Chapter 13- The Brain 🧠⚡️💡 Flashcards
How many neurons are estimated to be in the human brain?
Approximately 100 billion neurons.
What are the four major areas of the human brain?
- Brainstem
- Cerebellum
- Diencephalon
- Cerebrum
What are the components of the brainstem?
- Medulla Oblongata
- Pons
- Midbrain
- Reticular Formation
Which part of the brain is known as the ‘thinking brain’?
Cerebrum
What is the function of the brainstem?
Connects spinal cord to rest of brain and is essential for survival.
What are some reflexes controlled by the brainstem?
- Breathing
- Swallowing
- Coughing
- Vomiting
- Heart rate
- Sneezing
Where is the Medulla Oblongata located?
Most inferior part of the brainstem.
What are the functions of the Medulla Oblongata?
Mostly involved with respiration. Regulating breathing with the pons.
Swallowing, coughing, vomiting, heart rate, and sneezing
What is the role of the Pons in the brain?
Sleep center.
Regulates respiration and acts as a relay center between cerebrum and cerebellum.
What structures are contained within the Midbrain?
Corpora quadrigemina, which includes superior and inferior colliculi.
Red nuclei and substantia nigra
True or False: Most motor neurons in the brainstem decussate.
True
Fill in the blank: The brainstem is essential for survival because it controls many _______.
reflexes
What is the function of the superior colliculi?
Visual reflexes (turn head in response to stimuli)
Involved in visual processing and reflexive movements related to vision.
What role do the inferior colliculi play?
Involved in hearing pathway
They are critical for auditory processing.
What is the function of the red nuclei?
Unconscious regulation of motor activities
They play a role in motor coordination.
What is the function of the substantia nigra?
Maintaining muscle tone & coordinating movement
It is important for smooth and controlled movements.
What does the reticular formation control?
Cyclic activities in the brainstem. Awareness, posture, pain, sleep wake cycle.
It integrates sensory information from various sources.
What is the role of the reticular activating system (RAS)?
Involved in waking and maintaining consciousness
It filters stimuli during sleep and activates in response to loud stimuli and light.
What can affect the RAS?
Smells, lights, sounds.
Certain drugs can stimulate or depress the RAS
These drugs can impact alertness and sleep patterns.
What is the cerebellum commonly referred to as?
‘Little brain’
It plays a significant role in motor control.
What are the three large nerve tracts connecting the cerebellum?
Superior, middle, and inferior peduncles
These connect the cerebellum to the midbrain, pons, and medulla.
What is the composition of the cerebellum’s cortex and inner structure?
Cortex is gray matter; inside is white matter (arbor vitae)
This structure is crucial for processing and coordinating movement.
List four functions controlled by the cerebellum.
- Balance
- Posture
- Fine motor coordination
- Eye movements
- Locomotion
Functions are distributed across hemispheres.
What area is located between the brainstem and cerebrum?
Diencephalon
It contains several key structures for sensory and hormonal regulation.
What are the components of the diencephalon?
- Thalamus
- Epithalamus
- Hypothalamus
- Subthalamus
- Pineal gland
Each part has distinct functions related to sensory and regulatory processes.
How are the two hemispheres of the thalamus connected?
By the intermediate mass
This structure is surrounded by the third ventricle.
What is the primary sensory relay center in the brain?
Thalamus
Most sensory input synapses onto thalamic neurons which send axons to the cerebral cortex.
What role does the thalamus play in relation to mood?
Influences mood & actions associated with strong emotion
Some thalamic nuclei are connected to the limbic system and pre-frontal cortex.
Where is the subthalamus located?
Just below the thalamus
It contains ascending and descending tracts and the subthalamic nucleus.
What is the function of the subthalamic nucleus?
Involved in controlling motor functions
It works in conjunction with the basal nuclei of the cerebrum.
What structures are found in the epithalamus?
Habenular nuclei, pineal gland, and melatonin
The habenular nuclei are involved in smells and emotional responses.
What is the role of the pineal gland?
Possibly involved in sleep/wake cycle and releases melatonin
It may also play a role in the onset of puberty.
What is ‘brain sand’?
~75% of us have this in the epithalamus
It refers to calcified structures found in the pineal gland.
Where is the hypothalamus located?
Below the thalamus
It plays a significant role in various bodily functions.
What is the hypothalamus’s connection to the pituitary gland?
Attached by the infundibulum
It plays a large endocrine role in the body.
What are the functions of the hypothalamus?
- Temperature regulation
- Olfactory reflexes
- Controls pituitary gland hormones
- Regulates food and water intake
- Muscle control
- Autonomic nervous system control
- Tied to mood and emotion
- Regulates sleep/wake cycle
These functions highlight its importance in homeostasis.
What sensory inputs does the hypothalamus receive?
- Visceral organs
- Taste buds
- Limbic system
- External genitalia
- Prefrontal cortex
These inputs contribute to its role in mood and emotional responses.
True or False: The mammillary bodies are involved in emotional responses to odors.
True
Found in the hypothalamus— They are similar in function to the habenular nucleus of the epithalamus.
What does the hypothalamus house
The thirst (leptin) and hunger center (grehlin)
What is the largest portion of the human brain?
Cerebrum
The cerebrum is divided into right and left hemispheres.
What fissure divides the right and left hemispheres of the cerebrum?
Longitudinal fissure
This fissure separates the two hemispheres of the cerebrum.
What are gyri and sulci?
Gyri are the ridges; sulci are the grooves
These structures increase the surface area of the brain.
What is the gray matter on the outside of the cerebrum called?
Cortex
The inner white matter is referred to as medulla.
What divides the primary motor and primary sensory cortex?
Central Sulcus
This structure separates the precentral gyrus from the postcentral gyrus.
What is the primary motor area of the brain?
Precentral gyrus
This area is responsible for voluntary motor functions.
What is the primary sensory area of the brain?
Postcentral gyrus
This area processes sensory information from the body.
What are the functions of the frontal lobe?
Voluntary motor function, motivation, aggression, mood, smell
The frontal lobe plays a key role in higher cognitive functions.
What is the main function of the occipital lobe?
Vision
This lobe is primarily responsible for processing visual information.
What functions are associated with the temporal lobe?
Smell, hearing, abstract thought & judgment, memory
The temporal lobe is involved in processing auditory information and memory.
What is the function of the parietal lobe?
Receives sensory information other than smell, hearing & vision
This lobe integrates sensory information from different modalities.
What is Broca’s Area responsible for?
Motor function of speech in the frontal lobe
This area is crucial for speech production.
What is Wernicke’s Area responsible for?
Understanding and formulating coherent speech in the parietal lobe
This area is essential for language comprehension.
What are the three types of white matter fibers in the cerebrum?
- Association Fibers
- Commissural Fibers
- Projection Fibers
These fibers connect different parts of the brain and spinal cord.
Where are the Basal Nuclei located?
In the base of the cerebrum, diencephalon, and midbrain
These nuclei are involved in motor functions and unintentional movement.
What is the amygdaloid nucleus associated with?
Fear response
This nucleus plays a significant role in emotional processing.
What are the components of the corpus striatum?
- Caudate nucleus
- Lentiform nucleus
The corpus striatum is part of the basal nuclei and is the largest structure in the brain.
What functions does the Limbic System serve?
Memory, reproduction, nutrition, emotions
The Limbic System forms a ring in the center of the brain.
What is considered a ‘primitive’ part of the brain?
Includes: Amygdaloid nucleus, hippocampus, olfactory cortex, portions of hypothalamus, mamillary bodies, fornix, cingulate gyrus.
What role does the amygdaloid nucleus play?
Fear
What functions are associated with the portions of the hypothalamus?
Mood, emotion
What is the cingulate gyrus known as?
‘Satisfaction center’ for feeding and sex
What can lesions in the limbic system cause?
- Increased appetite
- Increased and perverse sexual activity
- Loss of fear or anger
How does the limbic system influence visceral responses?
Changes in blood pressure and respiration
What are the three layers of the meninges?
- Dura Mater
- Arachnoid Mater
- Pia Mater
What is the Falx Cerebri?
A fold of meninges down into the longitudinal fissure
What is the Tentorium Cerebelli?
A fold of meninges between cerebrum and cerebellum
What does the dural sinus contain?
Venous blood
What is found in the subarachnoid space?
Cerebrospinal fluid (CSF)
What can damage to the dural sinus cause?
Bleeding into the subdural space, leading to subdural hematoma
What is a potential consequence of a subdural hematoma?
Pressure on the brain
How many lateral ventricles are there, and what percentage of CSF is formed there?
Two lateral ventricles, 80-90% of CSF formed
Where is the 3rd ventricle located?
Near the thalamus
Where is the 4th ventricle located?
Near the cerebellum
Fill in the blank: CSF flows from the lateral ventricles through the _______ to the third ventricle.
[interventricular foramen]
Fill in the blank: CSF flows from the third ventricle through the _______ to the 4th ventricle.
[cerebral aqueduct]
What happens to CSF after it exits the interior of the brain?
It circulates brain and spinal cord in subarachnoid space
How does CSF exit the subarachnoid space?
Through arachnoid granulations projecting into the sagittal sinus
What can a skull fracture lead to regarding CSF?
Leakage of CSF, which can result in meningitis if bacteria enters meninges
What is the primary function of the internal carotids?
To take fresh blood to the brain
They branch into an elaborate network to supply the brain, known as the Circle of Willis.
Where are the arteries to the brain located?
In the subarachnoid space
Smaller branches enter the pia mater and branch extensively into capillaries.
What forms the blood-brain barrier?
Tight junctions of endothelial cells and processes from neuroglial astrocytes
These structures completely surround the endothelial cells of capillaries.
Which substances can diffuse through the blood-brain barrier?
Lipid soluble substances, like nicotine and alcohol
What are the three functions of cranial nerves?
- Sensory (special and general senses)
- Somatic motor (control of skeletal muscle)
- Parasympathetic (regulation of glands, smooth muscle or cardiac muscle)
What is the function of the Olfactory nerve?
Exclusively sensory function for smell
What is the primary function of the Optic nerve?
Exclusively sensory function for sight
What functions does the Oculomotor nerve serve?
- Somatic motor
- Parasympathetic functions
Innervates eye muscles to move the eye and controls the diameter of the pupil.
What is the exclusive function of the Trochlear nerve?
Exclusively somatic motor function to move the eyeball
What functions are associated with the Trigeminal nerve?
- Somatic motor
- Proprioreception
- Sensory function
Innervates muscles of mastication and has the greatest sensory function of all cranial nerves.
What functions does the Abducens nerve have?
- Motor
- Proprioreception functions
Primarily responsible for moving the eyeball.
What are the functions of the Facial nerve?
- Somatic motor
- Sensory
- Parasympathetic functions
Controls facial expression and provides sensory for taste.
What is the primary function of the Vestibulocochlear nerve?
Exclusively sensory for special senses of hearing and balance
What functions does the Glossopharyngeal nerve serve?
- Somatic motor
- Sensory
- Parasympathetic functions
Involves taste and sensory from the tongue, middle ear, and pharynx.
What are the functions of the Vagus nerve?
- Somatic motor
- Sensory
- Parasympathetic
Involved in the motor functions for speaking and sensory functions for taste and blood pressure.
What is the primary function of the Accessory nerve?
Somatic motor - assists vagus nerve and innervates sternocleidomastoid and trapezius
What is the function of the Hypoglossal nerve?
Somatic motor - innervates tongue muscles and throat muscles
What is the brianstem mostly composed of
White matter
What is contained in the medulla, ponsC and midbrain
Ascending and descending tracts
How does the medulla oblongsts force you to breath
Had chemireceptors which detect acidic environment and makes you inhale
What occurs to motor neurons in the medulla oblongata
Decussate (crosses over), thus half of the brain controls the opposite half of the body
Important areas of the pons
Sleep center
Respiratory center coordinates with medulla
Superior colliculi
Involved in visual reflexes, receieve info from inferior, eyes, skin, cerebrum
Inferior colliculi is involved in
Hearing
Inner white matter of cerebellum
Arbor vitae
What can the cerebellum do with movements
Can learn muscle patterns with help from frontal lobe
Competitive function
Function of the cerebellum- Received feedback from proprioreceptors which relay spatial info to cerebellum. Compares action movements with intended movements and making corrections if necessary.
Cerebellar disorder
Poor balance
Poor posture
Poor hand eye coordination
Poor locomotion
Missing objects when reaching
Intention tremors
Alcohol affects cerebellum
How does the hypothalamus receive information
Through sensory neurons from visceral organs, taste buds, limbic system, external genitalia, and prefrontal cortex (mood)
What is the hypothalamus important in the regulation of
Mood, emotion, sexual pleasure, saturation, rage, fear
Hypothalamus dysfunctions
Endocrine disorders
Inability to regulate temperature
Increased thirst
Appetite changes
Difficulty sleeping
Mood swings
Lack of sex drive
