Chapter 5: The Central Nervous System

One of the major regulatory systems alongside the nervous system. Regulates activities that require duration rather than speed, such as growth. It is especially important in controlling the concentration of nutrients and, by adjusting kidney function, controlling the volume and electrolyte composition of the ECF.

Endocrine system

Both are “___”, with the nervous system sending electrical signals through distinct, highly organized pathways. These pathways have interconnected parts

wired

Which system can be compared to the nervous system? Exocrine or Endocrine

Endocrine

The nervous system transmits electrical impulses to ___ and the ___

Skeletal muscles; exocrine glands

The endocrine system secretes hormones (___) into the circulating blood to distant sites in the body

chemical messengers

Endocrine ___ are not connected, they are scattered throughout the body.

glands

Each ___ has a close anatomic relationship to its target cells. It has a narrow range of influence

neuron

A neuron releases a specific ___ to a specific target cell. The target cells have specific receptors that bind to the ___ secreted by the neuron. Although that neuron can potentially signal other cells, it is limited to the target cells in close proximity.

neurotransmitter

A group of endocrine cells secretes a specific ___ into the blood. Although the ___ is circulated throughout the body, only specific target cells have receptors for a specific ___. A ___ cannot influence all body cells, just the target cells with receptors that bind to that ___.

hormone

The nervous system coordinates rapid, precise response. Its signal is an action potential. The duration of this signal is ___. The target cells are skeletal muscle and glands

short

The endocrine system controls activities of ___ duration. This system requires a flow of blood to send a message. The effect of a hormone lasts longer.

longer

The nervous and endocrine system are interconnected functionally. Often they influence the same body process, such as the ___. Neuroendocrinology is the study of the relationships between these two systems

rate of heartbeat

The nervous system has two branches: ___ and ___

Central; peripheral

The ___ consists of the brain and spinal cord

CNS

The __ has two main divisions. The afferent (sensory) division (sensory) and efferent (motor) division.

PNS

The ___ division sends information to the CNS

Afferent (sensory)

The ___ division sends information away from the CNS and to effector organs

Efferent (motor)

The efferent (___) system consists of two systems. The somatic and autonomic nervous system.

motor

The ___ nervous system signals skeletal muscles

somatic

The ___ system signals smooth and cardiac muscles, plus glands.

autonomic

Draw nervous system and divisions diagram

Draw nervous system and divisions diagram

There are three classes of neurons. Afferent, efferent, and ___

interneuron

An ___ neuron sends signals towards the CNS. It generates action potentials from sensory receptors at its peripheral end. It has a long axon and is found mainly in the PNS

afferent

An ___ neuron sends signals away from the CNS to an effector organ. It has a long peripheral axon in the PNS.

efferent

An ___ is found entirely within the CNS. It lies between afferent and efferent neurons.

interneuron

Draw afferent, efferent, interneuron diagram.

Draw afferent, efferent, interneuron diagram.

___ do not send signals. They support interneurons (also called internuncial neurons) physically, metabolically, and functionally. There are four main kinds: astrocyte, oligodendrocyte (microglia, and ependymal)

Glial cells

An ___ has many functions. It holds neurons together, guides neurons during development, establishes a blood-brain barrier, repairs brain injuries, plays a role in neurotransmitter activity, and takes up excess K+ from the brain ECF.

astrocyte

The ___ forms myelin sheaths around axons in the CNS.

oligodendrocyte

Broad category of immune cells that protect the body by engulfing and destroying harmful foreign particles, microbes, and dead cells

Phagocytes

Large, tissue-bound phagocytes

Macrophages

___ are the immune defense cells of the CNS. They are scavengers (modified macrophages)

Microglia

___  line the internal, fluid filled cavities of the CNS. The cells lining the ventricles help form cerebrospinal fluid (CSF). Contributes to the flow of CSF through the ventricles

Ependymal cells

The CNS is protected several ways. The ___ encloses the brain. The ___ encloses the spinal cord.

Cranium; vertebral column

Three membranes, the ___, wrap the CNS. From the outermost to the innermost layer they are the dura mater, arachnoid mater, and the pia mater. (mater ~ mother / protective)

meninges

The ___ is a tough, inelastic covering that consists of two layers (periosteal and meningeal). Usually, these layers adhere closely, but in some regions they are separated to form blood filled cavities, dural sinuses.

dura mater

Blood filled cavities that exist in some regions in between periosteal and meningeal.

Dural sinuses

___ sinuses are the large cavity version of dural sinuses.

Venous sinuses

___ (oxygen poor) blood draining from the brain empties into these sinuses to be returned to the heart. CSF also reenters the blood at one of these sinus sites.

Venous

The ___ is a delicate, richly vascularized layer with a “cobwebby” appearance.

arachnoid mater

___ is the space between the arachnoid layer and the underlying pia mater. It is filled with CSF

Subarachnoid space

___ are protrusions of arachnoid tissue. Penetrate through gaps in the overlying dura and project into the dural sinuses. Reabsorbs/drains CSF back into the blood.

Arachnoid villi

The innermost meningeal layer, the ___, is the most fragile. It is highly vascular and closely adheres to the surfaces of the brain and spinal cord, following every ridge and valley. In certain areas it dips deeply into the brain to bring a rich blood supply into close contact with the ependymal cells lining the ventricles.

Pia mater

Draw structure of meninges

Draw structure of meninges

___ consist of richly vascularized, cauliflower-like masses of pia mater tissues that dip into pockets formed by ependymal cells. Contained within the ventricles of the brain

Choroid plexus

___ is produced by the choroid plexuses inside the ventricles (i.e. it is a blood filtrate). It circulates through the ventricles. From the fourth ventricle it enters the subarachnoid space (between the arachnoid matar and pia matar)

CSF

CSF is found in and around the ___ and ___. Forms a liquid cushion that gives buoyancy to the CNS organs. Helps nourish the brain.

Brain; spinal cord

CSF reduces brain weight by ___ and prevents brain from crushing under its own weight

97%

CSF may carry chemical signals like ___ as well as sleep and appetite inducing molecules.

hormones

CSF has a similar composition to ___

blood plasma

CSF is kept circulating by ___ cells of ventricles

ependymal

Draw formation of CSF diagram

Draw formation of CSF diagram

Draw flow of CSF in the CNS diagram

Draw flow of CSF in the CNS diagram

The blood brain barrier is highly ___

selective

Series of capillaries that regulate the exchange between the blood and the brain. These capillaries allow a limited number of substances to pass from blood to the brain. Protective mechanism that helps maintain a stable environment for the brain. limits access of blood-borne substances to the brain

Blood brain barrier

The brain needs a constant input of ___ and ___ from the blood

Oxygen; glucose

Blood brain barrier is ___ against fats, fatty acids, other fat soluble molecules, oxygen, and carbon dioxide.

ineffective

The blood brain barrier is ___ uniform

Not completely

Bloodborne substances within the brain’s capillaries are separated from the ___ and ___.

extracellular space; neurons

Separates bloodborne substances: continuous ___ of ___ wall

Endothelium; capillary

Separates bloodborne substances: Relatively thick ___ surrounding the external face of the capillaries. ___ is a specialized, gel-like layer of extracellular matrix situated directly beneath epithelial cells. It serves as a structural scaffold, a barrier for tissue separation, and a molecular filter, …

basal lamina

a thin, specialized layer of extracellular matrix secreted directly by cells. It acts as a structural scaffold that supports tissues, separates cell layers, and serves as a selective molecular filter

basal lamina

Separates bloodborne substances: Bulbous “feet” of the ___ that cling to the capillaries

astrocytes

The spinal cord (cable of nerves) extends through the vertebral canal. There are _ pairs of spinal nerves

31

The spinal cord ranges vertically from the ___ (a large hole at the base of the skull)

foramen magnum

Attaches spinal nerve pairs _ cervical, _ thoracic, _ lumbar, _ sacral, _ coccygeal (answer ex: ‘1 2 4 2 5’)

8 12 5 5 1

___ is the portion of the central nervous system composed of bundles or tracts of myelinated nerve fibers (axons). Appearance is due to lipid composition in myelin. ‘Wires’ that connect computers together

White matter

___ is the portion of the central nervous system composed primarily of densely packaged neuronal cell bodies and their dendrites as well as most glial cells. ‘Computers of the CNS.’

Gray matter

The spinal cord consists of inner ___ matter and outer ___ matter

Gray; white

Draw diagram of vertebrae section, placement of gray/white matter

Draw diagram of vertebrae section, placement of gray/white matter

The ___ matter of the spinal cord consists of tracts for vertical relay

white

Ascending tracts range through the entire CNS, sending signals from the ___ up through regions of the brain

cord

Descending tracts range through the entire CNS, sending signals away from ___ down through the cord

higher brain centers

Draw the diagram of the ascending and descending tracts.

Draw the diagram of the ascending and descending tracts.

Draw diagram of spinal cord front view

Draw diagram of spinal cord front view

The ___ matter of the spinal cord consists of three pairs of horns: ventral, lateral, and dorsal, as well as the central canal. It contains interneurons (internuncial neurons).

gray

The ___ is filled with CSF and lies in the center of the gray matter.

central canal

The ___ horn contains bodies of interneurons on which afferent neurons terminate

dorsal

The ___ horn contains cell bodies of the somatic efferent neurons supplying skeletal muscles.

ventral

Autonomic nerve fibers supplying cardiac and smooth muscle and exocrine glands originate at cell bodies found in the___.

lateral horn

Draw spinal cord portion of gray matter diagram

Draw spinal cord portion of gray matter diagram

A ___ (as opposed to a neuron/nerve cell) is a bundle of peripheral axons.

nerve

Spinal nerves contain ___ and ___ fibers (axon portion)

Afferent; efferent

A neural pathway that produces reflexes. And has 5 components: Receptor, afferent pathway, integrating center, efferent pathway, effector

Reflex arc

One function of the association of neurons (efferent, afferent, autonomic) in the spinal cord ___ matter → integrate basic reflexes. They are part of the reflex arc

gray

Draw both reflex arc diagrams

Draw both reflex arc diagrams

The ___ detects a stimulus (e.g., touching a hotplate)

receptor

The ___ makes the response of the reflex (e.g., withdrawal of the arm)

effector

The ___ is within the gray matter of the spinal cord. Its neurons connect a given input (from the afferent pathway) to the proper output (from the efferent pathway)

integrating center

Draw stretch reflex diagram

Draw stretch reflex diagram

Draw deep tendon reflex diagram

Draw deep tendon reflex diagram

Draw crossed extensor reflex diagram

Draw crossed extensor reflex diagram