ch 12 n 13

Study Guide for Chapter 12

1. Central Nervous System (CNS) and Peripheral Nervous System (PNS)

  • Difference between CNS and PNS:

    • CNS: Consists of the brain and spinal cord; responsible for processing and transmitting neural information.

    • PNS: Includes all neural pathways that lie outside the CNS; serves as a communication line between the CNS and the rest of the body.

a. Subdivisions of CNS and PNS:

  • CNS Subdivisions:

    • Sensory (Afferent): Carries signals from sensory receptors to the CNS.

    • Motor (Efferent): Carries signals from the CNS to effectors in muscles and glands.

  • PNS Subdivisions:

    • Visceral (Autonomic): Controls involuntary bodily functions, including sympathetic and parasympathetic responses.

    • Somatic: Controls voluntary movements and the relay of sensory information.

b. Difference between Sympathetic and Parasympathetic Systems:

  • Sympathetic System: Often referred to as the "fight or flight" system; prepares the body for stressful or emergency situations.

  • Parasympathetic System: Often termed the "rest and digest" system; conserves energy and is active during restful states.

2. Neurons vs. Glial Cells

  • Neuron: A nerve cell that transmits impulses via electrical signals; fundamental unit of the nervous system.

  • Glial Cells: Support cells that assist neurons in their functions; non-excitatory and include several types.

3. Blood-Brain Barrier

  • Definition: A selective permeability barrier that protects the brain from harmful substances in the bloodstream while allowing essential nutrients to pass through.

  • Cells Making Up the Blood-Brain Barrier: Comprised mainly of astrocytes and endothelial cells that line the capillaries in the brain.

4. List of Glial Cells

  • Astrocytes: Maintain the blood-brain barrier, provide nutrients to neurons, and repair the brain and spinal cord following injury.

  • Oligodendrocytes: Produce myelin in the CNS, insulating neuronal axons and enhancing signal transmission.

  • Ependymal Cells: Line the ventricles of the brain and the central canal of the spinal cord; involved in the production and circulation of cerebrospinal fluid (CSF).

  • Microglial Cells: Act as the immune defense in the CNS, cleaning up debris and dead cells from injuries.

5. Multiple Sclerosis (MS)

  • Definition: An autoimmune disease that affects the central nervous system, characterized by the degradation of myelin sheaths surrounding axons.

  • Symptoms: Include fatigue, vision disturbances, and motor control issues.

6. Layers of the Meninges

  • Dura Mater: The tough outer layer that surrounds the brain and spinal cord.

  • Arachnoid Mater: The middle layer, characterized by a web-like structure; contains CSF in the subarachnoid space.

  • Pia Mater: The innermost layer that closely adheres to the surface of the brain and spinal cord, providing a barrier and supplying blood.

7. Myelinated vs. Unmyelinated Nerves

  • Myelinated Nerves: Have myelin sheaths which increase the speed of nerve impulse transmission via saltatory conduction.

  • Unmyelinated Nerves: Lack myelin sheaths and transmit signals more slowly through continuous conduction.

8. Pain Impulse Transmission

  • Nerve Impulses Involving Pain Travel: Through specialized neurons known as nociceptors, which detect harmful stimuli and relay signals to the brain via afferent pathways.

9. Types of Neural Circuits

  • Diverging Circuit: A neural circuit where one neuron synapses with multiple neurons. This allows one signal to spread and affect many areas.

  • Converging Circuit: A neural circuit where multiple neurons synapse onto a single neuron, allowing for integration of multiple signals.

10. Brain Cancer

  • Why you can or cannot get Cancer of the Brain: Neuronal cells (neurons) typically do not divide after maturation; thus, they rarely develop tumors. However, glial cells can undergo mitosis and give rise to gliomas or other brain tumors.

Study Guide for Chapter 13

1. Lobes of the Brain and Their Functions

  • Frontal Lobe: Involved in reasoning, planning, problem-solving, emotions, judgment, and voluntary movement.

  • Parietal Lobe: Processes sensory information such as touch, temperature, taste, and pain; integrates sensory input.

  • Occipital Lobe: Responsible for visual processing; interprets signals from the eyes.

  • Temporal Lobe: Involved in processing auditory information and is crucial for memory and language.

2. Cranial Meninges

  • Dura Mater: The tough outer shell of the meninges, highly protective.

  • Arachnoid Mater: The middle layer with a mesh-like structure; contains blood vessels and CSF.

  • Pia Mater: The delicate innermost layer that encases the brain’s surface.

3. Structures and Their Functions

a. Thalamus

  • Location: Near the center of the brain.

  • Function: Acts as a relay station for sensory and motor signals to the cerebral cortex.

b. Hypothalamus

  • Location: Below the thalamus, part of the limbic system.

  • Function: Regulates body temperature, hunger, thirst, and circadian rhythms.

c. Pineal Gland

  • Location: In the epithalamus, near the center of the brain.

  • Function: Produces melatonin, regulates sleep-wake cycles.

d. Pituitary Gland

  • Location: At the base of the brain, below the hypothalamus.

  • Function: Often called the "master gland"; releases various hormones that control other endocrine glands.

e. Corpus Callosum

  • Location: Thick band of neural fibers connecting the left and right cerebral hemispheres.

  • Function: Facilitates communication between the two hemispheres.

f. Insula

  • Location: Deep within the lateral sulcus of the brain.

  • Function: Involved in consciousness, emotion regulation, and the perception of bodily sensations.

g. Hippocampus

  • Location: In the medial temporal lobe.

  • Function: Critical for memory formation and spatial navigation.

h. Amygdala

  • Location: Almond-shaped cluster of nuclei located deep in the temporal lobe.

  • Function: Involved in emotion regulation, particularly fear and pleasure.

i. Pons

  • Location: Above the medulla oblongata and below the midbrain.

  • Function: Connects upper and lower parts of the brain; involved in regulating sleep and arousal.

j. Medulla Oblongata

  • Location: Located just above the spinal cord.

  • Function: Controls vital autonomic functions such as breathing, heart rate, and blood pressure.

4. Cerebrospinal Fluid (CSF)

  • Definition and Function: A clear fluid produced in the brain that surrounds and cushions the brain and spinal cord; also serves to transport nutrients and remove waste products.

5. Blood-Brain Barrier (.bb)

  • Reiteration of its role in protecting the brain; formed by endothelial cells of capillaries and astrocytes.

6. Ventricles of the Brain

  • Definition: A series of interconnected cavities filled with cerebrospinal fluid (CSF).

  • Location:

    • Lateral Ventricles: Located in each hemisphere of the brain.

    • Third Ventricle: Located at the midline of the brain.

    • Fourth Ventricle: Located between the brainstem and cerebellum.

  • Function: Circulate CSF to maintain brain homeostasis and cushion brain tissue.

7. Embryonic Development of the Nervous System

  • Diencephalon: Develops into thalamus and hypothalamus.

  • Mesencephalon (Midbrain): Forms part of the brainstem and associated structures.

  • Other regions: Include forebrain, midbrain, hindbrain, and their roles in developing the adult nervous system.