Nervous system
- Be able to draw the motor neuron with labels cell body ,dendrites , axon,myelin sheath,and describe the functions of the parts
- The dendrites receive information from another cell and transmit the message to the cell body.
- The cell body contains the nucleus, mitochondria and other organelles typical of eukaryotic cells.
- The axon conducts messages away from the cell body.
- The myelin sheathLayers of specialized glial cells, called Schwann cells, that coat the axons of many neurons.
- How is the nervous system is organized ?
- The Central Nervous System (CNS) includes the brain and spinal cord.
- The Peripheral Nervous System (PNS) connects the CNS to other parts of the body, and is composed of nerves (bundles of neurons)
- Automic Nervous System
- Sensory organ
- Describe the structure and function of the supporting cells '' neuroglia ' ?
Supporting cells in the CNS are called neuroglia , they support, insulate and protect the delicate neurons
- How do nerve impulses occur ?
- A nerve impulse is a self propagating wave of electrical disturbance that travels along the surface of a neuron's plasma membrane ,
- The membrane of each resting neuron has a slight positive charge on the outside and a negative charge on the inside
- There is normally an excess of sodium ions(Na+) on the outside of the membrane
- When a section of membrane is stimulated , its Na+ channels suddenly open,and Na+ rushes inward , and outside negative
- The electrical disturbance stimulates Na+ channels in the next section of the membrane to open
- What are the role of the meninges ? what are three layers called ?
Meninges - a tough, fluid containing membrane that sourrounds and protects the brain and spinal cord,There are three layers of meninges:
- Dura mater - the tough outer layer of meninges
- Pia mater - the innermost membrane covering of meninges
- Arachnoid mater - the membrane between the dura and the pia mater. the arachnoid mater resembles with fluid in its spaces
- How does the central nervous system protect itself eg CSF , blood brain barrier ?
Cerebrospinal Fluid (CSF)
- Watery solution similar in composition to blood plasma
- Contains less protein and different ion concentrations than plasma
- Forms a liquid cushion that gives buoyancy to the CNS organs
- Prevents the brain from crushing under its own weight
- Protects the CNS from blows and other trauma
- Nourishes the brain and carries chemical signals throughout it
blood brain barrier function
- Selective barrier that allows nutrients to pass freely
- Is ineffective against substances that can diffuse through plasma membranes
- Absent in some areas (vomiting center and the hypothalamus), allowing these areas to monitor the chemical composition of the blood
- Stress increases the ability of chemicals to pass through the blood-brain barrier
- Describe the structure of cerebral hemispheres
Cerebral is made up of two (left and right) cerebral hemispheres , it surface is covered with grey matter(dentrites and cell bodies), white matter(nerve fibers)composes the interior to the cerebrum
- Identify on a diagram the different lobes of the brain and the main sulci eg. frontal lobe , temporal lobe , occipital lobe, parietal lobe,primary motor area, somatosensory cortex, central sulcus , lateral sulcus , somatic sensory area
- Identify the correct nerve type with its function eg efferent , afferent ,sensory , motor ,association, visceral
afferent --otherwise known as sensory or receptor neurons--carry nerve impulses from receptors or sense organs toward the CNS , located in various parts of the body
efferent nerves – otherwise known as motor or effector neurons – carry nerve impulses away from the CNS to effectors such as muscle or glands (and also the ciliated cells of the inner ear)
- Be able to identify or describe the 5 steps to a reflex arc
Step 2. activation of sensory neuron
Step 3. information processing by postsynaptic
Step 4. activation of motor neuron
Step 5. response of peripheral effector to a conduction passageway of the reflex arc
- Describe what the different parts of the brain allow to do eg broccas area allows to speak
- Broca's Area: responsible for speech production (close to motor areas)
- Wernicke's Area: responsible for speech comprehension (close to auditory areas)
Wernicke's area is in the posterior part of the temporal lobe. Broca's area and Wernicke's area are connected by a bundle of nerve fibers called the arcuate fasciculus
Other Areas
Despite the fact that Broca's and Wernicke's Areas are in different lobes, they are actually quite near each other and intimately connected by a tract of nerves called the arcuate fascilicus. There are also people who have damage to the arcuate fascilicus, which results in an aphasia known as conduction aphasia. These people have it a bit better than other aphasias: They can understand speech, and they can (although with difficulty) produce coherent speech, they cannot repeat words or sentences that they hear.
Reading and writing are a part of language as well, of course. But since these skills have only been around a few thousand years, they are not as clearly marked in terms of brain functioning as the basic comprehension and production areas. But there is an area of the brain called the angular gyrus that lies about halfway between Wernicke's area and the visual cortex of the occipital lobe. It was discovered, after a young patient with reading problems died and his brain was examined during autopsy. The angular gyrus showed significant abnormalities.
The angular gyrus has been implicated in problems such as alexia (the inability to read), dyslexia (difficulties with reading), and agraphia (the inability to write). In research involving the use of PET scans on people with these problems, the angular gyrus is not as active as it is in other people while engaged in reading or writing. However, problems such as dyslexia also can involve other areas of the brain, or not involve brain disorders at all.
source from :http://webspace.ship.edu/cgboer/speechbrain.html
Despite the fact that Broca's and Wernicke's Areas are in different lobes, they are actually quite near each other and intimately connected by a tract of nerves called the arcuate fascilicus. There are also people who have damage to the arcuate fascilicus, which results in an aphasia known as conduction aphasia. These people have it a bit better than other aphasias: They can understand speech, and they can (although with difficulty) produce coherent speech, they cannot repeat words or sentences that they hear.
Reading and writing are a part of language as well, of course. But since these skills have only been around a few thousand years, they are not as clearly marked in terms of brain functioning as the basic comprehension and production areas. But there is an area of the brain called the angular gyrus that lies about halfway between Wernicke's area and the visual cortex of the occipital lobe. It was discovered, after a young patient with reading problems died and his brain was examined during autopsy. The angular gyrus showed significant abnormalities.
The angular gyrus has been implicated in problems such as alexia (the inability to read), dyslexia (difficulties with reading), and agraphia (the inability to write). In research involving the use of PET scans on people with these problems, the angular gyrus is not as active as it is in other people while engaged in reading or writing. However, problems such as dyslexia also can involve other areas of the brain, or not involve brain disorders at all.
source from :http://webspace.ship.edu/cgboer/speechbrain.html
- Describe how the RAS is affected by repeated stimuli
the RAS is to detect new and novel stimuli. When something new or different is perceived in the environment, the RAS alerts the brain to possible danger by causing an ''arousal state.'' If a stimulus, such as a sound, is repetitive in nature, the RAS calms the brain and causes it to enter various peaceful states, depending upon the nature of the stimulus.
The input signals to the RAS to that initiate the arousal reaction may come from a variety of sensory inputs (e.g., touching sensations, light, noises, etc). The type and strength of the input signals to the RAS causes varying degrees of reaction. Both pain from external stimuli and protective (proprioceptive) signals from the body are the most potent signals in terms of eliciting RAS activity.
http://www.bookrags.com/research/reticular-activiating-system-ras-wap/
- Describe where the reticular formation is and how it is related to the RAS
The activity of this system is crucial for maintaining the state of consciousness. It is situated at the core of the brain stem between the myelencephalon medulla oblongata and mesencephalon midbrain
It is involved with the circadian rhythm; damage can lead to permanent coma. It is thought to be the area affected by many psychotopic drugs. General anaesthetics work through their effect on the reticular formation.Fibers from the reticular formation are also vital in controlling respiration, cardiac rhythms, and other essential functions
- What is the corpus callosum ?
Function: Connects the Left and Right Hemispheres
Location: The corpus callosum is a thick band of fibers located between the cerebral hemispheres.
It is the largest white matter structure in the brain, consisting of 200-250 million contralateral axonal projections. It is a wide, flat bundle of axons beneath the cortex. Much of the inter-hemispheric communication in the brain is conducted across the corpus callosum.
| Dissection of Corpus Callosum, Superior View | |
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- When can nerve cells regenerate themselves ?
- What are basal nuclei?
Function:
- Controls Cognition
- Movement Coordination
- Voluntary Movement
Location:
The basal ganglia is located deep within the cerebral hemispheres in the telencephalon region of the brain. It consists of the corpus stratium, subthalamic nucleus and the substantia nigra.- Describe features of the diencephalons-thalamus,hypothalamus,limbic system,choroid plexus and describe their jobs
Location:
- The diencephalon is located between the cerebral hemispheres and above the midbrain.
Structures:
- Structures of the diencephalon include the thalamus, hypothalamus, the optic tracts, optic chiasma, infundibulum, Ventricle III, mammillary bodies, posterior pituitary gland and the pineal gland.
Function:
- Chewing
- Directs Sense Impulses Throughout the Body
- Equilibrium
- Eye Movement, Vision
- Facial Sensation
- Hearing
- Phonation
- Respiration
- Salivation, Swallowing
- Smell, Taste
The thalamus is a large, dual lobed mass of grey matter cells located at the top of the brainstem, superior to the hypothalamus.
Function:
- Motor Control
- Receives Auditory, Somatosensory and Visual Sensory Signals
- Relays Sensory Signals to the Cerebral Cortex
The hypothalamus is located below the thalamus and posterior to the optic chiasma.
Function:
- Controls Autonomic Functions
- Emotions
- Endocrine Functions
- Homeostasis
- Motor Functions
- Regulates Food and Water Intake
- Regulates Sleep Wake Cycle
Limbic system : The limbic system underlies the corpus callosum and is a collective term referring to several brain parts, including the hippocampus and the amygdala. The limbic structures are important in the regulation of visceral motor activity and emotional expression
The choroid plexus is located behind the pons and medulla oblongata
Function:
- Produces Cerebrospinal Fluid(CSF)
- Barrier Between Blood and Cerebrospinal Fluid
- Describe the structure and function of the brain stem - midbrain , pons, medulla oblongata
Brainstem The stalk-like part of the brain connecting the spinal cord and the forebrain made up of the pons, the medulla oblongata and the midbrain. The brainstem functions as an important relay station; every nerve impulse that passes between the brain and the spinal cord must pass through the brainstem to allow the body to function normally.
Pons : A component of the hindbrain and the brainstem situated between the midbrain and the medulla. The pons functions to relay signals from the cortex to assist in the control of movement and is also involved with the control of sleep and arousal
Medulla (medulla oblongata) A brain part forming part of the hindbrain and the brainstem, connecting the spinal cord to the pons.The medulla oblongata is involved with the control of unconscious, essential functions such as breathing, blood circulation and muscle tone.
Midbrain Positioned between the hindbrain and the forebrain, the midbrain forms part of the brainstem and connects the brainstem to the forebrain.The midbrain is responsible for controlling sensory processes.
- Describe the structure of the spinal cord
- spinal cord lies inside the spinal column in the spinal cavity and extends from the occipital bone down to the bottom of the first lumbar vertebra
- Its inner portion is composed of grey matter and outer portion is composed of white matter(spinal tracts)
- spinal cord tracts provide two-way conduction paths to and from the brain -ascending tracts and descending tracts
- The spinal cord switches or transfers incoming sensory impulses to outgoing motor impulses ,most of the skeleto muscular reflexes are routed through the spinal cord by passing the brain
- Describe the structure and function of the cerebellum
structure : the walnut-shaped , situated at the base of the brain like the cerebrum, has a cortex or outer covering of gray matter. The types/names of neurons and layers in the two cortices differ.
Function:
- Controls Fine Movement Coordination
- Balance and Equilibrium
- Muscle Tone
- Identify regions of the spinal cord eg cauda , lumbar and spinal nerves
Just below the last Thoracic (T12) and first Lumbar (L1) vertebra the spinal cord ends at the Conus Medullaris. From this point the spinal nerves, resembling a horse’s tail become known as the Cauda Equina extending to the coccyx. These nerves are suspended in spinal fluid.
31 pairs of spinal nerves are attached to the spinal cord in the following orders :
8 pairs(C1-C8) are attached to the cervical segments
12 pairs (T1-T12) are attached to the throacic segments
5 Pairs(L1-L5)are attached to the lumbar segments
5 pairs(S1-S5)are attached to the sacrospinal segments
1 pairs is are attached to the coccygeal segments
- Label a diagram of the cross section of the spinal cord including the menigeal layers
- Match the spinal nerves with their appropriate dermatomes
C3,4 and 5 supply the diaphragm (the large muscle between the chest and the belly that we use to breath).
C5 also supplies the shoulder muscles and the muscle that we use to bend our elbow .
C6 is for bending the wrist back.
C7 is for straightening the elbow.
C8 bends the fingers.
T1 spreads the fingers.
T1 –T12 supplies the chest wall & abdominal muscles.
L2 bends the hip.
L3 straightens the knee.
L4 pulls the foot up.
L5 wiggles the toes.
S1 pulls the foot down.
S3,4 and 5 supply the bladder. bowel and sex organs and the anal and other pelvic muscles.
Myotomes - Relationship between the spinal nerve & muscle
Dermatomes - Relationship between the spinal nerve & skin
- Describe where CSF is made and which structures it passes by before returning to the blood
The majority of the cerebrospinal fluid ( CSF) which fills the ventricles of the brain and the central canal of the spinal cord is secreted by the choroid plexuses. The entire CSF is replaced four times a day so that the total amount of CSF produced is approximately 600ml in 24 hours
The one- way flow of CSF from the ventricular system, around the spinal cord, into the subarachnoid space and into the venous sinuses is a way in which potentially harmful metabolites are removed.
- Just above the medulla spinal cord junction , most of the nerve fibers cross over to opposite side , what is this called ?
Decussation and synapses :The corticospinal or pyramidal tract leads to an understanding of why for the most part, one side of the body is controlled by the opposite side of the brain.
- Most of the cortico-spinal fibers (about 80%) cross over to the contralateral side in the medulla oblongata (pyramidal decussation). Those that cross in the medulla oblongata travel in the lateral corticospinal tract.
- 10% enter the lateral corticospinal tract on the same side
- The remainder of them (10%) cross over at the level that they exit the spinal cord, and these travel in the anterior corticospinal tract.
Whichever of these two tracts it travels in, a cortico-spinal axon will synapse with another neuron in the ventral horn. This ventral horn neuron is considered a second-order neuron in this pathway, but is not part of the corticospinal tract itself.
- Match the 12 cranial nerves up with their function activity or sensation
Cranial Nerve Name Main function
Cranial Nerve 1 Olfactory Nerve Smell
Cranial Nerve 2 Optic Nerve Vision
Cranial Nerve 3 Oculomotor Nerve Eye movement
Cranial Nerve 4 Trochlear Nerve Eye movement
Cranial Nerve 5 Trigeminal Nerve Facial sensation
Cranial Nerve 6 Abducens Nerve Eye movement
Cranial Nerve 7 Facial Nerve Facial movement
Cranial Nerve 8 Auditory Nerve Hearing and sense balance
Cranial Nerve 9 Glossopharyngeal Nerve Organs and Taste
Cranial Nerve 10 Vagus Nerve Organs and Taste
Cranial Nerve 11 Accessory Nerve Shoulder shrug & head turn
Cranial Nerve 12 Hypoglossal Nerve Tongue movement
- Identify the plexus or major Spinal nerves that serve the different body areas
Cervical plexus – phrenic nerve – diaphragm
C1-C8 – other branches – muscles of the neck and skin of upper chest, neck, and ears
Brachial plexus – axillary nerve – deltoid and teres minor muscles and skin of shoulder
C5-T1:
- Musculocutaneous nerve – flexor muscles of the arm and forearm – skin on lateral surface of forearm
- Median nerve – flexor muscles of forearm and hand – skin over lateral surface of hand
- Radial nerve – extensor muscles of the arm, forearm, and hand and skin on posterolateral surface of the arm
- Ulnar nerve – flexor muscles of forearm and small digital muscles, as well as skin of medial surface of hand
Lumbosacral plexus – obturator nerve – adductors of hip and skin over medial surface of thigh
Lumbar plexus (T12-L4) – femoral nerve – adductors of hip, extensors of knee, and skin over medial surfaces of thigh and leg
Sacral plexus (L4-S4):
- Gluteal nerve – adductors and extensors of hip and skin over posterior surface of thigh
- Sciatic nerve – flexors of knee and ankle, flexors and extensors of toes, and skin over anterior and posterior surfaces of leg and foot
- Saphenous nerve - skin over medial surface of leg
- Identify how different parts of the body are affected by the autonomic nervous system eg. sympathetic NS dilates pupils and parasympathetic constricts them
| Organ | Sympathetic Stimulation | Parasympathetic Stimulation |
|---|---|---|
| Heart | Increased heart rate beta1 (& beta2) | Decreased heart rate |
| Increased force of contraction beta1 (& beta2) | Decreased force of contraction | |
| Increased conduction velocity | Decreased conduction velocity | |
| Arteries | Constriction (alpha1) | Dilation |
| Dilation (beta2) | ||
| Veins | Constriction (alpha1) | |
| Dilation (beta2) | ||
| Lungs | Bronchial muscle relaxation (beta2) | Bronchial muscle contraction |
| Increased bronchial gland secretions | ||
| Gastro- intestinal tract | Decreased motility (beta2) | Increased motility |
| Contraction of sphincters (alpha) | Relaxation of sphincters | |
| Liver | Glycogenolysis (beta2 & alpha) | Glycogen synthesis |
| Gluconeogenesis (beta2 & alpha) | ||
| Lipolysis (beta2 & alpha) | ||
| Kidney | Renin secretion (beta2) | |
| Bladder | Detrusor relaxation (beta2) | Detrusor contraction |
| Contraction of sphincter (alpha) | Relaxation of sphincter | |
| Uterus | Contraction of pregnant uterus (alpha) | |
| Relaxation of pregnant and non-pregnant uterus (beta2) | ||
| Eye | Dilates pupil (alpha) | Constricts pupil |
| Increased lacrimal gland secretions | ||
| Submandibular & parotid glands | Viscous salivary secretions (alpha) | Watery salivary secretions |
source from http://www.nda.ox.ac.uk/wfsa/html/u05/u05_b02.htm
- Describe how memories and smell are related
Once an olfactory receptor cell has bonded with an odorant and begun relaying a message to the brain via the olfactory bulb, the information is directed to several areas within the brain. The major areas are piriform cortex in the temporal lobe, the orbitofrontal cortex, amygdala and hypothalamus, and the hippocampus
