BIO 251 1st Edition Lecture 8 Outline of Last Lecture I. Introduction II. Perceiving reality III. Perception IV. Receptor physiology V. Responses of receptors structures VI. Adoption of receptors to stimulus VII. Taste and smellOutline of Current Lecture I. Autonomic nervous system a. Structure b. Neurotransmittersc. Response of effector organs to sympathetic and parasympathetic II. Fight or flightIII. Parasympathetic housekeepingIV. How does Viagra workV. ALSVI. Human male sex cycle VII. Human female sex cycleVIII. Somatic nervous system IX. Structure of motor neurons X. Control XI. Structure XII. functionCurrent Lecture-Introduction oEfferent is communication link by which CNS controls activities (effect organs-muscles, organs, glands ect.)oOrganization (7.1)-Autonomic-Involuntary branch-2 parts-Sympathetic (activity)-Parasympathetic (routine housekeeping)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Somatic -Voluntary branch, affects skeletal muscle -Autonomic nervous system oStructure common to both sympathetic & Parasympathetic (11.2)-Every pathway in each Autonomic pathway consists of 2 neuron chain-Cell body of 1st neuron in CNS-Axon synapses w/ cell body of 2nd neuron in chain in a ganglion -Axon of 2nd neuron innervates effect or organ oStructure sympathetic only (11.3)-Originate in thoracic and lumbar regions of spinal cord-Adrenal Medulla is modified sympathetic ganglion (11.5)-Secretes hormones into blood when stimulatedoStructure: Parasympathetic only (11.6)-Originate in cranial and sacral areas of CNSoNeurotransmitters (11.7)-Sympathetic -1st neuron in chain releases acetylcholine -2nd releases norepinephrine -Adrenal Medulla releases mostly epinephrine into blood-Parasympathetic -1st neuron in chain releases acetylcholine -2nd releases acetylcholine -SO: onto effect organs, sympathic releases NE and Epinephrine while parasymp releases acetylcholine oResponse of effector organs to sympathetic and Parasympathetic -Depends on effect or organ & its receptors as well as neurotransmitter!!!-Acetylcholine receptors called chollinergic -Located on 2nd neuron in all Autonomic neuron chains (nicotinic receptors)-On membrane of effect or organs (called muscarininc receptors)-NE & epi receptors distributed on effect or organs-Alpha-binds NE preferentially usually causes constriction/contraction -Fight or flight oBlood vessels to most organs constrict (alpha bind to NE)oBlood vessels to skeletal muscle dilate (beta-2 bind to Epic)oBlood vessels to heart dilate (beta-2 bind epic)oIncreased heart function (beta-1 bind epic & NE)oAirways in lung dilate (beta-2 bind epic)oLiver releases glucose (beta-2 bind epic)oPupils dilate (alpha bind NE-contracts radial muscle)-Parasympathetic housekeeping oDown regulates heart function oIncreases GI motility oStimulates GI secretions oRelaxes GI sphincter oContracts airways in lungs oPupils constrict oEye muscles contract for near visions-How does Viagra work?oCompound called cGMP facilitates blood flow in penisoEnzyme called PDE5 found mostly in penis which breaks down cGMPoViagra inhibits PDE5 so that more cGMP builds up=facilitates erection -Problem o50 yr old manoRecently started-Falling -Dropping things-Muscle twitches-^ALS (lou gehrigs disease)oProgressive neurodegenerative disease, attacks motor neurons in the brain and spinal cordoProgressive degeneration of motor neurons oMotor neurons die, ability of the brain to initiate and control muscle movement lose oAll voluntary msucel action affected oPatients in later stages of disease become totally paralyzedoUsually mind is unaffected -Human male sex cycleoErection -The penis contains spongy tissue derived from veins and capillaries; during sexual arousal fills with blood; increased pressure closes off veins that drain blood from penis = vasocongestion = erection-Erection controlled by spinal reflex between highly sensitive mechanoreceptors in the penis and the “erection generating center” in the spinal cord-Efferent response is parasympthathetic which leads to vasodilation of blood vessels which leads to vasocongestion = erection-In ways that are not well understood, various regions in brain can either enhance or retard erection reflexoEmission of sperm from testis -when stimulation becomes intense, the penis-spinal reflex described above switches to a sympathetic efferent response that causes muscle in penis and testes to contract to emit sperm & seminal fluids into urethra. oExpulsion of sperm from penis-Urethra filling with semen triggers sympathetic response that activates muscle at the base of the penis and muscle in the penis-rythmic contraction of these muscles at 0.8 second intervals increases pressue inside penis which then forcibly expels the semen = orgasm-refractory period follows male orgasm; no erection possible. Seems to be caused by release of hormone called prolactin from pituitary gland-Human female sexual cycleoSexual stimuli trigger spinal reflexes that cuase parasympathetically induced vasodilationof blood vessel in vagina and clitoris (very similar to malesoClitoris is composed of spongy vascular tissue like penis and becomes erect like penisoas in males, brain can enhance or retard sexual spinal reflexoVasocongestion of vagina causes release of lubricating secretions which allow smooth entry of penisoVasocongestion also occurs in breasts (enlarging them) and face become flushed from increased blood flow in skin oFurther vasocongestion of vagina reduces its inner circumfrenceoUteris raises upward lifting the cervix, creating a space for ejaculate depositionoIf stimulation continues, sympathetic induced rythmic contractions of pelvis muscles, especially in lower 1/3 of vaginal canal, at 0.8 second intervals = orgasmoNo refractory period = multiple orgasms possible Somatic Nervous system -Motor neurons innervates skeletal muscle, constitute somatic nervous system -Structure of motor neurons (11.13)oCell bodies are in ventral horn of the spinal cordoAxon of motor neuron is continuous from spinal cord to termination in skeletal muscleoAxon terminals release acetylcholine (Ach) -Control of motor neuron functionoAch release causes excitation and contraction of the muscleoCan only stimulate skeletal muscle oControl and level of activity