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BIO 235 Midterm 2 > Chapter 14: The Brain and Cranial Nerves > Flashcards

Chapter 14: The Brain and Cranial Nerves Flashcards

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Biology 101 flashcards
1
Q

Describe how the brain and spinal cord develop using the following terms:

Neural tube
Primary brain vesicles
Secondary brain vesicles

A

The brain and spinal cord develop from the ecodermal neuronal tube

Anterior portion expands, along with the associated neuronal crest tissue and is then contracted to create 3 regions called the primary brain vesicles (prosencephalon/forebain, mesencephalon/midbrain, and rhombencephalon/hindbrain)

The prosencephalon and rhombencephalon subdivide further into the secondary brain vesicles

  • prosencephalon = telencephalon and diencephalon
  • rhombencephalon = mesencephalon and myelincehpalon
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2
Q

Identify the 4 major parts of the brain

A

Brain stem - continuous with the spinal cord and consists of the medial oblongata, pons and midbrain

Cerebellum - posterior to brain stem

Diencephalon - superior to brain stem and consists of thalamus, hypothalamus, and epithalamus

Cerebrum - supporter on the brainstem and dienchaplon and is the largest part of the brain

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3
Q

Describe the locations of the cranial meninges

A

Cranial meninges are continuous with spinal meninges and have the same basic structure and names:

  • Dura mater (outer)
  • Arachnoid mater (middle)
  • Pia mater (inner)

However, the cranial dura mater has 2 layers whereas the spinal dura mater has only one

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4
Q

Explain the blood supply to the brain and the importance of the blood-brain barrier

A

blood flows into the brain mainly by the internal carotid and vertebral arteries

the BBB consists of tight junctions that seal together the endothelial cells of the brain blood capillaries and a thick basement membrane that surrounds the capillaries

The BBB protects the tissue by only allowing water-soluble substances to cross by actin transport; preventing potentially harmful substances

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5
Q

What structures produce CSF and where are they located?

A

Majority of CSF production is from the choroid plexuses, networks of blood capillaries in the walls of the ventricles (4)

Ependymal cells that cover the choroid plexuses secrete substances and accounts for continuous CSF production

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6
Q

Define CSF and list the 4 CSF-filled cavities within the brain

A

CSF is a clear liquid composed of mainly water that protects the brain and spinal cord from chemical and physical injuries

CSF-filled cavities are called ventricles and there are 4:

  • Lateral ventricle in each hemisphere of cerebrum (2)
  • Third ventricle is a narrow slit lit cavity along the midline superior to the hypothalamus and between the thalamus
  • Forth ventricle lies between the brainstem (anterior) and cerebrum (posterior)
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7
Q

__________ is a thin membrane that separates the lateral ventricles

A

Septul pellucidum

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8
Q

What are the 3 basic functions of CSF?

A
  1. Mechanical protection - serves as shock-absorbing medium
  2. Homeostatic Function - CSF pH affects pulmonary ventilation and cerebral blood flow and serves as a transport system for hormones
  3. Circulation - Medium for minor exchange of nutrients and waste products
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9
Q

What is the difference between the BBB and blood-cerebrospinal fluid barrier?

A

BBB is formed mainly by tight junctions of brain capillary endothelial cells

blood-CSF barrier is formed by tight junctions of ependymal cells - permitting only certain substances to enter the CSF

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10
Q

Describe the pathway of CSF circulation

A
  1. Formed in each lateral ventricle and flows into the 3rd ventricle through narrow oval opening called interventricular foramina
  2. More CSF is added and then flows through the aqueduct of the midbrain which passes through the midbrain into the 4th ventricle
  3. More CSF is added and it enters the subarachnoid space through three openings in the roof the 4th ventricle:
    - Single median aperture
    - Paired lateral apertures on each side
  4. CSF then circulates in the central canal of the spina cord & subarachnoid space and is gradually reabsorbed into the blood through arachnoid villi
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11
Q

What are the 3 structures of the brain stem?

A

Medulla oblongata
Pons
Midbrain

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12
Q

Describe the location of the medulla

A

It is continuous with the superior part of the spinal cord; forming the inferior part of the brain stem

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13
Q

What is the main function of the medulla?

A

Contains sensory (ascending) and motor (descending) tracts

Regulates heartbeat and blood vessel diameter (cardiovascular center)

Regulates breathing (medullary respiratory center)

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14
Q

What part of the brain stem contains the pyramids? Describe them

A

Pyramids are protrusions of white mater that forms on the anterior aspect of the medulla

They are formed by large cortiospinal tracts that pass from the cerebrum to the spinal cord and control voluntary movements of the limbs and trunk

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15
Q

Describe the decussation of pyramids

A

Superior to the function of the medulla with the spinal cord, 90% of the axons in the left pyramid cross to the right side and 90% of the axons in the right cross the the left side

This explains why each side of the brain controls voluntary movements of the opposite side of the body

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16
Q

Describe the functions of the following nuclei found in the medulla:

Cardiovacular center
Medullary respiratory center

A

Cardiovascular center - regulates heart beat and diameter of blood vessels

Medullary respiratory center - adjusts basic rhythm of breathing

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17
Q

Describe the structure and location of the pons

A

Lies directly superior to the medulla and anterior to the cerebellum and is about 2.5 cm long

It is a bridge that connects parts of the brain with on another

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18
Q

What are the principal functions of the pons?

A

Pontine nuclei relay nerve impulses from motor area of cortex to cerebellum - essential role in coordinating and maximizing the efficiency of voluntary motor output

Vestibular nuclei assist in equilibrium

Pontine respiratory group helps control breathing

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19
Q

Where is the pontine respiratory group located and what is its function?

A

Located in the pons and together with the medullary respiratory center helps control breathing

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20
Q

Describe the structure and location of the midbrain

A

The midbrain extends from the pons to the diencephalon and is out 2.5cm long

The aqueduct of the midbrain connects the third and fourth ventricles

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21
Q

What are the principal functions of the midbrain?

A

Superior colliculi coordinate movements of head, eyes, and trunk in response to visual stimuli

Inferior colliculi coordinate movements of head, eyes, and trunk in response to auditory stimuli

Substantia nigra and red nucleus contribute to control of movement

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22
Q

What part of the brain stem contains the cerebral peduncles?

A

Located in the anterior part of the midbrain and are paired bundles of axons which conduct nerve impulses from motor areas in the cerebral cortex to the spinal cord, medulla, and pons

main sites through which tracts extend and nerve impulses are conducted between the superior parts of the brain and the inferior parts of the brain and the spi- nal cord.

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23
Q

Define the reticular formation and its location

A

The reticular formation is a netlike arrangement of white and gray matter that extends from the superior part of the spinal cord, throughout the brainstem and into the inferior part of the diencephalon

Neurons within have both ascending (sensory) and descending (motor) functions

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24
Q

What is the reticular activating system (RAS)? What are its functions?

A

It is the ascending portion of the reticular formation, consisting of sensory axons the project to the cerebral cortex both directly and through the thalamus

Functions:

  • Consciousness
  • Active during arousal
  • Helps maintain attention
  • Prevents sensory overload by filtering information
  • Inactivation produces sleep but damage can result in a coma
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25
Q

Where are the transverse fissure and tentorium cerebelli found and what is their function?

A

Supports posterior portion of cerebrum and separates the cerebellum from the cerebrum

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26
Q

What are the principal functions of the cerebellum?

A

Smooths and coordinates contractions of skeletal muscles

Regulates posture and balance

May have a role in cognition and language processing

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27
Q

The shape of the cerebellum resembles a butterfly. The central constricted area is the _____ and the lateral wings are the ________

A

vermis

cerebellar hemispheres

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28
Q

What is the superficial layer of the cerebellum?

A

It is called the cerebellar cortex and it consists of gray matter in a series of slender, parallel folds called folia

Deep to the gray matter are tracts of white matter called arbor vitae that resemble tree branches and even deeper are cerebellar nuclei

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29
Q

What are cerebellar peduncles?

A

There are 3 pairs of peduncles that attach the cerebellum to the brain stem and allow communication with other parts of the brain

Superior - contain axons that extend from cerebellum to the red nuclei of the midbrain and nuclei of the thalamus

Middle (largest) carry impulse for voluntary movements from the pontine nuclei into the cerebellum

Inferior - carries impulses for sensory info from trunk/limbs and proprioception from ear/head

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30
Q

Describe the components the diencephalon

A

dienephalon contains numerous nuclei involves in a variety of sensory and motor processing and it extends from the brain stem to the cerebrum and surrounds the 3rd ventricle; has 3 components:

Thalamus - makes up 80% of diencephalon that consists of paired oval masses of gray matter organized into nuclei with interspersed tracts of white matter

Hypothalamus - small part of the diencephalon located inferior to thalamus

Epithalamus: a small region superior and posterior to thalamus, consists of the pineal gland and habenuclear nuclei

31
Q

What is the function of the thalamus?

A

Relays almost all sensory input to cerebral cortex

Contributed to motor functioning by transmitting info from cerebellum to basal nuclei to primary motor area of cortex

Plays important role in consciousness

32
Q

What is the functioning of the hypothalamus?

A

Controls and integrates activities of ANS

Produces hormones - including releasing hormones, inhibiting hormones

Regulates emotional and behavioural patterns (together with limbic system)

Regulates eating/drinking - contains satiety and thirst centres

Controls body temperature

Regulates circadian rhythms and states of consciousness

33
Q

What are the functions of the pineal gland and habenular nuclei of the epithalamus?

A

Pineal gland - part of the endocrine system become it secretes the hormone melatonin

habenular nuclei - involved in olfaction, especially emotional responses to doors

34
Q

Define a circumventricular organ (CVO)

A

Parts of the diencephalon are called CVOs because they lie in the wall of the third ventricle, can minority chemical changes in the blood because the lack a BB

CVOs include part of the hypothalamus, pineal gland, and a few nearby striations that coordinate hemostatic activities of the endocrine and nervous system

Thought to be the entry point for viruses that get in the brain but are unable to cross the BBB such as HIV

35
Q

Define the cerebrum

A

The seat of intelligence - provides is with the ability to read, write, and speak; make calculations/compose music, remember

36
Q

Define cerebral cortex

A

region of gray matter that forms the outer rim of the cerebrum

Has large SA because it folds in on itself

  • folds are called gyri (convictions)
  • deep grooves between folds are called fissures
  • shallow grooves between folds are called sulci
37
Q

The _______ tissue separated the cerebrum into right and left calves called cerebrebal hemispheres

A

longitudinal

38
Q

The _______ separates the frontal lobe and the parietal lobe

A

central sulcus

39
Q

The ______ is located anteriorly to the central sulcus and contains the primary motor area of the cortex

A

Precentral gyrus

40
Q

The ______ is located posteriorly to the central sulcus and contains the primary somatosensory area of the cortex

A

Postcentral gyrus

41
Q

The frontal lobe and temporal lobe are separated by the ________ sulcus

A

Lateral cerebral sulcus (fissure)

42
Q

The ______ sulcus suppurates the parietal lobes from the occipital lobe

A

parieto-occipital sulcus

43
Q

Where is the insula

A

Cannot be seen at surface of brain because it lies within the lateral cerebral sulcus, deep the the parietal, frontal, and temporal lobes

44
Q

What are the 3 types of tracts in cerebral white matter?

A

Association tracts - conduct nerve impulses between gyri in the same hemisphere

Commissural tracts - conduct nerve ipules from gyri in one hemisphere to corresponding grey in the other hemisphere

Projection tracts - conduct nerve impulses from the cerebrum to lower parts of the CNS or from lower parts to the cerebrum

45
Q

Describe the functions of the basal nuclei

A

Receive input from the cortex and provide output to motor parts of the cortex via the medial and ventral group nuclei of the thalamus

Helps regulate initiation and termination of movements

Controls subconscious contractions of skeletal muscles

Helps initiate and terminate some cognitive processes (attention, memory, planning) and may act with the limbic system to regulate emotional behaviours

46
Q

Describe the functions of the limbic system

A

Called the emotional brain because it plays a primary role in a range of emotions, including pain, pleasure, docility, affection, and anger

It also is involved in olfaction and memory

47
Q

Describe the location and function of the primary somatosensory area

A

Located in the post central gyrus of each parietal lobe, immediately posterior to the central sulcus

It receives input for touch, pressure, vibration, itch, tickle, temperature, pain, and proprioception

A ‘map’ of the entire body is present within this area and each point within the area receives input from a specific part of the body (sensory homunculus)

48
Q

Describe the location and function of the primary visual area

A

Located at the tip of the occipital lobe responsible for integrating visual input

49
Q

Describe the location and function of the primary auditory area

A

Located in the superior part of the temporal lobe near the lateral cerebral sulcus

Receives information for sound and is involved in auditory perception

50
Q

Describe the location and function of the primary gustatory area

A

Located at the base of the post central gyrus superior to the lateral cerebral sulus in the parietal cortex

Receives input for taste and is response of taste discrimination

51
Q

Describe the location and function of the primary olfactory area

A

Located in the temporal lobe on the medial aspect (not visible) receives input for smell

52
Q

Describe the location and function of the primary motor area

A

Located in the precentral gyrus of the frontal lobe

A map of the entire body is present - each region within the area controls voluntary contractions of specific muscles or groups of muscle (motor homunculus)

53
Q

Describe the location and function of the Broca’s speech area

A

Located in the frontal lobe close to the lateral cerebral sulcus

From this area impulses pass to the premotor regions that control muscles of the larynx, pharynx, and mouth resulting in coordinated muscle contractions

Simultaneously impulses are sent to control breathing

Coordination of breathing and speech contractions allow you to speak

54
Q

Describe the location and function of the somatosensory association area

A

Located posteriorly and receives input from somatosensory area

Permits you to determine the exact shape and texture of an object, determine oration of an object with respect to another by feeling it, and sense of the relationship of one body part to another

Also stores past somatic sensory experiences

55
Q

Describe the location and function of the visual association area

A

Located in occipital lobe, receives input from primary visual cortex and thalamus

Relates present and past visual experiences and is essential for recognizing and evaluating what is seen

56
Q

Describe the location and function of the auditory association area

A

Located inferior and posterior to the primary auditory area in temporal cortex

Allows you to recognize a particular sound as speech, music, or noise

57
Q

Describe the location and function of Wernicke’s area (posterior language area)

A

Broad region in left temporal and parietal lobes that interprets the meaning of speech by recognizing spoken words

58
Q

Describe the location and function of the common integrative area

A

Bordered by somatosensory, visual, and auditory assoication areas

Receives impulses from these areas and from the primary gustatory & olfactory read, the thalamus, and parts of the brains stem

It integrates interpretation of visual, auditory, and somatic sensations

59
Q

Describe the location and function of the prefrontal cortex

A

Anterior portion of frontal lobe

Concerned with the makeup of a persons personality, mood, and cognition

60
Q

Describe the location and function of the premotor area

A

Located immediately anterior to the primary motor area

Deals with learned motor activities of a complex and sequential nature and serves as a memory bank for such movements

61
Q

Describe the location and function of the frontal eye field area

A

In the frontal cortex and sometimes included in the premotor area

Controls voluntary scanning movements of eye

62
Q

Explain the significance of hemispheric lateralization

A

Although the hemispheres are symmetrical in size, there are anatomical asymmetry and physiological differences

Right: music, art, space/patterns, face recognition, mental imaging, odour discrimination

Left: reasoning, numeracy, sign language, written language

Damage to right hemisphere can affect voice and emotional infection and damage to the left can cause aphasia

63
Q

What is an electroencephalogram EEG?

A

A record of brain eaves generated by neurons close to the serve, detected by electrodes placed n the forehead and scale

64
Q

Describe the following types of brain waves

Alpha
Beta
Theta
Delta

A

Alpha - appear only when someone is awake

Beta - appear when the NS is active, during periods of sensory input and mental activity

Theta - appear during emotional stress

Delta - Occur in deep sleep in adults but are normal in awake infants; when produced in awake adults they indicate brain damage

65
Q

Define the term cranial nerve and identify the twelve pairs of cranial nerves by name, number and functions

A

Cranial nerves pass through various lamina in the bones of the cranium and arise from the brain inside the cranial cavity

Oh Oh Oh To Touch and Feel Very Green Vegetables AH!

Olfactory (I) - smell
Optic (II) - vision
Oculomotor (III) Control some muscles of moving eyeballs, changes in size of pupil and shape of lens
Trochelar (IV) - control some muscles moving eyeball
Trigemial (V) -carry neve impsules associated with head sensations and chewing muscles
Abducens (VI) - control some of the muscles moving eyeballs
Facial (VII) - carry impsules associated with taste, salivation, and muscles of facial expression
Vestibulocochelar (VIII) - carry impulses associated with hearing and equilibrium
Glossopharyngeal (IX) - carry impulses associated with swallowing, salivation, and taste
Vagus (X) - carry impulses to and from many organs in thoracic and abdominal cavities
Accessory (XI) - control head and shoulder muscles
Hypoglossal (XII) - control tongue muscles

66
Q

Define special sensory nerves

A

Includes 3 cranial nerves:
I - olfactory; II - optic; VIII -vestibucochlear

as they are unique to the head and are associated with special senses fo smelling, seeing, and hearing

67
Q

Define motor nerves

A

5 cranial nerves:
III - oculomotor; IV - trochlear; VI -abducens; XI - accesstory; XII - hypogloassal

contain only axons of motor neurons as they leave the brain stem

68
Q

Define mixed nerves

A

The 4 remaining cranial nerves:

V - trigeminal; VII - facial; IX - glossopharyngeal; X - vagus

contain axons of both sensory neurons entering the brain stem and motor neurons leaving the brain stem

69
Q

Briefly describe a cerebrovascular accident (CVA)

A

aka stroke or brain attack

An abrupt onset of persisting neurological symptoms that arise from destruction of brain tissue

Common causes by hemorrhage, emboli, and atherosclerosis of arteries

70
Q

Briefly describe transient ischemic attack (TIA)

A

An episode of temporary cerebral dysfunction caused by impaired blood flow to part of the brain

Usually persists for 5-10 min and leaves with no permanent neurological deficits

Causes include blood clots, atherosclerosis, and blood disorders

71
Q

Briefly describe alzheimer’s disease

A

A disabling senile dementia, the loss of reasoning and ability to care for oneself

Due to build of of beta amyloid plaques and neurofiburlary ranges and loss of neurons that liberate ACh

72
Q

Briefly describe ADHD

A

learning disorder characterized by poor or short attention span, a consistent level of hyperactivity, and level of impulsiveness inappropriate for the childs’ age

72
Q

Briefly describe ADHD

A

learning disorder characterized by poor or short attention span, a consistent level of hyperactivity, and level of impulsiveness inappropriate for the childs’ age

BIO 235 Midterm 2 (8 decks)

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