chapter14

CSF circulates:

•From choroid plexus•Through ventricles•To central canal of spinal cord•Into subarachnoid space

•Transient Ischemic Attack (TIA)

a "mini-stroke" caused by a temporary blood clot

•Ischemic stroke or thrombotic stroke

(also called cerebral thrombosis or cerebral infarction) occurs when diseased or damaged cerebral arteries become blocked by the formation of a blood clot within the brain.

•Hemorrhagic Stroke

(caused by ruptured blood vessels that cause brain bleeding)

Functions of the Cerebellum

1.Adjusts postural muscles2.Fine-tunes conscious and subconscious movements•The cerebellum receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements.•The cerebellum coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity

Three Functional Principles of the Cerebrum

1.Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of the body2.The two hemispheres have different functions, although their structures are alike3.Correspondence between a specific function and a specific region of cerebral cortex is not precise

•Three divisions of the diencephalon

1.Leftthalamus 2.Rightthalamus 3.Hypothalamus

Functions of the Hypothalamus

1.Provides subconscious control of skeletal muscle like posture.The subconsciousis the part of your mind which operates without your awareness and over which you do not have active control.2.Controls autonomic function -is a division of the peripheral nervous system that influences the function of internal organs.3.Coordinates activities of nervous and endocrine systems4.Secretes hormones ADH and OXT•Antidiuretic hormone (ADH)It's a hormonemade by the hypothalamus in the brain and stored in the pituitary gland.•ADH tells your kidneys how much water to conserve and constantly regulates and balances the amount of water in your blood•Oxytocin(OT; OXT)The two main actions of oxytocinin the body are contraction of the womb (uterus) during childbirth and lactation. Oxytocinstimulates the uterine muscles to contract and also increases production of prostaglandins which increase the contractions further.5.Produces emotions and behavioral drives•The feedingcenter(hunger)•The thirstcenter(thirst)6.Coordinates voluntary and autonomic functions

•Temporal lobes

are involved in high-level auditory processing (hearing), such as hearing, and holds the primary auditory cortex.

Dural Sinuses

are venous channels found between layers of dura materin the brain.[1]•They receive blood from internal and external veins of the brain, receive cerebrospinal fluid(CSF) from the subarachnoid space,•Empty into the internal jugular vein

The Limbic System

is composed of several components•Is a functional grouping that:•Establishes emotional states•Links conscious functions of cerebral cortex with autonomic functions of brain stem•Facilitates memory storage and retrieval

•Occiptial lobe

is important to being able to correctly understand what your eyes are seeing.

The Cerebrum: The cerebrum or cortex

is the largest part of the human brain, associated with higher brain function such as thought and action.

The Pons

process and relay information to and from cerebellum.•The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture

•Frontal lobe

regulates decision making, problem solving, control of purposeful behaviors, consciousness, and emotions and regulating

•Parietal lobe

regulates sensation and perception and is concerned with integrating sensory input, primarily with the visual system.

Synchronization

•A pacemaker mechanism•Synchronizes electrical activity between hemispheres•Brain damage can cause desynchronization

The Medulla Oblongata

•Allows brain and spinal cord to communicate•Coordinates complex autonomic reflexes•Controls visceral functions•The medulla oblongata helps regulate breathing, heart and blood vessel function, digestion, sneezing, and swallowing.•This part of the brain is a center for respiration and circulation.•Sensory and motor neurons (nerve cells) from the forebrain and midbrain travel through the medulla.

Midbrain

•Also called mesencephalon•Processes sight, sound, and associated reflexes•Maintains consciousness

Disorders of the Cerebellum

•Ataxia the loss of full control of bodily movements•Damage from trauma or stroke•Intoxication (temporary impairment)•Disturbs muscle coordination•Persistent ataxia usually results from damage to your cerebellum—the part of your brain that controls muscle coordination.•Many conditions can cause ataxia, including alcohol abuse, stroke, tumor, cerebral palsy and multiple sclerosis. An inherited defective gene also can cause ataxia.

•Biochemical Isolation

•Blood-brain barrier

•Physical Protection of the Brain

•Bones of the cranium•Cranial meninges•Cerebrospinal fluid

Monitoring Brain Activity

•Brain activity is assessed by an electroencephalogram(EEG)•Electrodes are placed on the skull•Patterns of electrical activity (brainwaves) are printed out

Medulla Oblongata

•Connects brain to spinal cord•Relays information•Regulates autonomic functions•Heart rate, blood pressure, and digestion

Pons

•Connects cerebellum to brain stem•Is involved in somatic and visceral motor control

•Cerebrovascular Disease

•Disorders interfere with blood circulation to brain•Stroke or cerebrovascular accident (CVA)•Shuts off blood to portion of brain•Neurons die•There are numerous types of CVA's

Ventricles of the Brain

•Each cerebral hemisphere contains one large lateral ventricle• The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF)•Separated by a thin partition

Hemispheric Lateralization

•Functional differences between left and right hemispheres•Each cerebral hemisphere performs certain functions that are not ordinarily performed by the opposite hemisphere

Structures of the Cerebrum

•Gyri-Increase surface area (number of cortical neurons)•Insula("island" of cortex) -Lies medial to lateral sulcus•Longitudinal fissure -Separates cerebral hemispheres•Lobes are the Divisions of hemisphere•The lobes are divided by sulcus

The Cranial Meninges

•Have three layers 1.Duramater -Outer layer 2.Arachnoidmater -Mid-Layer3.Piamater-Attached to brain surface•Are continuous with spinal meninges•Protect the brain from cranial trauma

The Left Hemisphere

•In most people, left brain (dominanthemisphere) controls:•Reading, writing, and math•Decision making•Speech and language•

•The Diencephalon

•Integrates sensory information and motor commands•Diencephalonis made up of four distinct components: Thalamus, epithalamus, and hypothalamus•The pineal gland •Found in posterior epithalamus•Secretes hormone melatonin

•Seizure

•Is a temporary cerebral disorder•Changes the electroencephalogram•Symptoms depend on regions affected

The Cerebrum

•Is the largest part of the brain•Controls all conscious thoughts and intellectual functions•Processes somatic sensory and motor information•The somatosensorysystem is the part of the sensory system concerned with the conscious perception of touch, pressure, pain, temperature, position, movement, and vibration, which arise from the muscles, joints and skin.

Blood-Brain Barrier(BBB)

•Isolates CNS neural tissue from general circulation•Formed by network of little channels connecting cells of CNS capillaries•Lipid-soluble compounds (O2, CO2), steroids, and prostaglandins•Diffuse into interstitial fluid of brain and spinal cord•Astrocytes control blood-brain bar

Hypothalamus

•Links the nervous system to the endocrine system via the pituitary gland•Centers controlling Emotions, Hormone production and Autonomic functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and the release of other hormones within the body.

The Cerebrum is divided into 4Lobes

•Lobes of the Cerebrum1.Frontallobe, anterior2.Parietallobe, posterior3.Temporallobe4.Occipitallobe

Diencephalon

•Located under cerebrum and cerebellum•Links cerebrum with brain stem

Pituitary gland

•Major endocrine gland•Connected to hypothalamus•Via infundibulum(stalk)•Interfaces nervous and endocrine systems•Important in controlling growth and development and the functioning of the other endocrine glands.

Protection and Support

•Meninges stabilize brain in cranial cavity•Cerebrospinal fluid protects against sudden movement•CSF provides nutrients and removes wastes•Blood-brain barrier and blood-CSF barrier•Selectively isolate brain from chemicals in blood that might disrupt neural function

Hypothalamus

•One of the most important functions of the hypothalamusis to link the nervous system to the endocrine system via the pituitary gland. The hormones of the pituitary gland help regulate the functions of other endocrine glands.•Mammillarybodies of theHypothalamus•Process olfactory (smell) sensory information•Involved with recollection memory•Infundibulum•A narrow stalk•Connects hypothalamus to pituitary gland•Tuberalarea•Located between the infundibulum and mammillary bodies•Helps control pituitary gland function

The Brain Stem

•Processes information between:•Spinal cord and cerebrum or cerebellum• Includes:•Midbrain •Pons •Medulla oblongata

Thalamus

•Relays and processes sensory information•Important in consciousness, sleep, and sensory interpretation

The Right Hemisphere

•Right cerebral hemisphere relates to:•Senses (touch, smell, sight, taste, feel)•Recognition (faces, voice inflections)

Choroid plexus

•Specialized cells and capillaries•Secrete CSF into ventricles•Remove waste products from CSF•Adjust composition of CSF•Produces about 500 mL of CSF/day

•Blood Supply to the Brain

•Supplies nutrients and oxygen to brain•Delivered by carotid arteries and vertebral arteries• Removed from Dural Sinuses by jugular veins

Cerebrospinal Fluid (CSF)

•Surrounds all exposed surfaces of CNS•Interchanges with interstitial fluid (extracellular fluid)of brain•Functions of CSF•Cushions delicate neural structures•Supports brain•Transports nutrients, chemical messengers, and waste products

The Brain

•The brain is a large, delicate mass of neural tissue•Containing internal passageways and chambers filled with cerebrospinal fluid•Each of the six major brain regions has specific functions•Conscious thought and intelligence•Are produced in the neural cortex of the cerebral hemispheres

Structures of the Midbrain

•The midbrain consists of the tectum and tegmentum.•The midbrain is associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation.

The Thalamus

•The thalamus can be thought of as a "relay station," receiving signals from the cerebral cortex, interpreting them, then sending them to other areas of the brain to complete their job.The Thalamus manages our sensitivity to temperature, light and physical touch and controlling the flow of visual, auditory and motor information;•The thalamus is involved in motivation, attention and wakefulness;•It's in charge of our sense of balance and awareness of our arms and legs;•It controls how we experience pain;•It's also involved in aspects of learning, memory, speech and understanding language; and•Even emotional experiences, expression and our personalities involve the thalamus.