Lecture 2: Neurons & Glia

Bipolar, Unipolar, and Multipolar Neurons

• Bipolar: one axon, one dendrite

• Pseudounipolar Neurons: a single extension branches in two directions, forming an input and output zone (touch & pain senses)

• Multipolar Neurons: one axon, many branching dendrites, recieve and integrate large amounts of information.

Dendrites

receive incoming signals from other neurons and carry them toward the cell body

Axons

transmit outgoing electrical signals away from the cell body to other cells

Sensory Neurons

respond to stimuli such as light, odor, or touch)

Motor Neurons

contact muscles or glands

Interneurons

receive input from and sent input to other neurons

Myelin

is a layer of lipid which wraps around axons

Producers of Myeline

• Oligodendrocytes (located in CNS)

• Schwann cells (located in PNS)

Glial Cells located in CNS

• Astrocytes

• Oligodendrocytes

• Microglia

• Ependymal

Glial Cells located in PNS

• Schwann Cells

• Satellite Glial Cells

The human nervous system is made up of neurons…

… (86 billion in the brain) and glial cells.

Nodes of Ranvier

exposed part of the axon that is not covered my the myelin sheath

Brain Plane

• Coronal: separates front to back, butterfly shape

• Sagittal: separates down midline, half brain shape

• Horizontal: separates top to bottom, island shape

3 types of studies to test hypotheses for the biological bases of behavior

• Somatic Intervention: manipulating the body (IV) causes changes in behavior (DV)

• Behavioral Intervention: manipulating the behavior (IV) causes changes in the body and brain (DV)

• Correlation Study: measures how closely the body and behavior measures:

  • Negative Correlation (↑↓), Positive Correlation (↑↑ or ↓↓)

True or False: A Correlation Experiment shows causality between variables, but cannot prove association.

False - A Correlation Experiment shows association between two variables, but cannot prove causality (cause and effect).

The Cerebrum (3)

• largest part of brain

• left half and right half

• controls thinking, speech, and 5 senses

The Cerebellum (2)

• small part at back of head

• helps with balance, posture and body coordination

The Brainstem

• connects brain to spinal cord

• controls actions like breathing and heart rate

Central Nervous System (CNS)

• made up of the brain and spinal cord which work together to control the body

• brain: controls thinking, memory, feelings, and movement

• spinal cord: long bundle of nerve tissue inside the spine that sends messages between the brain and body

Input Zone

neurons collect and process information, either from the environment or from other cells

Integration Zone

where the decision to produce a neural signal is made

Conduction Zone

where information can be electrically transmitted over great distances

Output Zone

where the neuron transfers information to other cells

White matter

• composed of axon bundles

• white color comes from myelin sheath cover the axons

Gray matter

composed of clusters of cell bodies

Peripheral Nervous System (PNS)

made up of all the neural tissue located outside of the body structures of the brain and spinal cord

Cranial Nerves

• 12 pairs emerging from the brain

• Sensory Nerves (3 Pairs): Olfactory, Optic, Vestibulocochlear

• Motor Nerves (5 Pairs): Oculomotor, Trochlear, Abducens, Spinal accessory, Hypoglossal

• Sensory & Motor (4 Pairs): Trigeminal, Facial, Glossopharyngeal, Vagus

Spinal Nerves

• 31 pairs emerging from the spinal cord → mixed nerves carrying sensory (incoming) and motor (outgoing) messages

• Nerves: 8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal

• Each nerve consists of motor axons (project) and sensory axons (enter)

The Neuron Doctrine

• nervous system is made up of discrete, individual cells that communicate across tiny gaps called synapses via chemical or electrical signals

• proved by Santiago Ramon y Cajal by applying the Golgi Stain