review
name
1. know the definition for the word parts on page 206
do not need to write anything for this question
2. describe the general structure of a neuron and name its parts. p 311
3. understand the difference between the cns and the pns
4. what is the difference between white and gray matter? how does the
presence of myelin affect the neurons function?
5. name of the nervous system under your conscious control?
what part of your nervous system do you use to pick up a can of pepsi?
6. describe some functions of the autonomic nervous system?
7. how are the sympathetic and the parasympathetic nervous systems
different?
8. explain the function of neuroglia cells and neurons?

Question

Accepted Answer

### Question 2: Describe the general structure of a neuron and name its parts.
# Brief Explanations:
A neuron has a cell body (soma) containing the nucleus. Dendrites branch from the soma, receiving signals. The axon is a long projection that transmits signals, often myelinated. Axon terminals at the axon's end release neurotransmitters to communicate with other cells.
# Answer:
General structure of a neuron: It has a **cell body (soma)** (with nucleus/organelles), **dendrites** (branch - like, receive signals), an **axon** (long projection, transmits signals, may have myelin sheath), and **axon terminals** (release neurotransmitters to synapse with other cells). Parts: Cell body, dendrites, axon, axon terminals (also includes structures like myelin sheath, nodes of Ranvier in myelinated neurons).

### Question 3: Understand the difference between the CNS and the PNS
# Brief Explanations:
CNS (Central Nervous System) includes the brain and spinal cord, processing and integrating information. PNS (Peripheral Nervous System) consists of nerves outside CNS, connecting CNS to limbs/ organs, with sensory (afferent) and motor (efferent, including somatic and autonomic) divisions.
# Answer:
- **CNS (Central Nervous System)**: Comprises the brain and spinal cord. Functions: Processes, integrates, and coordinates neural information; is the “control center” for most bodily functions.
- **PNS (Peripheral Nervous System)**: Consists of nerves (cranial and spinal) outside the brain and spinal cord. Functions: Connects the CNS to the rest of the body (limbs, organs). Divided into:
    - Sensory (afferent): Carries sensory info to CNS.
    - Motor (efferent): Carries motor commands from CNS. Motor is split into somatic (voluntary, controls skeletal muscle) and autonomic (involuntary, controls smooth muscle, cardiac muscle, glands; further split into sympathetic and parasympathetic).

### Question 4: What is the difference between white and gray matter? How does the presence of myelin affect the neuron's function?
# Brief Explanations:
Gray matter has neuron cell bodies, dendrites, unmyelinated axons (in CNS: brain cortex, spinal cord gray matter; involved in processing). White matter has myelinated axons (in CNS: tracts; in PNS: nerves’ myelinated axons), for fast signal transmission. Myelin (insulating sheath, by oligodendrocytes in CNS, Schwann cells in PNS) increases signal speed (saltatory conduction at nodes of Ranvier), protects axons, and maintains signal integrity.
# Answer:
#### Difference between white and gray matter:
- **Gray matter**: Made of neuron cell bodies, dendrites, and unmyelinated axons. In CNS: Forms brain cortex, spinal cord gray matter (butterfly - shaped in spinal cord). Function: Involved in information processing/ integration.
- **White matter**: Composed of myelinated axons (and some glial cells). In CNS: Forms tracts (bundles of axons); in PNS: Myelinated axons in nerves. Function: Transmits neural signals rapidly between brain regions, between CNS and PNS.

#### Effect of myelin on neuron function:
Myelin (insulating layer around axon, from oligodendrocytes (CNS) or Schwann cells (PNS)) enables **saltatory conduction**: Action potentials “jump” between nodes of Ranvier (gaps in myelin), greatly increasing signal transmission speed (vs. continuous conduction in unmyelinated axons). It also protects axons and helps maintain signal integrity (reduces electrical interference).

### Question 5: Name of the nervous system under your conscious control? What part of your nervous system do you use to pick up a can of pepsi?
# Brief Explanations:
The somatic nervous system (part of PNS) is under conscious control, controlling skeletal muscle. To pick up a can, the somatic nervous system sends motor commands from CNS (brain) via PNS motor neurons to skeletal muscles of the hand/arm, with sensory input (from PNS sensory neurons) about the can’s position/shape.
# Answer:
- Nervous system under conscious control: **Somatic Nervous System** (part of PNS, controls voluntary skeletal muscle movements).
- Part for picking up a can: The **somatic nervous system** (sensory neurons detect the can, motor neurons from CNS (brain) via PNS send signals to skeletal muscles of the hand/arm to contract and grasp the can; also involves CNS (brain) for planning/coordinating the movement).

### Question 6: Describe some functions of the autonomic nervous system?
# Brief Explanations:
Autonomic Nervous System (ANS, part of PNS) controls involuntary functions. Sympathetic: “Fight - or - flight” (increases heart rate, dilates pupils, redirects blood to muscles). Parasympathetic: “Rest - and - digest” (decreases heart rate, stimulates digestion, constricts pupils). Both regulate smooth muscle (e.g., gut, blood vessels), cardiac muscle, and glands (e.g., sweat, digestive glands).
# Answer:
The Autonomic Nervous System (ANS, involuntary, part of PNS) has two divisions:
- **Sympathetic**: Prepares body for “fight or flight” (e.g., increases heart rate, dilates bronchioles for more oxygen, diverts blood from digestion to muscles, dilates pupils).
- **Parasympathetic**: Promotes “rest and digest” (e.g., decreases heart rate, stimulates salivation/digestion, constricts pupils, relaxes bronchioles).
General functions: Regulates smooth muscle (e.g., in digestive tract, blood vessels), cardiac muscle (heart rate/contractility), and glandular activity (e.g., sweat glands, digestive glands).

### Question 7: How are the sympathetic and the parasympathetic nervous systems different?
# Brief Explanations:
Sympathetic (SNS) and Parasympathetic (PSNS) are divisions of ANS. SNS: “Fight - or - flight,” short preganglionic axons, long postganglionic, neurotransmitter norepinephrine at postganglionic synapses. PSNS: “Rest - and - digest,” long preganglionic, short postganglionic, neurotransmitter acetylcholine at postganglionic synapses. SNS activates during stress, PSNS during relaxation. Organs can have dual innervation (opposite effects, e.g., SNS increases heart rate, PSNS decreases it).
# Answer:
| Feature | Sympathetic Nervous System (SNS) | Parasympathetic Nervous System (PSNS) |
| --- | --- | --- |
| General Role | “Fight - or - flight” (prepares for stress/emergency) | “Rest - and - digest” (conserves energy, promotes relaxation) |
| Preganglionic Axon Length | Short | Long |
| Postganglionic Axon Length | Long | Short |
| Neurotransmitter at Postganglionic Synapse | Norepinephrine (adrenergic) | Acetylcholine (cholinergic) |
| Effect on Heart Rate | Increases | Decreases |
| Effect on Digestion | Inhibits (redirects blood from gut) | Stimulates (increases gut motility/secretions) |
| Effect on Pupils | Dilates | Constricts |
| Ganglia Location | Close to spinal cord (paravertebral ganglia) | Near or within target organs |

### Question 8: Explain the function of neuroglia cells and neurons?
# Brief Explanations:
Neurons: Transmit electrical/chemical signals (action potentials, neurotransmitters) for communication, information processing, and motor control. Neuroglia (glial cells): Support neurons. Types: Oligodendrocytes (CNS, myelinate axons), Schwann cells (PNS, myelinate axons), astrocytes (CNS, support/regulate nutrients, form blood - brain barrier), microglia (CNS, immune - like, remove debris), ependymal cells (CNS, line ventricles, produce cerebrospinal fluid).
# Answer:
- **Neurons**: Specialized cells for **neural communication**: Generate/transmit electrical signals (action potentials) and chemical signals (neurotransmitters) to process information, control movements, mediate sensory perception, and enable cognitive functions (learning, memory, thinking).
- **Neuroglia (Glial Cells)**: Support neurons:
    - **Oligodendrocytes (CNS) / Schwann Cells (PNS)**: Myelinate axons (increase signal speed).
    - **Astrocytes (CNS)**: Regulate nutrient supply, maintain chemical environment, form blood - brain barrier.
    - **Microglia (CNS)**: Immune - like function (remove debris, pathogens).
    - **Ependymal Cells (CNS)**: Line brain ventricles/spinal cord central canal, produce cerebrospinal fluid (CSF, cushions/ nourishes CNS).

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Question 2: Describe the general structure of a neuron and name its parts.

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Question 3: Understand the difference between the CNS and the PNS