BASIC PRINCIPLES OF BRAIN ORGANISATION AND NEIROANATOMY

Question 1

Brain:

Answer 1

Made up of 86 billion neurons linked by 100 trillion connections

Question 2

Reticular Theory

Answer 2

Early theories of brain organisation, system of neighbouring elements fused in a netlike arrangement or ‘reticulum’

Question 2

Neuron Theory:

Answer 2

Detailed images of neurons and their processes. Neurons are individual elements able to make contact but not continually fused

Question 3

Neurons

Answer 3

• Neurons or cells that are specialised for long-distance electrical signalling and intercellular communication.

Question 4

• Dendrites

Answer 4

are branched projections of neurons that receive signals or electrical impulses (known as action potentials or spikes) from other neurons and propagate these signals to the cell body, or soma, of the neuron.

Question 5

Axons

Answer 5

• Axons are long, slender projections of neurons that conducts electrical impulses away from the cell body or soma.

Question 6

Grey matter

Answer 6

Gray matter refers to any accumulation of cell bodies and neu- ropil in the brain and spinal cord.

Question 7

White Matter

Answer 7

White matter (named for its relatively light appearance, the result of the lipid content of myelin) refers to axon tracts and commissures.

Question 8

nerve cells

Answer 8

Nerve cells are specialized for electrical signaling over long distances

Question 9

Glial Cells

Answer 9

glial cells support the signaling functions of nerve cells rather than generating electrical signals them- selves. glia are essential contributors to repairing nervous system damage, acting as stem cells in some brain areas where they promote regrowth of damaged neurons in regions where re- generation can usefully occur

Question 10

three types of differentiated glial cells

Answer 10

three types of differentiated glial cells in the mature nervous system: astrocytes, oligodendrocytes, and microglial cells.

Question 11

astrocytes

Answer 11

astrocytes, are restricted to the central nervous system. A ma- jor function of astrocytes is to maintain, in a variety of ways, an appropriate chemical environment for neuronal signaling, including formation of the blood-brain bar- rier. In addition, recent observations suggest that astrocytes secrete substances that influence the construction of new synaptic connections.

Question 12

Oligodendrocytes,

Answer 12

Oligodendrocytes, which are also restricted to the central nervous system, lay down a laminated, lipid-rich wrapping called myelin around some, but not all, axons. Myelin has important effects on the speed of the transmission of electrical signals. In the peripheral nervous system, the cells that provide myelin are called Schwann cells.

Question 13

Microglial cells

Answer 13

Microglial cells share many properties with macrophages found in other tissues: They are primarily scavenger cells that remove cellular debris from sites of injury or normal cell turnover. In addition, microglia, like their macrophage counterparts, secrete signaling molecules—particularly a wide range of cytokines that are also produced by cells of the immune system. That can modulate local inflammation and in- fluence whether other cells survive or die.

Question 14

Afferent and efferent neurons

Answer 14

Nerve cells that carry information from the periphery toward the brain or spinal cord (or deeper centrally within the spinal cord and brain) are called afferent neurons; nerve cells that carry information away from the brain or spinal cord (or away from the circuit in question) are efferent neurons.