Exam 3 Review KEY, BIOL 255 SI

Exam 3 Review KEY, BIOL 255 SI

3A

1) The nervous system is made up of the CentralNervousSystem (CNS) which contains the brain and the spinalcord and the PeripheralNervousSystem (PNS) which is all nerves outside of the brain and spinal cord.

2) Sensoryneurons that bring information to the brain are referred to as afferent, and Motor neurons that carry information away from the brain are efferent.

3) The CNS neuroglia protects and supports. In the CNS astrocytes are star shaped cells which attach neurons to blood vessels and form the bloodbrain barrier, which controls the neuron environment.

4) In the CNS oligodendrocytes extend processes, to form myelin sheath, the nodes of ranvierare further apart.

5) In the Peripheral Nervous System (PNS) the schwann cells, also called neurolemmocytes, form the myelin sheath, where as, the satellite cells support neurons of ganglia.

6) The smaller / bigger the size of the nerve fiber, the slower / faster the speed of nerve impulse. And the less / more myelin which means larger diameter of the nerve fiber the greater the speed.

7) Bundles of afferent and efferent neurons outside the CNS but inside the PNS are referred to as nerves. While bundle of afferent and efferent neurons within the CNS are referred to as tracts.

8) In the PNS the Schwann cells wrap around the axon and are referred to as the neurilemma. Between adjacent neurilemmas are spaces made up of neurofibril nodes and these nodes are referred to as the Nodes of Ranvier. The speed of the stimulus increases as it jumps from node of ranvier to node of ranvier.

9) Multipolar neurons have several dendrites and one axon extended from the cell body which is the most common type.

10) The bipolar neuron has one dendrite and one axon with the cell body in between, these are rare and found only in specialized sense organs.

11) Most synapses, are chemical synapses in which the neurotransmitter is secreted by the pre-synaptic cell which then diffuses across the synaptic cleft to the post-synaptic cell. This occurs in a one way direction and is slower than the action potential.

3B

12) Cerebrospinal fluid (CSF) is a watery, clear solution similar to blood plasma, although it contains less protein and has different ions. Its function is to cushion, gives buoyancy prevents delicate brain matter from being crushed, protects, nourishes and carries chemical signals through it.

13) In Spinal Cord and Spinal Nerves the white matter is aggregations of myelinated axons and myelin is white. While the gray matter is make up of cell bodies or dendriteswhich is unmyelinated fibers.

14) In the spinal cord, the posterior white column or funiculus contains sensory input which is received from the PNS to the brain, on tracts that ascend into the brain bringing sensations of touch, pressure and body movement.

15) The anterior and lateral white columns or funiculus contain sensory motor input which travel on ascending tracts to the thalamus, where sensory input is sorted such as pain and temperature, and the cerebellum where coordinate movements like walking and motor output are sorted then the tracts descend to motor neurons which eventually stimulate muscles.

16) So when you think about the spinal cord, everything towards the

front or anterior or ventral is associated with motor neurons or efferent neurons.

As where everything in the

back or posterior or dorsal is associated with sensory neurons or afferent neurons.

3C

17) The cerebral hemispheres function differently:

18) The thalamus gland is the relay station for sensory input, except for smell, to the cerebrum. Its role is in mediating sensation, motoractivities,cortical arousal, learning, and memory. It has four groups of nuclei on each side: anterior, ventral, dorsal, and posterior.

3D

19) In the Autonomic Nervous System (ANS) motor neurons innervate the viscera of smooth and cardiac muscle and also glands, as it regulates the viscera to ensure homeostasis during body activities.

20) In the Autonomic Nervous System the neurotransmitters used are as follows:

Parasympathetic pre ganglionic neurons use - acetylcholine

Parasympathetic post ganglionic neurons use – acetylcholine

In the:

Sympathetic pre ganglionic neurons use – acetylcholine

But:

Sympathetic POST ganglionic neurons use – Norepinephrine.

21) In the developmental aspects of the PNS sensory receptors atrophy with age and muscle tone lessens but peripheral nerves remain viable throughout life unless subjected to trauma.

3E

22)Sensory receptor also classed by location are the Proprioceptors which respond to the degree of stretch of organs and are found in skeletal muscles, tendons, joints, ligaments, and connective tissue coveringsof bones and muscles and are constantly “advising” the brain of one’s movements and body position.

23)Simple Receptors can beunencapsulated which have free dendritic nerve endings and respond chiefly to temperature and pain such asMerkel discs and hair follicle receptors while

Encapsulated receptors which are surrounded by tissue. Examples would beMeissner’s andPaciniancorpuscles .

24)Endoneuriumis the nerve covering around individual fibers. Fascicles are groups of nerve fibers wrapped in perineuriumand the epineurium is around entire nerve.

3F

25)In the Olfactory Pathway, receptor cells synapse with olfactory bulb neurons, which process odor signals and send them to theOlfactory cortex, theHypothalamus, the amygdala, and limbic system but totally by pass the Thalamus.

26)The tongue has three main papillae types wherefiliform, fungiform, and circumvallate are found but only thefungiform and circumvallate papillae contain taste buds.

27)In the sensory tunic of the retina the photoreceptors cells are made up of rods which respond to dim light and are used for peripheral vision, while cones respond to bright light andhave high-acuity color vision and are found in the maculalutea where they are concentrated in the foveacentralis, where no rodsare found.

28)The cochlea is divided into three chambers:

– Scala vestibuliis connected to vestibule - ↑and ↓pressure in perilymph

-Scala media (cochlear duct) - ↑and ↓pressure in endolymph

-Scala tympani- ↑and ↓pressure in perilymph.

29)Scala vestibuli connected to scala tympani at helicotrema in the cochlea where low pitch sounds detected near helicotrema, while high pitch sounds detected near oval window.

30)Ceruminous glands in your external ear produce ear wax for waterproofing.