1 / 73

The Nervous System AP Biology

The Nervous System AP Biology. The Nervous System. Function: environment is constantly changing – nervous system detects those changes and helps the organism respond/adapt Irritability: ability to respond to a stimulus. The Nervous System.

adsila
Download Presentation

The Nervous System AP Biology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Nervous System AP Biology

  2. The Nervous System • Function: environment is constantly changing – nervous system detects those changes and helps the organism respond/adapt • Irritability: ability to respond to a stimulus

  3. The Nervous System • Nervous System detects (sensory input), processes (integration), and responds (motor output) • Peripheral Nervous System detects and responds • Central Nervous System processes information

  4. The Neuron (Nerve Cell) • Three types of neurons: • Sensory – carry impulses from the sense organs (receptors) to the CNS • Motor – carry impulses from the CNS to the muscles or glands (effectors) • Interneurons – connect and carry impulses between sensory and motor neurons

  5. Three components of Neurons • Cell body – largest part; most metabolic activities take place here; contains nucleus • Dendrites – carry impulses from the environment or other neurons toward the cell body

  6. Three components of Neurons • Axon – long fiber that carries impulses away from the cell body • Terminal branches – branching of axon • Synaptic knobs – ends of axon; contain vesicles with neurotransmitters

  7. The Nerve Impulse • Resting potential – a nerve cell has an electric potential because OPPOSITELY charged ions are on each side of the membrane • Anions are mainly on the inside of the the cell; cations on the outside ++++++++++++++++++++++++ -----------------------------------------

  8. The Nerve Impulse • Ungated ion channels allow ions to diffuse across the plasma membrane • These channels are always open • This diffusion does not achieve an equilibrium since sodium-potassium pumps transport these ions against their gradients

  9. Hyperpolarization • Gated K+ channels open  K+ diffuses out of the cell  the membrane potential becomes more negative

  10. Depolarization • Gated Na+ channels open  Na+ diffuses into the cell  the membrane potential becomes less negative

  11. The Nerve Impulse • Action Potential – a rush of Na+ flow into the membrane causing an imbalance in the charge on each side of the membrane • This causes the POLARITY to shift and a wave (impulse) moves down the length of the neuron +++++++++++++++++----------- ----------------------------+++++++ +

  12. Step 1: Resting State

  13. Step 2: Threshold

  14. Step 3: Depolarization

  15. Step 4: Repolarizing

  16. Step 5: Undershoot

  17. Na+ gates close & K+ gates open K+ gates close Na+ gates open Stimulus

  18. During hyperpolarization or undershoot, Na+ channels are closed • Neuron cannot depolarize in response to another stimulus: refractory period • The refractory period assures impulse conduction is unidirectional

  19. Myelin • Is composed of 80% lipid and 20% protein • Used for insulation and to help speed up the nerve impulse • Wraps around the axon of some neurons

  20. Myelin • Gaps in myelin sheath cells called Nodes of Ranvier – allow impulses to move more quickly down neurons

  21. Myelin • In Saltatory Conduction, only the Nodes of Ranvier depolarize and therefore conduct an impulse faster

  22. The Synapse • SYNAPSE: the space between the axon of one neuron and the dendrite of another • Axon terminals have vesicles containing chemicals: NEUROTRANSMITTERS • These chemicals are secreted from the axon of one neuron  stimulates receptor sites on the effector or the dendrite of the next neuron

  23. Neurotransmitter Action at Synapse • Action potential arrives at axon terminal of presynaptic neuron • Synaptic vesicles rupture, releasing neurotransmitter into synapse • Neurotransmitter diffuses across synapse & binds to receptor protein on postsynaptic cell • Postsynaptic cell is excited or inhibited • Neurotransmitter in synapse is deactivated

  24. Nervous System Organization • Cnidaria - nerve net • loose organization of bi-directional neurons • no centralization • Flatworms - ladder • 2 anterior ganglia (rudimentary brain) with paired, longitudinal nerve cords • paired sensory organs (eyespots)

  25. Nervous System Organization • Segmented worms - advanced ladder • prominent brain • solid, fused, ventral nerve cord • segmentally arranged ganglia

  26. Nervous System Organization • Arthropods • prominent brain • solid, fused, ventral nerve cord • extensive fusion of ganglia • well-developed sensory organs • exhibit complex behaviors

  27. Organization of the NS • The human nervous system is divided into 2 major divisions: • Central Nervous System (CNS) • Control center of body, brain and spinal cord • Peripheral Nervous System (PNS) • Nerves (bundles of axons)

  28. CNS: Parts of the Brain • Forebrain • Midbrain • Hindbrain

  29. Hindbrain • Cerebellum • coordinates muscular movements • Medullaoblongata • regulates heart rate, blood pressure and breathing • contains reflex centers for vomiting, swallowing, sneezing, hiccupping, and coughing • Pons • helps regulate respiration

  30. Forebrain • Thalamus – switching station for sensory input for all senses but smell; relays sensory info to cerebrum and motor info from the cerebrum • Hypothalamus – control hunger, thirst, fatigue, anger, and body temp; regulates pituitary gland

  31. Forebrain • Cerebrum – divided into left and right hemispheres • Corpuscallosum – major connection between hemispheres • Left hemisphere primarily responsible for right side of body; right hemisphere primarily responsible for left side

  32. Forebrain • Cerebralcortex – outer covering of gray matter • The more convoluted the surface, the more surface area, the more neurons

  33. Forebrain • Cerebrum – divided into frontal, temporal, parietal, and occipital lobes • Frontal lobe • Contains the primary motor cortex (controls actions of skeletal muscles) and olfactory cortex (smell)

  34. Forebrain • Parietal lobe • Contains the primary somatosensory cortex and gustatory cortex (taste) • Temporal lobe • Contains auditory cortex (sound) • Occipital lobe • Contains visual cortex (sight)

  35. PNS • Sensory – transmits impulses from the sense organs (such as the ears and taste buds) to the CNS • Motor – transmits impulses from the CNS to the muscles or glands (somatic or autonomic)

  36. Somatic – conscious movement of the body • Autonomic – regulates activities that are automatic or involuntary • Sympathetic (stress, high energy) and Parasympathic (leisure, rest) are antagonistic systems that turn an autonomic response on or off

  37. Sympathetic effects: • dilates pupil • accelerates heartbeat & respiration • inhibits stomach & intestine activity • relaxes urinary bladder Parasympathetic effects: • constricts pupil • slows heartbeat & respiration • stimulates stomach & intestine activity • contracts urinary bladder

  38. Reflex Arc • Some actions don’t/can’t wait for your brain to interpret the signal • Reflexes are involuntary actions; they travel from ____ to ____: • Receptors (nerve “endings”) • Sensory neurons • Interneurons • Motor neurons • Effectors (muscles or glands)

More Related