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.