Lecture Notes from Week 1 material for Exam 3
Lecture Notes from Week 1 material for Exam 3 ECOL 182R
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This 7 page Class Notes was uploaded by Camille Hizon on Wednesday March 2, 2016. The Class Notes belongs to ECOL 182R at University of Arizona taught by Bonine, Hunter, Martinez in Spring 2016. Since its upload, it has received 89 views. For similar materials see Introductory Biology II in Science at University of Arizona.
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Date Created: 03/02/16
Animal Homeostasis - Oxygen, etc. Cont... I. Lymph System A. No red blood cells; therefore not red B. Drains interstitial spaces C. Has valves and smooth musculature D. Empties into thoracic duct at vena cavae E. Transport system for large hormones and fats into blood stream F. Filariasis, elephantiasis II. Local Circulatory System Control A. Vasodilation or Vasoconstriction 1. Decreased O2 levels with opposite effects on the lhy? W 2. Homeostasis maintainonstant nternal environment B. Vasodilation typically when 1. Temp up 2. [Oxygen] down 3. [CO2] up = pH down) III. Poiseuille’s Law A. Use to approximate flow in a vessel B. Small change in radius large change in flow rate IV. Hemodynamics in Vessels A. Flow depends primarily opressure gradient and resistance B. ½ radius 1/16the flow V. How can blood carry even more oxygen? A. Carrierproteins that bind oxygen and thereby take it out of solution (temporarily) 1. Do endotherms or ectotherms have higher oxygen transport needs? Why? VI. Hemoglobin A. 4 heme + 4 protein chains B. 98% of O2 transported via carrier molecules C. can carry 4 O2 VII. Hemoglobin Fun Facts A. Fetal Hemoglobin: gamma chains (not beta) with higher affinity for O2 1. Enhance O2 transfer from mother to fetus 2. Affinity for CO = 200x greater than for O2 B. Antarctic icefish lack pigment 1. low metabolic needs = low metabolism 2. high cardiac output, blood volume 3. large heart VIII. oxygen dissociation curve A. Hyperbolic (myoglobin) B. Sigmoidal hemoglobin) rate of binding changes C. Hemoglobin cooperativity 1. binding of 1st O2 facilitates more binding 2. oxygenation of 1st heme group increases affinity of other 3 for O2 D. Steep part of oxygen dissociation curve: quickly unload oxygen E. Unload more oxygen when tissues need more F. Why does partial pressure of oxygenecreaseith exercise? Nervous System, Sensors, etc. I. When reflexes occur, sensory information bypasses the brain A. Signaltransduction B. Electricaand chemical signals C. Effector responds II. Squid A. Squid usewaterjet propulssystem for making brief but very fast movements usually whe escaping predatorBetween the tentacles of a squidiphon through which water can be rapidly expelled bast contractio of the body walluscles f the animal. This contraction is iniction potentian the giant axo. Action potentials travel n a larger axthan a smaller one, and squid have evolved the giant axon to improve the speed of their escape response. B. We study squid giant axon (up to 1 mm) because it is BIG! C. “Squid axons are important to physiologists, and to the squid” III. Nervous System A. Role is to quicransmit informatioand signals B. Evolved to also be importantearning and memory C. Works via combination chemical nd electricaignaling IV. Typical Neuron: A. (cell body, terminal, axon) (afferent, efferent) V. Kneejerk Reflex A. Antagonistic Muscle Pair B. Role of Spinal Cord C. Monosynapse D. Polysynapse 1. Afferentin) 2. Interneuron) 3. (Brain) 4. Efferent(out) E. Steps: 1. A hammer tap stretches the tendon in the knee, stretching a receptor in the extensor muscle 2. A stretch receptor fires an action potential 3. In a monosynaptic pathway, the sensory neuron synapses with a motor neuron in the ventral horn of the spinal cord. 4. The motor neuron conducts an action potential to the extensor muscle, causing contraction 5. In the polysynaptic pathway, an action potential travels from the sensory neuron via a spinal interneuron that then inhibits the motor neuron of the antagonistic flexor muscle. 6. The leg extends F. Glialells “support” neurons 1. Glial cells outnumber neurons 10:1 in the mammalian brain G. Centraland Peripheralervous System (CNS, PNS) 1. CNS a) Afferent and Efferent b) Brain and spinal cord 2. PNS a) Somatic sensory neurons and receptors b) Autonomic sensory neurons and receptors c) Autonomic motor neurons (1) Sympathetic and parasympathetic (a) Autonomic effectors d) Somatic Motor neurons e) Striated muscle 3. Efferent Nervous System a) Somatic/oluntary 4. Autonomic a) Smooth muscle b) Cardiac muscle c) Glands d) “Housekeeping (1) Sympathetic= Fight or flight (2) Parasympathetic rest and digest e) Antagonistic Pair Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. An example of an antagonistic pair is the biceps and and triceps; to contract the triceps relaxes while the biceps contracts to lift the arm. H. Nervous system began more simply 1. Sea anemone anerve neserves simple behaviors such as contraction and relaxation 2. In theearthworm,ganglia in each segment coordinate movement and an anterior “brain” controls more complex behavior 3. Insquid, more complex behaviors are served by collections or neurons in specialized ganglia I. Cortical Maps(definition: collections (areas) of minicolumns in the brain cortex that have been identified as performing a specific information processing function; like texture maps, color maps, contour mamore neurons make more precise movements J. Application of cortical mapping: Cortical mapping in medicine is establishing the relationship between various structures of the brain and their functions. It is a technique used in neurosurgery to determine which parts of a diseased brain may be safely excised. Helps minimize damage done when removing tumors, etc. 1. Sensitivity varies 2. Sensory (afferent) 3. Motor (efferent) VI. Nervous System A. Comprises 1. Neurons/Nerve cells 2. Glial cells (support) B. Signaling via combination of Electrical and chemical C. Integrate information AFFERENT D. Coordinate response EFFERENT E. How does this signaling work? VII. Relative Ion Concentrations A. ATP used to generate these ion gradients 1. Potassium 2. Sodium 3. Calcium 4. Chloride B. Neuron Function 1 Electrical 1. Electricity Drives Function 2. Ions re the electricity 3. How increase conduction velocity in axon? a) Diameter b) Insulation 4. Long axons require insulationsupport cells) 5. Glial cells fyelination fatty tissue)aka: a) Schwann cells in peripheral nerves b) Oligodendrocytes in CNS 6. Multiple sclerosis caused by demyelination C. Neuron Function 2 Chemical 1. Axon Terminal a) Vesicles b) Neurotransmitter c) Synapse 2. Chemical Synapses 2+ a) Exocytosis = role of Ca b) Ionotropic FASTER (1) Ionotropic receptors transmembrane molecules that can “open” or “close” a channel that would allow different kinds of ions to travel in and out of the cell. Receptors are not opened until a ligand (the neurotransmitter) binds to the receptor c) Metabotropic SLOWER (1) Metabotropic recepto do not have a channel that opens or closes. Instead, they are linked to another small chemical called a Gprotein. As soon as the ligand binds to the metabotropic receptor, the receptor activates the Gprotein (meaning it changes it). Then the Gprotein activates a secondary messenger. d) Note: don’t need to have definitions of ionotropic and metabotropic because not included in lecture, but reading it and understanding it helps make sense of the fact that ionotropic is faster and metabotropic is slower. D. Action Potential 1. If an AP is initiated from the spikeinitiationravel to the axon terminals without degradation 2. Intensityof signal at the synapse can only be altered by changing the frequency f APs because they aralways the same siz . 3. More AP’s = more neurotransmitters released 4. Weak stimulus releases little neurotransmitter a graded potential that is barely above threshold causes a series of action potentials to pass down the axon and release neurotransmitter 5. Strong stimulus causes more action potentiaand releases more neurotransmitters a stronger graded potential increases the frequency of action potential firing in the axon 6. Vision Example a) Photoreceptors in the back of the eye b) Fovea where highest acuity and highest # of cones (1) Bats have sound fovea (2) Starnosed male has touch fovea c) TRANSDUCTION (1) Photoreceptorsrods and cones) contain stacks of membranes (a) Transduce photons (light) into electrical signal (2) Rhodopsins visual pigments) def. : transmembrane protein complex (a) Opsin (7transmembrane lipoprotein) plus (b) Retinal (absorbs photon (c) The retinal molecule inside rhodopsin changes shape when retinal absorbs light E. Vision Receptor Cells 1. Rods: dim light, low resolution 2. Cones: bright light, high resolution 3. Blind spot the optic disk; the region of the retina where the optic nerve and blood vessels leave the eye 4. Rhodopsins (visual pigments) located in stacked lamellae 5. Membranes hyperpolarize in response to light 6. Na+ ‘dark current’ + 7. When light hits, th current into the cell is stopped and membrane hyperpolarizes stopping release of NT F. Bleaching of retinal photoreceptors 1. Cones respond to particular wavelengths of light 2. Their response involves “bleaching” of their responsive pigment, so that for some seconds they are able to respond again G. Rod and Cone Details 1. Action spectrum (where absorb light) a) 3 (humans, fish) b) 5 (birds) 2. Different photopigments 3. Sensitivity vs. acuity H. Rhodopsin mechanism: 1. Cistranisomerizatiof retinal molecule 2. Changes conformation of opsin molecule and therefore initiates transduction 3. Activated retinal changes conformation of opsin molecule (opsin and retinal separate) and initiates transduction I. Bats are not blind 1. Many speciesmit highfrequency soun then listen for faint returning echoes 2. “See” a reflecound mage of surroundings 3. Increase frequencof calls when nearrey 4. Energeticalxpensive very brie“shut down”theiearing J. Type of sensation received depends on where in CNS (brain) Aabeled es (l lines) 1. rub eyes and see light 2. Synesthesia eg.smell colors K. Pit Viper Infrared Imagery 1. “See” infraredpectrum when heatsensing pits 2. Detect differences between sides of 0.003C 3. Heat imate in brain a) Similar to image from eyes
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