Brain Flashcards
What are meninges?
Meninges are three membranes that cover the brain and spinal cord. The meninges are called dura mater, arachnoid mater, pia mater. Each menix forms part of the brains protection, along with fluid and bone. The cranial meninges are continuous with spinal meninges.
What are extensions of dura mater
Falx cerebri, falx cerebelli and tentorium cerebelli extend from the dura mater.
How is the brain protected?
The cranium and cranium meninges (layers) surround and protect the brain.
What is dura mater?
Dura mater is the outer most menix (one of the cranial meninges)
What is arachoid mater?
Dura mater is the middle menix (one of the three cranial meninges)
What is pia mater?
Pia mater is the innermost layer of the three meninges (coverings) of the brain and spinal cord.
What is the function of cranial sinuses?
They are venous channels that drain blood from the brain and deliver it to internal jugular veins.
What is the falx cerebri?
The falx carebri is an extension of dura mater (one of the meninges). Falx cerebri separates the two hemispheres of the cerebrum.
What is the falx cerebelli?
The falx cerebelli is an extension of dura mater (one of the meninges). Falx cerebelli separates the two hemispheres of the cerebellum.
What are the major parts of the brain?
The major parts of the brain are the brain stem, cerebellum, the diencephalon and the cerebrum.
The brain stem includes the medulla oblongata, pons and midbrain.
The diencephalon consists of the thalamus, hypothalamus and epithalamus.
- di = through
- encephalon = brain
The brain represent 2% of body weight - how much oxygen and glucose does it use?
The brain uses 20% of the body’s oxygen and glucose, even when resting. There is no glucose stored in the brain and so the supply must be continuous.
What happens if there is an interruption of blood flow to the brain?
An interruption of blood flow to the brain can cause disorientation or a loss of oxygen. Typically an interruption of 1-2 minutes impairs neuronal function and a deprivation of 4 minutes causes permanent damage.
What is the blood-brain barrier?
The blood-brain barrier consists of specialised brain capillaries and astrocytes that prevent the passage of materials from the blood to the cerebrospinal fluid and brain.
The blood-brain barrier consists of mainly tight junctions that seal together endothelial cells of blood brain capillaries, and a thick basement membrane that surrounds the capillaries. Astrocytes processes cover capillaries and secrete chemicals that maintain membrane permeability.
NB: Trauma can break down the BBB
How do neurons synthesize ATP?
Neurons synthesize ATP almost exclusively from glucose, through reactions that use oxygen. When the activity of neurons and neuroglia increases to a particular region of the brain, blood flow to that area also increases.
What can low blood-glucose levels cause?
Blood with low glucose can cause mental confusion, dizziness, convulsions and a loss of consciousness.
People with diabetes ned to watch their glucose level as diabetic shock can cause a seizure, coma and possibly death.
What substances can pass the blood-brain barrier?
The blood brain barrier protects cells from some toxins and pathogens. A few water soluble substance (eg glucose) can cross the BBB by active transport. Urea and (most) ions can cross the BBB very slowly. Lipid soluble substances (such as oxygen, carbon dioxide, alcohol and anesthetics) can cross freely.
Proteins and most antibiotics are unable to cross the BBB.
What is CSF and what is its function?
Cerebrospinal fluid (CSF) is a clear, colourless fluid composed manly of water. CSF also carries small amounts of oxygen, glucose and other needed chemicals from the blood to neurons and neuroglia.
Functions:
- Protection: CSF protects the brain and spinal cord from chemical and physical injury.
- Homeostatic function: The pH of CSF regulates pulmonary ventilation and cerebral blood flow.
- Circulation: CSF helps exchange of nutrients and waste between blood and adjacent nervous tissue.
What is the total volume of CSF?
Cerebrospinal fluid is 80-150ml in an adult. 7.
What is CSF made up of?
CSF is made up of mainly water oxygen, glucose, oxygen, lactic acid, urea, cations, anions, and some white blood cells.
How is cerebrospinal fluid formed?
Cerebrospinal fluid is continuously formed and drained. CSF is formed in the choroid plexus, a network of blood capillaries in the walls of the ventricles. The choroid plexus is covered with ependymal cells joined by tight junctions (blood-cerebrospinal fluid barrier). Blood plasma is filtered by the capillaries and then ependymal cells secrete what becomes CSF.
What are ventricles, and how many are in the brain?
Ventricles are CSF-filled cavities in the brain - there are four. There are two lateral ventricles (one in each hemisphere of the cerebrum, a third ventricle and a fourth ventricle.
How is CSF drained?
One median aperture & two lateral apertures allow CSF to exit from the interior of the brain.
CSF is reabsorbed through arachnoid villi at 20ml p/hr. Production rate = reabsorption / draining rate.
The cerebrospinal fluid surrounds the brain and spinal cord and to do this it flows in the subarachnoid space
What is the thalamus?
The thalamus is a large, oval srtucture of gray matter organised into nuclei. The thalamus is the relay center for sensory impulses.
What is grey matter & white matter?
Gray matter lies upon white matter. Folds of gray matter is called gyri or convulsions.
Gray matter is usually unmyelinated and contains neuronal cell bodies, axons, axon terminals and neurolglia.
White matter is aggregations or bundles of myelinated or unmyelinated axons, located in the spinal cord or brain.
The Hypothalamas is located inferior to the thalamus and is composed of a dozen or so nuclei in four regions. What are the functions?
- Controls and integrates activities of the ANS which regulates smooth, cardiac muscle and glands.
- Synthesizes regulatory hormones that control the anterior pituitary.
- Contains cell bodies of axons that end in posterior pituitary where they secrete hormones.
- Regulates rage, aggression, pain, pleasure & arousal.
- Feeding, thirst & satiety centers.
- Controls body temperature.
- Regulates daily patterns of sleep.
What is the cerebral cortex?
The cerebral cortex is an area of gray matter that forms the outer rim of the ceremrum, 2-4mm thick. The cerebral cortex contains layers of billions of neurons.
What is basal nuclei?
Basal nuclei is clusters of gray matter deep in each cerebral hemisphere. Basal nuclei helps to initiate and suppress movement, and help to regulate muscle tone and skeletal muscle movement.
What is the limbic system?
The limbic system is part of the forebrain concerned with various aspects of emotions and behaviour. The limbic system is sometimes termed the visceral brain.
What is the cerebrum?
The cerebrum is the seat of intelligence, providing us with the ability to read, write, speak, remember, plan, create and imagine.
medulla oblongata
The medulla oblongata is a continuation of the spinal cord and the inferior part of the brain stem. The medulla is a nuclei of 5 cranial nerves:
- Cardiovascular center, affects the force & rate of heart beat and the diameter of blood vessels
- Respiratory center, medullary rhythmicity area
- Deglutition center
- Reflex centers for coughing, sneezing, swallowing etc
What is nuclei?
Nuclei is a group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.
The primary visual area and visual association area of the cerebral cortex are both located in the:
a) Frontal lobe
b) Temporal lobe
c) Insula
d) Occipital lobe
d) Occipital lobe
The primary motor area of the cerebral cortex is located in the:
a) Precentral gyrus
b) Postcentral gyrus
c) Temporal lobe
d) Occipital lobe
a) Precentral gyrus
The cerebral hemispheres are connected internally by the:
a) Intermediate mass
b) Corpus callosum
c) Basal ganglia
d) Arachnoid villi
b) Corpus callosum
The hypothalamus, in the diencephalon, is the control center for the:
a) Endocrine and visual systems
b) Endocrine and digestive system
c) Autonomic and central nervous system
d) Endocrine and central and autonomic nervous system
d) Endocrine and central and autonomic nervous system
The main relay center for conducting information between the spinal cord and the cerebrum is the:
a) Hypothalamus
b) Corpus callosum
c) Thalamus
d) Cerebellar peduncles
c) Thalamus
The cerebellum is concerned mainly with what function:
a) Visual processing
b) Respiration
c) Precise voluntary movement, posture and balance
d) Auditory processing
c) Precise voluntary movement, posture and balance
The brain stem is where most of the spinal tracts:
a) Turn left
b) Decussate or cross
c) Turn around
d) Process information
b) Decussate or cross
The brain stem contains many centers for the coordination of:
a) Breathing, swallowing, coughing, sneezing and hiccoughing
b) Breathing, swallowing, urinating and sneezing
c) Breathing, swallowing, coughing, sneezing and lifting heavy objects
d) Breathing, swallowing, chewing, hiccoughing and blood flow
a) Breathing, swallowing, coughing, sneezing and hiccoughing
The cerebrospinal fluid is absorbed back into the venous sinuses via the:
a) Villi of pia
b) Arachnoid villi
c) Circle of Willis
d) Basilar artery
b) Arachnoid villi
The functions of the cerebrospinal fluid are:
a) Nutrition, waste removal, shock absorption and to separate the meninges
b) Nutrition, carbon dioxide removal and to separate the meninges
c) Carbon dioxide, waste removal, chemical protection to assist with neural transmission
d) Shock absorption, waste removal, nutrition and chemical balance to assist with neural transmission
d) Shock absorption, waste removal, nutrition and chemical balance to assist with neural transmission
The cerebrospinal fluid surrounds the brain and spinal cord and to do this it flows in the:
a) Subarachnoid space
b) Subdural space
c) Intertheacal space
d) Epidural space
a) Subarachnoid space
The cerebrospinal fluid is produced in the choroid processes of the:
a) Midbrain
b) Brain ventricles
c) Diencephalon
d) Heart ventricles
b) Brain ventricles
The basement membrane capillaries of the brain are tightly packed together with a large number of astrocytes pressing up against them, this is referred to as the:
a) Blood brain defense mechanism
b) Blood cerebrospinal fluid barrier
c) Blood brain membrane
d) Blood brain barrier
d) Blood brain barrier
The three membranes that cover the brain are referred to as the meninges, they are:
a) Pia mater, arachnoid and choroids mater
b) Pia mater, arachnoid and dura mater
c) Pia mater, arachnoid and tentorium mater
d) Pia mater, arachnoid and falx cerebri
b) Pia mater, arachnoid and dura mater
The diencephalon brain consists of the:
a) Thalamus, epithalamus and hypothalamus
b) Thalamus, epithalamus and the cerebrum
c) Thalamus, epithalamus and the brain stem
d) Thalamus, epithalamus and midbrain
a) Thalamus, epithalamus and hypothalamus
The brain stem consists of the:
a) Medulla oblongata, pons and the hypothalamus
b) Medulla oblongata, pons and the cerebellum
c) Medulla oblongata, pons and the midbrain
d) Pons, midbrain and the hypothalamus
c) Medulla oblongata, pons and the midbrain
The brain consists of four main areas, these are:
a) Brain stem, midbrain, cerebellum and the cerebrum
b) Brain stem, cerebellum, diencephalon and the cerebrum
c) Brain stem, hypothalamus, diencephalon and the cerebrum
d) Brain stem, cerebral cortex, diencephalon and the cerebellum
b) Brain stem, cerebellum, diencephalon and the cerebrum
