Lecture 8: Sensory Systems - Neuronal Organization and the Brain Flashcards
Central Nervous System
CNS
Made up of brain and spinal cord
Covered with 3 protective layers called meninges.
Dura Mater
The outermost layer
Protects the brain and spinal cord
Contains Vein like structures that carry blood from the brain back to the heart
Arachnoid Mater
The middle layer
Pia Mater
The last, innermost layer
It directly contacts and covers the brain and spinal cord
Cerebrospinal fluid
Space between arachnoid and Pia mater
Produced by choroid plexus in ventricles
Acts as cushion and shock absorber and makes the brain neutrally buoyant
Functions to circulate chemical substances throughout the brain and spinal cord
Hydrocephalus
Swelling which causes the brain to be pushed back against the skull
As a result of constant production of CSF in ventricles which eventually blocks the ventricles and CSF builds up
May cause seizures, cognitive problems
Autonomic Nervous System
Serves as the relay between the CNS and the internal organs
Controls the lungs, the heart, smooth muscle, and exocrine and endocrine glands.
Controls largely without conscious control
Usually involves 2 synapses: a preganglionic neuron synapses to a neuron in a ganglion that synapses on the target organ
Made up of 2 divisions: Sympathetic and Parasympathetic nervous systems
Sympathetic Nervous System
Responsible for the “fight or flight” response that occurs when an animal encounters a dangerous situation.
Examples are accelerated heart rate and inhibited digestion
Help prepare an organism’s body for the physical strain required to escape a potentially dangerous situation.
Parasympathetic Nervous System
Allow animal to “rest or digest”
Resets organ function after sympathetic nervous system is activated.
Sensory-somatic nervous system
Made up of cranial and spinal nerves and contains both sensory and motor neurons
Sensory Neurons
Transmit sensory information from the skin, skeletal muscle, and sensory organs to the CNS.
Have cell bodies which are grouped in dorsal root ganglia
Has one projection with a sensory receptor ending in the skin, muscle, or sensory organs and another which synapses with a neuron in the dorsal spinal cord.
Motor Neurons
Transmit messages about the desired movement from the CNS to the muscles to make them contract.
Have cell bodies in the ventral gray matter of the spinal cord that project to muscle through ventral root
Cranial Nerves
Nerves that emerge from or enter the skull
Humans have 12
Some transmit only sensory information (Olfactory Nerve) while some others transmit solely motor information (Oculomotor nerve) and some have a mix of both (Glossopharyngeal nerve)
Spinal Nerves
Nerves that emerge from the vertebral column.
Transmit sensory and motor information between the spinal cord and the rest of the body.
Humans have 31 (All contain both sensory and motor axons)
Peripheral Nervous System
Contains both the autonomic and sensory-somatic nervous system.
Glia
Cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons.
Brain
Part of the central nervous system that is contained in the cranial cavity of the skull.
Includes cerebral cortex, limbic system, basal ganglia, thalamus, hypothalamus, and cerebellum.
Cerebral cortex
The outermost part of the brain
Thick piece of nervous system tissue.
Folded into hills called gyri and valleys called sulci.
Made up of right and left hemisphere separated by a large sulcus.
Corpus Callosum
Thick fibre bundle which connects the two hemispheres and allows information to be passed from one side to the other.
Lobes of the hemispheres of the brain
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe
Frontal Lobe
Located at the front of the brain, over the eyes.
Controls the olfactory bulb (Processes smells)
Contains the motor cortex (Important for planning and implementing movement)
Control cognitive function such as maintaining attention, speech and decision-making.
Parietal Lobe
Located at the top of the brain
Neurons are involved in speech and reading.
Somatosensation: Touch sensations like pressure, pain, heat or cold
Proprioception: The sense of how parts of the body are oriented in space
Contains a somatosensory map of the body
Occipital Lobe
Located at the back of the brain
Primarily involved in vision-seeing, recognizing and identifying the visual world.
Temporal Lobe
Located at the base of the brain by ears
Involved in processing and interpreting sounds.
Contains the hippocampus, a structure that process memory formation.
