Chapter 12

Decussation

The anatomical crossing over of neurons from left to right

List and describe the structures and general functions of 4 main regions of the adult brain

The cerebrum, which is the part with the folds and crevices that we most associate with a mental image of the brain. It consists of two cerebral hemispheres which are divided by the longitudinal fissure down the center of the cerebrum. The cerebellum, which is also known as the hindbrain. It is in the posterior region of the brain and inferior to the back of the cerebrum. In cross-section, it has an almost-cauliflower appearance, while its exterior consists of thin parallel folds. The brain stem connects directly to the spinal cord but is noticeably thicker than the spinal cord below it. · The diencephalon is in the interior of the brain and can only be seen in its entirety if the brain is cut open. In intact brains, only the floor of the diencephalon can be seen directly superior to the brain stem.

paralysis

temporary or permanent loss of motor control

The primary somatosensory cortex receives somatic ? information?

that receives and processes SENSORY information from the entire body

The primary motor cortex directs voluntary

movements

Where in the body is a spinal tap performed? What is another name for the procedure?

· A lumbar puncture (spinal tap) is performed in your lower back, in the lumbar region. During a lumbar puncture, a needle is inserted between two lumbar bones (vertebrae) to remove a sample of cerebrospinal fluid. This is the fluid that surrounds your brain and spinal cord to protect them from injury.

When you are consciously aware of sensations which part of the brain (generally) is active?

· Cerebrum is responsible for the awareness of sensation.

Briefly, what role does the cerebellum play in muscle movement?

· 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.

What are the functions of the hippocampus and the amygdala?

· The hippocampus is responsible for the processing and storage of short-term memory. The amygdala is responsible for emotions, moods, and other functions related to depression and anxiety.

Which brain region could be called the "thermostat" of the body because it regulates body temperature?

· The hypothalamus in the brain is the master switch that works as a thermostat to regulate the body's core temperature.

Which brain structure secretes melatonin? What is the role of melatonin?

· The pineal gland is an endocrine structure of the diencephalon of the brain, and is located inferior and posterior to the thalamus. It is made up of pinealocytes. These cells produce and secrete the hormone melatonin in response to low light levels. · Melatonin: A hormone that is produced by the pineal gland and is intimately involved in regulating the sleeping and waking cycles, among other processes.

Define gyrus, sulcus and fissure.

Gyrus: elevated ridge Sulcus: shallow groove Fissure: deep groove; helps to separate larger regions of the brain

Explain lateralization of hemisphere function. Which cerebral hemisphere is dominant for language in most people?

Hemispheric lateralization refers to the distinction between functions of the right and left hemispheres of the brain. If one hemisphere is more heavily involved in a specific function, it is often referred to as being dominant. In most people the left hemisphere of the brain is dominant for language.

Which brain system is critically involved in mediating emotional responses

Limbic System

Describe the meninges, cerebrospinal fluid, choroid plexus, and the blood brain barrier. Why is alcohol able to cross the blood-brain barrier

Meninges: The three membranes that cover the brain and spinal cord (singular: meninx) · Cerebrospinal fluid: A clear, colorless body fluid found in the brain and spinal cord. · Choroid plexus: Consists of many capillaries, separated from the ventricles by choroid epithelial cells. · Blood-brain barrier: A highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside. ----Ethanol crosses the blood-brain-barrier very easily. This is due to its chemical characteristics—although it is somewhat polar, it is also lipophilic, and so it mixes easily with the fat in the membrane.

Describe the basic organization of the spinal cord (location of grey/white matter)

The spinal cord is a cylindrical structure of nervous tissue composed of white and gray matter, it is made up of a: Spinal nerve posterior/anterior median fissures dorsal root Gray matter contains neural cells, dendrites, and axon terminals, while white matter consists of axons and myelin

paresthesia

abnormal sensation of numbness and tingling without objective cause

True or false: the spinal cord extends from the foramen magnum to the sacrum.

false; The dura mater extends from the foramen magnum to the sacrum

What are the 3 components of the brain stem?

medulla oblongata, pons, midbrain

Ascending tracts transmit __?__ impulses while descending tracts conduct _?___ impulses.

sensory; motor