AP2 2.1: The Brain Flashcards
two main divisions of the central nervous
The two main divisions of the central nervous system are the brain and spinal cord.
brain
The human brain consists of the following divisions: the cerebrum, brainstem, diencephalon, and the cerebellum. The protective structures of the brain are important because neurons are not replaceable. Nervous tissue is damaged by even the slightest pressure. The brain is protected by the skull of the skeletal system, meninges, a cushion of cerebrospinal fluid, and the blood-brain barrier. There are four ventricles inside of the brain.
Ventricles
Ventricles are cavities within the brain that are filled with cerebrospinal fluid (CSF). The ventricles include the two lateral ventricles, third ventricle, and fourth ventricle. The fourth ventricle drains into the central canal of the spinal cord, which also contains CSF.
meninges
The meninges are three layers of connective tissue membranes that cover and protect central nervous system organs and enclose cerebrospinal fluid.
choroid plexus
The choroid plexus is formed from a network of blood vessels within the ventricles. CSF circulates through the ventricles and into the meninges. It cushions the brain and spinal cord by providing buoyancy, allowing the brain to float. Once formed, the CSF circulates through the ventricles and into the subarachnoid space, bathing the brain in fluid.
blood-brain barrier
The blood-brain barrier is a diffusion barrier that prevents most particles from entering the central nervous system tissue, keeping the brain and spinal cord separate from general blood circulation. The blood-brain barrier is formed by the relatively impermeable brain capillaries, due to the glial cells astrocytes.
Cerebrospinal fluid (CSF)
Cerebrospinal fluid (CSF) is a special fluid formed in the walls of the ventricles from blood plasma by permeating through the choroid plexus.
dura mater
meninges three layers of connective tissue membranes
The leathery dura mater is the double-layered outer meninx.
arachnoid meninx
meninges three layers of connective tissue membranes
The middle arachnoid meninx is a loose layer separated from the dura mater by the subdural space. Beneath the arachnoid meninx is the subarachnoid space, which contains blood vessels and is filled with cerebrospinal fluid.
pia mater
meninges three layers of connective tissue membranes
The inner pia mater meninx is a thin connective tissue tightly attached to the brain.
astrocytes
Maintenance of the blood-brain-barrier is important to provide a stable chemical environment for the nervous system. A stable internal environment is important to protect neurons from chemical variations that could cause uncontrollable firing of neurons.
cerebrum
The cerebrum, the foremost part of the brain, is the largest part of the brain in humans comprising about 83% of total brain mass. It consists of two large masses called the left and right cerebral hemispheres.
The left cerebral hemisphere controls the right side of the body, and the right cerebral hemisphere controls the left side of the body.
median longitudinal fissure
The median longitudinal fissure separates the left and right cerebral hemispheres from one another. The brain is highly specialized in its control over body function.
gyri
The cerebral cortex is marked by raised ridges of tissue called gyri separated by shallow grooves called sulci.
fissures
The cerebral cortex is marked by raised ridges of tissue called gyri separated by shallow grooves called sulci. The deeper grooves, called fissures, separate large regions of the brain.