Transcript Animal form & function nervous system

Animal form & function
nervous system
Primary cell
 Neuron:
 many dendrites
 1 axon
 Many axon terminals
 Myelin sheath: saltatory conduction
Synapse
 Pre-synaptic neuron; synaptic vesicles:
neurotransmitter: acetyl choline
 Post-synaptic neuron: receptors
 Synaptic space: neurotransmitter across then,
consumed: acetyl choline esterase
 neurotransmitter
Neurotransmitters
 Acetylcholine: stims skeletal muscle
 Norepinephrines (also hormone) stim or inhibit
 Dopamine: (pleasure pathway, drugs) excitatory
 Serotonin: relaxation. Inhibitory
Membrane potentials
 Resting potential:
 Ion pumps maintain gradient across plasma membrane
 Na and Cl outside
K inside
 Cell more negative inside
 Depolarization
 Open of gated ion channels: allow Na Cl to flow in
 Graded response
 ACTION POTENTIAL: when stim enough neuron will fire.

All or none
 Repolarization post stim: channels back in action
Taxonomy
 Cnidarians:
 Nerve net
 Sea star
 Nerves and nerve net
 More evolved
 nerves
 Flat worms: planaria
 Small brain and long nerve cords = simplest CNS
Evolved complexity
 cephalization: allowed for more complex system.
 Clustering of neurons in a brain (anteriorly)
CNS and PNS
 CNS: central nervous system
 Brain and spinal cord
 PNS: peripheral nervous system
 Peripheral nerves
 Cranial nerves


Somatic: conscious control
Autonomic: visceral, not conscious control
Parasympathetic: relax
 Sympathertic: excited: dilate pupils, increase heart rate, lung
funct.

Process information
 Simplest pathway: reflex arc
 Sensory input: specialized nerves receive stimuli.
 Carried in on afferent nerves
 Integration:
 Reflex: spinal cord.
 For conscious aware: brain
 Motor output:
 Response. Info carried on efferent nerve
Brain
 Brain stem:
 Medulla and pons: homeostatic control
 Cerebellum
 coordination
 Diencephalon
 Thalamus(sensory input). Hypothalamus(homeostatic)
 Circadian rhythms
 Cerebrum
 Higher thought and learning
 Voluntary control
Ear: hearing and balance
Sound
 Sounds waves
 Pinna: outer ear: directs sound waves into ear
 Tympanic membrane: eardrum vibrates
 3 bones: ossicles
 Oval window
 Cochlea: filled with fluid. Small hairs stimulated by
vibrations and movement of fluid. Cochlea nerve to
brain.
Equilibrium
 Inner ear
 Semicircular canals
 In 3 different planes
 Fluid filled, small hairs,
 Fluid moves with movement of the head.
Lateral line system
 fish
 Mechano receptors along sides.
 Detect low frequency waves like inner ear.
Vision
 Invertebrated have some kind of light – detecting
organs
 Vertebrate eye:
 Cornea, iris, pupil
 Lens (focus light), ciliary body(pull on lens)
 Retina: image formed (rods-black and whited and
cones-color
 Optic nerve
Animal skeleton
 Hydrostatic skeleton: fluid held under pressure in a
closed body compartment
 Animals control their form and movement by using
muscles to deform this compartment

Cnidarians, flatwarms, nematodes, annelids
 Exoskeleton:
 Shell, mollusks: calcium carbonate
 Arthropods: cuticle, chitin
 Endoskeleton
 bones
Muscles
 Skeletal: conscious control. Brain to mm contraction
 Smooth: peristalsis
 Cardiac: desmosomes
 Thin filament: actin
 Thick filament: myosin
 Sacromere
 Sliding filament model
 Sarcoplasmic reticulum, Ca++
Muscle
 Hormone control of Calcium concentration in blood
 Why need Ca in blood:
 Blood clotting
 Muscle contraction
 Control Ca in and out of bones
 PTH: parathyroid hormone: stim osteoclasts get calcium from
bones
 Calcitonin: stim osteoblasts to build up bone