Psychology Themes and Variations Chapter 3 The Biological Bases of Behaviour

(Processes info) Living tissue composed of cells.

Glia & Neurons are the 2 main categories of cells making up the nervous system.

GLIA: (Glue)

Cells in the nervous system that provide support for neurons. Nourish neurons. Myelin sheath is made of certain types of Glia cells.

NEURONS:

Cells in the nervous system that receive, integrate, & transmit info

Soma:

Cell body. Contains cell nucleus and chemical material.

Dendrites

RECEIVE info. Bring info to the soma.

Axon:

Takes info AWAY from cell body. Transmits signals away from soma to other neurons or to muscles or glands

Myelin Sheath:

Insulating material that encases some axons. Speeds up transmission of signals. (Note: Multiple Sclerosis (loss of muscle control) is due to the degeneration of myelin sheaths)

Terminal button:

Small knobs that secrete chemicals neurotransmitters.

Neurotransmitters:

Chemicals that may activate neighboring neurons.

Synapse:

Where info is chemically transmitted from 1 neuron to another.

Synaptic Cleft:

Area between 1 neuron's terminal button & the cell membrane of another neuron.

Neural Transmission

NEURAL TRANSMISSION involves electrical and chemical messages.

NEURAL TRANSMISSION

involves electrical and chemical messages.

NEURAL IMPULSE is the electrical message.

Each neuron has an electric charge created by ions in the neuron. Fluid inside and outside the neuron has positively and negatively charged ions.

A neuron's resting potential is a stable negative charge when the neuron is inactive

When the neuron is stimulated (message is coming in) its cell membrane chambers open briefly allowing in a rush of positive ions. The neurons charge becomes less negative to positive, creating an action potential (brief shift in electrical charge traveling along the axon).

Absolute Refractory Period

The neuron's cell membrane channels close up and cannot fire again for approx. 1 to 2 milliseconds. This "down" time is called the absolute refractory period.

Ions:

Electrically charged molecules and atoms.

All-or-None Law:

Neuron either fires or doesn't.

Afferent Nerves

Incoming nerves

Carries info TO the CNS from periphery of body (ex: hand to spine)

Efferent Nerves

Carries info FROM the CNS to periphery of body (ex: brain to hand)

Sympathetic

Get body ready for action/exertion (mobilizes resources). Activates fight-or-flight response.

How do they work together to keep info flowing effectively?

ORGANIZATION

PERIPHERAL Nervous System

(includes somatic and autonomic)

SOMATIC NS

Nerves that connect to voluntary skeletal muscles & sensory receptors. Carry info from skin, muscles, joints to CNS & vice versa.

AUTONOMIC NS

Nerves that connect to heart, blood vessels, glands, smooth muscles. Automatic, involuntary actions. Ex: Digestion, heart rate, emotional arousal.

Central NS (includes Spinal cord and brain)

Brain

Spinal cord

Connects the brain to the rest of the body.

Carries info from brain to peripheral nerves.

Plays a critical role in body movements. (ex: paralysis resulting from spinal injury)

Parasympathetic

Conserves bodily resources to save energy. (saves and stores resources)

NERVOUS SYSTEM

Nerves: Bundles of axons

Estimated 100 billion neurons in the human brain