Study Guide

Neurotransmitters and Hormones

  • Specific area of the brain where ACh is found: ACh is notably found in the basal forebrain and brainstem.

  • Location outside the brain: ACh is found at the neuromuscular junction.

  • Function of ACh outside the brain: ACh stimulates muscle contraction in skeletal muscles.


Difference between a neurotransmitter and a hormone: 

  •  Neurotransmitter: A chemical messenger that transmits signals across a synapse from one neuron to another.

  •  Hormone: A chemical messenger released into the bloodstream that affects distant target organs or tissues.


 Nervous System Terminology

  • Central Nervous System (CNS): Comprises the brain and spinal cord.

  •  Peripheral Nervous System (PNS): All the nerves outside the CNS that connect the CNS to limbs and organs.

  • Brain: The organ that coordinates sensory and motor functions, emotions, and cognition.

  • Spinal Cord: A cylindrical structure that connects the brain to the peripheral nervous system, facilitating communication.

  •  Forebrain: The anterior part of the brain, including the cerebral cortex, thalamus, and hypothalamus.

  •  Midbrain: A part of the brain that connects the forebrain to the hindbrain, involved in vision and hearing.

  •  Hindbrain: The posterior part of the brain, including the cerebellum, pons, and medulla oblongata.

  •  Somatic Nervous System: The part of the PNS that controls voluntary movements.

  •  Afferent Nervous System: Nerves that carry sensory information to the CNS.

  •  Efferent Nervous System: Nerves that carry motor commands from the CNS to muscles.

  •  Autonomic Nervous System: The part of the PNS that controls involuntary functions, such as heart rate and digestion.

  •  Sympathetic Nervous System: Part of the autonomic system that prepares the body for 'fight or flight' responses.

  • Parasympathetic Nervous System: Part of the autonomic system that conserves energy and maintains 'rest and digest' functions.


 Spinal Cord Information

  •  Where sensory neurons enter: Sensory neurons enter the spinal cord through the dorsal roots.

  •  Where motor neurons exit: Motor neurons exit the spinal cord through the ventral roots.

  •  Dorsal vs. Ventral: 

    •  Dorsal: Refers to the back side.

    •  Ventral: Refers to the front side.

 Brain Protection

  •  Three ways the brain is protected: 

  1.  Skull: The bony structure encasing the brain.

  2.  Meninges: Three protective membranes (dura mater, arachnoid mater, pia mater) surrounding the brain and spinal cord.

  3.  Cerebrospinal Fluid (CSF): A fluid that cushions the brain and spinal cord.



  •  How meninges protect the brain: They act as a barrier against physical impacts, infections, and help circulate CSF.

  • Functions of CSF: Provides cushioning, nutrient delivery, waste removal, and maintains intracranial pressure.

  •  Ventricles: Hollow cavities in the brain filled with CSF; they help circulate the fluid around the brain.

  •  Sign of brain disease in the ventricles: Enlargement of the ventricles may indicate conditions like hydrocephalus or brain atrophy.


 Brain Subdivisions and Functions

 Three subdivisions of the brain: 

  1. Hindbrain

  2. Midbrain

  3. Forebrain

  •  Oldest subdivision (evolutionarily): Hindbrain.

  • Subdivision most similar to other animals: Hindbrain.

  •  Subdivision least similar to other animals: Forebrain

  •  Definitions: 

    •  Lobe: A distinct region of the brain, each associated with different functions.

    •  Cortex: The outer layer of the brain involved in complex brain functions.

    •  Subcortex: The inner regions of the brain involved in basic survival functions.

  •  Hindbrain areas: Cerebellum, medulla, pons.

  •  Forebrain areas: Thalamus, hypothalamus, cerebral cortex, hippocampus, amygdala.


 Cerebellum Functions

  •  Functions of the cerebellum: Coordination of movement, balance, and motor learning.

  •  Demonstration of cerebellum function: Activities requiring fine motor control, such as balancing or precise hand movements.

  •  Identify cerebellum on a brain diagram: Look for the rounded, posterior part of the brain, under the occipital lobe.


 Brainstem and Midbrain Functions

  •  Functions of the reticular formation: Regulates arousal, sleep, and attention.

  •  Location of the reticular formation: Midbrain.

  •  Functions of the medulla: Controls autonomic functions like heart rate, breathing, and                                         blood pressure.

  •  Location of the medulla: Hindbrain.

  •  Functions of the midbrain: Involved in visual and auditory processing, motor control, and regulating sleep-wake cycles.

  •  Functions of superior and inferior colliculi: 

    •  Superior colliculi: Visual processing and eye movement.

  •   Inferior colliculi: Auditory processing.

  •  Substantia nigra function: Involved in movement and reward.

  •  Prevalent neurotransmitter in the midbrain: Dopamine.

  •  Low dopamine problem: Causes Parkinson's disease.

  •  High dopamine problem: Can cause schizophrenia.

 Limbic System Functions

  • Functions of thalamus: Relay sensory and motor signals to the cerebral cortex.

  •  Functions of hypothalamus: Regulates autonomic functions, temperature, hunger, thirst, and circadian rhythms.

  •  Functions of hippocampus: Involved in memory formation and spatial navigation.

  •  Functions of amygdala: Processes emotions, particularly fear and pleasure.

  •  Functions of corpus callosum: Connects the left and right cerebral hemispheres, facilitating communication between them.

 Lobes and Their Functions

  •  Difference between a lobe and its cortex: A lobe is a distinct region, while the cortex refers to the outer layer of that region involved in higher functions.

  • Functions of lobes:

    •  Frontal lobe: Involved in reasoning, planning, movement, and problem-solving.

    •  Parietal lobe: Processes sensory information, including touch, temperature, and pain.

    •  Temporal lobe: Involved in auditory perception, memory, and language.

    •  Occipital lobe: Responsible for visual processing.


Motor and Somatosensory Cortex

  •  Function of motor cortex: Controls voluntary movements of muscles.

  • Location: Found in the frontal lobe.

  •  Function of somatosensory cortex: Processes sensory input from the body, particularly touch.

  •  Location: Found in the parietal lobe.

  •  Label motor cortex and somatosensory cortex: They are adjacent areas in the frontal and parietal lobes, respectively

  •  Left hemisphere somatosensory cortex: Processes information from the right side of the body.

  •  Left hemisphere motor cortex: Controls the right side of the body.

Split-Brain Experiment

  •  When a person with an intact corpus callosum sees a figure: 

    •  The figures flashed to the left of the cross are processed in the right hemisphere.

    •  The figures flashed to the right of the cross are processed in the left hemisphere

  •  Responses: 

    •   Left side figure: The person cannot say what they saw but may draw it with their left hand.

    •  Right side figure: The person can say what they saw and draw it with their right hand.

  •  Intact corpus callosum function: Allows communication between hemispheres, enabling verbal response and drawing.

 Severed Corpus Callosum (Joe)

  •  If Joe sees the word SHIP to the right: He will be able to say it aloud since it is processed in the left hemisphere.

  •  If Joe sees the word PHONE to the left: He will not be able to say it aloud since it is processed in the right hemisphere, which does not have language ability.

  •  If Joe sees the word PHONE to the left: He can draw it with his left hand, as the right hemisphere controls the left hand.

  •  Importance of using the left hand: This demonstrates that non-verbal responses can occur through the right hemisphere, which handles visual and spatial tasks

  •  Language ability location: The experiment shows that language ability primarily resides in the left hemisphere.

 Hemispheric Functions

  •  Right hemisphere: Responsible for processing information about faces.

  •  Left hemisphere: Responsible for processing information regarding cause and effect.


 Broca's and Wernicke's Areas

  •  Function of Broca's area: Responsible for speech production and language processing.

  •  Location of Broca's area: Found in the left hemisphere, specifically in the frontal lobe.

  •  Identification on a brain diagram: Look for an area in the left frontal lobe, usually in the inferior frontal gyrus.

  •  Function of Wernicke's area: Responsible for language comprehension and understanding spoken and written language.

  •  Location of Wernicke's area: Primarily located in the left hemisphere, typically in the temporal lobe.

  •  Identification on a brain diagram: Found in the superior temporal gyrus of the left hemisphere.

 Auditory Cortex

  •  Function of the auditory cortex: Processes auditory information and is involved in the perception of sound.

  •  Identification on a brain diagram: Located in the temporal lobe, specifically the transverse temporal gyrus (Heschl's gyrus).

 Additional Terms

  •  Topographical: Refers to the representation of spatial relationships; in neuroscience, it describes how areas of the brain correspond to specific body parts or functions.

  •  Homunculus: A visual representation of the body within the brain, illustrating how different body parts are represented in the motor and somatosensory cortices.

 Cortical Representation

  •  Cortex sections arranged in a homunculus: The motor cortex and somatosensory cortex are organized in a homunculus.

  •  Proportionality of cortical representation: The size of cortical representation is not proportional to the size of the body part but is proportional to the precision of movement or acuity of sensation. This means areas that require more fine control or sensory feedback have a larger representation in the cortex.

 Areas of Acuity and Movement

  •  Parts of the body with most acuity in skin senses: Fingers, lips, and tongue have the highest sensory acuity.

  •  Parts of the body with most refined movements: Hands and facial muscles allow for the most precise movements.

  •  Observation in somatosensory and motor cortex: You can tell by the size of the areas dedicated to these body parts in the homunculus representation; larger areas indicate greater acuity or finer movement control.


 Electromagnetic Radiation Spectrum

  •  Definition: The electromagnetic radiation spectrum encompasses all types of electromagnetic radiation, including visible light, ultraviolet light, infrared light, radio waves, etc.

  •  Wavelength: The distance between consecutive peaks of a wave; in light energy, it determines the color perceived.

  •  Amplitude: The height of the wave, which relates to the brightness of light; higher amplitude means brighter light.

  •  Visible light: The portion of the electromagnetic spectrum that is detectable by the human eye.

  • Range of wavelengths visible to humans: Approximately 380 to 750 nanometers (nm).


 Sensation and Perception

  •  Sensation: The process of detecting physical energy from the environment through sensory receptors.

  • Perception: The interpretation and organization of sensory information to understand the environment.

Visual System and Light Perception

  •  Features of visible light sensed by specialized cells: Wavelength, amplitude, and purity (color and brightness).

  •  Wavelength perception: Different wavelengths are perceived as different colors by the human visual system.

  •  Amplitude perception: Higher amplitudes are perceived as brighter light, while lower amplitudes are perceived as dimmer.

  •  Purity perception: The number of wavelengths in light affects its saturation (color richness) perceived by the visual system.

 Specific Colors

  •  Color perceived at 470 nm: Blue.

  •  Color perceived at 700 nm: Red.

 Location of Specialized Cells

  •  Where specialized cells sensing light are found: Specialized cells called photoreceptors (rods and cones) are located in the retina of the human eye.



Key Neurotransmitters

  1. Acetylcholine:

    • Functions: Various, including muscle control.

    • Pathway: Basal forebrain pathways project to hippocampus and cortex (important for learning and memory).

    • Receptors:

      • Nicotinic: Fast-acting; responds to nicotine.

      • Muscarinic: Slow-acting, long-lasting; responds to muscarine.

  2. Glutamate:

    • Excitatory; most common in CNS.

  3. GABA:

    • Inhibitory; reduces brain activity.

  4. Dopamine:

    • Functions in pleasure, Parkinson's disease, schizophrenia, and addiction.

  5. Serotonin:

    • Functions include mood regulation, feeding, and sex drive.

  6. Norepinephrine:

    • Excitatory/inhibitory; involved in arousal and attention.

  7. Endorphins:

    • Function as painkillers; associated with pleasure and sleep.

TTX (Tetrodotoxin)

  • A poison that disrupts Na+ channels; present in many animals.

  • Use: Pain relief in neuropathic conditions and withdrawal symptoms.

Neurotransmitter Interaction with Receptors

  • Ionotropic Receptors: Fast-acting, temporary effects.

  • Metabotropic Receptors: Slow-acting, long-lasting effects related to genetic-level changes.

  • Agonists: Mimic neurotransmitter activity (e.g., nicotine for acetylcholine).

  • Antagonists: Block neurotransmitter activity.