Chapter 35: Nervous System

(Neuron types) What do sensory neurons do?

• Detect & send information about external and internal environments (light, temp, touch, smell, taste)

(Neuron types) What do interneurons do?

• Process information from sensory neurons and relay it to motor neurons

(Neuron types) What do motor neurons do?

• Produce responses by sending signals to muscles or glands

(Neuron structure) What is the function of dendrites?

• Receive signals from other neurons or sensory receptors

(Neuron structure) What is the function of cell body (soma)

• Integrates signals and contains nucleus/organelles

(Neuron structure) What is the function of the axon?

• Transmits signals to other neurons

What is an action potential?

• A rapid, temporary electrical signal traveling along an axon

Are action potentials stronger or weaker depending on stimulus?

• No, all or none once threshold is reached

What is membrane potential?

• Difference in electrical charge inside vs outside the cell

What creates resting membrane potential?

• Ion gradients (high K+ in, high Na+ out) + selective permeability (leaky K+)

What do glial cells do?

• Support neurons, provide nutrients, insulation (myelin), and protection

Do glial cells conduct action potentials?

• No

(AP Steps) What happens during 1. depolarization to threshold?

• Na+ enters, membrane reaches threshold

(AP Steps) What happens during 2. rapid depolarization?

• Voltage-gated Na+ channels open, Na+ rushes in

(AP Steps) What happens during 3. repolarization?

• Na+ channels close, K+ channels open, K+ leaves

(AP Steps) What happens during 4. hyperpolarization?

• Too much K+ leaves, membrane becomes more negative than resting

(AP Steps) What restores resting potential (5.)

• Na+/K+ pump

What is action potential propagation?

• Rapid transmission of the signal along the axon

How does myelin affect propagation?

• Speeds it up by allowing signal to jump between Nodes of Ranvier

How do neurons encode information?

• By frequency of action potentials

What does a higher frequency in action potential mean?

• Stronger stimulus

What is temporal summation?

• One neuron fires repeatedly over time

What is spatial summation?

• Multiple neurons fire at the same time

What are EPSPs?

• Excitatory Post-Synaptic Potential → signals that increase likelihood of firing

What are IPSPs?

• Inhibitory Post-Synaptic Potential → Signals that decrease likelihood of firing

What makes up the central nervous system? (CNS)

• Brain and spinal cord

What makes up the peripheral nervous system (PNS)?

• Cranial and spinal nerves connecting body to CNS

What does the frontal lobe do?

• Decision-making & planning - the executive

What does the parietal lobe do?

• Processes touch, pain, temperature, body awareness

What does the temporal lobe do?

• For hearing and memory

What does the occipital lobe do?

• Processes vision

What is gray matter?

• Mostly neuron cell bodies, dendrites, and synapses

• Processing centers (thinking, decision-making)

• In outer layer of brain (cortex)

What is white matter?

• Myelinated axons for communication between gray matter/other brain regions

• Myelin (fatty covering) gives it a white color

What does the cerebral cortex do?

• In forebrain

• High-level thinking (memory, reasoning, language)

What does the thalamus do?

• In forebrain

• Relays info to cortex

What does the hypothalamus do?

• In forebrain

• Links nervous and endocrine system

What does the hindbrain control?

• Basic life functions

• ex. breathing and heart rate

What does the cerebellum do?

• Coordinates movement

What is the somatic nervous system?

• Voluntary movement

What is the autonomic nervous system?

• Involuntary control of organs

What are the two divisions of the autonomic system?

• Sympathetic (fight/flight) and parasympathetic (rest/digest)

What do chemoreceptors detect?

• Chemicals

• Taste & smell

What do mechanoreceptors detect?

• Physical pressure and movement

• Touch & hearing

What do photoreceptors detect?

• Light