KIN 1223 Unit 4 Lecture 2 Types of smooth muscle 1 Single unit or Visceral smooth muscle more common In walls of hollow organs stomach intestines a b Organized into two layers of sheets of cells i Outer longitudinal layer running the length of the structure 1 Contraction dilates shortens organ ii Inner circular layer 1 Contraction constricts elongates organ c Displays Rhythmicity i Repeated rhythmic contractions without external stimulation ii Has gap junctions self exciting fibers pacemakers which depolarize spontaneously 1 Pacemakers are rhythmic responsible for Peristalsis wave like series of contractions that move materials through digestive track iii Gap junctions transmit stimulus to adjacent fibers iv Fibers contract as a single unit 2 Multiunit smooth muscle a Fibers not well organized occur as separate fibers not in sheets b Require stimulation by motor nerves not self exciting c Found in Irises of eyes i ii Arrector pili muscles iii Large airways of lungs Systems of Integration and Coordination Nervous System Master control communication center Integrates coordinates everything Very complex many structures functions Learn individual parts then conceptualize NS Important abbreviations CNS Central Nervous System PNS Peripheral Nervous System CN Cranial Nerves ANS Autonomic Nervous System Terms Afferent Toward a structure or Sensory information o Info being sent to brain or spinal cord o Structures carrying information to brain or spinal cord o Functions divided into Visceral afferents information from visceral organs Somatic afferents information from body muscles joints skin Efferent Away from a structure or Motor information o Info from brain or spinal cord to muscles or glands o Structures carrying information from brain or spinal cord o Functions divided into Somatic Nervous System SNS Conducts impulses to skeletal muscles Voluntary NS conscious control of muscles Autonomic Nervous System ANS Regulates smooth cardiac muscle and glands Divided into Involuntary system no conscious control o Sympathetic Nervous System o Parasympathetic Nervous System Functions 1 Collecting information a Receptors monitor changes inside outside body b Gathers sensory or afferent input 2 Evaluating decision making a Processes interprets sensory input b Decisions integration 3 Triggers responses a Activate muscles and glands b Motor or efferent output 2 Major divisions a Functions 1 Central Nervous System CNS Brain and spinal cord Integration command centers Interpret incoming sensory information i ii iii Dictate responses based on 1 Past experiences 2 Reflexes 3 Current conditions 2 Peripheral Nervous System PNS outside CNS mainly nerves a Carry sensory information to and motor information from brain and cord b Cranial Nerves CN peripheral nerves off brain c Spinal Nerves Peripheral nerves off cord i Innervate most skeletal muscles Cells of the Nervous System NS highly cellular 80 cells o Cells densely packed intertwined Functionally 2 types Supporting cells several kinds o Majority of cells 9X more numerous o Provide support for neurons Framework or scaffolding Assist segregate insulate neurons o Able to reproduce by undergoing mitosis o 3 general types 1 Schwann cells Can repair damaged tissue neurons cannot reproduce In Peripheral Nervous System PNS a b Form Myelin Sheaths wrap around nerves in c Serve as phagocytes to remove cell debris PNS injury 2 Satellite cells a Also in PNS b Arranged around cell bodies of neurons in peripheral ganglia c Closely associated with Schwann cells d Role in controlling chemical environment 3 Neuroglial or glial cells a Supporting cells of Central Nervous System CNS i Supportive framework for neurons ii Electrically insulate neurons iii Regulate fluid gas exchange with neurons environment b 4 distinctive kinds i Astrocytes star shaped 1 Largest most elaborate 2 Most numerous of neural tissue by volume 3 Have bulbous ends that cling to neurons capillaries 4 Function a Form a living barrier between capillaries neurons b Active role in neuron metabolism c Control chemical environment around neurons ii Microglia 1 Scavengers of CNS 2 3 Phagocytize microorganisms Increase numbers with injury dead tissue iii Ependymal cells 1 Squamous to columnar in shape and ciliated 2 Line central canal and ventricles 3 Form permeable barrier between cerebrospinal fluid CSF and tissue fluid 4 Cilia help circulate CSF iv Oligodendrocytes 1 Small cells 2 Wrap around nerve fibers in CNS 3 Produce myelin sheaths in the CNS Conducting cell neuron nerve cell o Basic functional unit of NS o Conducts impulses information throughout system o Special characteristics include Long lived High metabolic rate Requires lots of O2 and glucose Amitotic can t reproduce If injured or destroyed it can t be replaced o Cell body 2 types of processes Cell body or Perikaryon Usually located in CNS Protected by cranial bones or vertebrae Some cell bodies in PNS ganglia Plasma membrane o Regulates exchange of materials in out of cell o Participates in reception propagation and transmission of nerve impulse Nucleus o Contains DNA Nucleolus Cytoplasm o Large amounts of RNA o Large number of mitochondria o Golgi Complex o Lysosomes o No centrioles no mitosis o Rough ER or Nissl Bodies o Neurofibrils Bundles of microtubules and microfilaments Important in intracellular transport Extend from cell body into processes Processes Extend out from cell body may be long Myelin fibers segmented sheath covering some nerve o Whitish fatty protein phospholipid glycolipid cholesterol o Protects and electrically insulates fibers o Increases propagation speed o PNS Schwann cells o CNS Oligodendrocytes o Myelin sheath begins below axon hillock and extends to telodendria o Each Swann cell is an independent sheath o Creates spaces or nodes between cells Nodes of Ranvier o Process of myelination in PNS Schwann cell indents to receive axon Wraps around axon Cytoplasm and nucleus squeezed to outer part Plasma membrane cytoplasm form Neurilemma which surrounds myelin sheath Concentric coils of Schwann cell plasma membrane Thickness of spirals Unmyelinated fibers Schwann cell indents partly encloses several axons o Process of myelination in CNS Oligocencrocyte extensions coil One oligodendrocyte serves around axons several axons Myelinated white Unmyelinated gray matter matter Dendrites Axon o Short thick many branches o Afferent process carry info to cell body o Dendrite spines extensions like thorns Increase surface area to