BIOS 1710: Biological Sciences II, Week 1 Notes
BIOS 1710: Biological Sciences II, Week 1 Notes BIOS1710
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This 5 page Class Notes was uploaded by Sydney Jones on Friday August 26, 2016. The Class Notes belongs to BIOS1710 at Ohio University taught by Scott Moody in Fall 2017. Since its upload, it has received 202 views. For similar materials see Biological Sciences II: Ecology, Evolution, Animal Body Systems in Biology at Ohio University.
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This material talks about chapter 36 from the lecture. It is very helpful since I don't have to worry about missing anything he says and plus this goes into more detail.
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Date Created: 08/26/16
Week 1 August 22-26 Ch 35 Nervous Systems 3 types: • Sensory- receive and transmit information • Interneurons- process and transmit to different regions • Motor- create proper responses Sensory Interneruons Motor Phylogeny of Multicellularity Sponges Cnidarians (jelly Multicellular ▯ish, corals) Has nervous system Bilaterians (humans) Cephalization- concentration of nervous system components at one end of the body Why? For locomotion and predation **100-200 areas of the brain Anatomy of a Neuron • Soma/cell body- receives information that then is integrated • Dendrites- very short (max 2mm long), receives information • Axon hillock- axon near the soma, sends signals to synapses • Axon- can be very long (2mm-2m) • Synaptic cleft- (10-20nm), where information is passed between neurons • Dendritic spines- sight of synapsis **the three different types have different functions so their for have different shapes In Class Question Which is false: 1. Axons are linger than dendrites 2. Dendrites generally conduct information to the soma 3. Information is received on the dendrites, but rarely on the axon or soma 4. All the above are true Correct Answer is 3: you can have information read on the dendrites as well as the soma Glial Cells They are more numerous than neurons in the human cortex Function: to provide nutrition and physical support 2 types of Myelin Sheaths: • Schwanna cells- Peripheral Nervous System (PNS) • Oligodenrocytes- Central Nervous System (CNS) **Astrocytes- contribute to the blood-brain barrier in some animals Grey and White Matter -Myelin sheaths make the brain look white -Grey matter is the cell bodies, dendrites, and un-myelinated axons This means the white matter part of the brain is where thought processes/transfer takes place. Resting and Action Potential Resting Membrane Potential • The resting potential represents energy stored as concentration gradients in a series of ions Outside of axon (+) Inside of axon (-) **Ions automatically move to the area with the lower concentration -There is a high concentration of Na (sodium) outside but low concentration of K (potassium) -There is a low concentration of Na inside and high concentration ***They never balance out because of the potassium leak channel, K constantly moves in and out***** You can find Equilibrium Potential with the Nernst Equation ???????? ???? ▯ ???? ▯ ???????? ???? ????▯ ATPase Pump - Used to maintain resting potential -Needs ATP since it pushes against the gradient -K (2) out and Na (3) in Action Potential *Rapid, temporary changes in membrane potentials; moving information down axon with voltage -Starts with voltage-dependent ion channels at axon hillock permeable to either Na+ or K+ are involved in creating the action potential Three parts: (Na is used as example since it can be vice versa) 1. Depolarization- when the ions are not polar from each other anymore a. Import from the axon hillock overflows the axon until reaching the threshold b. This opens opening the voltage-gated Na channel spiking the membrane potential 2. Repolarization- putting the charges on polar sides a. Once the voltage-gated K channels see that it is depolarized they open slowly b. The voltage-gated Na channel close and become inactive 3. Hyperpolarization- when the ions become two polar a. Since the voltage-gated K channels open and close slowly they undershoot and become hyperpolarized b. Na channel becomes active but not open c. K channel becomes inactive *This continues all the way down the axon Facts: -Neurons have a refractory period so they cannot go back only forward -All three parts are always there - The 3 phases take about 1-2 milliseconds Velocity of Propagation **Diameter is the most important factor ▯ small = slow Myelin Sheaths (make up for small axons) -jumps the action potential down to the Node of Ranvier (the spots that are covered) by covering the channels The Synapsis Transmission from Pre to Post synapsis 1. Action potential from the axon enters the terminal 2. Depolarization causes the voltage-gated Ca channels 3. Vesicles holding the neurotransmitters respond by fusing with the membrane and into the synaptic cleft 4. Neurotransmitters bind with receptors 5. Left over receptors are reabsorbed or cycled Major Neurotransmitters • Glutamate- primary excitatory NT in the CNS Important for learning and memory • GABA- primary inhibitory NT in the CNS • Glycine- inhibitory in the spinal cord • Acetylcholine- excitatory at neuromuscular junctions (inhibitory in others eg the heart) • Monoamines- often modularity; can be excitatory or inhibitory (G-Proteins) o Dopamine o Serotonin o Norepinephrine ***Each affect is based on the specific transmitter Types of Postsynaptic Potentials Excitatory postsynaptic potentials (EPSPs)- causes membrane to depolarize by opening mixed Na/K channels; brining cells toward threshold Inhibitory Postsynaptic Potentials (IPSPs)- usually causes the membrane to hyperpolarize by opening a k or Cl channel If both occur close together: **Dendrites closer to the soma have a bigger impact CNS and PNS Central Nervous System (CNS)- brain and spinal cord Peripheral Nervous System (PNS)- everything else Nerve- a bundle of axons Brain and Spinal cord and CNS Centralized Ganglia Afferent (Sensory) EffFrom CNS tor) PNS To CNS Sympathetic Parasympathetic "Fight /Flight" "Rest/Digest" Sympathetic Division Parasympathetic Division Dilates pupils of eyes Constricts pupil of eyes Inhibits salivary gland Stimulates salivary glands Accelerates heart Slows hearts Relaxes bronchi in lungs Constricts bronchi in lungs Inhibits activity or stomach/intestines Stimulates stomach and intestines Inhibits activity of pancreas Stimulates activity in panaceas Stimulates glucose and inhibits gallbladder Stimulates gallbladder Stimulates adrenal medulla Promotes voiding for bladder Inhibits voiding from bladder Promotes erection Promotes ejaculation and vaginal contractions
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