B&C: Brain Anatomy Flashcards
There are roughly as many ______ in the brain as there are neurons. Give 4 known functions for this cell
Glial cells provide structural support, carry out other roles in the nervous system, such as helping to form the blood–brain barrier and aiding in the speed of information transfer. They also appear to have a previously unrecognized role in modulating neural activity.
What are the three main types of glial cells in the central nervous system?
Astrocytes, oligodendrocytes and microglial cells
which glial cell is linked to modulating neural activity and what study findings support this?
In vitro studies indicate that astrocytes respond to and release neurotransmitters and other neuroactive substances that affect neuronal activity and modulate synaptic strength. More recently, in vivo studies found that when astrocyte activity is blocked, neural activity increases.
Where are astrocytes found?
they surround neurons and are in close contact with the brain’s vasculature.
Where do astrocytes make contact with blood vessels and what function does this allow them to carry out?
at specializations called end feet, which permit the astrocyte to transport ions across the vascular wall. The astrocytes create a barrier, called the blood–brain barrier (BBB), between the tissues of the central nervous system and the blood.
What does this BBB do?
The BBB restricts the diffusion of microscopic objects (such as most bacteria) and large hydrophilic molecules in the blood from entering the neural tissue, but it allows the diffusion of small hydrophobic molecules such as oxygen, carbon dioxide, and hormones.
What are the role of microglial cells?
Microglial cells, come into play when tissue is damaged. They are phagocytes, literally devouring and removing damaged cells.
Unlike many other cells in the body, glial cells can _______ even in adults
Proliferate (multiply rapidly)
What else do glial cells form in the body? How does this differ by location?
Glial cells are also the myelin formers in the nervous system. In the central nervous system, oligodendrocytes form myelin; in the peripheral nervous system, Schwann cells carry out this task
How do these glial cells form this myelin?
by wrapping their cell membranes around the axon in a concentric manner during development and maturation. The cytoplasm in that portion of the glial cell is squeezed out, leaving primarily the lipid bilayer of the glial cell sheathing the membrane.
Roughly how many synapses does a typical cortical neuron have and how does this differ from a purkinje neuron?
A typical cortical neuron has between 1,000 and 5,000 synapses, while a Purkinje neuron may have up to 200,000 synapses.
What is meant by convergence and divergence in the nervous system?
The axons from these input neurons can originate in widely distributed regions. Thus, there is tremendous convergence in the nervous system. There is also divergence, in which a single neuron can project to multiple target neurons in different regions
Give the name for connections between two cortical regions and other areas (How they are named)
Connections between two cortical regions are referred to as corticocortical connections, following the convention that the first part of the term identifies the source and the second part identifies the target. Inputs that originate in subcortical structures such as the thalamus would be referred to as thalamocortical connections; the reverse are corticothalamic, or more generally, corticofugal projections
What are meant by neural circuits?
Groups of interconnected neurons that process specific kinds of information
What basic features do neural circuits share?
They take in information (afferent inputs), they evaluate the input either at a synapse or within one or a group of neurons (local circuit neurons), and they convey the results to other neurons, muscles, or glands (efferent outputs).
What can happen in neural circuits during development and learning?
The patterns of activation within a neural circuit can change
What do neural circuits combine and form? Give and example
Neural circuits, in turn, can be combined to form neural systems i.e the visual system
What two main systems exist within the PNS?
the somatic motor system that controls the voluntary muscles of the body and the autonomic motor system that controls visceral functions. (controlling the involuntary action of smooth muscles, the heart, and various glands.)
What two subdivisions exist in the autonomic system? what transmitter does each system utilise?
the sympathetic (norepinephrine) and parasympathetic (acetylcholine) branches
How do these two branches work together ?
Antagonistically; activation of the sympathetic system increases heart rate, diverts blood from the digestive tract to the somatic musculature, and prepares the body for action (fight or flight) by stimulating the adrenal glands to release adrenaline. In contrast, activation of the parasympathetic system slows heart rate, stimulates digestion, and in general helps the body with functions germane to maintaining the body.
What are both the brain and spinal cord covered in
Three protective membranes—the meninges. ( as well as the cerebrospinal fluid, CSF and bone)
Name each membrane of the CSF
The outer membrane is the thick dura mater; the middle is the arachnoid mater ; and the inner and most delicate is the pia mater, which firmly adheres to the surface of the brain.
Where is the CSF located?
the subarachnoid space between the arachnoid membrane and the pia mater, as well as the brain ventricles, cisterns and sulci, and the central canal of the spinal cord
describe two of the most common organisational clusters of neurons in the CNS?
In a Nucleus ( a relatively compact arrangement of nerve cell bodies and their connections, ranging from hundreds to millions of neurons, with functionally similar inputs and outputs.) and in a layer such as the cerebral cortex of the brain which in contrast has billions of neurons arranged in layers of thin sheets, folded across the surfaces of the cerebral hemispheres
Contrast white and grey matter in location and composition
When we look at a slice of the brain, we see the cortex as a thin grayish layer overlaying the whitish in- terior. The gray matter is composed of neuronal cell bodies, and the white matter consists of axons and glial cells
How are axons much like nerves in the PNS?
these axons are grouped to- gether in tracts that run in association tracts from one re- gion to another within a hemisphere, or may cross into the other hemisphere
What are tracts that cross into the other hemisphere called?
Commissures
What are projection tracts?
tracts that run from the cerebral cortex to the deeper subcortical structures and the spinal cord
What is evolutionarily the youngest part off our brains?
Prefrontal cortex
How is the spinal cord divided? How does this relate to nerves?
into 31 segments. Each segment has a right and a left spinal nerve that enters and exits from the vertebral column through openings called foramen.
What is contained in these spinal nerves?
Each spinal nerve has both sensory and motor axons: one afferent neuron carries sensory input through the dorsal root into the spinal cord, and the other efferent neuron carries motor output through the ventral root away from it.
Give the different names for different sides of the brain
Rostral= front Caudal= back Dorsal= top Ventral=Bottom Lateral= sides
The brain has no skeletal or structural support yet weighs a considerable amount, how does it overcome this potential difficulty?
the brain is immersed in a fluid called cerebrospinal fluid (CSF). This fluid allows the brain to float to help offset the pressure that would be present if the brain were merely sitting on the base of the skull.
What other function does CSF have
CSF also reduces shock to the brain and spinal cord during rapid accelerations
or decelerations, such as when we fall or are struck on the head.
