Nervous system

Division by Location:

•Brain and spinal cord –central nervous system (CNS)

•Everything else – peripheral nervous system (PNS

Cells:

• Neurons - transmits messages; the functional cell

• Glial cells – provides framework and support for neurons

• Axon - extension of the neuron that carries an electrical signal (action

potential) away from the cell body toward a target cell

• Dendrite - one of many branchlike processes (extension) that extends

from the neuron cell body and functions as a contact for incoming

signals (synapses) from other neurons or sensory cells

• Soma - in neurons, that portion of the cell that contains the nucleus;

the cell body, as opposed to the cell processes (axons and dendrites

• gray matter -the regions with many cell bodies and dendrites

• white matter -the regions with many axons

Functions:

1. Receive information from the environment around us

2. Integration of current information with previous learning

3. Respond to the information

*sensory information may be changed through homeostasis

*Somatic nervous systems- responsible for conscious perception and voluntary motor responses

*Autonomic nervous system- responsible for involuntary control of the body, usually for the sake of homeostasis

*Enteric nervous system- is responsible for controlling the smooth muscle and glandular tissue in your digestive system

Types of sensory receptors:

• Thermoreceptors- sense temperature

• Photoreceptors- sense light (vision)

• Gustatory receptors- sense chemicals dissolved in saliva (taste)

• Olfactory receptors- sense chemicals in air (smell)

• Mechanoreceptors- sense movement (touch, hearing, and balance)

• Nociceptors- pain

How nerves work:

1. Concentration gradient setup for sodium and potassium with more sodium outside the cell and potassium inside the cell

2. More negativity charged cells inside cell means the resting potential is -70 millivolts of electricity

3. Sodium channels open and sodium flows into the cell (depolarization) and the inside becomes more positive up to +40 millivolts

4. Sodium channels close and potassium channels open which allows the potassium ions to leave the cell (repolarization). The difference in electricity goes lower than -70 MV

5. in the refractory period the sodium/potassium ions pump reestablishes the concentration gradient and the -70 MV resting potential

Brain lobes: know and be able to label the 4 lobes

Frontal

Parietal

Temporal

Occipital

Brain Vocabulary:

• Cerebellum - region of the adult brain connected primarily to the pons that developed from the metencephalon (along with the pons) and is largely responsible for comparing information from the cerebrum with sensory feedback from the periphery through the spinal cord

• Cerebrum - region of the adult brain that develops from the telencephalon and is responsible for higher neurological functions such as memory, emotion, and consciousness

• corpus collosum - large white matter structure that connects the right and left cerebral hemispheres

• enteric nervous system - peripheral structures, namely ganglia and nerves, that are incorporated into the digestive system organs

• Hippocampus - gray matter deep in the temporal lobe that is very important for long-term

memory formation

• Hypothalamus - major region of the diencephalon that is responsible for coordinating autonomic

and endocrine control of homeostasis

• • olfactory nerve - first cranial nerve; responsible for the sense of smell

  • optic nerve - second cranial nerve; responsible for visual sensation

  
  

Know these:

1. What are three ways that the anatomy (form) of a

neuron allows it to function?

• Dendrites: These are tree-like extensions that are designed to receive incoming signals from other neurons.

• Axon: This is a long, slender projection that carries electrical impulses away from the cell body toward other neurons, muscles, or glands.

• Axon Terminals (Synaptic Boutons): These are at the end of the axon and are where the neuron's message is passed on to the next cell using chemical signals across the synapse.

2. How is electricity involved in the work of neurons?

• Electricity is the initial step in communication, as neurons are excitable cells that generate and transmit electrical impulses called action potentials. When an action potential reaches the axon terminals, it triggers the release of neurotransmitters, which serve as chemical messengers to convey information between neurons.

3. How or why does myelin speed up signals?

• Myelin, a fatty insulating layer that wraps many axons, speeds up signal transmission because the action potential jumps from one node of Ranvier to the next in a process called saltatory conduction, which significantly boosts speed and efficiency.

4. Explain how the anatomy of the receptors impacts thepassing of the message along through the synapse.

• Receptors on the postsynaptic neuron's membrane are highly specific, acting like "locks accepting only certain keys" (the neurotransmitters).

• The binding of the neurotransmitter alters the shape of the receptor.

• This shape change opens ion channels which determines the message's effect:

5. List eight neurotransmitters and what each does.

6. Explain neural networks.

Neural networks are vast circuits in which individual neurons are connected to process specific types of information and generate coherent outputs. These networks can span multiple brain regions and are the basis for functions like the spinal reflex arc or complex abstract reasoning.

7. Explain neural plasticity.

Neural plasticity is the brain’s ability to rewire itself in response to experience, ensuring that neural circuits can adapt, learn, and recover from injury.

• It involves strengthening or weakening synapses in processes like:

• Long-term potentiation

• Long-term depression

8. What is the anatomical cause of Alzheimer's disease?

The anatomical cause of Alzheimer's disease is that neurons in memory-related regions degenerate, and the communication between them breaks down.