Brain Flashcards
What are the characteristics of the nervous system?
IRRITABILITY – responds to stimuli
CONDUCTION – transmits action potentials over long distances
INTEGRATION – can analyse and interpret information
What are the basic components of a nerve cell?
Nerve cells consist of a cell body, dendrites that receive signals, and an axon for signal transmission.
Differentiate between the central and peripheral nervous systems.
The central nervous system includes the brain and spinal cord, while the peripheral nervous system comprises nerves extending throughout the body.
Define sensory and motor nerves.
Sensory nerves transmit signals from sensory organs to the central nervous system, while motor nerves carry signals from the CNS to muscles and glands.
Explain the concept of specialised sensory nerve endings (receptors).
Receptors are structures at the ends of sensory neurons that detect specific stimuli, converting them into electrical signals for transmission.
What factors influence the ability to localise a particular sensation?
The ability to localise a particular sensation depends on:-
1.Number of Receptors
2.Sensitivity of Receptors
3.Size and Arrangement of Receptive Fields
Describe the adaptation of sensory nerve endings.
Sensory nerve endings adapt by decreasing their responsiveness to a constant stimulus, allowing the nervous system to focus on changes in the environment rather than constant stimuli.
What is a receptive field?
The area of skin supplied by a single Sensory Neuron
What is the function of the receptive field?
Each Receptive Field may contain many receptors
Each Sensory Neuron will give information about a specific area of the body surface
What is two-point discrimination in the context of sensory perception?
Two-point discrimination refers to the ability to distinguish between two separate points of tactile stimulation on the skin.
How does two-point discrimination vary across different regions of the body?
Two-point discrimination varies across different regions of the body due to differences in the density of sensory receptors.
Areas with a high receptor density, like the fingertips, lips, and tongue, exhibit better discrimination because each receptor has a smaller receptive field.
Areas with lower receptor density, such as the back, have poorer two-point discrimination.
This phenomenon is linked to the precision of spatial localisation in sensory perception.
What factors contribute to the differences in two-point discrimination across body regions?
Receptor density - the size of receptive fields
Neural processing in the somatosensory cortex
What are the basic structural features of the spinal cord, including white matter, grey matter, dorsal and ventral roots, and spinal nerves?
The spinal cord comprises of:
- white matter (nerve fibers)
- grey matter (neuronal cell bodies)
- dorsal and ventral roots (containing sensory and motor fibers, respectively)
- spinal nerves formed by the combination of these roots.
Define white matter, grey matter, dorsal, and ventral roots, and spinal nerves.
White matter contains nerve fibres
Grey matter houses neuronal cell bodies
Dorsal roots carry sensory information into the spinal cord
Ventral roots transmit motor signals out
Spinal nerves are bundles formed by the combination of dorsal and ventral roots.
What are the components of a reflex?
Reflexes consist of a sensory receptor - afferent neuron -integrating center (often in the spinal cord) - efferent neuron - effector organ.
Provide an example of a simple spinal reflex, such as the stretch reflex.
The stretch reflex occurs when a muscle is stretched, activating sensory receptors (muscle spindles), leading to a rapid contraction of the muscle to prevent overstretching.
What types of sensory information are conveyed by the two major ascending pathways?
The spinothalamic pathway transmits pain and temperature sensations
The dorsal column pathway conveys touch, pressure, and proprioceptive information (body position).
Explain the functions of the major descending pathways, specifically the corticospinal and extrapyramidal pathways.
The corticospinal pathway controls voluntary movements
The extrapyramidal pathway regulates subconscious and reflexive movements.
Describe the concept of the crossing of sensory and motor nerve pathways in the CNS.
Sensory pathways typically cross to the opposite side of the brain, ensuring that sensory information from one side of the body is processed in the contralateral hemisphere. Motor pathways, like the corticospinal tract, cross at the level of the medulla or spinal cord, leading to contralateral motor control.
Give a general account of the main parts of the brain and their basic functions (cerebrum, diencephalon, thalamus, hypothalamus, midbrain, pons, medulla, cerebellum).
The cerebrum is responsible for movement and temperature
The diencephalon includes the thalamus (sensory relay) and hypothalamus (homeostasis)
The midbrain controls reflexes
The pons and medulla regulate vital functions
The cerebellum coordinates motor activities.
Describe the locations of the functionally important regions of the cortex: - e.g. primary sensory, visual, auditory areas
Somatosensory in parietal lobe
Visual in occipital lobe
Auditory in temporal lobe.
Describe how the different body parts are represented on the sensory and motor areas of the cortex
Motor areas control voluntary movements
Sensory areas process sensations from specific body regions.
Give a simple account of the location and general function of the cranial nerves
Cranial nerves, located in the brainstem, serve various functions like sensory input (vision, hearing) and motor control (facial expressions, swallowing), connecting the brain to the head and neck.
Describe the two fluids circulating in the brain - the cerebrospinal fluid (CSF) and the blood, and be familiar with the concept of the blood-brain barrier
Cerebrospinal fluid (CSF) circulates within the brain and spinal cord, providing cushioning and nutrient exchange. Blood, carrying oxygen and nutrients, is supplied to the brain. The blood-brain barrier regulates substance passage between blood and brain, maintaining a stable environment.
