BIOL 1101: The Brain - Unit 4A

The Brain: Unit 4A

The Brain Is The Most Important Organ (According To The Brain)

CNS vs PNS

  • Recall the distinction between the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Word Up!!

  • Nuclei: Collections of cell bodies in the CNS. Function as nerves or clusters of brain cells with the same job or connecting to the same places. Part of gray matter.

  • Tracts: Pathways consisting of large groups of axons in the CNS. Part of white matter. Connect the CNS and spinal cord. In the PNS, tracts are referred to as nerves.

  • Ganglia: Groups of nerves or brain cells that are closely related in the PNS.

  • White Matter: Primarily composed of axons, appearing white due to myelination.

How Many Neurons In Brain?

  • The brain contains approximately 100 billion neurons, comparable to the number of stars in the Milky Way galaxy.

Brain Growth

  • Increase in brain size is not primarily due to the production of new neurons.

  • The increase in brain size results from:

    • Increase in neuron size.

    • Increase in the number of neural synapses/connections between neurons.

    • Increase in myelin formation.

    • Increase in the number of neuroglia (glia cells).

  • Experiences create more connections as we age.

Brain Anatomy

  • Key brain structures include:

    • Prefrontal Cortex

    • Pituitary Gland

    • Amygdala

    • Brain Stem

    • Hypothalamus

    • Cerebellum

    • Hippocampus

Organization/Parts of the Brain

  • The brain controls highly programmed, automatic functions needed for survival (e.g., heart rate, breathing, blood pressure).

  • Controls most mental and physical activity.

  • Coordination, posture, and balance are maintained. The 4 Major Parts of the Brain include:

    • Brain Stem

    • Diencephalon

    • Cerebrum

    • Cerebellum

  • Relays Sensory Info between brain areas.

4 Main Sub-divisions of Brain

  • Brainstem:

    • Regulates automatic, highly programmed activities needed for survival like heart rate, blood pressure, and breathing.

    • Parts include: Medulla Oblongata, Pons, Midbrain.

  • Diencephalon:

    • Parts include: Thalamus, Hypothalamus, Epithalamus (posterior part, forms the roof of the 3rd Ventricle, contains the Pineal Gland).

  • Cerebrum:

    • Makes up ⅔-¾ of the brain.

    • Controls most mental and physical activities including thinking, movement, and personality.

  • Cerebellum:

    • Controls subconscious activity such as posture, balance, and coordination.

Parts & Areas of Human Brain – and What They Do Know:

  • Where located

  • What it does (functions)

  • Parts in it & what they do

  • Clinical Applications

Anatomy of the Brain Outline

  • Brain Stem

    • Medulla Oblongata

      • Pyramids of Medulla

    • Pons

      • Pontine Respiratory Center

    • Midbrain

      • Corpora Quadrigemina

      • Substantia Nigra & Red Nuclei

  • Diencephalon

    • Thalamus

      • Several Nuclei

    • Hypothalamus

    • Epithalamus

      • Pineal Gland

  • Cerebrum

    • 5 Lobes

    • Cerebral Cortex: Motor, Sensory, Multimodal & Association Areas

      • What happens if damaged?

  • Cerebellum

  • Meninges

    • Dura Mater, Arachnoid, Pia Mater

    • Subdural & Subarachnoid Space

  • Cerebral Spinal Fluid

    • Ventricles & Flow Route

  • Blood Supply

    • Arteries, Veins & Blood Brain Barrier

  • Know ALL of Brain Parts, Sub-parts and Functions. Be able to ID what would happen if that brain part was damaged.

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles & Flow

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Brainstem

  • Has 3 regions and all 3 regions have major sensory and motor tracts (axons) carrying info between upper brain regions and lower brain regions/spinal cord.

  • Sensory tracts – carry sensory info TO cerebral cortex which processes incoming sensory info.

  • Motor tracts – carry motor info FROM cerebrum down to lower brain regions/spinal cord

Area/Parts of Brain: Brain Stem

  • 3 Major Parts of Brain Stem:

    • Medulla oblongata (green)

    • Pons (blue)

    • Midbrain (red)

REMINDER… In the BRAIN ….

  • Tracts are pathways consisting of large groups of axons. Part of white matter. Connect CNS and spinal cord. In the PNS, ‘tracts” are referred to as nerves.

  • Nuclei are collections of cell bodies in the CNS. In the CNS they are nerves or clusters of brain cells with the same job or connecting to the same places. Part of gray matter.

Motor Tracts

Sensory Tracts

A. Medulla Oblongata

  • Most inferior region of spinal cord.

  • Joins w/ spinal cord – but wider.

  • Has most major sensory & motor tracts.

Pyramids of Medulla

  • Paired white matter structures of medulla oblongata

  • Contain most motor tracts

  • Decussation of Pyramids = point at junction of medulla & spinal cord where motor axon fibers from medullary pyramids …

Location of where pyramids (bundles of motor tracts) "CROSS" OVER is called Decussation of Pyramids

Medulla Oblongata (cont)

  • Nuclei (cell bodies/gray matter) here can regulate vital functions and non-vital functions such as…

Clinical Application: Increased Intracranial Pressure

  • Increased intra- cranial pressure forces medulla inferiorly

  • Increased intracranial pressure

    • Increasing pressure in skull from blood or edema.

  • Only one major opening in or out of skull cavity

  • When pressure in skull builds up, brain is pushed down through foramen magnum.

Clinical Application for Medulla Oblongata: Increased Intracranial Pressure

  • Can happen due to bleeding, swelling from head injury, fall, tumor, etc.

  • Increased intracranial pressure pushes brain down (inferiorly).

  • This compresses the medulla by the Foramen Magnum of occipital bone in the skull.

  • Pressure on the medulla can trigger the vomiting center, so a few days after the injury the person may start vomiting. Need to take them to get checked out right away.

  • Can cause death

    • so if someone hurts head, take to ER right away to get checked out as symptoms may not appear until a few days later and they may be walking around looking fine for a few days and then “crash.”

B. Pons

  • Has major sensory & motor tracts.

  • Contains the pontine respiratory centers.

    • Pneumotaxic center

    • Apneustic center

  • Reticular formation

    • Sleep wake cycles

    • Breathing regulation

    • Facial expressions

  • Symptoms of Strokes That Occur in the Pons

    • Balance difficulty

    • Double vision

    • Swallowing difficulty

    • Dizziness Numbness

    • Loss of coordination articulating words

    • Vertigo (spinning sensation)

C. Midbrain

  • Most SUPERIOR part of Brainstem.

C. Midbrain

  • Most superior part of brain stem, joins with thalamus superiorly.

  • Has a small canal running through it – the cerebral aqueduct- carries cerebrospinal fluid (CSF) from 3rd to 4th ventricle.

C. Midbrain (cont.)

  • Corpora Quadrigemina =

    • bodies of 4 twins

    • 4-= quadri, twins = gemina

    • Upper masses = help

    • Lower masses =

Midbrain (cont.)

  • Buried in white matter of midbrain are 2 other pairs of nuclei:

    • Superior colliculus-

    • Periaqueductal gray-matter

    • Oculomotor nucleus

    • Medial lemniscus

    • Red nucleus

    • Substantia nigra

    • Corticospinal fibers

    • Reticular formation

    • Cerebral peduncle

    • Cerebral aqueduct

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

    • Cerebral (basal) Nuclei

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Parts of Brain: Diencephalon

  • Has 3 Sections:

    • a. Thalamus

    • b. Hypothalamus

    • c. Epithalamus – Pineal Gland

  • Relays sensory info btw brain regions and controls many autonomic functions of the PNS

A. Thalamus (of Diencephalon)

  • “Yo-yo” shaped – 2 haves joined by area called intermediate mass of thalamus.

  • Space between the two halves is 3rd ventricle – filled with CSF.

  • Thalamus = relay station for all incoming sensory info (touch, pain, pressure, itch, temperature, etc., from skin, skeletal muscles, bones, and joints), EXCEPT for smell.

  • Crudely interprets incoming sensory info

b. Hypothalamus (of Diencephalon)

  • Located BELOW thalamus.

  • No clear demarcation of where it & thalamus are found/differ in brain.

  • Small area w/ lots of functions.

Hypothalamus Functions

  • aka “ ____ ”

    • joy, affection, enjoyment or fun, pleasure, sadness, sorrow, anger, etc.

  • “Sexy” center of brain

    • sex drive, arousal, & sexual satisfaction

  • Regulate secretion of some hormones from pituitary.

  • Receives info (e.g. blood), but not sensory information

b. Hypothalamus

  • Connected to pituitary gland by (little stalk)

  • Pituitary is "master endocrine gland"

C. Epithalamus

  • “Above” thalamus. Has :

    • Pineal Gland.

      • Pineal Gland – (pine cone shaped)

      • Part of endocrine system.

      • Produces hormone Pineal gland

      • Also part of Epithalamus

Epithalamus: Pineal Gland & Melatonin

  • Midwest rates of SAD about 10%

  • Higher levels of melatonin =

    • Increases sleepiness (at night),

    • decreases happiness,

    • decreases libido.

Pineal Gland & Melatonin

  • While any kind of light can suppress melatonin secretion, blue light at night does so more powerfully.

  • Blue light can suppress melatonin for about twice as long as other colored lights & shifts circadian rhythms by twice as much (3 hours vs. 1.5 hours with other light)

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, gyri fissures, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Anatomy of Brain (cont.): Cerebrum

  • When think of “brain” this is usually it.

  • Largest area = cerebrum of brain by weight.

Fissure vs Sulci vs Gyri of Cerebrum

  • Fissures: Deep grooves

  • Sulci: Shallow grooves

  • Gyri: Thick folds

  • Longitudinal fissure: Separates the cerebral hemispheres

4 of 5 Lobes & Functions

  • Frontal Lobe

    • Motor control (premotor cortex)

    • Problem solving (prefrontal area)

    • Speech production (Broca's area)

  • Parietal Lobe

    • Touch perception (somatosensory cortex)

    • Body orientation and sensory discrimination

  • Temporal Lobe

    • Auditory processing (hearing)

    • Language comprehension (Wernicke's area)

    • Memory / information retrieval

  • Occipital Lobe

    • Sight (visual cortex)

    • Visual reception and visual interpretation

  • Brainstem

    • Involuntary responses

  • Cerebellum

    • Balance and coordination

5th Lobe is Insula

  • Processes intensity, quality, &

  • Not visible from brain surface … is where surface of brain _ inward.

Insula

  • Note: it is a FOLD btw and under frontal & temporal lobes.

Parts of the Brain: Cerebral Cortex

  • RECALL: Gray Matter of the Brain

  • Outer surface of brain made of GRAY MATTER = neuron cell bodies.

  • Basically controls most sensory and motor functions, personality, communication, etc.

  • Due to myelinated axons

Parts of Cerebral Cortex

  • Motor Areas = Control voluntary motor function/movement

  • Sensory Areas = Enter for incoming sensory info. Each of five senses (sight, sound, touch, taste, and hearing) have different areas in this region.

  • Association Areas = involved with memories, learning, and receiving information from sensory areas and then integrating that sensory info to give it meaning (this is “higher order thinking” / “higher brain functioning”). There is an association area for each of the sensory areas.

  • Multi-module Association Areas = involve higher brain function

  • Know name, what it does, & what happens if damaged.

Parts of the Cerebral Cortex

  • Motor Association Areas

    • Primary Motor Cortex

    • Pre-Motor Cortex

    • Broca’s Area

    • Frontal Eye Field

  • Multi-Modal Association Areas

    • Wernicke’s Area

    • Affective Language Association Area

    • Prefrontal Cortex

    • Posterior Association Area

  • Sensory Cortex + Sensory Association Areas

    • Primary Sensory Cortex (touch) – Somatosensory Association Cortex

    • Primary Visual Cortex – Visual Association Cortex

    • Primary Auditory Cortex – Auditory Association Area

    • Primary Gustatory Cortex – Gustatory Association Area

    • Primary Olfactory Cortex – Olfactory Association Area

    • Equilibrium Cortex (balance) – Equilibrium Association Area

    • Visceral/ Sensory Cortex (“filled organs) – Visceral/ Sensory/Association Area

A. Cerebral cortex: motor, sensory, and multimodal assn areas

  • All Motor Assoc. Areas located in frontal lobe.

a. Primary Motor Cortex

  • Located on the gyrus (ridge) just before the central sulcus.

Motor homunculus

  • Mapping of the primary motor cortex, showing which neurons of this area control which specific muscles in the body.

  • Pharynx has neurons for muscle speech & controls tongue – fine more skills thus its large size.

  • Amount of space dedicated to body area NOT represented by muscle size, but by…

b. Premotor Cortex

  • Anterior the primary motor cortex.

c. Broca’s Area

  • Broca’s area is located on one side only -- typically _side of brain.

  • Coordinates motor movements needed for…

d. Frontal Eye Field

  • Function: Voluntary

Summary Slide of Motor Area Locations on the Cerebral Cortex

  • Remember: Need to know name and what they do.

(2) Sensory/Sensory Association Areas of the Cerebral Cortex

(2) Sensory/Sensory Association Areas of the Cerebral Cortex

  • Sensory Cortex Areas -

    • Each of the 5 basic senses (touch, vision, hearing, smell and taste) is represented by specific regions of the brain.

    • Incoming sensory info is received & interpreted at these locations.

  • Sensory Association Areas

    • store MEMORIES of previous sensory events and allow you to interpret incoming info based on those memories (allow you to make associations between incoming info and memory).

  • KEY:

    • Primary Sensory Cortex (Areas)

    • Sensory Association Areas

Sections of the Sensory Areas & Sensory Association Areas

  • Involves…

    • Specific Sensory Cortex Area = for picking the SENSATION AND its

    • Sensory Associated Area = for what we ID it as (associate that SENSATION with a feeling or word label based upon our memory of it.)

    • Sensory Association Areas are very near to their Sensory Cortex & often bigger in size.

  • THINK…

    • 5 Senses(touch,vision,auditory,taste(gustatory), olfactory(smell) PLUS… Balance(equilibrium)& Visceral(hollow organs that can be filled)

a. Primary Somatosensory

  • Located on the gyrus just posterior to the central sulcus

  • Receives & interprets incoming somatic sensory info from skin, skeletal muscles, bones & joints all over the body.

Sensory Homunculus

  • Neurons in specific regions of the primary somatosensory cortex receive sensory info from specific body regions.

  • Sensory homunculus – mapping of primary somatosensory cortex indicating which region of this gyrus receive sensory info from each specific body region.

  • Body regions on primary sensory cortex (sensory homunculus) not related to size of body area, but by how sensitive that body area is.

  • SO very sensitive body areas (e.g. face) have more neurons dedicated to them and thus take up more space on primary sensory cortex.

b. Somatosensory Association Cortex

  • Stores memories of previous somatic sensory events & allows you to make associations /give meaning to the incoming info.

  • If area damaged, can't identify things by touch/sensation

  • Only can re-make these memories from new experiences

c. Primary Visual Cortex – occipital lobe.

  • Receives and interprets incoming visual info – color, pattern, shape, etc.

d. Visual Association Cortex

  • stores memories of previous visual events & allows associations btw incoming info & memories. (Gives meaning to incoming visual info.)

  • if this area is damaged you cant remember what something is that you're seeing

e. Primary Auditory Cortex on temporal lobe.

  • Receives & interprets incoming auditory info- intensity, pitch, rhythm, etc, if damaged=no hearing

f. Auditory Association Cortex – temporal lobe.

  • Stores memoires of previous auditory events, allows interpreting incoming info based on memories.

g. Primary Gustatory Cortex & Association Area (in insula)

  • Receives & interprets incoming taste info.

  • Gustatory Association Area = processes memories of previous taste information(cannot see area on this image)

The motor and sensory cortexes and the association areas for each

h. Primary Olfactory Cortex (area behind nose inside).

Damaged primary olfactory cortex

  • If primary olfactory cortex and/or association area get damaged, lose ability to smell and/or interpret scents

i. Equilibrium Cortex & Assoc. Area

  • provides a conscious awareness of balance & "uprightness)

j . Visceral Sensory/Association Area

  • receives & interprets conscious visceral info. Stores memories of previous visceral sensations allowing associations btw incoming info & memory.

  • Damage to this are = loss of conscious visceral organ sensation & memory

(2) SUMMARY SLIDE of Sensory/Sensory Association Areas of the Cerebral Cortex

Multimodal Association Areas of Cerebrum

  • All the other parts of the brain we've talked about so far have either been associated with Motor function (red area in brain pic) or with a specific sensation (eg, touch, OR vision, OR sight, OR smell, OR taste),

  • Multimodal association areas of the cerebral cortex receive info from MANY different senses and Associations from these various different senses.

  • They receive information from various different sensory inputs, and then they interpret that information.

  • Usually involved with higher order brain functions -- such as thought patterns and communication.

(3) Multimodal Association Areas of the Cerebral Cortex

  • Receive and interpret incoming info from many different sensory inputs.

  • Makes associations between various kinds of sensory info, instead of just one sensation (like vision, or touch).

Types of Multimodal Areas

  • Wernike’s Area

  • Affective Language Association Area

  • Pre-Frontal Cortex (aka Interior Association Area)

  • Posterior Association Area

a. Wernicke’s Area – one side only, usually LEFT.

  • Language comprehension area.

  • allows us to mentally formulate speech & understand spoken and written language

Wernike’s Area --Damage

  • Damage = Loss of speech comprehension or toss out random words in own speech

  • This is a common area damaged in stroke--watch for "word salad"-- call for help

  • Not another area for this on other side of brain -- once it is damaged-- its damaged

b. Affective Language Association Area

  • (one side only – opposite Broca’s and Wernicke’s areas, so typically on RIGHT).

  • Emotional speech area – uses tone of voice & nonverbals to understand & convey emotional content of speech

  • RIGHT Cerebral Hemisphere

c. Prefrontal Cortex (anterior association area)

  • most anterior part of frontal lobe.

  • Associated w/ personality, reasoning, judgement, intelligence, persistence, abstract thinking, conscience, motivation, etc.

d. Posterior Association Area in temporal, occipital & parietal lobes.

  • Storage bank for complex sensory memories, makes decisions based on memory.

  • Provides an awareness of self in surroundings.

  • Recognizes body as "yours"

  • If "X" happens based upon past experiences I should…

SUMMARY of ALL Regions of Cerebral Cortex.

2 Cerebral Hemispheres

Hemispheric Lateralization of Cerebrum

  • The two cerebral hemispheres are mirror images of each other, but each specializes in specific activities.

  • Left Hemisphere =

    • sensory & motor for RIGHT side of body

    • Math & Science skills, reasoning, logic, organization

  • Right Hemisphere –

    • sensory & motor for LEFT side of body

    • Your artsy, creative side.

    • Artistic, musical abilities, imagination, etc.

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

    • Cerebral (basal) Nuclei

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Parts of the Brain (cont.)

  • 4. Cerebellum

4. Cerebellum

  • Posterior to brainstem, has 2 hemispheres, and small convolutions “leaves” on surface.

  • Like the cerebrum, it has gray matter on the surface and white matter underneath.

  • _present location to desired movement location and decides force, direction, and degree of muscle contraction needed to achieve desired movement, while maintaining balance & coordinated movements.

  • White matter = “arbor vitae” (“tree of life”), Semiconscious & subconscious control of -

Cerebellum (cont.)

  • If this area doesn't work we get ataxia =

Summary of Major Areas of Brain & Their Functions

  • FRONTAL LOBE

    • REASONING BEHAVIOR MEMORY MOVEMENT INTELLIGENCE PERSONALITY LANGUAGE READING

  • PaRieTaL LOBE

    • REASONING SENSATION INTELLIGENCE

  • TEMPORAL LOBE

    • SPEECH BEHAVIOR HEARING EMOTIONS MEMORY

  • OCCIPITAL LOBE

    • VISION

  • BRain STem

    • BREATHING BLOOD PRESSURE CONTROL SWALLOWING

  • CEREBELLum

    • COORDINATION BALANCE

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

    • Cerebral (basal) Nuclei

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Coverings around the brain.

  • Functions: encloses cerebral spinal fluid(CSF), protects brain and vessels, form portions in the skull cavity

    • Dura Mater

    • Arachnoid (Mater)

    • Pia Mater

    • Subdural Space / Subarachnoid Space (spaces bwt each of 3 meninges)

A. Dura Mater (of Meninges)

  • Outer covering around the brain – Both layers are tough, dense CT & in most of brain they are fused together.

  • 2 Layers of dura mater:

    • 1) Periosteal Dura Mater:

      • Outer layer

    • 2) Meningeal Dura Mater:

      • Inner layer

Other Parts of the Meninges (cont).

  • B. Arachnoid

    • Middle layer of meninges – spider web apprence

  • C. Pia mater

    • Innermost layer, transparent c.t., attached tightly to surface of bra

  • D. Subdural Space & Subarachnoid space

    • = Spaces between each meninges

Meninges Also In Spinal Cord

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

    • Cerebral (basal) Nuclei

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid(CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Parts of Brain (cont): CSF

7. Cerebrospinal Fluid (CSF)

  • LOCATION: Found in subarachnoid space around brain and spinal cord, central canal of spinal cord, and ventricles in brain.

  • Functions of CSF:

    • shock absorber

    • Decreases effective brain weight- "floats" brain

    • upper parts of cerebrum weight could crush lower parts of brain(like cerebellum)

Cerebrospinal Fluid

  • solution secreted by choroid plexus (region on walls of ventricles).

  • is of ventricle

  • Choroid plexus is similar to kidney tissue (capillaries and transporting epithelium from the ependyma).

  • Pump sodium and solutes from plasma into ventricles, creating an osmotic gradient that draws water along with the solutes.

  • CSF flows from ventricles into subarachnoid space, flows around body and absorbed back by special villi on arachnoid membrane.

  • 2 purposes of CSF: physical and chemical protection.

Ventricles in the Brain

  • Ventricles are hollow spaces in the brain filled with cerebrospinal fluid (CSF).

  • There are 4 ventricles: 2 Lateral Ventricles, the 3rd Ventricles, & the 4th Ventricle

  • Each ventricle has its own choroid plexus to produce CSF

Ventricles in the Brain (cont.)

  • Two lateral ventricles (the first and second ventricles – shown in blue) one in each cerebral hemisphere.

  • They are backward “C” shaped.

Ventricles in the Brain (cont.)

  • For part of their length, the lateral ventricles run side by side, and are separated by a thin membrane, called the Septum Pellucidum.

Ventricles in the Brain (cont.)

  • Two lateral ventricles (the first and second ventricles – shown in blue) one in each cerebral hemisphere.

  • They are backward “C” shaped.

Know the Flow !!

  • Flow of CSF Through Ventricles of Brain

    • Lateral Ventricles (2)

    • Interventricular Foramina (2)

    • 3rd Ventricle

    • Cerebral Aqueduct

    • 4th Ventricle

    • Central Canal

    • Then…..

Cerebrospinal Fluid Circulation

  • When CSF leaves the 4th ventricle, it goes into the subarachnoid space (pink color) around the brain and spinal cord and the central canal of the spinal cord & then re- absorbed.

  • Know the Flow!!

  • Remember: Afterwards CSF is re-absorbed through VEINS(thus dura sinuses involved)

CSF Clinical Application: Hydrocephalus

  • If CSF is still produced but cannot be re-absorbed (due to tumor or brain swelling), it can accumulate in ventricles & ventricles can get really full=water on the brain/hydrocephalus

  • After sutures closed, skull cannot expand outward and the excess fluid can create pressure in the brain, compressing brain cells & causing brain damage.

  • In an infant (before brain sutures closed), skull can expand outward resulting in an increase is size of the brain(photo in next slide)

Hydrocephalus

  • Before the sutures have closed, excess CSF can push the skull bones apart, increasing the size of the infant’s head.

  • Because of this, the infant is less likely to experience brain damage (less compression of brain cells since skull bones can move outward as fluid accumulates).

Hydrocephalus Treatment

  • Uses to transport excess CSF from the brain to the abdominal cavity.

  • In children, are periodically replaced periodically as they grow.

Parts & Areas of Human Brain

  • Brain Stem – medulla oblongata, pons, midbrain

  • Diencephalon – thalamus, hypothalamus, epithalamus

  • Cerebrum – (lobes, fissures, insula, sulcus)

    • Cerebral Cortex (surface) = Motor Areas, Sensory Areas, Multimodal Areas

    • Cerebral (basal) Nuclei

  • Cerebellum

  • Meninges – Dura Mater, Arachnoid, Pia Mater, Subdural Space & Subarachnoid Space

  • Cerebral Spinal Fluid (CSF) – Ventricles

  • Blood Supply to Brain – Arteries, Veins, Blood Brain Barrier.

Parts of Brain: Blood Supply

  • Arteries

  • Veins

  • Blood Brain Barrier

  • Clinical Applications

Blood supply to/from brain

A. Arteries