BIOL 12 note cards

What is an example of a long association tract?

The cingulum.

Where is the BBB present?

In most brain capillaries.

Which tract type solves these communication problems: adjacent cortex in one hemisphere, opposite hemisphere, cortex to spinal cord?

Association; commissural; projection.

If corresponding cortical areas in opposite hemispheres need to communicate, which tract class is used?

Commissural tracts.

Does all CSF leaving the fourth ventricle enter the subarachnoid space?

Most does; a small amount enters the central canal of the spinal cord.

How does the choroid plexus produce most CSF?

By selective secretion of ions and water from the blood.

What forms the main blood-CSF barrier at the choroid plexus?

Tight junctions between choroid-plexus epithelial cells.

A tissue region contains many neuronal cell bodies, dendrites, synapses, and glia. Is it gray matter or white matter?

Gray matter.

Which CNS barrier is associated with the pia-arachnoid interface between CSF and brain tissue?

The brain-CSF barrier/interface.

Where is the third ventricle located?

Between the thalami.

What does interoception mean in the context of insular function?

Processing/awareness of the internal state of the body.

What is subcortical white matter?

Axon tracts connecting different regions of the CNS.

What do association areas do?

They integrate information from multiple cortical regions.

What is somatosensory processing, and which cerebral lobe is most strongly associated with it?

Processing body sensations such as touch, pain, temperature, pressure, vibration, and proprioception; mainly the parietal lobe.

If a brain region is a deep collection of neuronal cell bodies surrounded by white matter, what is it called?

A deep gray-matter nucleus.

How do arachnoid mater and pia mater differ in their relationship to the brain surface?

Arachnoid spans over the surface; pia closely follows the gyri and sulci.

Trace the route a substance encounters from choroid-plexus blood toward CSF.

Blood → fenestrated capillary → stroma → choroid-plexus epithelial cell → CSF.

What does intrahemispheric mean in the context of association tracts?

Within the same cerebral hemisphere.

What does it mean that BBB tight junctions prevent paracellular diffusion?

They restrict movement between neighboring endothelial cells.

A structure lies inferior to the thalamus and regulates both the ANS and pituitary gland. What is it?

The hypothalamus.

How can essential hydrophilic substances such as glucose and amino acids cross the BBB?

Through selective transport proteins.

If the cerebral aqueduct were blocked, which normal connection in CSF flow would be interrupted?

Flow from the third ventricle to the fourth ventricle.

What three structures make up the diencephalon?

Thalamus, hypothalamus, and epithalamus.

Which CNS tissue is associated mainly with processing, and which with communication?

Gray matter = processing/integration; white matter = communication.

Are most brain capillaries fenestrated?

No. Most are continuous and lack fenestrations.

What are the three functional categories of cerebral cortical areas?

Primary, secondary, and association areas.

What broad functions are associated with the diencephalon?

Sensory relay, homeostasis, and autonomic/endocrine regulation.

What do commissural tracts connect?

Cortical regions across the two cerebral hemispheres, often corresponding regions.

A fiber bundle connects two cortical regions in the same hemisphere. Which tract class is it?

Association tract.

How are the superior sagittal sinus and falx cerebri both related to dura mater?

The sinus is a venous channel between dural layers; the falx cerebri is a fold of dura.

If tight junctions between choroid-plexus epithelial cells failed, which physiological barrier would be directly impaired?

The blood-CSF barrier.

What structures dominate white matter, and what is its main general role?

Bundles of axons, many myelinated; communication between CNS regions.

What do the median and lateral apertures allow CSF to do?

Leave the fourth ventricle and enter the subarachnoid space around the brain and spinal cord.

Where does most CSF circulate after it leaves the fourth ventricle?

In the subarachnoid space around the brain and spinal cord.

What does executive function include in the frontal-lobe context?

Planning and decision-making.

From which structures does the thalamus relay motor information toward the cerebral cortex?

The cerebellum and basal nuclei.

Why is the cerebral cortex gray matter while the subcortical region is largely white matter?

The cortex contains many neuronal cell bodies and synapses; subcortical white matter contains many axon tracts.

What alternative name is used for the cerebral aqueduct?

Aqueduct of Sylvius.

Why does the CNS need selective physiological barriers instead of unrestricted exchange with blood?

To limit harmful substances and help maintain a stable chemical environment for neural tissue.

If a task involves integrating touch and body-position information, which cerebral lobe is most directly involved?

Parietal lobe.

A short tract connects two adjacent gyri in one hemisphere. What type of fiber is it?

A short association fiber, or U-fiber.

If choroid-plexus capillaries are fenestrated, why can substances not simply move freely into CSF?

They must still cross choroid-plexus epithelial cells joined by tight junctions.

What surface features fold the cerebral cortex?

Gyri and sulci.

What are capillary fenestrations?

Small pores/openings in capillary endothelial cells that increase permeability.

How does CSF act as a shock absorber for the CNS?

It cushions the brain and spinal cord by reducing and distributing mechanical forces from sudden movement or impact.

Which diencephalic structure links homeostasis, autonomic regulation, and endocrine regulation?

The hypothalamus.

Where is the thalamus located relative to the brainstem?

Superior to the brainstem.

Compare the major emphasized roles of thalamus, hypothalamus, and epithalamus.

Thalamus = sensory/motor relay; hypothalamus = homeostatic/autonomic/endocrine regulation; epithalamus = contains pineal gland.

How is the forebrain different from the three major adult brain divisions?

Forebrain = cerebrum + diencephalon; the major adult divisions are cerebrum, cerebellum, and brainstem.

Which lobe is most associated with visual processing and interpretation?

Occipital lobe.

Where are dural venous sinuses located within the cranial dura?

Between the periosteal and meningeal dura layers.

What is the complete major pathway of CSF flow from the lateral ventricles to the venous system?

Lateral ventricles → interventricular foramina → third ventricle → cerebral aqueduct → fourth ventricle → median/lateral apertures → subarachnoid space → arachnoid granulations → dural venous sinuses.

If an axon bundle travels from cerebral cortex toward the brainstem, is it association, commissural, or projection?

Projection.

Why are circumventricular organs useful even though most of the brain is protected by the BBB?

Some brain regions need to monitor the blood directly.

What is the ventricular system?

A network of interconnected cavities that contain CSF and provide a pathway for its movement.

What substances does the BBB restrict from uncontrolled entry?

Toxins, pathogens, and many large or hydrophilic molecules.

Which meninx is the tough outer meningeal layer?

Dura mater.

Motor/executive/speech; somatosensory/spatial; vision; hearing/language/memory; visceral/taste/interoception. Which lobes match these functions in order?

Frontal; parietal; occipital; temporal; insula.

How does the hypothalamus regulate endocrine function?

Through the pituitary gland.

What are primary cortical areas?

The first cortical regions involved in processing specific sensory information or generating voluntary motor output.

What do short association fibers connect?

Adjacent gyri.

What comes immediately after the third ventricle in CSF flow?

Cerebral aqueduct.

Where is gray matter located in the cerebrum?

In the outer cerebral cortex and in deep gray-matter nuclei.

What major function is associated with the occipital lobe?

Visual processing and interpretation.

What is the major function of the choroid plexus?

It produces most cerebrospinal fluid.

What does BBB stand for?

Blood-brain barrier.

How are cerebral lobes defined anatomically?

Largely by major sulci and surface landmarks.

If the cerebral aqueduct were blocked, which ventricles are upstream of the blockage?

The lateral ventricles and third ventricle.

What are the three major anatomical divisions of the human brain?

Cerebrum, cerebellum, and brainstem.

What is the main structural barrier of the BBB?

Capillary endothelial cells joined by tight junctions.

Into what venous structures does CSF drain after passing through arachnoid granulations?

Dural venous sinuses.

If a cerebral region contains axon tracts connecting CNS areas, which major cerebrum component is it?

Subcortical white matter.

What does emotional and salience processing mean in the context of the insula?

Helping identify emotionally important or behaviorally relevant internal and external signals that deserve attention.

What small lipid-soluble molecules can cross the BBB relatively readily?

O₂ and CO₂.

A function involves taste plus visceral sensory information rather than vision or hearing. Which lobe is strongly associated with it?

The insula.

How does gray/white matter distribution differ between the cerebrum and spinal cord?

Cerebrum: gray mainly outside and white inside. Spinal cord: gray inside and white outside.

How do the BBB and blood-CSF barrier both restrict uncontrolled movement despite using different cell layers?

Both use tight junctions, but the BBB uses endothelial cells while the blood-CSF barrier uses epithelial cells.

Which barrier has leaky fenestrated capillaries but a tight epithelial layer, and which has tight nonfenestrated capillaries?

Blood-CSF barrier: fenestrated capillaries + tight epithelium. BBB: tight, continuous capillary endothelium.

Why does the BBB not mean that nothing can enter brain tissue from blood?

The BBB is selective: some small molecules cross readily and essential substances use transport proteins.

Which cerebral lobe is associated with memory formation and processing?

Temporal lobe.

What are dural venous sinuses?

Large venous channels within the dura mater.

Match the examples to tract classes: cingulum, corpus callosum, corticospinal fibers.

Association; commissural; projection.

If arachnoid granulations could not transfer CSF into venous blood, which part of CSF circulation would be directly impaired?

CSF reabsorption.

How do ependymal-cell cilia contribute to CSF movement?

They help move and mix CSF.

If a function involves circadian rhythm or body-temperature regulation, which diencephalic structure is most directly associated?

The hypothalamus.

Which meninx is the thin middle meningeal layer?

Arachnoid mater.

Which major sensory modality is the exception to the usual thalamic relay?

Olfaction.

Put the three meninges and the CSF-containing space in order from superficial to deep.

Dura mater → arachnoid mater → subarachnoid space with CSF → pia mater.

What are the three major types of cerebral white-matter tracts?

Association, commissural, and projection tracts.

What major motor-fiber example is given for projection tracts?

Corticospinal fibers.

What is the cerebral cortex structurally?

The outer layer of cerebral gray matter.

What qualifier should be remembered about the classical locations of Broca’s and Wernicke’s areas?

They are classically located in the dominant hemisphere.

Why is the insula sometimes difficult to see from the external brain surface?

It lies deep within the lateral sulcus.

What is the blood-brain barrier (BBB)?

A highly selective permeability barrier separating circulating blood from brain extracellular fluid.

How do capillaries at the BBB differ from capillaries in the choroid plexus?

BBB capillaries are continuous and usually nonfenestrated; choroid-plexus capillaries are fenestrated and relatively permeable.

Into what structures do arachnoid granulations project?

Dural venous sinuses.

What major structure is contained in the epithalamus?

The pineal gland.

What tissue forms the falx cerebri?

Dura mater.

What are cerebral white-matter tracts?

Bundles of axons that connect different regions of the CNS.

What is the subarachnoid space, and what does it contain?

An actual space beneath arachnoid mater that contains CSF.