Chapter 11

What are the two main divisions of the nervous system?

The central nervous system (CNS) and the peripheral nervous system (PNS).

What does the CNS consist of and do?

The brain and spinal cord; it acts as the coordinating center for incoming and outgoing information.

What does the PNS consist of and do?

Nerves that connect the CNS to the rest of the body; includes sensory and motor pathways.

What are the types of neurons and their roles?

Sensory (afferent) neurons bring information to the CNS, interneurons process information, and motor (efferent) neurons send signals to effectors.

What is the structure of a neuron?

Dendrite (receives signal), cell body, axon (transmits signal), myelin sheath (insulates), axon terminal (releases neurotransmitters).

How do neurons communicate with each other?

Through electrochemical signals, either via electrical synapses (direct contact) or chemical synapses (neurotransmitters across a synaptic cleft).

Which is faster, chemical diffusion or electrical signal transmission?

Electrical signal transmission is faster.

What is the "all-or-none" principle?

A neuron either fires a full action potential or not at all; there is no in-between.

Why do nerve impulses only travel in one direction?

After firing, ion channels reset during the refractory period, preventing backward transmission.

What are neurotransmitters?

Chemical messengers released from the presynaptic neuron that bind to receptors on the postsynaptic neuron to trigger a response.

What protects the brain and spinal cord?

three layers of meninges and cerebrospinal fluid.

What is the function of the spinal cord?

Carries messages between the brain and PNS; processes reflexes.

What direction do afferent and efferent neurons go?

Afferent neurons go into the CNS; efferent neurons exit the CNS.

What is the function of the hypothalamus?

Maintains homeostasis by regulating temperature, hormones, and other autonomic functions.

What are the two parts of the PNS?

Afferent system (sensory input to CNS) and efferent system (motor output from CNS).

What are the two subdivisions of the efferent system?

Somatic (voluntary movement) and autonomic (involuntary control of organs).

What are the two divisions of the autonomic nervous system?

Sympathetic (fight or flight) and parasympathetic (rest and digest).

What are the five types of sensory receptors?

Mechanoreceptors (touch/pressure/orientation)

chemoreceptors: (tase/smell)

thermoreceptors: (Temperature)

nociceptors: (pain)

photoreceptors: (light)

What is sensory adaptation?

When receptors become less sensitive after repeated stimulation.

How does vision work?

Light hits rods and cones in the retina → signal passes to bipolar cells → optic nerve → visual cortex.

How does hearing work?

Vibrations travel from eardrum→ auditory nerve → brain.

how does Touch work?

distorts proteins in receptors = nerves = brain

how does taste work?

tounge = different chemo receptors = brain

how does smell work?

nose = chemoreceptors = brain