Midterm Study Guide Physio PDF

lOMoARcPSD|37398262 Midterm Study Guide Physio human physiology (West Coast University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Susanna Khachatryan ([email protected]) ...

lOMoARcPSD|37398262 Midterm Study Guide Physio human physiology (West Coast University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 Physiology MIDTERM STUDY GUIDE This midterm exam includes material covered in weeks 1 to 4 which includes chapters 1, 2, 4, 5, 7, 8, 9, 10, 22, and 23 of your textbook. Chapter 1 Outline ¥ Levels of organization - Physiology encompasses the broadest range- works as a whole- how it works at a molecular level- more complex - Cell: Smallest structure capable of carrying out all life processes - In order from smallest to largest: atoms > molecules > cells > tissues > organs > organ systems > organisms > populations of one species > ecosystem of diûerent species > biosphere ¥ Homeostasis, positive vs. negative feedback, placebo, dependent vs independent variable - Homeostasis: is the ability of the body to maintain a constant internal environment by returning changed conditions to normal - Placebo eûect: positive psychological aspect Expectations and thoughts can really impact our bodies physiology - Nocebo eûect: negative psychological aspect - Dependent: is what the researcher (you) measures - Independent: is what the researcher (you) changes from group to group - Control: is the group that you leave alone ¥ Experimental design (blind, double-blind, crossover, double-blind crossover) - Crossover: control group in the Þrst half of the experiment becomes the experimental group in the second half, and vice versa - Blind: subjects are blind- subjects has no idea of what theyÕre getting. Drug or placebo. - Double-blind: subjects and researchers are blind - Double-blind crossover: subjects and researchers are blind, control group in the Þrst half becomes the experimental group in the second half, and vice versa Chapter 2 Outline ¥ Atom, atomic number, atomic mass, protons, electrons, neutrons - Atom = Protons, Electrons, Neutrons - Protons: An atom that gains or loses protons becomes a diûerence element. - Electrons: An atom that gains or loses electrons becomes an Ion in the same element. - Neutrons: An atom that gains or loses neutrons becomes an isotope of the same element. 2 - Atomic number - Atomic Mass He 4.00 - Atomic Symbol ¥ Free radicals - a molecule or ion with unpaired electrons (normally there are pairs of electrons on the electron shells), which will try to ÒstealÓ an electron from another molecule ¥ Chemical bonds (covalent, ionic, hydrogen, van wer Waals) - Covalent bonds: strong bonds formed when adjacent atoms share one or more pairs of electronsÉto form molecules - Ionic bonds: strong bonds between cations and anions (opposite charges attract) Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Ions: an atom gaining or losing electrons. Ions are indicated by a superscript of the number of charges followed by the sign of the charge (i.e., Na+ = sodium that lost one electron) - Hydrogen bonds: An attractive force between a hydrogen atom and a nearby Fluorine, Oxygen, or Nitrogen. Water surface tension, boiling and freezing temperature - Van Wer Waals forces: Attraction between the nucleus of any atom and the electrons of nearby atoms ¥ Biomolecules (carbohydrates, proteins, lipids, nucleotides and nucleic acids) - Carbohydrates: Most abundant (carbon/hydrogen/oxygen), simple sugars (monosaccharides/disaccharides), complex polymers (polysaccharides) - Lipids: Made up of C and H (a little oxygen), non polar (therefore are NOT very water soluble), Are fats when solid and oils when liquids, Structurally diverse (Triglycerides(most important and abundant form in the body), phospholipids, eicosanoids, steroids). - Proteins: Are made up of amino acids (20 in total - must be obtained through diet), protein structure, most versatile biomolecule. - Nucleotides: are biomolecules that play an important role in energy and information transfer. Single nucleotides include the energy-transforming compounds ATP (adenosine triphosphate), and ADP (adenosine diphosphate), as well as cyclic AMP, a molecule important in the transfer of signals between cells. - Nucleic acids: such as RNA and DNA store and transmit genetic information. The function in information storage and transmission. The sugar of one nucleotide links to the phosphate of the next, creating a chain of alternating sugar-phosphate chains, or backbone, are the same for every nucleic acid molecule. Nucleotides chains form strands of DNA and RNA. ¥ Protein structure - Amino acids > essential & non-essential: can link together by peptide bonds to form >> Oligopeptides & polypeptides & proteins (what have >>)> Primary structure* Secondary structure* Tertiary structure* Quaternary structure* - Primary structure: The 20 protein-forming amino acids assemble into polymers called peptides. The sequence of amino acids in a peptide chain is called the primary structure. The 20 amino acids can create an almost inÞnite number of combinations. - Secondary structure: is created primarily by hydrogen bonds between adjacent chains or loops. - Tertiary structure: is the structures three-dimensional shape. Tertiary structures can be a mix of secondary structures. Beta-sheets are shown as ßat ribbon arrows and alpha helices are shown as ribbon coils. - Quaternary structure: Multiple subunits combine with non covalent bonds. Hemoglobin molecules are made from four globular protein subunits. ¥ DNA, RNA, nucleotide pairing - RNA: (ribonucleic acid) is a single-strand nucleic acid with ribose as the sugar in the backbone, and four bases Ñ adenine, guanine, cytosine, and uracil. - DNA: (deoxyribonucleic acid) is a double helix, a three-dimensional structure that forms when two DNA strands link through hydrogen bonds between complementary base pairs. Deoxyribose is the sugar in the backbone, and the four bases are adenine, guanine cytosine, and thymine. - Nucleotide pairing: ¥ Polar vs. non-polar molecules, hydrophilic vs. hydrophobic - Polar molecules: They can be said to have positive and negative ends, or poles. - Non-polar molecules: is one whose shared electrons are distributed so evenly that there are no regions of partial positive or negative charge. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Hydrophilic: dissolve readily, are polar or ionic molecules whose positive and negative regions readily interact with water molecules - Hydrophobic: do not dissolve readily, are nonpolar molecules (lipids, i.e., fats and oils) ¥ pH, buûer - pH: the concentration of free H+ in body ßuids, or acidity, is measured in terms of pH( - Buûer: is any substance that moderates changes in pH Chapter 4 Outline ¥ Energy and work, potential vs. kinetic energy - Energy: is the capacity to do work - Work: 3 types of work - Chemical work: Is the making and breaking of chemical bonds - Transport work: Is the movement of ions, molecules, and larger particles through cell membranes. Creates concentration gradients = A molecules concentration is higher on one side of the membrane than the other - Mechanical work: Is used for movement; moving organelles around in a cell, cilia and ßagella beating, and muscle contraction - Potential energy: is the stored energy. Potential energy is stored in concentration gradients and chemical bonds. The stored potential energy gets transformed into kinetic energy when needed to do chemical, transport, or mechanical work - Kinetic energy: is the energy in motion Work is used to push a ball up a The ball sitting at the Energy can be converted from one ramp. Kinetic energy of top of the ramp has form to another: The ball rolling movement up the ramp is being potential energy, the down the ramp is converting the stored in the potential energy of potential to do work. potential energy to kinetic the ballÕs position. energy. ¥ Enzymes, activation energy - Activation energy: = the energy that must be put into reactants before a reaction can proceed - Low activation energy = spontaneous reaction - High activation energy = slow or no reaction - Enzymes: Enzymes speed up the rate of reactions. They lowering the activation energy of reactions by binding to their substrates and bringing them into the best position for reacting with each other. Enzymes are not changed in any way, thus they are biological catalysts. Most are proteins. ¥ Metabolism - refers to all chemical reactions that take place in an organism - Anabolic reactions = utilize energy to synthesize large biomolecules - Catabolic reactions = produce energy through breakdown of biomolecules ¥ Endergonic vs. exergonic reactions - Exergonic reaction: reaction releases energy. Energy released by an exergonic, or energy-producing, reaction may be used by other molecules to do work or may be given oû as heat. Exergonic reactions release energy because the products have less energy than the reactants. - Endergonic reaction: reactions that require a net input of energy. Endergonic reactions trap some activation energy in the products, which then have more free energy than the reactants. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 ¥ Aerobic metabolism - If cells have suûcient oxygen, aerobic metabolism occurs. ¥ Anaerobic metabolism - If cells lack oxygen, anaerobic metabolism occurs ¥ Protein synthesis (transcription, translation, nucleotide base pairing) - The genetic code of DNA is converted into a functional protein - 4 nitrongenous bases code for 20 diûerent amino acids which synthesize all proteins in the body - Transcription factors bind and activate promoter region - RNA polymerase binds and ÒunwindsÓ DNA - mRNA is created from the sense strand - mRNA is processed by - RNA interference and alternative splicing Chapter 5 Outline ¥ Properties of diûusion 1. Passive process (no outside energy, ATP, required) 2. High concentration to low concentration - Down the concentration/chemical gradient 3. Net movement until concentration is equal 4. Rapid over short distances, slower over long distances 5. Directly related to temperature - At higher temperatures, rate of diûusion increases 6. Inversely related to molecular size 7. In open system or across a partition - Diûusion can occur with no barriers, or across a barrier ¥ FickÕs law of diûusion - FickÕs law says that the diûusion rate increases with an increase in surface area, the concentration gradient, or the membrane permeability. FickÕs law of diûusion describes how particles under random thermal motion tend to spread from a region of higher concentration to a region of lower concentration ¥ Simple diûusion - Diûusion directly across the phospholipid bilayer of a membrane is called simple diûusion. - The rate of diûusion depends on the ability of the diûusing molecule to dissolve in the lipid layer of the membrane. - The rate of diûusion across a membrane is directly proportional to the surface area of the membrane. ¥ Facilitated diûusion - If mediated transport is passive and move molecules down their concentration gradient, and if net transport stops when concentrations are equal on both sides of the membrane ¥ Osmosis, water moves from hyposmotic to hyperosmotic solutions ¥ Primary active transport, sodium potassium pump - Mechanism of the Na+-K+-ATPase ATP is used as an energy source ¥ Passive vs. active transport - Active transport: If protein-mediated transport requires energy from ATP or another outside source and moves a substance against its concentration gradient. Active transport requires the input of energy from some outside source, such as the high- energy phosphate bond of ATP. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Passive transport: Does not require the input of energy other than the potential energy stored in a concentration gradient. ¥ Secondary active transport, sodium glucose linked transporter - Uses the kinetic energy of a molecule moving down its concentration gradient to push other molecules against their concentration gradient (e.g., SGLT Transporter, Sodium Glucose Linked Transporter) ¥ Exocytosis, endocytosis, phagocytosis - Phagocytosis: Cells engulf a particle into phagosomes, large membrane bound vesicles, by pushing out around the bacterium - Endocytosis: Membrane surface indents and forms vesicles, which are smaller - Active process (requires ATP) - Can use caveolae (little caves) or receptor-mediated clathrin-coated pits - Exocytosis: is the opposite of endocytosis. In exocytosis, intracellular vesicles move to the cell membrane, fuse with it, and then release their contents to the extracellular ßuid. Cells use exocytosis to export large xipophobic molecules, such as proteins synthesized in the cell, and to get rid of wastes left in lysosomes from intracellular digestion. ¥ Gated channels - Gated channels spend most of their time in a closed state, which allows these channels to regulate the movement of ions through them. When a gated channel opens, ions move through the channel just as they move through open channels. When a gated channel is closed, which it may be much of the time, it allows no ion movement between the intracellular and extracellular ßuid. - Chemically gated channels: the gating is controlled by intracellular messenger molecules or extracellular ligands that bind to the channel protein. - Voltage-gated channels: open and close when the electrical state of the cell changes. - Mechanically gated channels: respond to physical forces, such as increased temperature or pressure that puts tension on the membrane and pops the channel gate open. ¥ Electricity review, cations vs. anions, conductors, insulators, resting membrane potential, depolarization, repolarization, hyperpolarization - Conductor: The material through which + and Ð charges move freely toward each other (i.e., water) - Insulator: Material in which opposite charges cannot move toward each other (i.e., phsopholipid bilayer) - Cations vs. anions: Those with a negative charge are called anions and those with a positive charge are called cations. - Anion: is an ion that carries a negative charge, causing it to migrate to the anode (positive electrode) in electrolysis. It has more electrons than protons, resulting in the negative charge. Anions are nonmetals. - Cation: is an ion that carries a positive charge, causing it to migrate to the cathode (negative electrode) in a electrolysis. It has more protons than electrons, resulting in the positive charge. Cations are metals. - Resting membrane potential: Resting membrane potential is due mostly to K+ - A cells resting membrane potential is ~ -70 mV - The Na+/K+ pump is important in determining the resting membrane potential Action potential is a brief reversal of membrane potential in which the membrane potential changes from -70mV to +30mV. The action potential has three main stages: depolarization, repolarization, and hyperpolarization. - Depolarization: is caused when positively charged sodium ions rush into a neuron with the opening of voltage-gated sodium channels. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Repolarization: is caused by the closing of sodium ion channels and the opening of potassium ion channels - Hyperpolarization: occurs due to an excess of open potassium channels and potassium eÿux from the cell Chapter 8 Outline ¥ Organization of the nervous system (aûerent vs. eûerent nerves, sensory vs. motor nerves, CNS vs. PNS, autonomic (sympathetic vs. parasympathetic) vs. voluntary somatic motor) - Aûerent vs. eûerent nerves: - Aûerent nerves: neurons that bring information about the body to the CNS - These bring in sensory information - Sensory neurons - Eûerent nerves: send information from the CNS out to our body. - Autonomic (sympathetic vs. Parasympathetic) vs. Voluntary somatic motor: - Automatic neurons are involuntary smooth muscle glands. - Sympathetic=ßight or Þght - Parasympathetic=rest and digest - sensory vs. motor nervers: - CNS vs. PNS: ¥ Parts of a neuron and function - Dendrites receive incoming signals; axons carry outgoing information - The primary function of the axon is to transmit outgoing electrical signals from the cell body to the axon terminal ¥ Glial cells - Glial cells. are the unsung heroes of the nervous system, outnumbering neurons by 10-50 to 1. Although, glial cells do not participate directly in the transmission of electrical signals over long distances, they do communicate with neurons and provide important biochemical and structural support. ¥ Graded vs. action potentials, changing AP frequency, events at the synapse, calcium and exocytosis - Graded potentials are variable-strength signals that travel over short distances and loses strength as they travel through the cell. If a depolarizing graded potential is strong enough when it reaches an integrating region within a neuron, the graded potential initiates an action potential. - Action potentials are very brief, large depolarizations that travel for long distances through a neuron without losing strength. Their function is rapid signaling over long distances, such as from your toe to your brain. - Changing AP frequency ¥ AP conduction speed (diameter, myelin) ¥ Convergence vs. divergence - Divergence: the axon of a presynaptic neuron branches, and its collaterals (branches) synapse on multiple target neurons. - Convergence: When a group of presynaptic neurons provide input to a smaller number of postsynaptic neurons. ¥ Eûect of potassium on membrane potential - ¥ EPSP vs. IPSP (excitatory vs. inhibitory post synaptic potentials) - EPSP (excitatory postsynaptic potential): If the synaptic potential is depolarizing, it is called EPSP, because it makes the cell more likely to Þre an action potential. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - IPSP (inhibitory postsynaptic potential): If the synaptic potential is hyper polarizing, it is called IPSP, because hyper polarization moves the membrane potential away from threshold and makes the cell less likely to Þre an action potential. ¥ Temporal vs. spatial summation - Spacial summation: The combination of several nearly simultaneous graded potentials. - Temporal summation: Summation that occurs from graded potentials overlapping in time. Chapter 9 Outline ¥ Blood brain barrier - Brain needs extra layer of protection which is what the blood brain barrier is. - Astrocyte foot processes: secrete paracrines that promote tight junction formation. - The tight junction prevents solute movement or free movement between endothelial cells. - If anything were to try and go through the CNS it would have to go through the cell rather than the cords. - Although, not a literal barrier, the highly selective permeability of brain capillaries shelters the brain from toxins and from ßuctuations in hormones, ions, and neuroactive substances such as neurotransmitters in the blood. ¥ Metabolic needs of the brain (oxygen and glucose) - Oxygen: Passes freely across blood-brain barrier - Brain receives 15% of blood pumped by heart - Glucose: Membrane transporters move glucose from plasma into the brain interstitial ßuid - Brain responsible for about half of bodyÕs glucose consumption - Low blood glucose can lead to Hypoglycemia, which leads to confusion, unconsciousness, and death ¥ Gray vs. white matter - Gray matter: consists of unmyelinated nerve cell bodies, dendrites, and axons. The cell bodies are assembled in an organized fashion in both the brain and the spinal cord. - White matter: is mostly myelinated axons and contains very few neuronal cell bodies. Its pale color comes from the myelin sheaths that surround the axons. ¥ Functions of the hypothalamus, hippocampus, limbic - Hypothalamus: Center for homeostasis. Controls many autonomic and endocrine functions - Functions: Activates sympathetic nervous system - Maintains body temperature - Controls body osmolarity - Controls reproductive functions - Controls food intake - Interacts with limbic system to inßuence behavior and emotions - Inßuences cardiovascular control center in medulla oblongata - Secretes trophic hormones that control release of hormones from anterior pituitary gland - Hippocampus: learning and memory - Limbic: Surrounds the brain stem. The limbic system represents probably the most primitive region of the cerebrum. ¥ Cerebral lateralization - Each lobe has special functions. - Left Brain=Language Verbal skills. - Right Brain=Spatial skills Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 ¥ REM vs. non-REM sleep - REM sleep - Brain activity inhibits motor neurons to skeletal muscle, paralyzing them - Dreaming takes place - Non-REM sleep - Adjust body without conscious commands ¥ Associative vs. non-associative learning - Associative learning: occurs when two stimuli are associated with each other, such as PavlovÕs classic experiment in which he simultaneously presented dogs with food and rang a bell. After time, the dogs associated the sound of the bell with the food. - Nonassociative learning: is a change in behavior that takes place after repeated exposure to a single stimulus. This type of learning includes habituation and sensitization, two adaptive behaviors that allow us to Þlter out and ignore background stimuli while responding more sensitively to potentially disruptive stimuli. ¥ Receptive vs. expressive aphasia - Receptive aphasia: If damage occurs to Wernicks area, a person may have diûculty understanding spoken or visual information. A personÕs own speech may be nonsense because the person is unable to retrieve words. The person is unable to understand sensory input. - Expressive aphasia: Damage to BrocaÕs area causes an expressive aphasia, or Broca Aphasia. People with Broca aphasia understand simple, unambiguous spoken and written language but have diûculty interpreting complicated sentences with several elements linked together. Chapter 10 Outline ¥ Thermoreceptors, chemoreceptors, osmoreceptors, mechanoreceptors - Thermoreceptors: Varying degrees of heat - Chemoreceptors: Oxygen, pH, various organic molecules such as glucose - Osmoreceptors: - Mechanoreceptors: Pressure (baroreceptors), cell stretch (osmoreceptors), vibration, acceleration, sound ¥ Sensory pathways to the brain, thalamus - ¥ Receptive Þelds and 2-point discrimination - Receptive Þelds: Somatic sensory and visual neurons are activated by stimuli that fall within a speciÞc physical area known as the neurons receptive Þeld. - Two-point discrimination test: The size of secondary receptive Þelds determines how sensitive a given area is to a stimulus. For example, sensitivity to touch is demonstrated by a 2-point discrimination test. ¥ Nociceptors, referred pain -Nociceptors: - Free nerve ending - Are pain receptors that respond to strong noxious stimulus (chemical, mechanical, or thermal) that may damage tissue - Nociceptors may activate 2 pathways: 1. Reßexive protective response. Integrated in spinal cord. Withdrawal reßex Ð rapid unconscious protective reßex (touching a hot stove) 2. Ascending pathway to cerebral cortex. Becomes conscious sensation (pain or itch) - Referred pain from internal organs occurs when multiple primary sensory neurons converge onto a single ascending tract Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 ¥ Olfaction - Allows us to discriminate odors - Link between smell, memory, and emotion - Olfactory cells Ð primary sensory neurons in human olfaction - Located in the olfactory epithelium in nasal cavity - Rapidly regenerate ¥ The ear, hair cells, frequency of sound - The ear is a sense organ that is specialized for two functions: hearing and equilibrium - Can be divided into 3 sections: External, middle, and inner ear ¥ The eye, pupil, lens, ciliary muscles, fovea, optic disk, retina, rods, cones, concave vs. convex lense - Eye: is a sensory organ that functions much like a camera. It focuses light on a light- sensitive surface (the retina) using a lens and an aperture or opening (the pupil) whose size can be adjusted to change the amount of entering light. - Pupil: is an opening through which light can pass into the interior of the eye. - Lens: suspended by ligaments called zones, is a transparent disk that focuses light. - Ciliary muscles: a ring of smooth muscle that surrounds the lens and is attached to it by the inelastic ligaments called zones. - Fovea: one exception to this organizational pattern occurs in a small region of the retina known as the fovea. This area is free of neurons and blood vessels that would block light reception, so photoreceptors receive light directly, with minimal scattering. - Optic disk: the retina is seen to be crisscrossed with small arteries and veins that radiate out from one spot. - Retina: The light-sensitive lining of the eye that contains the photoreceptors - Rods: Function well in low light and are used in night vision, when objects are seen in black and white rather than in color. Rods and cones are two main types of photoreceptors in the eye. - Cones: are responsible for high-acuity vision and color vision during the daytime, when light levels are higher. - Concave vs. Convex lense: Chapter 7 Outline ¥ Endocrine system and hormones (classiÞcations, synthesis, action = cell surface receptors vs. nuclear receptors) Hormones: cell-to-cell communication molecules - Made in glands (groups of epithelial cells designed for secretion) or cells - Secreted into the blood for transport - Exerts its effect on distant target tissue receptors - Exerts its effects at very low concentrations - Half-life indicates length of activity - Activates physiological response Controls: - Rates of enzymatic reactions - Transport of ions or molecules across cell membranes - Gene expression and protein synthesis CLASSIFICATIONS Peptide or protein hormones (most) - Range from small peptides of 3 amino acids to large proteins - Are water soluble, lipophobic Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Synthesized as inactive preprohormones, processed into prohormones as it moves through the rough ER and golgi, then activated into hormones Steroid hormones - Derived from cholesterol Amine hormones - Derivatives of amino acids tryptophan or tyrosine SYNTHESIS - Protein hormones (lipophobic, hydrophilic) bind to surface receptor - Second messenger systems - Cellular response is rapid ¥ Hypothalamus and posterior pituitary 1. Posterior pituitary releases: Vasopressin (ADH)- Regulates water balance Oxytocin- Milk release during breast-feeding, Òbonding hormoneÓ ¥ Hypothalamus and anterior pituitary (hypothalamic hypophyseal portal system) 1. The Hypothalamic Hypophyseal Portal System- directs trophic hormone delivery from the hypothalamus to the anterior pituitary through blood vessels 2. Portal system- allows small levels of hormones to elicit a response ¥ Hormone interaction (synergism, permissiveness, antagonism) Multiple hormones act on a single cell thus understanding hormone interactions is critical 1. Synergism: Multiple stimuliÑmore than additive 2. Permissiveness: Need 2nd hormone to get full expression, i.e., 2nd hormone creates permissive environment for 1st hormone to work 3. Antagonism: Glucagons opposes insulin ¥ Hormone pathologies (hypersecretion, hyposecretion, receptor abnormality) 1. Hypersecretion: excess hormone: Caused by tumors or cancer of endocrine glands, GraveÕs diseaseÑoverproduction of thyroid hormone 2. Hyposecretion: deÞcient hormone: GoiterÑunderproduction of thyroid hormone, DiabetesÑunderproduction of insulin 3. Receptor Abnormalities: Down regulation of receptors, Receptor and signal transduction abnormalities, Abnormalities of control mechanisms ¥ Primary vs. secondary hormone pathology and negative feedback 1. Primary Pathology: Pathology arises in the last endocrine gland in a reßex 2. Secondary Pathology: Pathology arises in tissues that produce trophic hormones ¥ Melatonin 1. Evolutionary conservation of hormone function: Nonhuman hormones work in humans 2. Example: Pineal gland which releases melatonin Chapter 22 Outline ¥ Metabolism, metabolic rate, food intake Metabolism Metabolism is the sum of all chemical reactions in the body Metabolic Pathways: Anabolic pathways Ð synthesize large molecules from smaller ones Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 Catabolic pathways Ð break down large molecules to smaller ones Metabolic Rate A persons lowest metabolic rate is the basal metabolic rate (BMR) Many factors aûect metabolic rate of humans including: - Age and gender Ð Men have higher BMR than women (more adipose tissue, less lean muscle); BMR decreases with age - Amount of lean muscle mass - Activity level - Diet Ð metabolic rate increases after a meal, and fats cause relatively little diet-induced thermogenesis compared to proteins - Hormones Ð BMR increased by thyroid hormones, catecholamines (E and NE) and peptides that regulate food intake - Genetics Only diet and level of physical activity can be voluntarily controlledÉ and lean body mass with strength training ¥ Fed and fasted state Metabolic states: Fed state Ð Time following a meal when products of digestion are being absorbed, used and stored (Anabolic) Fasted state Ð Body taps into stored energy reserves (Catabolic) The goal of fastedstate metabolism is to maintain plasma [glucose] within an acceptable range so the brain and neurons have adequate fuel In the fasted-state, the liver is the primary source of glucose ¥ Pancreatic alpha vs. beta cells, glucagon vs. insulin Glucagon is dominant in the Fasted State - In general, its metabolic activity is antagonistic to insulin - When plasma glucose levels decline, insulin secretion slows and the eûects of glucagon increase to stimulate glucose release VS Insulin is the dominant hormone of the Fed State, promotes anabolism Insulin secretion is inßuenced by: - ± glucose concentrations, ± amino acids concentrations - Feedforward eûects of GI hormones, parasympathetic activity - Inhibited by sympathetic activity ¥ Diabetes mellitus (types I and II) Diabetes is characterized by abnormally elevated plasma glucose (hyperglycemia) resulting from inadequate insulin secretion, abnormal target cell responsiveness, or both Type I Ð (insulin-deÞcient) insulin deÞciency resulting from beta cell destruction (autoimmune disease) Type II Ð (insulin-resistant diabetes) insulin levels are normal or elevated initially, but become insulin deÞcient ¥ Body temperature control Chapter 23 Outline ¥ Steroid hormones and cholesterol - The adrenal cortex secretes three major types of steroid hormones: aldosterone, glucocorticoids, and sex hormones. - All steroid hormones begin with cholesterol to become aldosterone, glucocorticoids, or sex steroids - Cortisol is the main glucocorticoid secreted by the adrenal cortex. Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 -The hypothalamic-pituitary-adrenal (HPA) pathway controls cortisol secretion (Òstress hormoneÓ) - CRH Ð corticotropin-releasing hormone - ACTH Ð adrenocorticotropic hormone - Circadian Rhythm of Cortisol Secretion Cortisol secretion peaks in the morning and reduces at night - Cortisol also increases with stress ¥ Hormone release pathway, function, pathologies related to: ¥ Cortisol - Suppresses the immune system - Prevents cytokine release and antibody production by white blood cells - Inhibits the inßammatory response - By decreasing leukocyte mobility and migration - Used to treat - Bee stings, poison ivy, and pollen allergies - Prevents rejection of transplanted organs ¥ Thyroid hormone - Thyroid hormone synthesis takes place in the colloid of the thyroid follicle - Thyroid hormones are made from iodine and tyrosine (a.a.) - Thyroid hormone aûects quality of life: - Aûects body temperature and mood - Main function is to provide substrates for oxidative metabolism - In children, it is necessary for normal growth and development - Myelin and synapse formation require T3/T4 - Hyperthyroidism Ð excess thyroid hormone - ± O2 consumption, heart rate (tachycardia), metabolic heat production, protein catabolism and may cause muscle weakness - Hyperexcitable reßexes, irritability, insomnia, and psychosis - Hypothyroidism Ð reduced thyroid hormone - Slows metabolic rate, O2 consumption, heart rate (bradycardia) - ³ protein synthesis: In adults = brittle nails, thinning hair, dry and thin skin; In children = slow bone and tissue growth - Slowed reßexes, speech, thought processes, and fatigue - In infants, leads to Cretinism, a condition marked by decreased mental capacity GravesÕ disease is often accompanied by exophthalamus, a bug-eyed appearance caused by immune-mediated enlargement of muscles and tissue in the eye socket ¥ Growth hormone - GH is secreted throughout life - Secretion is controlled by stress and cortisol, circulating nutrients, other hormones, and circadian rhythms - Hypothalamus secretes GHRH (+) and somatostatin (Ð) to control GH release from the anterior pituitary - GH stimulates release of IGF from the liver and other tissues - GH and IGFs are anabolic and promote protein synthesis - GH is essential for normal growth in childrenÉfor example: - Severe GH deÞciency in children Ð leads to dwarÞsm - Oversecretion of GH in children Ð leads to giantism/gigantism - Oversecretion of GH in adults Ð leads to acromegaly ¥ Parathyroid hormone - Parathyroid hormone (parathyroid glands are found on the thyroid gland) raises Ca2+ - Mobilizes Ca2+ from bone Downloaded by Susanna Khachatryan ([email protected])  lOMoARcPSD|37398262 - Enhances renal reabsorption of Ca2+ - Indirectly increases intestinal absorption of Ca2+ through its inßuence on vitamin D3 ¥ Calcium balance, PTH, calcitonin, calcitriol - Calcium balance: Osteoclasts are responsible for bone resorption The central region of the osteoclast secretes acid and protease enzymes The enzyme and acids dissolve the calciÞed matrix and its collagen support This frees Ca2+, which enters the blood - Calcitriol (made from vitamin D3) raises Ca2+ - Helps mobilize Ca2+ from bone - Enhances renal reabsorption of Ca2+ - Increases intestinal absorption - Calcitonin (produced by C cells of the thyroid gland) reduces Ca2+ - Decreases bone resorption and increases renal Ca2+ excretion ¥ Osteoporosis - Osteoporosis: Metabolic disorder where bone resorption exceeds deposition Results in fragile, weakened bones Downloaded by Susanna Khachatryan ([email protected])