Chapter 2 Lecture Notes
Module 4 – Neural and Hormonal Systems
Overview of Nervous System
•Nervous System- ______
______
•Neuroscience – deals with the structure and function of the brain and the neurons, nerves, and nervous tissue that form the nervous system.
•Relationship to behavior and learning.
Structure of the Neuron
•Neurons - ______
______
•Parts of a Neuron
•______- branch-like structures that receive messages from other neurons.
•______- the cell body of the neuron, responsible for maintaining the life of the cell.
•______- long tube-like structure that carries the neural message to other cells.
Other Types of Brain Cells
•Glial cells- grey fatty cells that:
•______
•______
•produce myelin to coat axons,
•Myelin Sheath - ______
______
______
•Generated by a Schwann Cell
•clean up waste products and dead neurons.
•Note: Neurons only makeup 10% of cells in the brain; the remaining 90% is glial
Neurons in the Body
•Nerves– ______
•Neurilemma – Schwann’s membrane.
•______
•Most axons of the neurons in the brain and spinal cord do not usually have this coating, thus, more likely to be permanently damaged.
•______– disease that damages the myelin sheath (i.e., demyelination), which leads to a loss of function in those damaged cells.
Neuron
Generating the Message: Neural Impulse
•Ions– charged particles.
•Inside neuron – ______
•Outside neuron – ______
•Resting potential– the state of the neuron when not firing a neural impulse.
•______– Each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential
•______- the release of the neural impulse consisting of a reversal of the electrical charge within the axon.
•Allows positive sodium ions to enter the cell.
•All-or-none–______
______
•Difference between strong stimulation and weak stimulation? – strong message results in the neuron firing more quickly, and it will also cause more neurons to fire.
•______– neuron is incapable of repeating (i.e., firing) until returns to resting potential (very brief – often milliseconds)
•Return to resting potential.
Action Potential
Sending the Message to Other Cells
•Axon terminals- branches at the end of the axon.
•Synaptic knob (or terminal button)– rounded areas on the end of axon terminals.
•Synaptic vesicles- ______
______
•______- chemical found in the synaptic vesicles which, when released, has an effect on the next cell.
•Synapse/synaptic gap- microscopic fluid-filled space between the rounded areas on the end of the axon terminals of one cell and the dendrites or surface of the next cell.
•______- holes in the surface of the dendrites or certain cells of the muscles and glands, which are shaped to fit only certain neurotransmitters.
Cleaning up the Synapse
•______- process by which neurotransmitters are taken back into the synaptic vesicles; applies the “breaks” on neurotransmitter action.
•Enzyme - a complex protein that is manufactured by cells.
•e.g., one type specifically breaks up acetylcholine because muscle activity needs to happen rapidly, so reuptake would be too slow.
How Neurotransmitters Influence Us
- Serotonin pathways are involved with ______
- ______pathways are involved with diseases such as schizophrenia and Parkinson’s disease.
- ______– produce good feelings (e.g., “runner’s high”)
- explains painkilling effects of acupuncture
- explains indifference to pain when severely injured
- opiates____________
- when flooded with opiate drugs, the brain stops producing own natural opiates
- when drug is withdrawn, deprivation of opiates causes great discomfort (i.e., withdrawal)
Neuron Communication
•Neurons must be turned ON and OFF.
•Excitatory neurotransmitter- neurotransmitter that causes the receiving cell ______
•Inhibitory neurotransmitter- neurotransmitter that causes the receiving cell ______
•Chemical substances can affect neuronal communication: Agonists & Antagonists
- Lock & Key Mechanism – neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.
- Agonist – ______
- Some opiate drugs amplify normal sensations of arousal and pleasure (i.e., “high”)
- Black widow spider venom – ______= violent muscle contractions, convulsions, possible death
- Antagonist – ______
- ______– causes paralysis by blocking ACh release; can come from improperly canned food
- ______– smoothes wrinkles by paralyzing the underlying facial muscles
- Some antagonists will occupy receptor sites and block its effect; similar to the natural neurotransmitter, but not similar enough to stimulate the receptor
- ______– a poison that can be applied to hunting-dart tips
- Occupies and blocks ACh receptor sites, which does not allow the neurotransmitter to affect the muscles = paralysis
The Nervous System
Central Nervous System
•Central nervous system (CNS)- ______
______
•Spinal cord- a long bundle of neurons that carries messages to and from the body to the brain that is responsible for very fast, lifesaving reflexes.
The Reflex Arc: Three Types of Neurons
•Sensory neuron- ______
______
•Also called ______
•Motor neuron- ______
______
• Also called ______
•______- a neuron found in the center of the spinal cord that receives information from the sensory neurons and sends commands to the muscles through the motor neurons.
•This ______skips going to the brain – like a shortcut
•Interneurons also make up the bulk of the neurons in the brain.
The Spinal Cord & Reflexes
Peripheral Nervous System
•Peripheral nervous system (PNS)- ______
______
______
•Somatic nervous system
•Autonomic nervous system
Somatic Nervous System
•Soma = body.
•Somatic nervous system- ______
______
______
•Sensory pathway- nerves coming from the sensory organs to the CNS consisting of sensory neurons.
•Motor pathway- nerves coming from the CNS to the voluntary muscles, consisting of motor neurons – i.e., skeletal muscles
Autonomic Nervous System
•Autonomic nervous system (ANS)- division of the PNS consisting of nerves that control all of the ______muscles, organs, and glands sensory pathway nerves coming from the sensory organs to the CNS consisting of sensory neurons.
•______- part of the ANS that is responsible for reacting to stressful events and bodily arousal.
•______- part of the ANS that restores the body to normal functioning after arousal and is responsible for the day-to-day functioning of the organs and glands.
The Endocrine Glands
•Endocrine glands- glands that secrete chemicals called hormones directly into the bloodstream.
•Hormones - chemicals released into the bloodstream by endocrine glands.
•______- gland located in the brain that secretes human growth hormone and influences all other hormone-secreting glands (also known as the ______).
•Remember: influenced by the hypothalamus
•Pineal gland- endocrine gland located near the base of the cerebrum that secretes melatonin, which regulates ______
•Thyroid gland- endocrine gland found in the neck that secretes thyroxin, which regulates ______
•______- endocrine gland that controls the levels of sugar in the blood by secreting insulin and glucagons.
•Too little insulin = ______
•Too much insulin = ______ (low blood sugar) – feel hungry all the time
•Gonads - the sex glands that secrete hormones that regulate sexual development and behavior as well as reproduction.
•Ovaries - the female gonads.
•Testes - the male gonads.
•______- endocrine glands located on top of each kidney that secrete over 30 different hormones to deal with stress, regulate salt intake, and provide a secondary source of sex hormones affecting the sexual changes that occur during adolescence.
•______– one of the most “important” adrenal hormones
•Released when the body experiences ______