digestion ◦ Protein digestion begins • Inner lining - epithelium with pits and glands ◦ Necessary for secretion ◦ Mucous cells - secrete mucus (moisture) ‣ Helps moisten ‣ Makes it softer ◦ Chief cells - secrete pepsinogen ‣ Pepsinogen is an inactive enzyme ◦ Parietal cells - secrete hydrochloric acid • Lumen (Cavity) of Stomach ◦ Pepsinogen + HCL = Pepsin ‣ Breaks bonds with proteins • Minimal Absorption ◦ Lipid soluble material ‣ Ex. Aspirin, alcohol ◦ Region of Terminal Digestion and Absorption ‣ Whatever gets through this region without being absorbed is waste ‣ Small intestine • Verts • In insects it's called a midgut • Chemical digestion of lipids and nucleic acids begins and ends • Chemical digestion of carbohydrates and proteins are continued and completed here • In mammals ◦ 8 times the height of the organism ◦ Length = 8 x height ◦ Allows more absorption surface area • Three areas: ◦ Duodenum - many secretions into this region ◦ Jejunum ◦ Ileum • Absorption ◦ Simple epithelium ‣ Single layer of tissue ◦ Surface (lining) modifications to increase absorptive area: ‣ Plicae circulares - folds of the inner lining • Can increase surface area two to three times ‣ Villus (pl. villi) - finger-like projections • Can increase surface area by ten fold ‣ Microvilli -folding of plasma membrane of cells lining villus • Can increase surface area by twenty fold • Enhanced in mammals ◦ Region of H2O Absorption- ‣ Concentration of solids ‣ Large intestine - verts • Called hind guts in insects • Shorter than small intestine • Mammals ◦ 1.5 M • Lack plicae, villi, microvilli • H2O absorbed through epithelium • Function ◦ H2O (1400 ml absorbed a day) ◦ Compacts/eliminates waste ◦ Wastes: H2O - 75% Inorganic substances - 5% Fat - 5% Undigested protein, bile, dead cells - 7% Roughage - 8% ‣ Vitamin Synthesis • By bacteria ◦ Anus ‣ Opening to the outside ‣ Not all vertebrates/mammals have this ‣ Some have a cloaca • A chamber receiving the contents of the urinary, digestive and reproductive tracts • Accessory Digestive Glands - not part of digestive tube ◦ Pancreas - pancreatic duct to duodenum ‣ Secretes juices to break down carbohydrates and other things ◦ Liver ‣ Constantly producing a small amount of bile (necessary for the break down of large molecules) ◦ Gale Bladder - stores bile; releases bile into duodenum ‣ Can release a greater quantity ◦ Figure 45.6 Carbohydrates: • Polysaccharides ---> mono and disaccharides Proteins: • Polypeptides ---> amino acids Fats: • Glycerol and fatty acids Nucleic Acids: • Nucleotides Enzymes! • Speed up chemical reactions to occur at biological temperatures Nervous System • Closely tied with sensory system • Central Nervous System (CNS) ◦ Brain and spinal cord ◦ Ex: (brain to spinal cord ratio) ‣ Fish 2:1 ‣ Reptiles 25:1 ‣ Humans 55:1 • Peripheral Nervous System ◦ All neurons outside of CNS and their projections • Invertebrates - simple system; but distinction between CNS and PNS difficult to distinguish • Neurons ◦ Nerve cells ◦ Represent the structural and functional unit of the nervous system ‣ Communication network ‣ Signaling ◦ Function ‣ Send and receive chemical and electrical signals through the body ◦ All animals, but sponges have neurons ◦ Structure ‣ Soma - cell body • Distinct nucleus and all necessary organelles ‣ Dendrites • Extensions of the plasma membrane • Incoming signals ‣ Axons • Extensions of plasma membrane • Sending signals • Usually single ‣ Figure 41.2 • Glial Cells ◦ Support functions ‣ Provide support for neurons ◦ > 1,000 as numerous over neurons ◦ Ex: ‣ Oligodendrocytes - central nervous system • Myelin sheath - coating surrounding axon ‣ Schwann Cells - peripheral nervous system • Myelin sheath ‣ Microglial Cells • Remove cellular debris ‣ Astrocytes • Metabolic support • Associated with nutrition for the neurons • Important cells • Stem cells ‣ Radial Glial Cells • Layout pathway for neuron migration during embryonic development • Stem cells • Can also produce more neurons • 3 Types of Neurons ◦ Sensory neurons ‣ "Afferent" transmit signals to CNS ‣ Information from the outside is being picked up and being sent through the sensory neurons, through the spinal cord, to the brain, then a response is sent back through and out ◦ Motor Neurons ‣ "Efferent" carry signals away from CNS to elicit response ◦ Interneurons ‣ Interconnecting cells between other neurons ◦ All differ primarily in cell body • Reflex Arc ◦ Stimulus ---> receptor (striking knee) -------------> CNS-----------> flexor muscles--------->response Sensory neurons and Motor Effector neurons and interneurons interneurons • Electrical Properties ◦ Membrane potential ‣ "Gatekeeper" • Water has free passage, almost everything else is restricted ‣ Only neurons and muscle generate electrical signals ‣ Difference in charge between inside and outside ‣ Ion concentration differences (chemical) and electrical ‣ Cell is "polarized" • Difference in charge ‣ Ions move through channels • If they're open ◦ Resting Membrane Potential ‣ Neurons are not sending any signals ‣ Normal condition ‣ There's an imbalance between the chemicals inside and outside and the charge inside and outside ‣ Selectively permeable • Cations + • Anions - • Polarized ◦ Inside is more - ◦ Outside is more + • Anions inside drawn to cations on outside to edge ‣ 3 Factors Contributing to Rest. Pot. • Sodium potassium pump - ATP expenditure ◦ Carry system ◦ Active transport ◦ 3 Na pumped out for every 2 K pumped in ◦ Potassium moves easily ◦ Never balanced • Ion specific channels will allow passive ion movement ◦ Membrane is more permeable to K ◦ K channels most frequently open at resting potential • More - charged ions inside cell (polarity) • Electro-Chemical Gradient ◦ No net movement - opposing forces of electro/chem can cause near equilibrium (equal charge) ‣ No K flow ◦ Ion movement ‣ + or - ◦ Chemical movement ‣ K Na Cl ◦ Imbalance - created between inside and outside of membrane • Neuron Signaling ◦ Change in membrane potential are changes in degree of polarization ◦ Depolarization - membrane less negative to surrounding solution ‣ Gated channels for Na movement in • Becomes more positive ‣ Membrane is less polarized ◦ Hyperpolarization ‣ K moves out ‣ Membrane more negative to surrounding solution ‣ Membrane is more polarized ◦ All cells exhibit membrane potential ◦ Only neurons and muscle cells are "excitable" ‣ Capacity to generate electrical signals ◦ Use of Gated Ion Channels ‣ Voltage-gated : open/close in response to voltage charge ‣ Ligand (chemical) Gated : open/close in response to chemicals • Nerve Impulse ◦ Frequency - "language" of an impulse ‣ Higher the frequency, greater the excitation ◦ Resting potential ‣ Imbalance between K and Na inside and outside the cell ‣ Imbalance in charge inside and outside axon ‣ At rest, membrane is selectively permeable to K • Na and Cl channels closed Extra Within cellular axon of fluid neurons (outside) • Action Potential - "electrical potential" of impulse ◦ Rapid and brief change of the nerve fiber ◦ Self-propagating ◦ After passing, membrane returns to resting pot. ◦ A given point - Na channels open ‣ Na diffuses in; K diffuses out (due to electrical gradient change) • Sodium Potassium Pump ◦ Complex of proteins in membrane ‣ Pump out Na ‣ Carry in K ◦ 3 Na : 2K • Impulse Conduction Rates ◦ Variable ‣ Depends on organisms and complexity ‣ Sea anemones - 0.1 m/second ‣ Mammals - 120 m/second ◦ Invertebrates ‣ Speed is directly related to axon diameter ◦ Vertebrates ‣ Speed is related directly between the diameter of the axon and layers of myelin sheath • Myelin sheath is in sections ◦ Nodes of Ranvier ◦ Saltatorial conduction - "jumping"


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