Unit 2

What is the somatosensory?

responsible for processing sensory information from the body, including touch, temperature, pain, and proprioception. It involves a network of receptors, pathways, and brain regions that allow us to perceive and interpret sensory stimuli.

What is dual innervation?

The phenomenon where organs receive signals from both the sympathetic and parasympathetic branches of the autonomic nervous system, allowing for coordinated responses.

Where do the cell bodies of unipolar neurons reside?

Together in areas known as ganglia

A motor neuron is a multipolar structure.

True or False

True, it has multiple extensions.

Each neuron has multiple synapses with other neurons to either excite or inhibit the cell

True or False

as the communication points in the nervous system, allowing for complex processing of information.

What is the Refractory period?

The refractory period is the time after an action potential during which a neuron is unable to fire another action potential. It ensures that signals travel in one direction and helps to reset the neuron's membrane potential.

Why is there an absolute refractory period?

The absolute refractory period occurs because sodium channels that open during an action potential become inactivated and cannot reopen until the membrane potential returns to a resting state. This prevents any subsequent action potentials from occurring, ensuring the unidirectional flow of nerve impulses. This lasts 1ms

What can occur during relative refractory?

a neuron can fire another action potential, but only if the stimulus is stronger than usual. This is due to some sodium channels being reset while potassium channels are still open.

How are most muscles connected?

Across a Joint and they work in antagonistic pairs

If both muscles in a pair are contracted it is known as what?

An isometric contraction and there is no action.

If both muscles are relaxed then,

there is no action

What is extension?

Increasing the angle

What is flexion?

Decreasing the angle

What are helper muscles to main muscles?

Synergists

What is the origin?

The point of attachment of a muscle with the least movement

What is the insertion?

The point of attachment for a muscle where there is the most movement

What are flexion and extension in the ankel called?

Dorsiflexion and plantarflexion

What is adduction and abduction?

flexion and extension of the limbs towards and away from the midline of the body.

What is rotation towards the midline called?

Medial rotation

What is rotation away from the midline called?

Lateral rotation or external rotation.

What is medial and lateral rotation in the lower arm called?

Pronation and supination

What is medial and lateral rotation in the ankle called?

Inversion and eversion.

What is elevation and depression?

The movement of the body part superiorly and inferiorly respectively. The shoulder girdle and the mandible

What is retraction and protraction?

Retraction is the movement of a body part posteriorly, while protraction is the movement anteriorly, commonly referring to the shoulder girdle and mandible

What is the flexor of the neck

sternocleidomastoid

What is the flexor of the upper arm?

pectoralis major

What is the flexor of the lower arm?

Biceps brachii

What is the flexor of the Torso

Rectus Abdominus and transverse abdominus, external/internal obliques

What is the flexor of the upper leg/hip?

Iliopsoas

What is the flexor of the Knee/Lower Leg?

Quadriceps femoris (Rectus femoris, vastus lateralis, vastus intermedius, vastus medialis)

What is the extensor of the neck?

splenius capitis

What is the extensor of the upper arm?

latissimus dorsi

What is the extensor of the lower arm?

triceps brachii

What is the extensor of the deep back?

Spinalis, Longissimus, Iliocostalis

What is the extensor of the hip/upper leg

Gluteus maximus

What is the extensor of the knee/lower leg?

“hamstrings”; Bicep femoris, semimembranosus, semitendinosus

What does the absolute refractory period cause?

This period prevents the initiation of another action potential, ensuring that the neuron reestablishes its resting membrane potential after an action potential. This makes the neuron depolarize in a single direction, down the axon and not back towards the cell body.

What is the grey matter in the PNS and CNS?

In the PNS it is the ganglia, which are clusters of neuron cell bodies, while in the CNS it consists of neuronal cell bodies, dendrites, and unmyelinated axons, forming functional areas like the cortex and nuclei.

What is the white matter in the PNS and CNS?

In the PNS, it consists of bundles of myelinated axons, forming nerves, while in the CNS, it consists of myelinated axons called tracts that connect different regions of grey matter, facilitating communication between neurons.

What is not myelinated?

Cell bodies of neruons, short dendrites, and short axons

What are microglia?

the immune cells of the central nervous system, responsible for maintaining homeostasis, responding to injury, and clearing cellular debris. They are macrophages

What are ependymal cells?

The cells that line the brain and central canal of the spinal cord, and help make/secrete Cerebrospinal Fluid (CSF). The apical cilia circulate it within and outside CNS, the CNS floats in the CSF within the meninges

What is the equivalent of the peripheral nervous system schwann cells in the central nervous system?

Oligodendrocytes are the equivalent cells.

What are satellite glial cells?

are supportive cells found in the peripheral nervous system that surround neuron cell bodies in ganglia. They help regulate the microenvironment around neurons, providing nutrients and maintaining homeostasis. They are equivalent to astrocytes in the central nervous system.

What do neurolemmocytes and oligodendrocytes do?

Neurolemmocytes, also known as Schwann cells, are responsible for myelinating nerve fibers in the peripheral nervous system, which enhances the speed of electrical signal conduction. Oligodendrocytes perform a similar function in the central nervous system, myelinating multiple nerve fibers to improve signal transmission.

What are ependymal cells?

Ependymal cells are specialized glial cells that line the ventricles of the brain and the central canal of the spinal cord. They play a crucial role in the production and circulation of cerebrospinal fluid (CSF), contributing to the brain's homeostasis.

What are microglia?

the primary immune cells of the central nervous system, acting as the first line of defense against pathogens and removing damaged neurons or debris through phagocytosis. They also participate in inflammatory responses and help maintain homeostasis in the brain.

What is the astrocyte?

The most abundant glial cell type and is important to form the blood brain barrier. They have attachments to capillaries and other support structures keeping the neurons in the correct spatial configuration.

What do astrocytes control?

The transport of nutrients into neurons to maintain ion balance. Helping to repair injuries to neurons

What are neuroglia?

also known as glial cells, are non-neuronal cells in the central and peripheral nervous systems that provide support, protection, and nutrition to neurons. They play essential roles in maintaining homeostasis, forming myelin, and aiding in signal transmission. There are 2 in the PNS and 4 in the CNS

Are spinal nerves unipolar, bipolar or multi-polar?

uni-polar

Are cranial nerves unipolar, bipolar or multi-polar?

Bipolar or unipolar

What is a tract?

Bundles of bundles of myelinated axons of interneirons in the CNS

What is a nerve?

The bundles of bundles of mylelinated processes in the PNS

Nerves are surrounded in Dense Connective Tissue, what is the Epineurium?

The outermost layer of dense connective tissue that encases the entire nerve, providing protection and support.

Nerves are surrounded in Dense Connective Tissue, what is the Perineurium?

The layer of connective tissue surrounding individual fascicles of nerve fibers, providing additional protection and support.

Nerves are surrounded in Dense Connective Tissue, what is the Endoneurium?

The innermost layer of connective tissue that surrounds individual nerve fibers, providing insulation and support.

What makes nerves look white?

The presence of myelin, a fatty substance that insulates nerve fibers and increases the speed of signal transmission.

Cell bodies of neurons, short dendrites, and short axons are myelinated or not myelinated

not myelinated

What are long processes in the PNS?

A unipolar neuron dendrite and motor neuron axon

The long axons of interneurons are myelinated or not myelinated?

myelinated

What makes a nerve look grey?

If it is unmyelinated

What is saltatory conduction?

Saltatory conduction is the process by which action potentials jump from one node of Ranvier to another along myelinated axons, increasing the speed of neural transmission.

Why does myelin greatly speed up the aciton potential conduction?

It is an electrical insulator meaning that unlike unmyelinated axons which have velocities of 0.5 to 10m/s, myelinated axons move up to 150 m/s

What type of substance is myelin?

A phospholipid that layers upon itself

What are nodes of Ranvier?

Small gaps in the myelin sheath where ion channels are concentrated, facilitating rapid conduction of action potentials between segments of myelinated axons.

How many neurons are utilized in the somatic pathway, motor neurons?

One motor neuron

In the parasympathetic pathway how many neurons are utilized?

Two neurons, consisting of a preganglionic neuron and a postganglionic neuron.

In the sympathetic pathway how many neurons are used?

Two neurons, consisting of a preganglionic neuron and a postganglionic neuron.

What is the vegatative autonomic system?

the parasympathetic autonomic nervous system that conserves energy and promotes relaxation. This causes bronchoconstriction, decreased heart rate and increased digestion

What is the fight, flight, or fright response autonomic system?

The sympathetic autonomic nervous system that prepares the body for stressful situations, leading to increased heart rate, dilated airways, and reduced digestive activity.

What is the idea of dual innervation?

The concept that many organs receive input from both the sympathetic and parasympathetic autonomic nervous systems, allowing for balanced functions in response to various stimuli.

What do we mean when we say that the sympathetic nervous system is thoracolumbar?

It refers to the origin of the nerves, which arise from the thoracic and lumbar segments of the spinal cord, while the parasympathetic originates from the brain and sacral spinal cord.

What do we mean when we say that the parasympathetic nervous system is craniosacral?

It refers to the origin of the parasympathetic nervous system's nerves, which arise from the brainstem and sacral segments of the spinal cord, while the sympathetic system originates from the thoracic and lumbar regions.

In the parasympathetic nervous system which neuron is long the pre or post ganglion neuron?

The preganglionic neuron is long, extending from the central nervous system to the ganglia located near or within the target organs, while the postganglionic neuron is shorter.

What is the parasympathetic ganglion considered?

The terminal ganglion and is connected to smooth muscle, cardiac muscle or a gland.

In the sympathetic ganglia what is the ganglia known as?

The chain ganglia or paravertebral ganglia or pre-vertebral ganglia that are located close to the spinal cord and are part of the sympathetic nervous system.

If a nerve is connected to smooth muscle, cardiac muscle, or a gland how many nerves are in that pathway?

At least 2

If a nerve is connected to skeletal muscle how many nerves are in that pathway?

One nerve, as it directly innervates skeletal muscle.

What is a descending tract and an ascending tract?

A descending tract is a bundle of nerve fibers that convey motor commands from the brain to the body, while an ascending tract transmits sensory information from the body to the brain. These tracts are essential for the coordination of movement and the processing of sensory information in the central nervous system.

How does an antagonistic pair work?

involves two muscles that work in opposition to each other; when one muscle contracts, the other relaxes, allowing for coordinated movement. This mechanism is crucial for actions such as bending and straightening limbs.

How are interneurons and motor neurons in the somatic nervous system both inhibitory and excitatory in function?

Interneurons can facilitate or inhibit the transmission of signals between sensory and motor neurons, while motor neurons primarily convey excitatory signals to muscle fibers for contraction, but can also have inhibitory roles in certain reflex arcs. In other words the interneuron decides if the signal should be passed on or blocked, helping to regulate reflexes and other neural pathways.

true or false

Over 99% of all connections are polysynaptic

This statement is true, as polysynaptic connections involve multiple neurons and are essential for complex reflexes and processing in the nervous system.

What is an example of a reflex arc working with excitatory and inhibitory function.

A stimulus at the tendon of the knee (a stretch receptor) transmits a signal that stimulates the contraction of the quadriceps extensor (monosynaptic), while simultaneously inhibiting via an inhibitory interneuron the opposing hamstring muscles. This leads to extension of the lower leg.

Is grey matter in the CNS inside or outside of the spinal cord?

Grey matter is located inside the spinal cord, surrounded by white matter. The tracts which are the myelinated axons surround the grey matter which allows the signal to disperse outward.

What is the design of a monosynpatic system?

A sensory neuron synapsing directly with a motor neuron, an actionpotential in goes to the excitatory synapse generating an action potnetial out to an effector (muscle)

Is the dorsal or ventral root the sensory pathway?

The dorsal root is the sensory pathway, carrying sensory information from the peripheral nervous system to the central nervous system.

Is the dorsal or ventral root the motor pathway?

The ventral root is the motor pathway, carrying motor information from the central nervous system to the skeletal muscles.

Where is the spunal cord run?

From the Brain stem to the 2nd Lumbar

What is the Cauda Equina?

a bundle of spinal nerves and nerve roots that extends from the lower end of the spinal cord, specifically below the 2nd lumbar vertebra, resembling a horse's tail.

What occurs at the dorsal horn of the spinal cord

is the processing of sensory information, as it contains sensory neurons that receive input from the body.

What is the Dorsal portions of the lateral horn do?

They are involved in autonomic functions, specifically controlling involuntary processes like heart rate and blood pressure through sympathetic output. The viscerosensory nuclei

What is the ventral portions of the lateral horn?

are involved in motor functions, particularly controlling voluntary movements through somatic motor output to skeletal muscles. The visceromotor nuclei

What is the ventral horn inolved in?

It is involved in motor functions, facilitating communication from the spinal cord to skeletal muscles for voluntary movement. The somatomotor nucleiu

The corticospinal tract is what?

A major neural pathway that conducts motor signals from the cerebral cortex to the spinal cord, facilitating voluntary motor control over the body's muscles. It is a descending tract.

What is the ascending tract?

A neural pathway that carries sensory information from the spinal cord to the brain, enabling perception and response to stimuli. It conducts afferent signals.

There are multiple distinct brain areas what is the telencephalon?

The telencephalon is the largest part of the brain, encompassing regions such as the cerebral cortex, basal ganglia, and is involved in functions like cognition, sensory perception, and voluntary movement.

There are multiple distinct brain areas what is the diencephalon?

a region of the brain located between the cerebrum and the brainstem, including structures such as the thalamus and hypothalamus, and is crucial for functions like sensory relay and hormone regulation.

There are multiple distinct brain areas what is the mesencephalon?

The mesencephalon, or midbrain, is a key region of the brain located above the pons, involved in vision, hearing, motor control, and the regulation of sleep-wake cycles.

There are multiple distinct brain areas what is the rhomencephalon?

The rhombencephalon, or hindbrain, is the portion of the brain located below the midbrain, comprising structures like the cerebellum and medulla oblongata. It plays vital roles in coordination, balance, and autonomic functions like breathing and heart rate.