Week 3 Flashcards
Explain the concepts of lateralisation and contralateral arrangement in terms of the cerebral hemispheres
Lateralisation- means the two cerebral hemispheres are specialised to perform different functions
Contralateral arrangement- Idea that the left hemisphere of the brain controls the right side of the body and the right hemisphere controls the left side of the body
Explain the Brain Support System- the Cerebral Ventricles
Inside the brain is a series of chambers filled with cerebrospinal fluid (CSF). These cavities form what is known as the ventricular system.
The CSF circulating through the ventricular system has at least two main functions:
One is as a mechanical shock absorber. Floating in CSF, the brain is protected from sudden movements that would otherwise cause contact with the inside of the skull.
The second is as a medium for the exchange of materials, including nutrients, between blood vessels and brain tissue.
Explain the Brain Support System: the Meninges
The protective sheaths around the brain and the spinal cord are referred to as the meninges.
The meninges consist of three layers:
dura mater
arachnoid membrane
pia mater
Between the pia mater and the arachnoid membrane is a gap called the subarachnoid space. This space is filled with CSF.
Explain the Brain Support System: The Vascular System
Although it accounts for only about 2% of the weight of the average human body, the brain consumes more than 20% of the body’s energy. However, the brain has very little reserve of the basic metabolic fuels such as oxygen and glucose, and thus it depends critically on its blood supply to provide them.
Because of very tight junctions between the cells that form their walls, brain capillaries (tiny blood vessels) offer much greater resistance to the passage of large molecules across their walls than do capillaries found elsewhere in the body.
This blood-brain barrier is a protective mechanism that may have evolved to help protect the brain from infections and blood-borne toxins, but it also makes the delivery of drugs to the brain more difficult.
Explain the divisions of the CNS- the spinal cord
The principal function of the spinal cord is to distribute motor connections to the muscles and glands and to collect somatosensory information.
The spinal cord is protected by the vertebral column and passes through a hole in each of the vertebrae. Note that the spinal cord is only about two-thirds of the length of the vertebral column. The rest of the space is filled by a mass of spinal nerves composing the cauda equina.
Explain the divisions of the PNS: the Somatic Nervous System
Spinal nerves
Each spinal nerve consists of the fusion of two distinct branches, called roots. The spinal nerves begin at the junction of the dorsal and ventral roots of the spinal cord. The nerves leave the vertebral column and travel to the muscles or sensory receptors they innervate.
Afferent axons travel toward the CNS conveying sensory information.
Efferent axons travel away from the CNS conveying motor commands to muscles and glands.
Explain the divisions of the PNS: Autonomic Nervous System
The autonomic nervous system is concerned with the regulation of smooth muscle (eg. skin, blood vessels, walls of the gut), cardiac muscle, and glands.
The ANS consists of two anatomically separate systems: the sympathetic division and the parasympathetic division.
Explain the The Sympathetic Division of the ANS
The sympathetic division is most involved in activities associated with the expenditure of energy from reserves stored in the body.
Explain the The Parasympathetic Division of the ANS
The parasympathetic division supports activities that are involved with increases in the body’s supply of stored energy.
