L23 & 24: Central Nervous System and Control Flashcards
Which organ exerts centralised control over the other organs?
Brain
What is a benefit of centralised control?
Allows rapid and coordinated responses to changes in environment
How does the brain act on the rest of the body?
1) Generating patterns of muscle activity
2) Driving secretion of hormones
Why does sophisticated purposeful control of behaviour require the brain?
Complex sensory inputs require the information-integrating capabilities of the brain.
(It can understand and combine multiple sensory inputs)
What are the 4 functions of glial cells?
1) To surround neurons and hold them in place
2) To supply nutrients and oxygen to neurons
3) To insulate one neuron from another
4) To destroy pathogens and remove dead neurons
50% of CNS is made up of neuroglia, the other 50% is neurones. Where would tumours occur in adults? Is this different in children?
In adults, tumours occur in the neuroglia because adult neurones don’t divide. In children, they can occur in the neurones because their neurones are dividing as brain development takes place
How does cerebral spinal fluid provide protection for the brain?
Acts as a cushion to lessen impact of blow to the head
Where is the occipital lobe located?
To the rear of the brain, beneath the occipital bone of the skull
Where is the parietal lobe located?
On the side of the brain, beneath the parietal bone of the skull
Where is the frontal lobe located?
At the front of the brain, beneath the frontal bone
What are neuroglia?
Non-neuronal cells that support the brain
e.g. maintain homeostasis, form myelin, support and protect neurones
What are the 6 types of neuroglia?
- Satellite cells
- Schwann cells
- Oligodendrocytes
- Astrocytes
- Microglia
- Ependymal cells
What is the role of satellite cells?
- Surround neuron cell bodies in ganglia
- Regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
What is the role of Schwann cells?
- Surround axons in peripheral nervous system (PNS)
- Responsible for myelination of peripheral axons
- Participate in repair process after injury
What is the role of Oligodendrocytes
- Myelinate central nervous system (CNS) axons
- Provide structural framework
What is the role of astrocytes?
- Maintain blood-brain barrier
- Provide structural support
- Regulate substance concentrations
- Absorb and recycle neurotransmitters
- Form scar tissue after injury
What is the role of microglia?
- Remove cell debris, wastes, and pathogens by phagocytosis
What is the role of ependymal cells?
- Line ventricles (brain) and central canal (spinal cord)
- Assist in producing, circulating, and monitoring cerebrospinal fluid
What type of cell forms the choroid plexus, where cerebrospinal fluid is produced?
Ependymal cells
Which cells line the ventricles (brain) and central canal (spinal cord)?
Ependymal cells
Ependymal cells are involved with a fluid called cerebrospinal fluid. This fluid surrounds the brain and spinal cord; what are its functions?
- Protection - acts as a cushion for the brain
- Buoyancy - relieves pressure on the brain stem by floating the brain
- Excretion - CSF flows in a one-way system, and carries waste and toxins away from the brain
- Endocrine medium for the brain - transports hormones around the brain
Fill in the gap:
In early development/childhood, ependymal cells are ciliated. By adulthood, ciliation is limited to __?__.
the ventricles
True or false:
The main role of ependymal cells is sensory
True (e.g monitoring the composition of the CSF)
Fill in the gap:
In adults, the ependymal contains __?__ that can divide to produce additional neurones
stem cells
True or false: Ependymal cells have slender processes which contact other neuroglia, their role is unknown.
True
Which are the largest and most numerous of central nervous system neuroglia?
Astrocytes
Do dissolved compounds in blood have free access to the cerebrospinal fluid?
No, access is regulated by blood brain barrier (which is formed by endothelial cells and maintained by astrocytes)
What is the blood brain barrier comprised of?
Endothelial cells that form the blood vessels. Because they are leaky, astrocytes wrap around the capillaries to plug any holes.
How do astrocytes help in the structure of the CNS?
- Create cytoskeleton framework for neurons to build on
2. Build structures that prevent further harm to damaged neural tissue
Why is important to keep axons isolated from each other? What cells help with this?
To prevent cross firing. Oligodendrocytes and Schwann cells
What is the difference between Schwann cells and oligodendrocytes?
Schwann cells myelinate axons in the PNS and oligodendrocytes myelinate axons in the CNS. Schwann cells wrap their bodies around a single axon; oligodendrocytes have many processes that reach out to axons, allowing them to myelinate multiple axons at once.
What does myelination do to the speed of impulse transmission?
Increases transmission speed
You see a glial cell with many processes. Some are connected to a capillary while its other processes are connected to neuron axons. Which type of glial cell are you observing?
Astrocyte.
Astrocytes provide a link between the vasculature and neurons, transporting glucose and other substances out of the bloodstream
What is the main role of myelin?
The main role of myelin is to mediate rapid saltatory propagation of action potential between Nodes of Ranvier, thereby facilitating neuro-transmission
Which glial cells are immune effectors in the CNS?
Microglia
Which demyelination condition is autoimmune brought on by viral infection?
Guillain-Barre syndrome
How does diphtheria cause demyelination?
Destroys Schwann cells
Which demyelination condition affects axons in optic nerve, brain and spinal cord?
Multiplesclerosis
Which of the glial cells is responsible for CSF production?
Ependymal