LEC 13-14 - General neuroanatomy ANSCNS neuraxis Flashcards
Describe the two main cell types in the nervous system.
neurons and glia
Define neurons and their primary functions.
Neurons are excitable cells that generate action potentials in response to stimuli.
They conduct information as electrical signals.
Neurons are among the largest cells in the body.
How do glial cells support neurons in the nervous system?
support neurons by:
Protecting and nourishing them.
Electrically insulating them.
Removing waste and neurochemical debris.
Assisting in injury repair.
What is the renewal capacity of neurons compared to glial cells?
Neurons usually do not renew or divide, except for a little bit of new growth in adults.
Glial cells are more numerous and can multiply.
Describe the types of connections neurons have.
Synapses with another neuron
Neuromuscular synapses - w/muscles
Neuroglandular synapses - w/ glands
Define the main parts of a neuron.
cell soma (cell body), axon hillock (initial segment), axon, dendrite, dendritic spines, synapse, and terminal axonal boutons.
How do neurons communicate with each other?
Neurons communicate with each other through synapses, where neurotransmitters are released from terminal axonal boutons.
Describe the characteristics of nerve cells.
have a large nucleus and a prominent nucleolus
- contain a large amount of rough endoplasmic reticulum, which is relevant for making proteins.
What is the structural classification of neurons?
-Anaxonic neuron
-Bipolar neuron
-(Pseudo) unipolar neuron
-Multipolar neuron
What are anaxonic neurons?
- no axon
- in the brain and special sense organs
What are bipolar neurons?
- In special sense organs e.g. eye, ear, nose
What are (Pseudo) unipolar neurons?
- Sensory neurons e.g. dorsal root ganglia
What are multipolar neurons?
- motor neurons and interneurons
Explain the impulse direction in neurons.
In neurons, the impulse direction follows the pathway from dendrites to axons.
Describe the central nervous system (CNS) terminology.
nuclei = collection of neuronal cell bodies
tracts = are bundles of nerve fibers (axons/dendrites).
Define the peripheral nervous system (PNS) terminology.
ganglia = are collections of neuronal cell bodies
nerves = are bundles of nerve fibres (axons/dendrites).
What glial cells are in the CNS?
- Oligodendrocytes
- Microglia
- Astrocytes
- Ependymal cells
What glial cells are in the PNS?
- Schwann cells
- Satellite cells
What are the supporting cells (glial cells)?
Astrocytes (CNS): Provide physical/nutritional support, regulate extracellular fluid, form blood-brain barrier.
Satellite Cells (PNS): Provide physical support for neurons.
What are the phagocytic cells (glial cells)?
Microglia (CNS): Main phagocytic and antigen-presenting cells.
Macrophages (PNS): Main phagocytic and antigen-presenting cells.
What are the cells of the ventricular system (glial cells)?
Ependymal Cells (CNS): Line the ventricular system.
What is the myelin producing cells (glial cells)?
Oligodendrocytes (CNS): Form myelin sheaths around multiple axons.
Schwann Cells (PNS): Form myelin sheaths around individual axons.
What are the functions of astrocytes?
Provide structural support
Regulate ion concentration
Remove wastes
Clear excess neurotransmitters
Form the blood-brain barrier
Participate in synapses
What is the role of the blood-brain barrier (BBB)?
Maintains homeostasis of the microenvironment in the CNS.
How do capillary endothelial cells contribute to the blood-brain barrier?
They are joined by tight junctions, providing an effective barrier.
QHow do astrocytic processes interact with brain capillaries?
They contact brain capillaries, separating them from neurons.
Describe the role of microglia in the brain.
immune cells in the brain that act as the main phagocytic cells during development and injury, as well as serving as antigen-presenting cells.
-different origin to other glial cells
How do ependymal cells function in the central nervous system (CNS)?
line the fluid-filled cavities in the CNS, such as the ventricles, and cover the choroid plexus.
Describe the role of oligodendrocytes in the central nervous system (CNS).
myelinate CNS axons, with one cell myelinating numerous axons, which increases the speed of nerve conduction and prevents the escape of electrical energy.
How do oligodendrocytes contribute to nerve impulse transmission?
Oligodendrocytes allow impulses to jump from one node of Ranvier to the next, facilitating faster nerve impulse transmission.
What is the difference between oligodendrocytes and Schwann cells in terms of myelination?
Oligodendrocytes can myelinate multiple axons in the CNS, while Schwann cells can only myelinate one axon in the peripheral nervous system (PNS).
How do Schwann cells affect nerve conduction in the PNS?
Schwann cells myelinate individual axons, increasing the speed of nerve conduction and preventing the escape of electrical energy. Impulses jump from one node of Ranvier to the next.
Describe the function of myelin in the nervous system.
Myelin insulates axons, increases the speed of nerve conduction, and prevents the loss of electrical signals.
Describe the effects of demyelination in Multiple Sclerosis.
Causes neurological deficits
Leads to neurodegeneration
Symptoms include:
Blindness
Motor weakness
Abnormal sensations
Dizziness
Dysphagia
Define the Central Nervous System (CNS).
consists of the brain and spinal cord, and it integrates signals and performs higher cognitive functions.
How does the Peripheral Nervous System (PNS) function?
includes all nerves outside of the CNS, including spinal and cranial nerves, and it connects the CNS to peripheral organs and muscles.
Describe the connection of spinal nerves in the nervous system.
Spinal nerves attach to the spinal cord.
Describe the connection of cranial nerves in the nervous system.
Cranial nerves attach to the brain.
Define the two main divisions of the Autonomic Nervous System.
The two main divisions are the sympathetic and parasympathetic divisions.
Functions of the sympathetic nervous system
- increases metabolic rate
- increased heart rate
- increased blood pressure
- dilate airways
- reduced digestive and urinary function
- pupil dilation
- sweating
Functions of the parasympathetic nervous system
- decreases heart rate
- decreased metabolic rate
- decreased blood pressure
- constrict airways
- stimulates digestive and urinary functions
- pupil constriction
Define the primary neurotransmitter associated with the sympathetic nervous system.
norepinephrine - adrenaline
Define the primary neurotransmitter associated with the parasympathetic nervous system.
acetylcholine.
What are the parts of the brain?
- medulla oblongata
- pons
- midbrain
- diencephalon
- cerebellum
- cerebrum
What are the components of the hindbrain, brainstem, diencephalon, forebrain, and cerebrum?
Hindbrain = pons + cerebellum + medulla oblongata
Brainstem = midbrain + pons + medulla oblongata
Diencephalon = thalamus + hypothalamus
Forebrain = telencephalon + diencephalon
Cerebrum = telencephalon (rostral brain)
Define ipsilateral and contralateral in the context of anatomy.
ipsilateral = the same side of the body.
contralateral = opposite side of the body
Describe the term gyrus.
bump or ridge on the surface of the brain.
What is a lobe in relation to the brain’s structure?
A lobe is a part or broad subdivision of the cerebral cortex.
Explain the term eminence as it relates to brain anatomy.
a prominent protrusion on the surface of the brain (noticeable bump or raised area)
How do meninges function in the brain?
Meninges are membranes that cover and protect the brain.
Define sulcus and its significance in brain anatomy.
groove on the surface of the brain
What distinguishes a fissure from a sulcus?
A fissure is a deep cleft in the brain e.g. longitudinal fissur
Describe a fossa in the context of cranial anatomy.
A fossa is a shallow ditch or depression in the skull.
What is the function of ventricles in the brain?
Ventricles are fluid-filled cavities inside the brain that contain cerebrospinal fluid (CSF).
Define cisterna in relation to brain anatomy.
A cisterna is a cavity or space located between the pia mater and the arachnoid mater.
Explain the term sinus as it pertains to the brain’s structure.
A sinus is a canal or vessel within the dura mater
What is the tract, lemniscus, fasciculus, peduncle, and fibres?
Tract, Lemniscus, Fasciculus, Peduncle: prominent axon bundles connecting large brain regions.
Fibres: bundles of axons.
What is the commissure, chiasm, and decussation?
Commissure: inter-hemispheric bundle of axons crossing the midline.
Chiasm/Decussation: axon bundles crossing the midline to distinct areas.
What are afferent and efferent fibres?
Afferent: arriving fibres/axons.
Efferent: exiting fibres/axons.
What is the nucleus, ganglion, mass, layers, and columns in the nervous system?
Nucleus: cluster of neuron cell bodies, functionally related.
Ganglion: group of neuron cell bodies.
Mass/matter: prominent bundle or cluster of tissue.
Layers: stacked sheets of neurons.
Columns: radial arrangement of functionally related neurons.
Explain the matter in the spinal cord and what is dorsal and ventral?
spinal cord = grey matter surrounded by white matter
dorsal is sensory
ventrial is motor
Describe the components of the brainstem.
The brainstem consists of the midbrain (mesencephalon), pons, and medulla oblongata.
Define the primary functions of the brainstem.
The brainstem is responsible for integrative sensory and motor functions, control of autonomic body functions, and houses cranial nerves II to XII.
What are the surface features and functions of the midbrain (mesencephalon)?
Surface features: superior colliculi (SC), inferior colliculi (IC), and cerebral peduncles (CP).
Functions: Contains nuclei for visual (SC) & auditory information (IC) & controls reflexes associated with these senses
What are the functions of the pons?
Relays sensory info to the cerebellum.
Connects forebrain (motor) and hindbrain (sensory).
Regulates breathing, swallowing, hearing, facial expressions, and sleep cycles.
What are the features and functions of the medulla?
Features: pyramids, olives, obex, 4th ventricle.
Functions: connects spinal cord to the brain; regulates swallowing, coughing, hiccupping, and sneezing.
What is the reticular formation and its functions?
Location: centrally throughout the brainstem.
Functions: integrates movement, pain, breathing, heart rate, and consciousness/attention.
What are the functions of the cerebellum (little brain)?
Coordinates voluntary movement (precision).
Supports motor learning, balance, posture, and speech.
Involved in higher-order functions like attention, emotions, memory, and language.
What are the components of the diencephalon?
Links cerebrum to brainstem consist of:
- epithalamus
- thalamus
- hypothalamus
- subthalamus
What is the function of the epithalamus?
Contains the pineal gland, regulates day/night cycles.
What is the role of the thalamus?
Relays different types of sensory information; acts as a ‘gatekeeper’ to the cortex; involved in motor and limbic connections.
What does the hypothalamus regulate?
Maintains homeostasis (temperature, thirst, hunger, sex); involved in limbic functions; produces hormones for the pituitary gland.
What is the subthalamus associated with?
Part of the basal ganglia; modulates and integrates movement and muscle tone.
Describe the pathway from the basal ganglia to the premotor cortex.
The basal ganglia send signals to the premotor cortex.
Define the role of the thalamus in sensory processing.
The thalamus acts as the main sensory relay en route to the cortex, directing sensory information to primary cortical areas.
How do the retina and primary visual cortex (V1) interact?
The retina sends visual information to the primary visual cortex (V1).
Explain the connection between the inferior colliculus and the primary auditory cortex (A1).
The inferior colliculus transmits auditory information to the primary auditory cortex (A1).
Identify the sources that project to the prefrontal and association cortex.
The midbrain, parietal cortex, and temporal cortex project to the prefrontal and association cortex.
What is the sensory pathway for ascending somatosensory information?
Ascending somatosensory information is relayed to the primary somatosensory cortex (S1).
Describe the connections from the hypothalamus and hippocampus to the cingulate gyrus.
The hypothalamus and hippocampus send signals to the cingulate gyrus.
List the senses that do not project to the primary cortical areas via the thalamus.
The sense of smell does not project to primary cortical areas via the thalamus, all other sense do
How do the basal ganglia, amygdala, and hypothalamus interact with the prefrontal association and cingulate cortex?
The basal ganglia, amygdala, and hypothalamus project to the prefrontal association and cingulate cortex.
Explain the role of the cerebellum in motor control.
The cerebellum sends signals to both the premotor and primary motor cortex (M1) to assist in motor control.
What are the subcortical nuclei and their functions?
Striatum: caudate + putamen + globus pallidus.
Amygdala: regulates emotions; part of the limbic system.
Hippocampus: crucial for memory and spatial navigation (‘seahorse’ shape)
