Chapter 62 part 1.

Blood Supply and Cardiac Output

• Major arteries supplying blood to the brain include the internal carotid arteries and vertebral arteries.
• Approximately 15-20% of resting cardiac output is directed to cerebral blood flow.

Brain Energy and Blood Flow Interruption

• Glucose serves as the primary energy source for the brain.
• Cessation of blood flow for 5-10 seconds can lead to loss of consciousness and neurological impairment.

Diabetic Treatment and Sensory Receptors

• Over-treatment of diabetics with insulin can lead to hypoglycemia, resulting in neurological deficits.
• Nociceptors are sensory receptors that detect damage and respond to harmful stimuli.

Circuits and Hyperventilation Effects

• Fatigue in reverberatory circuits is attributed to the depletion of neurotransmitters and changes in membrane potentials.
• Hyperventilation can cause respiratory alkalosis, leading to vasoconstriction and reduced cerebral blood flow.

Dorsal Column-Medial Lemniscal System

• This system is responsible for transmitting fine touch and proprioceptive information to the brain.

Effects of Somatosensory Cortex Lesion

• Lesions in the somatosensory cortex may result in loss of proprioception and a diminished ability to perceive touch and pain.

Pain Transmission

• Type A-delta fibers transmit sharp, acute pain via the neospinothalamic tract.
• Hyperalgesia, an increased sensitivity to pain, is primarily caused by inflammatory mediators.

Trigeminal Neuralgia

• The disorder of the trigeminal nerve causing severe facial pain is known as trigeminal neuralgia.

Brown-Sequard Syndrome

• Contralateral symptoms of Brown-Sequard syndrome include loss of pain and temperature sensation on the opposite side of the lesion.

Vision and Accommodation

• The average refractive power of the eye is approximately 60 diopters.
• Presbyopia results from decreased lens elasticity due to protein denaturation, leading to reduced accommodation power with age.

Cataracts and Vision Restoration

• Cataracts, leading to cloudy vision, are the leading cause of blindness globally and are influenced by UV radiation exposure.
• Surgical implantation of a plastic lens can restore vision impacted by cataracts.

Retina Signal Transmission

• Signals in the retina are transmitted via electrotonic conduction, supporting a graded response proportional to light intensity.

Brain Blood Flow Control

• Blood flow in the brain is tightly regulated by mechanisms responsive to metabolic needs and vascular resistance.

Cerebrospinal Fluid and Blood Brain Barrier

• Cerebrospinal fluid (CSF) composition includes glucose, electrolytes, and proteins, facilitating nutrient and waste transport.
• The blood-brain barrier (BBB) selectively regulates substance entry, protecting the brain from toxins and pathogens.

Astrocytes and Blood Flow Regulation

• Astrocytes play a crucial role in maintaining homeostasis and regulating blood flow in response to neuronal activity.
• Increased arterial CO2 levels trigger vasodilation and consequently enhance blood flow to the brain.

Stroke Types and Blood Brain Barrier Permeability

• Ischemic strokes are caused by the interruption of blood supply, leading to tissue damage.
• Certain substances, including oxygen and glucose, can diffuse across the BBB due to their properties.

Mannitol and BBB Permeability

• Hypertonic solutions of mannitol can increase BBB permeability by drawing water out of endothelial cells, temporarily opening tight junctions.

Neurotransmitters in the CNS

• Gamma-aminobutyric acid (GABA) is the chief inhibitory neurotransmitter in the central nervous system (CNS).
• Glutamate serves as the principal excitatory neurotransmitter in the CNS, playing a vital role in synaptic plasticity and cognitive functions.

Test your knowledge on synaptic facilitation with this quiz. Learn about the role of Ca++ concentration, action potentials, and postsynaptic membrane potential in facilitating neurotransmitter release. Explore the definition and mechanisms of facilitation in neuronal communication.