A&P Lab Quiz #8 - The Brain

The Central Nervous System (CNS) contains:

The brain and spinal cord

Peripheral Nervous System (PNS)

• Sensory neurons

• Motor neurons → somatic nervous system (voluntary movement) and autonomic nervous system (involuntary responses)

**Autonomic nervous system has sympathetic division (“fight or flight”) and parasympathetic division (“rest and digest”)

Neurons

Special cells that transmit chemical and electrical signals throughout the body

Neuroglia

Cells that support the proper functioning and homeostasis of neurons

Oligodendrocyte (specialized type of neuroglia)

Found in the Central Nervous System (CNS) and wrap around neuronal axons to form a protective and insulating layer known as the myelin sheath (axon myelination).

Astrocyte (specialized type of neuroglia)

Most abundant cell in the nervous system forming the blood-brain barrier

Microglia (specialized type of neuroglia)

Cells that aid in keeping the nervous system clear of debris through phagocytosis

Ependymal Cells (specialized type of neuroglia)

Line inner cavities of the brain, and produce/circulate cerebrospinal fluid (CSF)

Neuron Structure - Axon

Carries the electrical impulses of the cell body to the dendrites of others

Neuron Structure - Dendrites

Carries electrical signals from the axons of other cells toward the cell body

Neuron Structure - Cell Body

Carries out metabolic functions of the cell, containing nucleus and organelles

Neuron Structure - Myelin

Lipid and fatty rich capsule surrounding the axon to allow for efficient impulse

Classifying Neuron by Structure

• Unipolar: A single process extending from the cell body (soma) that serves a combined or branching role in transmitting electrical signals

• Bipolar: Has two extensions emerging from opposite sides of the cell body (soma): one axon and one dendrite.

• Psuedounipolar: Has a single process extending from its cell body which then splits into two distinct branches: one that goes to the body (periphery) and one that goes to the spinal cord or brain (central nervous system)

• Multipolar: A type of nerve cell that has one axon and two or more dendrites extending from its cell body.

Classifying Neurons by Function

• Sensory neurons - Carry sensory information to CNS

• Motor Neurons - Transmit electrical and chemical signals from the central nervous system to muscles and glands to control voluntary and involuntary movements.

• Interneurons - Relay signals between sensory and motor neurons

Glycine (neuotransmitter)

Inhibitory neurotransmitter in the spinal cord

Glutamate (neuotransmitter)

Main excitatory transmitter in the CNS

GABA (neurotransmitter)

Main inhibitory transmitter in the CNS → slows down nerve signals to calm brain activity and prevent over excitability

Dopamine (neurotransmitter)

Modulates pleasure, motivation, and cognition

Norepinephrine (neurotransmitter)

Controls attention, alertness, and arousal in sympathetic nervous system

Serotonin (neurotransmitter)

Regulates mood, sleep and digestion functions

Histamine (neurotransmitter)

Aids in immune responses, digestion, neuroendocrine, body temp and brain function. Helps control sleep-wake cycles.

Label these layers

Meninges

Three protective layers of membrane that cover and protect the brain and spinal cord in the central nervous system

Three layers: Dura mater, arachnoid mater, pia mater

Dura Mater

The outermost (comes in contact with skull), thickest, and most durable of the three meninges

Arachnoid Mater

Middle of three layers of meninges, stringy and weblike fibers connecting the Dura and the Pia

Pia Mater

The delicate, innermost layer of the meninges, right against the brain tissues

Gray Matter

Contains neuron cell bodies, dendrites, and synapses. Responsible for processing and interpreting information.

White Matter

Contains mostly myelinated axons (nerve fibers covered in a fatty insulating layer). Carries signals between different areas of the brain and spinal cord.

Surface anatomy:

Define- Sulcus, Gyrus, Fissure

Sulcus: A shallow depression or furrow in the surface of the cerebral cortex between gyro

Gyrus: The raised ridges or bumps on the surface of the cerebral cortex.

Fissure: A deeper, larger groove in the cortex that often divides major regions or lobes

Cerebral Cortex

The outermost layer of grey matter in the brain

• Contains sulci and gyri

Important with: Memory, thinking, learning, reasoning, problem-solving, emotions, consciousness and functions related to your senses.

Frontal Cortex