by: allie dunn & sarah leitnaker. evolution of nervous system hydra (cndarian)- have one or...
TRANSCRIPT
Evolution of Nervous system
Hydra (Cndarian)- have one or more nerve net, made up of neurons.
Flatworm (planarians)- have ladder like nervous system with two nerve cords that run the length of
the body.Connected by transverse nerves Cephalization Ganglion- a cluster of neurons
Evolution of Nervous system
Earthworms (annelids) (Also molluscs and arthropods/insects)
True nervous systems A brain, well developed sense organs,
multiple ganglia, and increased number of neurons.
Evolution of Nervous system
Humans (vertebrates)-Central nervous system with
brain and spinal cord With ascending
and descending tracts. Peripheral nervous systems
Neurons
Cell body, dendrite, and axon Bundled axons form nerves and are
sometimes covered by myelin sheath Spiral neuroglia form myelin sheath
membrane.
Types of Neurons Motor (efferent):
Nerve impulses for CNS to musclesShape- have many dendrites and a single
axon (multipolar). Sensory (afferent):
Takes impulses from sensory receptors to CNSCell body divides into two directions, periphery CNS
(unipolar).
Interneurons: Only CNS Typical multipolar
Transmission of nerve impulses
At resting potential the axon has negative voltage
Action potential gated channels allow positive sodium ions to move freely into axon, voltage becomes positive.
Myelinated axons: action potential concentrated at the nodes.*refractory period
Synapse
Gap in between neurons (synaptic cleft) Neurotransmitter carry impulses across
synaptic cleft. They are released when calcium gates are open.
The neurotransmitters bind with the receptors.
Neuromodulators block the neurotransmitter or modifies its response.
Brain and Spinal Cord
Protected by bone i.e. skull and vertebrae
Wrapped in meninges, three protective membranes.
Spaces in between are filled cerebrospinal fluid
Spinal Cord
Bundle of nerve tissue from brain to below rib cage.
Reflex action center and communication.
Brain
Four chambers called ventricles Cerebrum is the largest portion in
humans. Communicates and coordinates activities in the brain.Divided into lobes.
DiencephalonHypothalamus regulates hunger sleep and
temperature. And controls the pituitary gland.Thalamus receives sensory input.
Brain
Limbic system: blends emotions and mental functions.
Two different parts: Hyppocampus: awareness of past
experiences Amygdala: emotional
overtones on these
experiences
Peripheral Nervous System
Outside central nervous systems with nerves.
Cranial nerves and spinal nerves and be sensory or motor.
Somatic system: serves the skin, joint, and skeletal muscles. Reflex arc: sensory receptors generate
nerve impulses. Info is integrated. Impulses travel along motor axons to an effector which brings about a response.
Autonomic System
Regulates cardiac and smooth muscles. Involuntary Use two neurons and one ganglion for
each impulse. Sympathetic division for emergency
situations.Parasympathetic division for relaxed state.
•Degenerative disease process that affects the basel ganglia of the brain •Caused by a deficiency of the neurotransmitter and aging
•Effects are a tremor, rigidity, and difficulty with spontaneous movements.
• Also expressionless face, monotone voice and a shuffling walk.
•A loss or deficiency of motor control
•Caused by injury to the brain before, during or after birth.
•Can also be caused by hypoxia, jaundice, and infection.
•Effects are involuntary spasms and lack of balance.
•Intelligence, posture and speech are frequently impaired.
•May also be associated with visual impairment, reduced hearing and behavioral problems
•May have fixed abnormalities