Chapter 1 Psychobiology Flashcards
What two parts is the Central Nervous System (CNS) comprised of?
Brain and Spinal Cord
What are the two divisions of the Peripheral Nervous System?
Autonomic and Somatic
What are the divisions of the autonomic nervous system?
Sympathetic and Parasympathetic
How many neurons are in the cerebral cortex?
12-15 billion
How many neurons are in the cerebellum
70 billion
How many neurons are in the spinal cord?
1 billion
What two types of cells comprise the human nervous system?
neurons and glia
What are neurons?
Highly specialized cells that possess electrical excitability, They function to process and transmit cellular signals.
What is a motor neuron?
- Receives excitation through its dendrites and conducts impulses along its axon to a muscle
- Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
- Efferent
- Soma is in the spinal cord
What is a sensory neuron?
Specialized at one end to be highly sensitive to a particular type of stimulation, such as light, sound or touch. neurons that carry incoming information from the sensory receptors to the brain and spinal cord: Afferent.
What is an interneuron/intrinsic neuron?
A neuron that carries nerve impulses from one neuron to another.
- dendrites and axons are completely contained within a structure
What are local neurons?
Neurons that have short axons, only exchange information with close neighbors, and do not produce action potentials.
What are Glial cells?
Greek for “glue”, glial cells provide support and protection for neurons. HSIFDCCC
• hold in place and surround
• supply nutrients & oxygen
• insulate
• form myelin
• destroy & remove decay & debris
• clearance of neurotransmitters & prevent toxic build-up
• can release certain neurotransmitters (e.g., glutamate)
• crucial to development (synaptic plasticity & genesis)
What is the glia to neuron ratio in cerebral gray matter?
3 glial cells for every 2 neurons.
What are the Glia cell types?
Astrocytes, Schwann Cells, Microglia, Oligodendrocytes, and Radial Glia (ASMOR)
Astrocytes are a type of glial cell that…
- synchronize the activity of the axon by wrapping around the presynaptic terminal and taking up chemicals released by the axon
Schwann cells are…
Glia in the PNS that build the myelin sheath that surrounds the axon of some neurons.
Microglia are….
Glia that remove waste material and other microorganisms that may be harmful to the neuron.
Oligodendrocytes are….
Glia in the CNS that build the myelin sheath that surrounds the axon of some neurons.
Radial Glia are….
Glia that guide the migration of neurons, & the growth of axons & dendrites during embryonic development.
Camilo Golgi (1843-1934)
Invented the neuronal cells staining procedure using silver chromate fixed to the neuronal membrane.
Santiago Ramon y Cajal (1852-1934)
Used Golgi’s cell-staining technique to develop the “neuron doctrine”.
- demonstrated that the individual cells comprising the nervous system remained separate but connected to each other by small zones [later called, synapses]
What are Purkinje cells?
Purkinje cells carry information primarily about body movement
- are aligned like dominos forming a 2-D grid
- cell outputs permit comparison of ongoing movement and sensory feedback derived from it
- thus, generates an error correction signal that can modify occurring movements
What are dendrites?
Dendrites are branching fibers lined with synaptic receptors.
- responsible for bringing in information from other neurons
- Dendrites - Sensory
What is the soma?
Cell body:
- contains the nucleus, mitochondria, ribosomes, and other structures found in cells
What is an axon?
A thin fiber of a neuron responsible for transmitting neural impulses to other neurons, glands or muscles:
- Axon - Motor
What is white matter?
Myelinated axons (appear white)
What is gray matter?
Cell bodies that are not myelinated (appear gray)
What are nerves?
Bundles of axons in the PNS
What are tracts?
Bundles of axons in the CNS
What are dendritic spines?
Fibers that further branch out to increase the surface area of the dendrite.
Louis Ranvier (1835-1922)
Discovered gaps in the myelin sheath, later to be named Nodes of Ranvier
- linked with Saltatory conduction
What is myelin?
- Layer that forms around the nerves (protective membrane)
- Quickens the transmission of impulses along nerve cells
What is Multiple Sclerosis
Condition that results from the inflammation and scarring of Myelin:
- immune system attacks oligodendrocytes
- consequence of auto-immune condition
- loss of conduction velocity and results in slowed cognition and limited energy
What does ‘afferent’ mean?
brings information to a structure
What does ‘efferent’ mean?
carries information from a structure
What are the meninges?
three protective membranes that surround the brain and spinal cord
What is the outermost layer of the meninges?
Dura Mater (Hard Mother)
- surrounding the brain and spinal cord
- thick material
What is the middle layer of the meninges?
Arachnoid layer:
- delicate middle
- where blood vessels are located
- where CSF is located
What is the innermost layer of the meninges?
Pia Mater (Soft Mother):
- thin inner membrane
Brain Vascular Bed
- 400 miles of capillaries
- surface area of 100 square feet
What is the circle of willis?
the joining area of several arteries at the bottom (inferior) side of the brain.
What is the Blood Brain Barrier (BBB)?
- a structure that surrounds the brain
- functions to block most non-toxic and toxic substances from entering
- single layer of glial cells that line blood vessels
- allows small, fat-soluble molecules of proper electrical affinity to pass through
Which molecules can pass through the BBB?
Small, uncharged, fat-soluble molecules:
- O2 and CO2 cross easily
- vitamins, psychoactive medication, nicotine, heroin, and marijuana also cross easily
Which molecules can pass through the BBB?
Small, uncharged, fat-soluble molecules:
- O2 and CO2 cross easily
- vitamins, psychoactive medication, nicotine, heroin, and marijuana also cross easily
What is active transport?
Energy-requiring process that moves material across a cell membrane against a concentration difference:
- active transport systems pump glucose and amino acids across the membrane of the BBB
What is Encephalitis?
Inflammation of the brain:
- infection that reaches BBB
- severe and potentially life-threatening
- inflammation leads to brain-swelling, causing: headache, stiff neck, light sensitivity, mental confusion & seizures.
What is primary encephalitis?
Encephalitis where the CNS is invaded; virus or bacteria infects the brain
What is secondary encephalitis?
when the immune system reacts to an infection elsewhere in the body and starts attacking brain cells
What are some infectious sources for encephalitis?
Viral infection: herpesviruses, arboviruses, rabies
Bacterial infection: meningitis, syphilis, lyme disease
Parasitic infection: protozoa, amoeba
What is Cerebral Spinal Fluid (CSF)?
- filtrate of blood produced from ventricles and choroid plexus
- A solution that fills the hollow cavities of the brain and circulates around the brain and spinal cord
- Provides nourishment, cushions, and removes wastes
- circulates within arachnoid layer and exits through arachnoid granulations back to venous blood, into super sagittal sinus
How many Ventricles are in the Ventricular System?
4 Ventricles:
- Lateral Ventricle
- Choroid Plexus
- Third Ventricle
- Fourth Ventricle
How much does the brain weigh?
- 1400 grams
- effective weight is 80 grams due to the buoyancy effect of CSF
