Lecture 1 - The Surface Features of the Human Brain Flashcards
(102 cards)
1
Q
What encases the human brain?
A
Cranial vault
2
Q
What is the average weight of the human brain?
A
1.05 kg to 1.8 kg (~3 lbs)
3
Q
How many neurons are typically found in a tiny piece of human brain tissue the size of a grain of rice?
A
10,000 nerve cells
4
Q
What are the two main divisions of the nervous system based on embryonic origin?
A
Central nervous system (CNS) and peripheral nervous system (PNS)
5
Q
What structures are included in the central nervous system (CNS)?
A
Brain and spinal cord
6
Q
What types of nerves are part of the peripheral nervous system (PNS)?
A
Cranial nerves and spinal nerves
7
Q
What are the three functional subdivisions of the peripheral nervous system?
A
- Somatic nervous system
- Autonomic nervous system
- Enteric nervous system
8
Q
What is the primary function of the somatic nervous system?
A
Conveying and processing sensory information and providing motor control of voluntary muscles
9
Q
What are the two branches of the autonomic nervous system?
A
- Sympathetic
- Parasympathetic
10
Q
What is the basic function of the sympathetic nervous system?
A
General arousal and preparing the body for emergencies (fight or flight)
11
Q
What is the primary role of the parasympathetic nervous system?
A
Relaxation and long-term body homeostasis
12
Q
What is the enteric nervous system responsible for?
A
Digestion and the passage of food through the body
13
Q
What is the average volume of the human brain?
A
1300 cubic centimeters (cm3)
14
Q
What are the main parts of the human brain?
A
- Cerebrum
- Cerebellum
- Brain stem
15
Q
What is the composition of the brain stem?
A
- Midbrain
- Pons
- Medulla oblongata
16
Q
What are the three main parts of the brain based on embryological development?
A
- Hindbrain (rhombencephalon)
- Midbrain (mesencephalon)
- Forebrain (prosencephalon)
17
Q
What is the significance of the longitudinal fissure in the cerebrum?
A
Separates the two large cerebral hemispheres
18
Q
What are the three planes used to describe orientation in the brain?
A
- Sagittal plane
- Coronal plane
- Axial plane
19
Q
What does the term ‘neuraxis’ refer to?
A
The long axis through the brain and spinal cord
20
Q
What are the directional terms used in the nervous system?
A
- Rostral-caudal (front-to-back)
- Dorsal-ventral (top-to-bottom)
- Medial-lateral (middle-to-side)
21
Q
What is the basic unit of signaling in the nervous system?
A
Neuron
22
Q
What are the three main parts of a typical neuron?
A
- Dendrite
- Soma (cell body)
- Axon
23
Q
What type of neurotransmitter is the most common in the brain?
A
Glutamate and gamma amino butyric acid (GABA)
24
Q
What is gray matter composed of?
A
- Neuronal cell bodies
- Dendrites
- Axon terminals
- Synapses
- Glial cells
25
What makes up white matter?
Bundles of axons, many containing myelin
26
What are groups of neuronal cell bodies in the CNS called?
Nuclei
27
What is the term for pathways that carry signals toward a structure?
Afferent
28
What is the term for pathways that carry signals away from a structure?
Efferent
29
True or False: The enteric nervous system receives direct input from the CNS.
False
30
What does contralateral refer to?
The opposite side of the body from a lesion.
31
What does ipsilateral refer to?
The same side of the body as a lesion.
32
What are afferent pathways?
Pathways that carry signals toward a structure.
33
What are efferent pathways?
Pathways that carry signals away from a structure.
34
List the six major ascending structural divisions of the brain.
* Spinal cord
* Myelencephalon
* Metencephalon
* Mesencephalon
* Diencephalon
* Telencephalon
35
What is the function of the spinal cord?
Integrates sensory input and motor output for each level of the body.
36
What does the Bell-Magendie Law state?
The dorsal part of the spinal cord receives sensory input; the ventral part sends motor output.
37
What is the primary function of the myelencephalon?
Life support system: breathing, heart rate, swallowing, and vomiting.
38
What is the function of the metencephalon?
Contains sleep-dream regions (pons) and integrates skilled unconscious movements (cerebellum).
39
What is the general function of the mesencephalon?
Visual-motor and auditory-motor integration.
40
What is the primary function of the diencephalon?
Massive sensory-motor integration before cerebral cortices.
41
What functions are associated with the telencephalon?
Higher ordered cognitive processes, emotion, perception, memory, language, production of speech.
42
What comprises the outer portion of the cerebrum?
Cortices or gray matter.
43
What is the thickness range of the cerebral cortex?
1.5 to 4.5 mm, with an average of 2.5 mm.
44
What is the surface area of the human cerebral cortex?
Around 2200 cm² (or 2.5 sq. ft).
45
What are gyri and sulci?
Gyri are ridges; sulci are grooves between the ridges on the cerebral surface.
46
What are the three major fissures of the cerebrum?
* Lateral fissure
* Central fissure
* Medial or longitudinal fissure
47
What is the main advantage of gyri in the brain?
Allows for a larger surface area to be packed into a smaller space.
48
What is the difference between lissencephalic and gyrencephalic brains?
Lissencephalic brains have no gyri; gyrencephalic brains have gyri.
49
What factors can affect brain weight and volume?
Individual, sex, and racial differences.
50
True or False: There is a correlation between brain weight and intelligence (I.Q.) in healthy individuals.
False.
51
What happens to brain volume after age 35?
Declines at a rate of around 0.5% per year.
52
Which lobe is most affected by brain volume loss?
Frontal lobes.
53
What does functional cerebral symmetry refer to?
The unique strategies each cerebral hemisphere has developed for processing information.
54
What is the significance of the left planum temporale in right-handed individuals?
It is about 5 times larger than the right planum temporale and is critical for language.
55
What is Broca’s area responsible for?
Production of grammar and language expression.
56
What is Wernicke’s area responsible for?
Understanding and processing speech.
57
What is the primary function of the frontal lobe?
Motor control, inhibition, language expression, and anticipation.
58
What is the function of the parietal lobe?
Integration and awareness of body image and boundary.
59
What is the primary function of the occipital lobe?
Visual recognition and processing.
60
What role does the temporal lobe play?
Language reception, hearing, and vestibular functions.
61
What is the function of the insular lobe?
Autonomic and visceral experiences.
62
What do the cingulate-limbic lobes contribute to?
Sense of self, meaningfulness, emotion, memory, and species-bonding behavior.
63
What are the components of the basal ganglia?
* Caudate
* Putamen
* Globus pallidus
64
What is the role of the hippocampus?
Gateway to memory.
65
What is the function of the amygdala?
Affect and meaningfulness.
66
What are the three layers of the meninges?
* Dura mater
* Arachnoid mater
* Pia mater
67
What is the dura mater?
A tough, dense membrane surrounding the brain and spinal cord.
68
What is the arachnoid mater?
A thin non-vascular membrane surrounding the brain.
69
What is the pia mater?
A delicate membrane that closely covers the surface of the brain.
70
What is cerebrospinal fluid (CSF) primarily responsible for?
Shock absorption and providing buoyancy for the brain.
71
What are the four fluid-filled cavities in the brain called?
Ventricles.
72
Where is the choroid plexus located?
Lining the walls of the ventricles.
73
How much CSF is produced daily?
About 500 ml.
74
What is the net weight of the brain suspended in CSF?
~ 25 g.
75
What is the main function of cerebrospinal fluid (CSF)?
To serve as a shock absorber by surrounding the brain and providing buoyance for it.
76
What is the actual weight of the human brain in grams?
Between 1200 to 1400 g.
77
How much does CSF reduce the net weight of the brain?
60-fold decrease.
78
List two functions of CSF besides providing buoyancy.
* Maintain interstitial homeostasis
* Reduce traction on emerging blood vessels and nerves
79
What happens to CSF when it contains too many white blood cells?
It turns cloudy.
80
What is a classical disease associated with enlargement of lateral ventricles?
Chronic schizophrenia.
81
What condition is characterized by blockage of CSF outflow?
Hydrocephalus.
82
Why do infants with hydrocephalus exhibit abnormal enlargement of the head?
Because the cranial sutures are not fused, allowing the accumulating fluid to enlarge the ventricles.
83
What is the consequence of not providing shunting for excess fluid in hydrocephalus?
It may result in seizures and significant intellectual disability.
84
What percentage of arterial blood flow does the brain receive from the heart?
15 to 20%.
85
What is the primary energy substrate of the brain?
Glucose.
86
How much glucose does the human brain consume per 100 g of tissue per minute?
5.6 mg.
87
What is the daily caloric consumption of the brain in relation to a 2000 kcal diet?
About 400 kcal, or about 1/5th of the diet.
88
What is the role of capillaries in the brain?
They are the principal suppliers of blood to brain tissue.
89
What is the transit time for blood to travel from the internal carotid artery to the internal jugular vein?
6 to 8 seconds.
90
Fill in the blank: The vasocapillary network occupies no more than ______ of the brain's total volume.
7%
91
What is the significance of regional cerebral blood flow (CBF)?
It is a major index of brain metabolism and reflects the activity of neurons.
92
True or False: Gray matter consumes more oxygen than white matter.
True.
93
What are the three pairs of major arteries that supply the cerebrum?
* Anterior cerebral artery (ACA)
* Middle cerebral artery (MCA)
* Posterior cerebral artery (PCA)
94
What are the classic symptoms of disruption of the left middle cerebral artery (MCA)?
Affect language and produce weakness or paralysis involving the upper right side of the body.
95
What symptoms are associated with disruption of the left anterior cerebral artery (ACA)?
* Affects the lower right side of the body
* Can result in deficits in motivation and initiation of behavior
96
What is the function of the Circle of Willis?
It provides an avenue for collateral circulation between vessels on both sides of the brain.
97
What percentage of subarachnoid or berry aneurysms occur in the anterior portion of the Circle of Willis?
About 90%.
98
What is a transient ischemic attack (TIA)?
A temporary spell resulting from impaired brain function due to a brief reduction in blood flow.
99
What are common symptoms of a TIA in the vertebral-basilar system?
* Occipital headaches
* Flashing lights
* Tinnitus
* Facial weakness
* Problems swallowing
* Slurred speech
* Ptosis
* Ataxia
* Numbness
100
What can happen if blood supply is deprived for more than three minutes during a stroke?
It can lead to cell death and necrosis.
101
What are arteriovenous malformations (AVMs)?
Anomalous occurrences where arterioles are fused with other arterioles or venules.
102
What is the common antecedent for subdural hematomas?
A small head injury.
