Brain And Soinal Cord Flashcards
What are the functions of the nervous system?
- Activation of muscles for movement
- Control of glandular secretions
- Regulation of heart rate and blood pressure.
- Maintenance of body temperature
- Sensation of various stimuli- pain, touch, physiologic changes (stretch, ischemia)
What is the neuron?
The functional cells of the nervous system, which carries nervous impulses to and from the body and central nervous Lys system
The structure and function of neurons permit rapid transmission of information from one cell to another using electrochemical signals
What is the function of the neuron cell body?
Cell body- contains nucleus, cytoplasm, other organelles- Golgi apparatus, mitichondria, lysosomes, RER
What are the functions of the dendrites?
Dendrites- portions that receive input and carries it toward the cell body, unmyelinated
What is the function of the axon?
Carries information away from the cell body
What are the functions of the axon hillock?
Conical projection of cell body, devoid of Nissl bodies, lacks large organelles
What is the function of the initial segment?
The part of the axon closest to the axon hillock
What is the function of the trigger zone?
Impulses arise from the junction of the axon hillock and the initial segment. It has numerous voltage sensitive channels
Classify neurons based on function
- sensory neurons- from the receptors to the CNS. They are pseudounipolar-(cell body sticking out on the side )they are in the dorsal portion of spinal cord
- motor neurons- from the CNS or ganglia to effector cells( they have a multipolar shape) or bipolar neurons
- interneurons- make up 99.9% of neurons
What are the support cells?
Neuroglial cells are cells that provide structural and biochemical support for neuronal function
PNS- Schwann cells and satellite cells
CNS- oligodendrocytes, astrocytes, microglia, ependymal cells
What are the functions of oligodendrocytes?
Forms and maintains myelin sheaths of multiple axons
What are the functions of astrocytes?
Strengthens and supports the neuronal tissue
- Forms the blood brain barrier
- maintains the homeostatic environment
Protects the brain from the environment (bloo-brain barrier)
What are the functions of the microglia?
Phagocytic, provides defense against in pleading microorganisms
Macrophage of the CNS
What are 5he functions of the ependymal cells?
- Produce and secrete CSF
- monitors CSF
Found in ventricles Of brain and central cabal of spinal cord
What are the functions of the Schwann and satellite cells?
Schwann cells- myelinate 1 portion of an axon
Satellite cells- provides structural support for the PNS. They also regulate exchange of materials between neuronal cell bodies and interstitial fluid
Briefly describe the organization of the nervous system
The nervous system is composed of 2 major structural divisions :
- CNS- brain and spinal cord
Bundles of cell body in CNS= nucleus - PNS- sensory receptors, nerves and ganglia outside the CNS
Explain the functional divisions of the nervous system
Functional classification-
- Somatic Nervous system- voluntary control to and from skin and body wall. (Joints, skin, striated muscle)
- Autonomic nervous system- involuntary to/from smooth muscle, cardiac muscle
Other divisions-
Sensory. -brings information from the periphery to the CNS- brain and spinal cord
Motor- sends information from the CNS to the periphery
The lobes of the brain are named after..
The bones that cover them
What is the function of the frontal lobe?
Motor planning and commands, impulse control, working memory and judgement
What is the function of the parietal lobe?
Reception and perception of sensory information
Name the parts of the brain in order of complexity
- Cerebral cortex
- Duancephalon- thalamus, hypothalamus and pituitary gland
- Cerebellum- midbrain, pons, medulla oblangata
Where does integration of info occur?
Cerebral cortex
What is the function of the temporal lobe?
Auditory, memory
What is the function of the occipital lobe?
Visual processing
What is the function of the limbic lobe?
Emotions, memory
What is the function of the insular lobe?
Gustatory lobe
What is the limbus system?
Part of grey matter in brain
-emotional responses (fear); cingulate gurus, amygdala
Learning and memory
Processing: hippocampus
What is the function of the cingulate gurus?
Plays a role in emotion
What is the function of the hippocampus?
Involved in learning and memory
What is the function of the amygdala?
Emotion and memory
Where does all sensory info go in the brain( use bro,Ann’s area)
Primary somatosensory cortex
What is the function of association tracts?
Contains axons that conduct nerve impulses between gyri in the same hemisphere. E.g. superior longitudinal fasciculus
What is the function of comissural tracts?
Contains axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere. E.gl corpus callosum
What are the projection tracts?
Axons that conduct nerve impulses from the cerebrum to lower parts of the CNS or vice versa e.g. internal corpuscle
What are the cerebral white matter ?
Myelinated axons
Consist of tracts(groups of axons like association, commiserate and projection)
What is cerebral spinal fluid?
An ultra filtrate of blood plasma
Samples can be obtained from the lumbar cistern
Explain where the cerebrospinal fluid is produced?
Is produced in the choroid plexus
The choroid plexus in the ventricles produces the cerebrospinal fluid that fills the ventricles
Choroid plexus: ependymal cells, pia mater, Fenestrated capillaries
Describe the flow of CSF
- Body and inferior horns of the lateral ventricles
- Roof of the 3rd ventricles the diencephalon
- Roof of the 4th ventricle in the medulla
Lateral ventricles —> third ventricles—> 4th ventricle —> subarachnoid space—> intracranial spaces blood stream
What are the functions of the CSF?
- it provides protection for the CNS and acts as a shock absorber
- Provides nutrients and removes toxic: waste products from the neurons and other structures in the CNS
- Maintains a healthy circulation through the brain and spinal cord
- the buoyancy provided by the CSF reduces the weight of the brain by 97%
- it can be used as a diagnostic tool- chemical composition
What is the blood brai; barrier?
Functional barrier made up of capillaries between interstitial fluid and blood
Tight endothelial cell junctions, induced by paracrine signals from astrocytes feet
= brain itself creates BBB
No blood brain barrier, for example in hypothalamus (hormones); vomitting center in medulla oblangata
What are the functions of the blood brain barrier?
- It maintains a constant environment for neurons in the CNS and protect brain from neurotoxins
- It prevents the escape of neurotransmitters from the CNS to the general circulation
What are the parts of the diencephalon?
Thalamus
Hypothalamus
Pituitary gland
Pineal gland
What is the function of the thalamus?
Relays and modulates sensory information traveling to the cortex and integrates motor information traveling from basal ganglia and cerebellum to cortex
What is the function of the hypothalamus ?
A host of functions related to homeostasis and the endocrine system
What is the function of the pituitary gland?
Endocrine and neuroendocrine gland; posterior pituitary and anterior pituitary
What is the function of the pineal gland?
Secretes melatonin which promotes sleep
What parts comprise the brain stem?
Midbrain
Pons
Medulla oblangata
What does the brain stem regulate?
Heart rate, breathing, consciousness, cranial nerves origin
What is the function of the cerebellum?
Movement, coordination
Equilibrium integration= maintenance of balance and posture
Memory of skills and movements coordination and speech
What blood vessels supply the brain?
Internal carotid artery
Subclavian artery
How does bone and connective tissue protect the CNS?
Bony skull/cranium
Spinal cord runs through the vertebral column
Meninges lie between bone and tissues
- dura mater (two layers in the brain)
- arachnoid
- pia mater
In the spinal cord cell bodies if the motor neurons would be in the..
Ventral horns and axons would be in the ventral white matter, sane for dorsal and sensory
Describe the spinal cord
The most caudal portion of the CNS
-extent- base of the skull to the L1/L2 vertebrae
31 pairs of spinal nerves
Cervical 8, thoracic- 12, lumbar 5 , sacral 5, coccygeal- 1
What is the intermediate zone?
Gray matter: located between the posterior and anterior horns (dorsal and ventral horns)
-it shapes motor outputs in response to sensory inputs and descending commands from brain
Describe the blood supply of the spinal cord
Major vessels:
- one anterior longitudinal artery
- two posterior longitudinal artery
- Collateral branches from the aorta
-Both anterior and posterior longitudinal arteries are branches of the vertebral artery which is a branch of the subclavian artery
