Cerebral Circulation and Brain Structures Quiz

Cerebral Circulation

• The brain receives 750 ml of blood per minute.
• The brain uses 20% of total O2 uptake.
• Glucose is the brain's only source of energy.

Meninges and Ventricles

• The brain has a set of communicating cavities within it called ventricles.
• Ventricles produce, transport, and remove cerebrospinal fluid (CSF).
• CSF is a watery fluid that bathes the CNS, surrounds and cushions the spinal cord and brain, and has three main functions: protection, buoyancy, and chemical stability.
• CSF is lined by ependymal cells, which form the choroid plexus.

Ventricular System Diseases

• Hydrocephalus and Ventriculitis can occur due to infection from a brain surgery.

Spinal Cord

• The spinal cord has three main functions: sending motor commands from the brain to the body, sending sensory information from the body to the brain, and coordinating reflexes.
• The spinal cord extends from the medulla oblongata of the brain stem at the level of the foramen magnum.
• Reflex arcs allow the body to respond to sensory information without waiting for input from the brain.
• In adults, the spinal cord tapers to an end, termed the conus medullaris, at the second lumbar vertebra level.
• Past the conus medullaris, a bundle of spinal roots extends, termed the cauda equina.
• The cauda equina and the subarachnoid space continue until S2, which is the target location for a lumbar puncture (spinal tap).

Blood-Brain Barrier (BBB)

• The BBB is a highly selective semi-permeable membrane located between the blood and brain interstitium.
• The main function of the BBB is brain homeostasis.
• Gases such as carbon dioxide and oxygen, as well as lipophilic molecules with a molecular weight under 400 Da, can freely diffuse across the BBB.
• Astrocytes play a significant role in stabilizing and maintaining BBB integrity.
• The BBB is composed of cerebral capillary wall endothelial cells (ECs) held together via tight junctions (TJs), surrounded by pericytes, astrocytes, and basal lamina.

Impulse Transmission

• Neuroglia (glial cells) provide nourishment, protection, and basic support to neurons.
• Neuroglia cells may be a source of tumor in the NS.
• Neuroglia are important in the transmission of impulses.
• Mature glial cells retain the ability to divide by undergoing mitosis.
• Neurons do not conduct nerve impulses.
• Human brain has generally roughly equal numbers of neurons and neuroglia.
• Having a relatively high number of neuroglia is associated with higher intelligence.
• An increase in the ratio of neuroglia to neurons is associated with greater intelligence in species.

Neuron Function

• Neurons transmit impulses through electrical signals that convey information along a neuron.
• The three processes involved in nerve impulse transmission are polarization, depolarization, and repolarization.

Neurogenesis

• Formation of new neurons by cell division may occur in a mature human brain, but only to a limited extent.
• The average brain contains about 100 billion brain cells, most of which were formed before birth.
• The hippocampus appears to be where much of the neurogenesis activity takes place.
• Research has found that the hippocampus can produce anywhere from 700 to 1,500 new neurons each day.

Brain Health

• 120 to 150 minutes of moderate-intensity exercise per week is good for the brain.

Types of Neurons

• Neurons can be classified functionally based on the direction in which they carry nerve impulses.
• There are three main types of neurons: sensory (afferent), motor (efferent), and interneurons.

The Five Basic Senses

• The five basic senses are sight, taste, touch, hearing, and smell.
• Perception is the ability to recognize objects with the use of the special senses.
• Sense of sight is mediated by photoreceptors (rods and cones).
• Sense of taste is mediated by gustatory receptors.
• Sense of touch is mediated by mechanoreceptors.
• Sense of hearing is mediated by mechanoreceptors.
• Sense of smell is mediated by olfactory receptors.

Sensory Receptors

• Sensory receptors are specialized areas in a sensory neuron that detect specific stimuli.
• Examples of sensory receptors include:
  • Touch/tactile receptors
  • Chemoreceptors
  • Nociceptors
  • Proprioceptors
  • Thermoreceptors
  • Mechanoreceptors
  • Hair cells
  • Free nerve endings