BIO 115, chapter 13 lecture notes

Gray matter

Houses motor neuron and interneuron cell bodies, dendrites, and unmyelinated axons

Gray matter cortex or nucleus

Functionally related clusters of neuron cell bodies in the brain involved in processing information and controlling reflexes.

Gray matter horns

Regions of gray matter, or clusters of neuron cell bodies in the spinal cord that contain neuron cell bodies associated with sensory and motor functions.

White matter

made up of myelinated axons which give it it’s color

White matter tract

Bundles of myelinated axons in the central nervous system that connect different gray matter areas and facilitate communication between them.

White matter Funiculi

Regions of white matter in the spinal cord, consisting of ascending and descending tracts that connect different parts of the central nervous system.

Functions of Meninges

• Separate the soft tissue of the brain from the bones of the cranium

• Enclose and protects blood vessels that supply the brain

• Contains and circulates cerebrospinal fluid

Dura mater

The tough outermost membrane of the meninges that surrounds and protects the brain and spinal cord.

Arachnoid mater

The middle layer of the meninges, situated between the dura mater and pia mater, characterized by a web-like appearance and contains the cerebrospinal fluid.

Pia mater

The innermost layer of the meninges that closely adheres to the surface of the brain and spinal cord, providing a protective barrier and containing blood vessels.

Lateral ventricles

The two large cavities located within the cerebral hemispheres of the brain, filled with cerebrospinal fluid that helps cushion and nourish the brain.

Third ventricle

A narrow cavity located between the two halves of the thalamus, part of the ventricular system of the brain, that also contains cerebrospinal fluid.

Fourth ventricle

A chamber located between the brainstem and cerebellum that connects the third ventricle to the central canal of the spinal cord, filled with cerebrospinal fluid.

Cerebrospinal fluid

A clear fluid that surrounds and protects the brain and spinal cord, providing nourishment and removing waste.

Choroid plexus

A network of cells in the ventricles of the brain that produces cerebrospinal fluid.

Cerebrospinal fluid

• Protection

• Buoyancy

• Environmental stability

Blood brain barrier

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

Sensory nervous system

The part of the nervous system responsible for processing and transmitting sensory information FROM the body TO the brain for interpretation.

Motor nervous system

The part of the nervous system responsible for transmitting signals FROM the brain TO the muscles to enable movement and coordinate actions.

Neuron’s functions

Act to receive, transmit, and process nerve impulses

Glial cells

Located around neurons, are responsible for protection, nourishment, and support of the neurons.

Serves as connective tissue of the CNS

Astrocytes

A type of glial cell that provides structural support, regulates blood flow, and maintains the blood-brain barrier in the central nervous system.

Oligodendrocytes

A type of glial cell in the central nervous system responsible for creating and maintaining the myelin sheath that insulates neuronal axons, facilitating efficient transmission of nerve impulses.

Microglia

A type of glial cell in the central nervous system that acts as the primary immune defense, responding to injury and disease by removing debris and pathogens.

Ependymal cells

Specialized glial cells lining the ventricles of the brain and spinal cord, involved in producing and circulating cerebrospinal fluid.

Dendrites

short processes that branch from the cell body that receive incoming signals and transfer them to the cell body

Axon

a long, slender projection of a neuron that transmits electrical impulses away from the cell body to other neurons or muscles.

Axon hillock

The specialized area of an axon where action potentials are initiated, located at the junction between the axon and the cell body.

Telodendria

Fine terminal branches at the end of an axon

Synaptic knobs

structures at the end of telodendria that release neurotransmitters into the synaptic cleft.

Sensory neurons

AFFERENT neurons, transmit nerve impulses FROM sensory receptors TO CNS

Motor neurons

EFFERENT neurons, transmit nerve impulses FROM CNS TO effectors such as muscles and glands.

Interneurons

Association neurons, found entirely in the CNS and retrieve, process and store information

Perivascular feet

structures at the end of astocyte processes that encase blood vessels in the brain, aiding in nutrient transport and blood-brain barrier maintenance.

Cerebrum

Location of conscious thought and origin of intellectual functions

Corpus collosum

A thick band of neural fibers that connects the left and right cerebral hemispheres, facilitating communication between them.

Gyri

Folds of the brain tissue 

Sulci

shallow depressions or grooves between folds

Fissures

deep grooves that separate gyri in the brain

Cerebral cortex

The thin, outer shell of gray matter that covers each hemisphere

Frontal lobe

The largest of the four lobes of the cerebral cortex, responsible for higher cognitive functions, including reasoning, planning, movement, and problem-solving.

Parietal lobe

The area of the brain located behind the frontal lobe, responsible for processing sensory information regarding the location of parts of the body as well as interpreting visual information.

temporal lobe

The region of the cerebral cortex located beneath the lateral fissure, involved in processing auditory information, memory, and language.

Occipital lobe

The lobe situated at the back of the brain, primarily responsible for processing visual information and interpreting visual stimuli.

Insula

A deep structure in the brain located within the lateral sulcus, involved in various functions including emotion, perception, and self-awareness.

Diencephalon

The portion of the brain situated between the cerebral hemispheres and the brainstem, comprising structures such as the thalamus and hypothalamus, and involved in sensory and regulatory functions.

Functional brain divisions

• Motor areas

• Sensory areas

• functional brain regions

Primary motor cortex

Located in the frontal lobe, precentral gyrus, control of voluntary skeletal muscle movement

Motor homunculus

Depicts location and relative amount of motor cortex devoted to output to muscles of each body part 

Bronca’s area

Located in the frontal lobe, involved in speech production and language processing.

Frontal eye feild

Region in the frontal lobe responsible for controlling eye movements. It plays a key role in visual attention and eye coordination.

Premotor cortex

Area of the frontal cortex involved in planning and coordinating movement before execution.

Somatosensory cortex

Localizes sensation and provides a level of intensity

Visual cortex

Located in the occipital lobe that processes visual information from the eyes, enabling perception of colors, shapes, and motion.

Auditory cortex

Region of the temporal lobe that processes auditory information, playing a key role in the perception of sound, including volume, pitch, and rhythm.

Primary olfactory cortex

Brain region responsible for processing smell, enabling the perception of odors and natural scents.

Primary gustatory cortex

Region of the brain that processes taste sensations, allowing for the perception of flavors such as sweet, sour, salty, bitter, and umami.

Prefrontal cortex

Region of the frontal lobe involved in complex cognitive behavior, decision making, and moderating social behavior.

Wernicke’s area

A region in the cerebral cortex associated with language comprehension, responsible for understanding SPOKEN and WRITTEN language.

Axon tracts

Composed of primarily myelinated axons (white matter) bundled into tracts

Association tracts

Connects regions within the same hemisphere, made out of unmyelinated white matter

Commissure tracts

Connects the two hemispheres (think corpus callosum)

Projection tracts

Connect the cerebral cortex to inferior brain regions and the spinal cord

Cerebral nuclei

Consists of several masses of gray matter deep within white matter

Functions of cerebral nuclei

• inhibits unwanted muscle movement

• Monitors and coordinates slow, sustained contractions

• Subconscious control of muscle tone

Hemispheric lateralization

The brain is not symmetrical, each hemisphere is specialized for certain tasks

Left hemisphere

specialized for language abilities, functions in categorization and analysis

Right hemisphere

Concerned with visuospatial relationships, imagination, comparison of senses

Brainstem

The lower extension of the brain where it connects to the spinal cord, responsible for regulating vital functions such as heart rate, breathing, and blood pressure.

Epithalamus

• Partially forms the roof of the diencephalon and covers the third ventricle

• Pineal gland

• Habenular nuclei

Pineal gland

A small endocrine gland in the brain that produces melatonin, regulating sleep-wake cycles and seasonal biological rhythms.

Habenular nuclei

Involved in visceral and emotional responses to odors

Thalamus

Paired, oval masses of gray matter that lie on each side of the third ventricle. Part of the diencephalon.

Interthalamic adhesion

small, midline mass of gray matter that connects the right and left thalamic bodies

Serves as the relay station and integration center for processing all sensory input on its way to the cerebral cortex except for olfaction

Thalamus

Thalamus function

Helps direct attention to stimuli of interest

Thalamus

capable of crude awareness of various types of sensation

Hypothalamus

Anterioinferior region of the diencephalon. 

Hypothalamus

Brain area most involved in directly regulating the internal environment by controlling autonomic functions and endocrine activity.

Infundibulum

Thin, stalk-like structure that extends inferiorly from the hypothalamus to attach to the pituitary gland

Hypothalamus function

Control of the autonomic nervous system which regulates bodily homeostasis and endocrine functions.

Hypothalamus function

Control of anterior pituitary hormone sectretion

A function of the hypothalamus

Control of body temperature

Hypothalamus function

Control of emotional behavior

Hypothalamus function

Control of hunger/thirst and food intake

Function of the Hypothalamus

Regulation of sleep/wake cycle

Brainstem

critical connecting link between the spinal cord and higher brain regions. Contains many autonomic and reflex centers required for survival as well as the nuclei of many cranial nerves

Midbrain

Part of the brainstem involved in vision, hearing, and motor control, also contains important centers for alertness. Contains superior and inferior colliculi

Superior colliculi

Found in the midbrain of the brainstem, the visual reflex center that controls eye movements and spatial attention.

Interior colliculi

Found in the midbrain of the brainstem the auditory reflex center that controls responses to sound and localization of auditory stimuli.

Pons

Part of the brainstem that regulated breathing, including the rate and depth of each breath. Contains nuclei and tracts for 4 cranial nerves

Medulla oblongata

The lower part of the brainstem that controls vital autonomic functions such as heart rate, blood pressure, and respiration. It also contains centers for reflex actions like swallowing and vomiting.Contains nuclei and tracts for 5 cranial nerves

Functions of the Autonomic Nuclei in the Medulla

• Cardiac center (regulates heart rate and blood pressure)

• Vasomotor center 

• Medullary respiratory center

• Autonomic reflexes (regulated breathing and swallowing, vomiting, and coughing)

Function of the cerebellum

Maintain posture and balance

Function of the cerebellum

Fine control and planning of voluntary muscle movement

Functional brain systems

Consist of separate regions of the brain that work together toward a common funcion

Functional systems

• Limbic system

• Reticular activating system

Limbic system

composed of multiple cerebral and deincephalic structures that process and experience emotions

Function of the limbic system

Establishing emotional states

Function of the limbic system

linking the conscious and unconscious functions of the brain