Biology - Nervous System

→ HOMEOSTASIS & NERVOUS SYSTEM

Nervous System
Central Nervous System (CNS) : Brain & Spinal Cord
● Brain
Receives and processes sensory info; initiates responses, stores memories, generates
thoughts and emotions.
● Spinal Cord
Conducta signals to and from the brain, controls reflex activities
Peripheral Nervous System (PNS) : Nerves outside brain & spinal cord
● Motor Neurons
CNS to muscles and glands
→ Somatic Nervous System: controls voluntary mvmnts (skeletal muscles)
→ Autonomic Nervous System: controls involuntary mvmnts
(ANS) → Sympathetic Division: fight or flight
→ Parasympathetic Division: rest & digest
● Sensory Neurons
Sensory organs to CNS

⭐︎ CNS → PNS: Motor
PNS → CNS → Sensory

Cells of the Nervous System
● Glial
- Non conducting
- Used for support and metabolism
- Help hold neurons close together
- “Glial” = glue
● Neurons
- Conducting
- Carries the nerve (electrochemical impulse)

⭐︎ Nerves are bundles of neurons.

Parts of a Neuron
● Dendrite: Has receptors to receive stimulation into neurons.
● Cell Body: Contains nucleus
● Myelin Sheath: Fatty protein used for insulation; Speeds up transmission. (White matter)
● Node of Ranvier: Gap between the cells of the Myelin Sheath where saltatory occurs.
● Axon Endings: Contain synaptic vesicles filled with neurotransmitters.
● Schwann Cells: Glial cells that form the myelin sheath.
● Axon: Extensions of cell body; Carries the impulse.

→ SYNAPSE