Anatomy Flashcards
Nervous System
Major controlling, regulatory and communication system of the body
Central nervous sytem components
Brain & spinal cord
Peripheral nervous system components
Spinal nerves & cranial nerves
Nueron
An elongated cell that consists of cell body, which contains nucleus and a variable number of processes (axons & dendrites)
- Excitable tissue
Dendrites
Receive information
Usually short
Axon
Transmit information to the end and then too other cells
- Usually only one axon per neuron
- Usually long
Example of nerve fibres
Dendrites & axons
Function of neuroglia (supporting cells)
- Hold the neurons and their processes in place
- provide nourishment
- insulate them from their surroundings (preventing ‘leakage’ of the impulses they convey)
What is the conducting portion of a neuron?
Axon
Clusters of cell bodies are called?
Ganglions
Cluster of cell dendrites or axons (fibres) are called?
Nerves
The junction between neurons is?
A synapse
What type of neurons constitute most of the nervous system?
Interneurons
true or false - Glial cells make up 90% of CNS
True
Four types of glial cells in CNS?
- Astrocytes
- Oligodendrocytes (myelin)
- Ependymal cells
- Microglia
One type of glial cell in PNS
Schwann cells (myelin)
What happens to glial cells during foetal development?
Glial cells wrap themselves around the axon. They eventually lose most of their cytoplasm and what remains is layers of tightly packed lipid membranes
Gaps in myelin sheath occur at regular intervals, forming nodes of Ranvier
Gaps in myelin sheath occur at regular intervals, forming
Nodes of Ranvier
What type of glial cell is the most abundant?
Astrocytes
- formation of blood-brain barrier
- Physical support
- Neurotransmitter recycling
- Brain repair
Astrocytes
- Most abundant glial cell
- Formation of blood-brain barrier
- Physical support
- Brain repair
- Neurotransmitter recycling
Ependymal cells
Line internal cavities of CNS
Form CSF: cilia
neural stem cells (stroke rehabilitation)
Associated with ventricles in the brain
Microglia
CNS immune defence cells
10-15% of cells
Mop up anything that gets passed blood-brain barrier
Oligodendrocytes (CNS) & Schwann cells (PNS)
Form lipid based myelin sheaths around axons
Fast conduction of nerve impulses
Energy efficient
Nodes of Ranvier: help current impulse
What is a nerve?
A nerve is a visible collection of neuronal fibres held together by connective tissue
No cell body
Found only in PNS
True or false:
Nerves exist in CNS & PNS
False, nerves only exist in PNS (called tracts in CNS)
What is a bundle of axons called in CNS?
Tract
Forebrain includes:
Telencephalon
Diencephalon
Telencephalon includes:
Cerebrum
Diencephalon includes:
Thalamus & Hypothalamus
Midbrain includes:
Mesencephalon
Hindbrain includes
Metencephalon & Myencephalon
Metencephalon includes
Pons & cerebellum
Myencephalon includes:
Medulla oblongata
Medulla oblongata: Location & function
Swollen tip of spinal cord
- Nerve impulses arise here:
- Stimulates intercostal muscles & diaphragm makes breathing possible
- Regulates heartbeat
- Regulate the diameter of arterioles thus adjusting blood flow
Pons: function?
Transverse bar-like structure with nerve fibre tracts that are continued into cerebellum
Relay station carrying signals from various parts of the cerebral cortex to the cerebellum.
Nerve impulses coming from the eyes, ears and touch receptors are sent to the cerebellum
Cerebellum: Function
- Coordinates body movements
Cephalon =
Head
Mesencephalon
Mid brain
Corpus callosum
White matter
Communication of right and left hemisphere of cerebrum
What is the largest part of the brain?
Cerebrum
What separates the cerebrum from the cerebellum?
Transverse fissure
What separates the right and left hemispheres of the cerebrum?
Longitudinal fissure
Ridges (in brain) are called
Gyri
Sulci are
Grooves in the brain
Grey and white matter in spinal cord
Grey on inside
White on outside
i.e. White cortex
Grey and white matter in brain stem
Grey on inside
White on outside
i.e. White cortex
Grey and white matter in cerebrum
Grey on outside
White on inside
i.e. Grey cortex
Grey and white matter in cerebellum
Grey on outside
White on inside
i.e. grey cortex
Cerebral cortex
Responsible for conscious experience of sensory input (perception) and conscious direction of body movement
Diencephalon location
Caudal part of forebrain
Rostral to brainstem
Diencephalon anatomy
Unpaired
Contains:
Epithalamus (including pineal gland) - the roof (epi=upn)
Thalamus (largest component)
Hypothalamus -The floor (hypo = under)
Only the most ventral component, the hypothalamus is visible on external surface of brain
Thalamus function
Acts as relay station for sensory information
All sensory pathways (except olfactory) pass through nuclei in thalamus –> cerebrum
Hypothalamus function
Link between nervous system and endocrine glands
Regulating centre for ANS
Metencephalon contains:
Pons and cerebellum
Medulla oblongata location
Myencephalon
What links cerebellum & fore/midbrain?
Pons
Mesencephalon location
Between Pons and diencephalon
Mesencephalon function
Has nerve fibres connecting cerebrum & brain stem
- Vision, hearing & sleep
Metencephalon location & anatomy
Rostral part of hindbrain
Consists of:
Pons (ventrally)
Cerebellum (dorsally)
Roughly spherical
Highly fissured mass
Located in brain
2 large paired hemispheres and a narrow median ridge
Cerebellum
On the ventral surface of the medulla oblongata it has a median fissure (groove) that is continuous with the spinal cord, and either side of this fissure are two prominent longitudinal ridges (nerve fibre tracts) known as ?
the pyramids
What are the ventricles in the brain?
The internal brain cavities
Result from the narrowing neural tube
What are the four ventricles in the brain?
- Lateral ventricles (L & R)
- within cerebral hemispheres
- Third ventricle
- Ventral to the cerebral hemispheres - Fourth ventricle
- Between the cerebellum & medulla oblongata - Mesencephalic aqueduct
- Connects third and fourth ventricles
- Passes through mid brain
What do ventricles contain
CSF
What are meninges?
Connective tissue enclosing CNS & roots of spinal nerves
Meninges function
Protects and nourishes the CNS
Contain CSF
What are the 3 layers of meninges
- Pia mater - Membrane follows the contour of the brain and spinal cord
- Arachnoid - Middle layer is spread web-like over the brain once the dura has been removed
- Dura - tough covering membrane of the CNS –> thick and hard, connected to bone part of skull cap
CSF function
Physically protects the nervous tissue
Chemical buffer
Transports nutrients & removes waste
Shock absorber (high intracranial pressure)
Where is CSF produced?
It is produced continuously by vascular tufts called choroid plexuses located in the brain ventricles
Spinal process?
Where muscles attach
Intumescence
A thickening, swelling of spinal cord
Fissure
A normal groove that divides an organ into lobes and parts
Dorsal sulcus
Little dip in the spinal cord
Ventral fissure
Large groove/dip in spinal cord that goes right up to grey matter
Dorsal horn
Takes in sensory information
Ventral horn
Relays motor information
In spinal cord are nerve tracts white or grey matter?
White matter
Afferent and efferent neurons are found in CNS or PNS?
PNS
Ascending and descending tracts are found in CNS or PNS?
CNS
Dorsal = ascending
Ventral = Descending
Lateral = both
What connects the PNS & the brain?
Spinal cord
PNS consists of:
Spinal nerves
Cranial nerves
Spinal nerve includes:
Dorsal branch
Ventral branch
How many cranial nerves are there?
12
What nervous system has two possible routes of output?
Autonomic nervous system
- Parasympathetic & sympathetic
Sympathetic NS
Excitatory
Prepares the body for activity in critical situations
Fight or flight response
Quick response mobilising system
Both local and mass response
Parasympathetic NS
Dampening system Returning body systems to normal after sympathetic stimulation Rest & digest Feed & breed Localised reaction ONLY!
In sympathetic NS are pre-ganglionic fibres or postganglionic fibres longer
Postganglionic fibres are longer
Vagus nerve
Part of parasympathetic NS
Longets cranial nerve
Nerve passes down the neck with sympathetic trunk forming the vagosympathtic trunk
Attached to carotid arteries
In parasympathetic NS are preganglionic or postganglionic fibres longer?
Preganglionic fibres are longer
Ganglia close to target organs
Where do the vagus nerves arise?
Medulla oblongata
What type of glial cell provides physical support for CNS?
Astrocytes
create structures for neurons to sit in
Ependymal have beer cilia to help
Move CSF around
What type of glial cell is referred to as neural stem cell?
Ependymal cells
Difference between oligodendrocytes and schwann cells?
Oligodendrocytes in CNS & Schwann cells in PNS
Schwann cells are seperate cells
Oligodendrocytes are several elongated projections
The spinal cord has 2 functions:
- Transmission of information
2. Reflex centre
Dermatome
Area on skin innervated by a specific spinal nerve
Where in the brain is the basal ganglia located?
Forebrain - within cerebrum
Brain stem function
Links spinal cord to higher brain regions
Relays sensation input & motor output
Modulate pain
Contributes to consciousness
Brain stem parts:
Medulla oblongata
Pons
Midbrain
Medulla oblongata
Vital cardiac, respiratory, vasomotor reflexes, digestion
Where is the optic chiasma in the brain located?
In the diencephalon
Hypothalamus function
Homeostasis: maintains stability of the internal environment
Where did primitive sensory processing occur?
Thalamus
What part of the brain is responsible for consciousness?
Cerebrum
Outer layer of cerebrum
Cerebral cortex
4 lobes of cerebral cortex?
- Frontal
- Parietal
- Occipital
- Temporal
Frontal lobe (cerebral cortex) function?
Primary motor cortex - controls voluntary skeletal muscle movement
Vocal abilities
Higher mental functions e.g. planning
Parietal lobe (cerebral cortex) function?
Receives and processes sensory input (perception)
Called the somatosensory cortex
Somatosensory (touch) & proprioception (body position) information processed here
What lobe of the cerebral cortex is called the somatosensory cortex?
Parietal lobe
Occipital lobe (cerebral cortex) function ?
Visual processing & vision related function
Temporal lobe (cerebral cortex) function?
Auditory information
Rhinencephalon location
ventral part of all 4 lobes of cerebral cortex
Rhinencephalon function
Olfactory processing
Basal ganglia
Grey matter under cerebral cortex
Regulates body movement and facial expression
Maintains purposeful motor activity
Suppresses useless or unwanted movements
Modifies ongoing activities
Limbic system
Not seperate structure Ring of forebrain structures surrounding brain stem Interconnected parts: - Cerebral cortex - Basal nuclei - Thalamus - Hypothalamus
Emotions, basic survival, behaviour, motivation & learning
What part of the brain is responsible for involuntary responses due to emotions?
Hypothalamus
Hippocampus function
Memory (short term, long term and working)
Amygdala function
Perception and sensation of fear
Conditioned stimulus - i.e. Association of one stimulus with another