Biol 224 Final Exam Study Notes PDF

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Biology Final Study the Muscularskeleto Produce a response to sensory input processed Effectors may Glands and organs (e. fish electric organs and squid Organs that help the animal change Locomotory One of the most studied for Muscles and skeletal Types of Animal Skeleton: For Body Support, Locomoti...

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Biology Final Study Notes Signaling the Muscularskeleto system Effectors  Produce a response to sensory input processed by CNS.  Effectors may be: o Glands and organs (e.g. fish electric organs and squid chromatophores from Ca2+ -ATPase  Ca2+ flows out of SR.  Ca2+ binds to troponin (TN) on actin filament.  Induces conformational changes in TN and tropomyosin (T M).  Change in TN and TM expose myosin binding site.  Muscle contracts (sliding filament).  When MAP passes, Ca2+ channel closes.  Ca2+ -ATPase sequesters Ca2+ back in to SR, cytoplasmic [Ca2+] decreases.  Ca2+ dissociates from TN - myosin-binding site covered. Muscle relaxes. Neuromuscular Innervation  Muscle fiber innervated by axon of Motor Neuron (MN) - excitatory.  Vertebrate twitch muscle: o Each fiber innervated by only 1MN. o 1 MN can innervate many fibers.  MN + Fibers = Motor unit (one) --> one muscle has several muscle units.  Recruitment of motor units controls muscle tension.  Arthropods: o Each fiber innervated by many MNs. o Polynerutronal innervation.  MNs can be excitatory or inhibitory,  Tension controlled by sum of EPSPs and IPSPs.

How Does a Muscle Twitch?  Contraction converts electrical energy to mechanical energy.  Transient change in muscle tension - twitch.  1 action potential from the muscle tension = twitch. Additional Notes:  Muscle fibers can be classified according to the metabolic pathway used for ATP synthesis: o Oxidative fibers: Do not fatigue easily, used for prolonged activity. o Glycolitic fibers: Fatigue rapidly, used for rapid intense actions. Oxidative Fibers  Contain large number of mitochondria: o High capacity for oxidative phosphorylation. o Surrounded by many small blood vessels. o ATP production depends on blood flow to deliver oxygen and nutrients. o Contain large amounts of the oxygen-binding protein myoglobin, as an intracellular reservoir of oxygen. o Myoglobin is like hemoglobin, they can bind oxygen. Myoglobin binds to 1 oxygen molecule, hemoglobin can bind to 4 oxygen molecules. Glycolytic Fibers  Few mitochondria but high concentration of glycolytic enzymes and large stores of glycogen. o Limited use of oxygen. o Few blood vessels. o Little myoglobin, responsible for pale colour. Exercise:  Can produce: o An increase in the size of muscle fibers. o Their capacity for ATP production. o The number of cells remains the same. o Increase in muscle size due to the increase in size of individual fibers. o Number of muscle fibers stays the same; the diameter of the fibers is what changes.

Homeostasis and Environmental Adaptation Animal body fluids: all multicellular organisms establish an internal environment in the form of extracellular fluid - Extracellular fluid is broken into two parts

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o Plasma: the fluid portion of the blood o Interstitial fluid: which surrounds the cells Hemolymph: fluid of the open circulatory system of arthropods (spiders, insects and crustaceans) o Analogous to the blood in vertebrates o Suspended cells called hemocytes o Direct contact eth the animals tissues

The Extracellular compartment - Interstitial, intravascular and transcellular compartments - The cell membrane are the outer barriers with an intracellular compartment The lymphatic system: is a network of vessels that carry a clear fluid called lymph - Part of the circulatory system and an accessory return route to the blood and a vital part of the immune system Homeostasis - The regulation of the body’s internal environment - Negative and positive feedback Mechanisms of intercellular signaling regulation - Modifies the output or activity of any organ or system to its normal range of functioning which is either negative or positive feedback

Negative feedback: stimulus resulting from a change in environment trigger compensatory responses - After getting the signal change occurs to correct deviation (depresses it) o Eg. Decrease in body temperature leads to response to increase body temperature

The hypothalamus - A small gland not larger than an almond in humans - Located below the hypothalamus and contains a number of small nuclei - Synthesizes and secrets neurohoromones o Hypothalamic neurohoromones secreted by the posterior pituitary gland o Hypothalamic releasing hormones stimulate or inhibit the secretion of hormones from the anterior pituitary gland Functions of the hypothalamus - Release of 8 major hormones by the pituitary gland - Control temperature, food/water intake, sexual behavior/reproduction, daily cycles in physiological states and behavior and emotional responses The hypothalamus is responsive to: - Light, day length and photoperiod for regulating circadian and seasonal rhythms - Olfactory stimuli including pheromones - Steroids including gonadal steroids and corticosteroids - Neurally transmitted information from the heart, stomach and reproductive tract - Autonomic inputs

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Blood Bourne stimuli including angiotensin, insulin, pituitary hormone, cytokines, plasma, osmolality

Three main regions of the hypothalamus - Large number of nuclei and fiber tracts have been described in three main regions o Supraoptic or anterior o Tuberal or middle o Mammillary or posterior Supraoptic Region: contains Supraoptic and paraventricular nuclei - Antidiuretic hormone (ADH): also called arginine vasopressin o Respond to thirst, water regulation, high body fluids osmolality release ADH, stimulates the kidneys to conserve water ad it also increases blood pressure - Oxytocin: responds to a suckling baby and it reaches the mammary glands, triggering milk secretion o During childbirth, trigger uterine contraction through positive feedback Positive feedback: accelerates or enhances the output created by a stimulus The Suprachiasmatic Nucleolus (SCN): A “ biological clock” that regulate body functions that vary at different times of the day - Body temp - Hormone secretion by pituitary gland - Hunger - Ovarian cycles Osmoregulation and Ion regulation Fundamental Problem  Intracellular aqueous environment affect organic molecule function.  All animals/cells face issues in their lives and how they live/adapt relates to what their environment is like.  Intracellular aqueous environment affect organic molecule function.  Protein function (e.g. enzymes) is affected by ion concentration.  Protein function is optimal within a narrow range of inorganic ion concentration. Intracellular Aqueous Environment Affect Protein Function  Their aqueous environment affects the function of macromolecules.  Affects the catalytic rate (Vmax) and affinity (Km, the apparent Michaelis constant) of enzymes.  Optimal function over a small range of inorganic electrolyte concentrations.  Vmax = how fast a enzyme can make a reaction occur.  Vmax changes due to the solute concentration.

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Solutes interact with proteins. Affect stability and function. In general, K+ is less inhibitory. Eukaryotic cells maintain [K+] = 100 to 150mM. K+ concentrations > 180mM inhibit protein synthesis. Organic molecules contribute to function and that depends on their environment. Inorganic molecules affect how organic molecules function. Animals must have some form of organic molecules to function.

Ion Composition of the Cell  Most cells use ATP to regulate intracellular ion composition.  Most cells in animals are water permeable.  Able to maintain ionic differe across the cell memnrane but not osmotic difference  Only some epithelial cells are capable of maintaining osmotic difference.  All cells use ATP to pump ions in/out.  Water cannot be pumped, this is a problem because water will always move to equal out concentrations. What About Water?  Water moves from low solute concentration (high water potential) to high solute concentration (low water potential) --> osmotic gradient.  Water can not be actively pumped.  Channal = aqua aporin. Osmolarity and Volume  Changes osmolarity cause a transmembrane osmotic gradient, and therefore water moves across the membrane affecting cell volume.  Osmolarity: Is the measure of solute concentration (number of osmoles per liter). o 1 mol of glucose = 1 osmol o 1 mol of NaCl = 2 osmol.  

Organic molecules live in environment with ions and other molecules. This is the same with cells in body. There is a competition for ions in the cell and in the environment.

Cell Volume Regulation  Cells respond to shrinking and swelling, they do this by controlling ion channels.  These ion regulators are very sensitive.  Cells want to be normal shape and volume. They activate either regulatory volume increase (RVI) or regulatory volume decrease (RVD) (done by active transport of ions).  Without proteins: the environment in the cell will need to change.

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Too many ions in the cell = proteins cannot function as well. Maintenance of a constant volume in the face of extracellular and intercellular osmotic perturbations is a critical problem faced by all cells. Most cells respond to swelling or shrinkage by activating specific membrane transport and/ or metabolic processes that serve to return cell volume to its normal resting state. Volume sensing mechanism are extremely sensitive, cells can sense and respond to volume changes of >3%. Volume perturbations activate volume regulatory mechanisms.

Gain or Loss of Inorganic Ions Problem: Large changes in the levels of inorganic ions are incompatible with long-term normal protein function. Gain of Loss of Organic Osmolytes  They do not affect fats, proteins.  Anything can be an osmoltye; any molecule in a solution.  The compatible osmolytes are used in a widespread scale.  Produce osmolytes to gain volume.  Loss osmoltyes to lower volume.  Perturbing: Disrupt metabolism when they are in high concentration or when large shifts in their concentrations occur. o E.g. Glycine, proline, inositol and sorbitol.  Compatible (non-perturbing): Do not affect protein function. o E.g. Urea.  Compatible osmoltye use is widespread, from some archaea to mammalian tissues such as kidney and brain. Question: Some cells from the loop of Henle (human kidney) are exposed to environments with varying osmotic concentration over time that can range from 600 to 1200 mOsm. What physiological mechanism allows these to survive these changes in the osmotic environment?  Ion channels are controlled and compatible osmolytes are regulated. Osmoconformers:  Sharks.  Their body conforms to the environment.  No water gradient from external and internal environment.  "Cheap" --> doesn’t use a lot of energy.  No control systems.  Large changes outside = large changes inside.

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In perfect world would change perfectly/linearly with the environment. This is not true as they have some periods that do not conform with the environment and then some periods where they sync up with the environment.

Osmoregulators:  Spend a lot of energy to keep internal environment constant.  Cells experience very little changes.  There is a control system around intracellular system.  Cells inside cannot deal with large changes. Overview:  When ion is exposed to osmotic stress, then water may move in and out. This makes a cell regulate channels to control its contents and ensure it has what is needed to keep its shape and volume.  Intracellular aqueous environment affect protein function. o Cell regulates ion composition and pH.  Optimal cell function in a narrow range of ion and water conditions.  Osmotiv pressure difference affects cell volume.  The environment affects the water and ion content of animals.  Animals have evolved different strategies to maintain osmotic homeostasis. Osmoconformers:  Mainly used by animals in oceans.  Less energy used.  Well regulated mechanism.  Goal: maintain extracellular space similar to the outside.  Inside the of the cells have the same osmotic pressure and the external environment.  Animals must keep narrow range in osmotic stress.  Organic osmoltyes are used, and they do not disturb macromolecules.  They do not want water to be using energy as it moves across membranes with the environment.  They concentrate organic osmoltyes.  Two types of osmoconformers.  Stenohaline: Narrow range changes.  Eurhaline: Large range changes.  ECF and ICF have same osmotic pressure (1000 mOsm).  Common organic osmolytes: o Carbs. o Free animo acids. o Methylamines. o Urea. o Methylsulfonium solutes.  Types of osmoconformers: o Stenohaline: Resriticted to a narrow range of salinity.

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 Cannot regulate their osmolytes to compensate. Euryhaline: Tolerant of changes in salinity.  Successful in intertidal zones.  Regulate organic osmolytes in their cells.

Compatible Osmolytes:  Strong selective pressures: Convergent evolution.  All function to keep the animal alive.  Learn the evolution of these, the names. Read the paper on these.  Bacteria moved environments, many mutations took place until one was able to survive. This was easier for bacteria due to how fast it can reproduce.  Conserved in osmoconformers and in many groups: o Bacteria, unicellular algae, vascular plants, invertebrates and vertebrates.  Strong selective pressures: o Convergent evolution.  Alternative to compatible osmolyte: Halobacterium strategy. o Lives in high salinity. o Accumulate intracellular KCl. o Halobacterium strategy requires massive amino acid substitution in thousands of proteins. o Can only survive in that one environment --> Stenohaline.  Compatible osmolyte advantage: Dunaliella o Euryhaline (tolerate a wide range of salinities) micro-algae. o Grow in saturated brine or very dilute solutions by regulating the level of intracellular compatiable osmolytes. o Genetically more "simple"--> No protein maintains optimal functional abilities over a wide range of salt concentrations. o Temporal far more flexible adaptive mechanism in the face of cyclic water stress. Osmoconforming Mosquito:  Larva live in the water and are able to adapt to this environment until they mature, then they have to regulate their bodies to become accustomed to a new environment.  When put in different environments, the larva were exposed to different levels of water stress. (Slide 11)  The animals were exposed to sodium chloride.  Conclusion: osmosconforming also requires osmoregulation because the body needs to regulate somewhat to the environment it is in to survive.  Osmoconformation is a strategy that may be well regulated and use ATP. It's not a lack of regulation.  The mosquito does not sense osmotic pressure, but sensed NaCl content. Sharks are Different

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All vertebrate are osmoregulators, except sharks. They don't need to self gradulate. Osmoregulator = fresh water, Osmoconformer= salt water. Urea: destabilizes molecule. TMAO: does the opposite of urea; becomes too rigid.

Euryhaline Sharks:  Penetrate fresh waters.  No compatible osmolytes. o Sharks maintain high concentration a perturbing osmolyte: Urea. o The effect of urea is conteracted by trimethylamine-N-oxide (TMAO).  Once they leave the ocean they are no longer osmoconformers.  Some sharks have been able to adapt to be osmoreguators since they can survive.  Most sharks are not able to survive the difference in pressures. Sharks can Penetrate Fresh Water:  Must have osmoregulatory strategies.  They loose 20%NaCl  50% of urea reduced. Osmoregulatory Organs:  Epithelia is one of the oldest issues, very important for osmoregulation.  Gills are main pathway for retaining ions for fresh water fish and excreting ions for salt water fish.  Two types of osmoregulators in aquatic environment.  Marine= sea water. They're hyposmotic, they loose water to environment.  Freshwater regulators are hyperosmotic.  Gills are very import as they have their own chloride cells that help with regulation. Osmoregulation Depends on Transporting Epithelia  Active ion transport.  The fundamental mechanisms are the same in all animal groups.  External surfaces: o Gills. o Skin.  Salt glands.  Gut.  Specialized internal organs (Kidneys). o Protonephrones. o Metanephrones. o Malpighian tibules. Osmoregulatory Organs  Gills of vertebrate and invertebrate animals.

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Involved in ion transport and excretion of nitrogenous waste. In teleost fish play a major role in osmoregulation.  Marine fish have chloride cells.

Skin. Best studied in frogs. Osmoregulators maintain a steady ECF osmotic pressure regardless of osmotic changes in the external environment. Marine osmoregulators are usual hypo-osmotic. o Some crustaceans and mosquito larvae in salty habitats, and most marine vertebrates. Freshwater osmoregulators are hyper-osmotic. o All freshwater animals. o

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Osmoregulator Depends on Transporting Epithelia  Active ion transport.  The fundamental mechanisms are the same in all animal groups. Hypo-Osmotic Osmoregulators  Maintain ECF ad cellular osmotic concentrations of 250-400mOsm.  Have low concentrations of organic osmolytes.  Marine animals must drink seawater and must absorb NaCl in order to absorb water, creating an excess of salt in the blood.  Gills use epithelial chloride cells to actively transport Na+ and Cl- outward. Hyper-Osmotic Osmoregulators Cope with the Low Osmolarity of Fresh Water  Valuable solutes are lost through the gills.  Mechanisms for regulating ECF osmolarity: o Active uptake of ions across gills and skin. o Hypotonic fluid excretion by kidneys or other structures. o Lower internal osmolarities. o Low permeability of integument. Some Fish (Salmon) Alternate Between Modes of Osmotic Adaptation  Hypo-osmotic in the ocean, but hyperosmotic in rivers.  Acclimatization regulation coupled with an anticipation mechanism.  As salmon eneter the ocean, cortisol triggers growth of seawater-type chloride cells in gills, which reverses the direction of ion transport and increases Na+/K+ ATPase activity.

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When returning to freshwater to spawn, prolactin stimulates return to free water-type chloride cells, once again reversing the direction of ion transport.

Chloride Cell  Na and Cl out of cell so that fish can survive.  CFDR: cystic fibrosis.  Low Na concentration in cell.  Want chloride to go into cell to get it out of body.  Inside cell is has a lot of negative charges.  Cl is removed from blood, and then wants to leave the cell because inside is negatively charged and it wants to repel.  This process is very similar to that of the kidney  CFTR= channel.

Salt Glands  Marine birds and reptiles.  Some animals can only access salt water.  Nasal glands: Very concentrated NaCl is secreted from the duct to allow the animal to have the water and survive.  Nasal salt glands: o Active NaCl transport. o Secrete hyper osmotic NaCl solution.

Animal drinks water, concentration spike in blood, this spike is detected by sensors, the kidney is shut down and the salt/naval glands are activated, they are stimulated by a

hormone from the hypothalamus. For every liter drank, one liter will remain in the bird and the other half will be secreted by the nasal glands.  The kidney must be shut down because when there is a hike in concentration in the blood, the kidneys are activated and want to get rid of the ions, this makes the animal urinate resulting in a greater loss of water. Blood -> Collecting Area  Two different mechanisms lead to primary urine. 1. Ultrafiltration. 2. Active secretion.  Animals that don’t have blood vessel use active secretion. Very similar to salt glands as it uses energy to transport ions. The Mammalian Kidney Kidney: internal organ mostly concerned with osmoregulation - Common architectural and physiological principles Regions of the Kidneys - Renal Cortex = outer kidney - Renal Medulla- inner kidney o Medulla is divided into renal pyramids in larger mammals - Renal Pelvis= drainage area in the center of the kidney where nephrons are fused together Nephron: is the smallest functional unit o...