Nervous System Overview Quiz

Nervous Systems Overview

• The nervous system coordinates body activities by detecting stimuli, processing information and directing responses.
• The nervous system is comprised of the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS includes the brain and spinal cord.
• The PNS includes nerves and ganglia.
• Nerves are bundles of axons from multiple nerve cells.

Vertebrate Nervous System Organization

• The spinal cord transmits information to and from the PNS
• The spinal cord also produces reflexes independently from the brain
• A reflex is an automatic response to a stimulus
• The spinal cord and brain develop from the embryonic nerve cord.

Vertebrate Brainstem

• The midbrain receives and processes sensory information.
• The pons plays a role in breathing.
• The medulla oblongata controls breathing and cardiovascular functions, including swallowing, vomiting and digestion.

Cerebellum

• The cerebellum is important for coordination, error checking and motor, perceptual and cognitive function.
• It is also involved with learning and remembering motor skills.

Diencephalon

• The diencephalon contains the epithalamus, thalamus and hypothalamus
• The epithalamus includes the pineal gland and is involved in generating cerebrospinal fluid.
• The thalamus is a main input centre for sensory information to the cerebrum.
• The thalamus is also a main output centre from the cerebrum.
• The hypothalamus regulates homeostasis and basic survival behaviours such as feeding, fighting, fleeing and reproducing.

Cerebrum

• The cerebrum has right and left cerebral hemispheres.
• Each hemisphere contains a cerebral cortex (gray matter) covering white matter and basal nuclei.
• In humans, the cerebral cortex is the most complex part of the brain.
• The basal nuclei are centres for planning and learning movement sequences.
• The corpus callosum is a thick band of axons that connects the right and left cerebral cortices.
• The right half of the cerebral cortex controls the left side of the body, and vice versa.

Human Brain Regions

• Forebrain: cerebrum, thalamus, hypothalamus, and the pituitary gland
• Midbrain: part of the brainstem involved with sensory information processing
• Hindbrain: pons, medulla oblongata, and cerebellum. The cerebellum controls movement coordination.

Peripheral Nervous System (PNS)

• The PNS transmits information to and from the CNS and regulates movement and the internal environment.
• Afferent neurons transmit information to the CNS.
• Efferent neurons transmit information away from the CNS.
• Cranial nerves originate in the brain and mostly terminate in organs of the head and upper body.
• Spinal nerves originate in the spinal cord and extend to parts of the body below the head.
• The ANS controls involuntary actions, which includes sympathetic, parasympathetic, and enteric divisions. The sympathetic division has a "fight-or-flight" response. The parasympathetic division promotes "rest and digest". The enteric division controls digestive activity..

Nervous System Disorders

• Nervous system disorders include schizophrenia, depression, Alzheimer's disease, and Parkinson's disease.
• Genetic and environmental factors contribute to the development of these disorders.

Drug Addiction

• The reward system in the brain rewards motivation with pleasure.
• Addictive drugs increase activity of the brain's reward system, including the dopamine pathway.
• Addiction is characterized by compulsive consumption and an inability to control intake and resulting in long-term changes to the reward circuitry.

Alzheimer's Disease

• Alzheimer's disease is a mental deterioration characterized by confusion, memory loss, and other symptoms.
• It is caused by neurofibrillary tangles and amyloid plaques in the brain.
• Successful treatment may hinge on early detection of amyloid plaques.
• There is no cure for this disease but some drugs are effective at relieving symptoms.

Stem Cell-Based Therapy

• Unlike the peripheral nervous system(PNS), the central nervous system(CNS) cannot fully repair itself.
• However, recent research has discovered that adult human brains contain stem cells able to differentiate into mature neurons.
• Induction of stem cell differentiation and transplantation of cultured stem cells are potential methods for replacing neurons lost due to trauma or disease.

Special Senses

• Receptors respond to physical deformation, chemicals, electromagnetic, thermoreceptors and pain.
• Specialized electromagnetic receptors in snakes detect prey's body heat.

Sensory Receptors

• Mechanoreceptors detect mechanical deformation.
• Chemoreceptors detect chemical concentrations.
• Electromagnetic receptors detect light, electricity and magnetism.
• Thermoreceptors detect heat and cold.
• Pain receptors (nociceptors) detect tissue damage.

The Ear

• Vibrating objects create percussion waves that cause the tympanic membrane to vibrate.
• Hearing is the perception of sound in the brain from the vibration of air waves.
• The three bones of the middle ear transmit the vibrations to the oval window on the cochlea.
• Vibrations create pressure waves in the fluid of the cochlea.
• Bending hair cells in the cochlea depolarize mechanoreceptors, sending signals to the brain via the auditory nerve.
• Each region of the basilar membrane vibrates most at a specific frequency and leads to auditory excitation of a specific area of the cerebral cortex.
• The semicircular canals, utricle and saccule are for equilibrium.

Taste and Smell

• In terrestrial animals, taste is the detection of chemicals called tastants, whereas smell is the detection of odorant molecules.
• In humans, taste receptors are modified epithelial cells organized into taste buds. The five taste perceptions are sweet, sour, salty, bitter and umami.
• Olfactory receptor cells in the nasal cavity are neurons that respond to odorant molecules, triggering a signal transduction pathway to the brain.

The Eye

• The eye has a sclera (white outer layer), choroid (pigmented layer), iris that regulates pupil size, retina that contains photoreceptors, and a lens that focuses light onto the retina.
• The eye has the aqueous humor and the vitreous humor. The ciliary body produces aqueous humour.
• Humans and other mammals focus light by changing the shape of the lens.
• The human retina has two types of photoreceptors, rods (light-sensitive, no color distinction) and cones (color distinction, less light sensitive). Cones are concentrated in the fovea.
• Visual pigments (rhodopsin) in rods and cones change shape when light is absorbed leading to a signal transduction pathway and hyperpolarization of the cell.
• Processing in visual information occurs in the retina. Three pigments, photopsins, detect red, green and blue light. Three distinct pathways of information from the retina to the brain are described.