Biomedical Engineering Reference
In-Depth Information
The
forebrain
, or Prosencephalon, forms the bulk of the brain tissue in mammals. It contains
the limbic system that regulates drives, hunger, hormones, emotions, and memory, as well as the cerebral
cortex.The regions of the forebrain are tightly connected together by tracts in complex feedback networks.
Table 1.4:
Diencephalon
Lateral and 3rd ventricles, limbic system
Epithalamus Pineal body, wake/sleep patterns
Thalamus Relay information to cerebral cortex
Hypothalamus Link to endocrine system, metabolism, hunger
Pituitary Gland Master endocrine gland
Telencephalon
Also called the cerebrum
White Matter Axons that connect cortex to other structures
Amygdala Process memory and emotions
Hippocampus Process memory and spatial navigation
Rhinencephalon Olfaction (smell)
Cerebral Cortex Higher level tasks
4
mm
of the forebrain and is composed of grey matter
organized into six layers. The cortex is split into a number of
lobes
which are roughly mirrored on left and
right
hemispheres
of the brain.
The
cerebral cortex
occupies the top 2
−
Table 1.5:
Structure Location Notes
Frontal Lobe Behind forehead Impulse control, language
Parietal Lobe Crown of head Sensory, numbers
Temporal Lobe Behind temples Auditory, speech, and vision
Occipital Lobe Back of head Primary visual center
Insula Between temporal and parietal Emotions, pain, addition
Cingulate Cortex Surrounds the corpus collosum Emotions
Corpus Collosum Connection between hemispheres Millions of axons
1.3.3 Blood Brain Barrier
In the body, capillaries are lined with endothelial cells that contain small gaps, allowing for easy diffusion
of chemicals and gasses to and from the blood. In the brain, a similar membrane, called the
blood brain
barrier
, is present but the cells are more packed tightly so that most chemicals can not diffuse through.The
only chemicals that can pass are either lipid soluble (e.g., O
2
,CO
2
, ethanol, steroid hormones) or carried
by a specific channel (e.g., sugars, amino acids). The result is that the brain is able to maintain a high rate
of metabolism but is protected from potentially dangerous chemicals and infections. In addition, glial
cells surround capillaries in the brain, forming a second barrier. There are, however, a few entry points
