In the krivenien show i have hosted a topic called body parts where i talk about human body parts, and i have started with the very top of the human body, which is the head. I have mentioned the very top of the head and the sides and the front and the back,but i have talked only little about the very top.
Today’s episode will talk about the things in the very top of the head I didn’t talk about, which is the brain. We are going to know more about the brain, so its going to be so much. I recommend you to prepare your self with drinks and snacks, i hope you enjoy it!
Some people confuse between the brain and the mind,so before i talk about the brain let me talk about that point. So the brain is organ in the animals and human head, and the mind is something like the soul,it doesn’t have place but its in our body,. This is the god’s gift for humans,which mean this can be found only in the humans.
Anyway The brain as i mentioned in the very top of the head, and it protected by the skull bones of the head, and the brain usually located close to the sensory organs for senses such as vision. The brain structure consist of Cerebral cortex, Cerebrum, Cerebellum,Cerebrospinal fluid, Neurons and Glial cells.
Alright let’s tear it up guys, but before i start, a you prepare for it ?, if you are not then prepare for it, if you are lets do it. And for that i will use the list–best style to make more fun and easy to read and use pictures otherwise it will be boring to read this episode.
Imagine your the anti-man from the movie,and you turned into a little small person and you are in the top of the human body,and you opened a little hole for you to get in, there is no way you can jump so you have to use the ladder, you put the ladder and you started going down inside the head,you are standing on the bones, and theses bones are the head bones i have talked about in the previous episode of body parts.
Now we already know the bones and everything we need to go even further you need to open another hole but you want to be careful this time because there is something so sensitive. You opened a hole now we wont use ladders because there is something sensitive and its the brain, we will just get close to it by the rope. We are going to hook the rope in the bone with hook, and get down slowly.
Now we are close to the brain, what you see is the cerebrum,now from this point i will use the list-best style, hope you enjoy it!
Okay as i said. By the way we still hanging with the rope so lets keep it going. Now as i said what you see is the cerebrum and this is the largest part in the brain, and its divided to two parts and these parts called “Cerebral Hemispheres”, there is the right hemisphere and the left hemisphere.
let’s get even more closer so we can see something called Cerebral cortex.
The Cerebral Cortex:
Okay so the Cerebral cortex is outer layer of gray matter of the cerebrum, here is a thing this thing only found in mammals,to be more specific larger mammals. And of course that including humans,and here is a crazy thing, the the cerebral cortex contains approximately 15–33 billion neurons.
Okay we cant go any further but i’m going to show a photo of that, i mean of course everyone hold a iPad now. So i will pass to everyone the photo and will explain everything in details. We still hanging with the rope close to the brain, don’t forget that.
So as you see in the picture the cerebrum consist of two cerebral hemispheres,separated from each other by a deep fissure called the longitudinal fissure.
So let me talk about the cerebral hemispheres for little, Each of these hemispheres has an outer layer of grey matter, and its supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum.
and also the cerebral hemisphere interior of the cerebral hemispheres is an inner layer or core of white matter known as the centrum semiovale. and The interior portion of the hemispheres of the cerebrum includes the lateral ventricles, the basal nuclei, and the white matter.
Okay if you zoom in in the picture you will see the Cerebral cortex generally classified into four lobes.
The First lobe is The Frontal:
Alright so The frontal lobe located at the front of the brain,and its one of the four major lobes of the cerebral cortex in the mammalian brain. The frontal lobe is located at the front of each cerebral hemisphere and positioned in front of the parietal lobe and above and in front of the temporal lobe.
The frontal lobe bottom can be divided into a lateral, polar and medial part. Each of these parts consists of particular gyri (the gyri also called a gyrus and its a ridge on the cerebral cortex. It is generally surrounded by one or more sulci ).
The Frontal lobe Function:
Okay so now let me mention for you the functions for this lobe The frontal lobe plays a large role in voluntary movement. And It houses the primary motor cortex which regulates activities like walking.
And also The function of the frontal lobe involves the ability to project future consequences resulting from current actions. For example like the choice between good and bad actions (or better and best) (also known as conscience), and the override and suppression of socially unacceptable responses, and the determination of similarities and differences between things or events.
The frontal lobe also plays an important part in integrating longer non-task based memories stored across the brain. These are often memories associated with emotions derived from input from the brain’s limbic system. The frontal lobe modifies those emotions to generally fit socially acceptable norms.
The second Lobe is The Parietal:
The second lobe is Parietal lobe, and this lobe also one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the occipital lobe and behind the frontal lobe and central sulcus.
The parietal lobe is defined by three anatomical boundaries, The central sulcus and which separates the parietal lobe from the frontal lobe,the parieto-occipital sulcus which separates the parietal and occipital lobes,the last one is the lateral sulcus (sylvian fissure) is the most lateral boundary,and separating it from the temporal lobe. And the medial longitudinal fissure divides the two hemispheres. Within each hemisphere, the somatosensory cortex represents the skin area on the contralateral surface of the body.
The Parietal lobe function:
Alright now let me talk about the functions for this lobe, First thing is The Parietal lobe Cortical functions of are:
Two point discrimination
and then through touch alone without other sensory input:
Graphesthesia: recognizing writing on skin by touch alone
Touch localization: (bilateral simultaneous stimulation)
Okay what i have mentioned is some functions for the parietal lobe, but the parietal lobe plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations,and in the manipulation of objects. Its function also includes processing information relating to the sense of touch.
And the portions of the parietal lobe are involved with visuospatial processing. Although multisensory in nature, the posterior parietal cortex is often referred to by vision scientists as the dorsal stream of vision (as opposed to the ventral stream in the temporal lobe). This dorsal stream has been called both the “where” stream (as in spatial vision) and the “how” stream (as in vision for action).
Several areas of the parietal lobe are important in language processing. The somatosensory cortex can be illustrated as a distorted figure, the homunculus mean in latin “little man”, in which the body parts are rendered according to how much of the somatosensory cortex is devoted to them
3-The Third Lobe is The Temporal:
Okay now we are going to know more about the third lobe which the temporal lobe, this lobe located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain, and also this lobe is one of major four lobes.
So in this lobe there is no much about, but there is one thing called “Medial temporal lobe“. And this consists of structures that are vital for declarative or long-term memory include the hippocampus (The hippocampus is critical for memory formation. The surrounding medial temporal cortex is currently theorized to be critical for memory storage) and its the explicit memory or it can be called “Declarative ” and its conscious memory divided into semantic memory (facts) and episodic memory (events).
The Temporal lobe Function:
The temporal lobe plays an important role in Visual memories, and it communicates with the hippocampus and plays a key role in the formation of explicit long-term memory modulated by the amygdala.
The temporal lobe also have role in Auditory, so the Adjacent areas in the superior, posterior, and lateral parts of the temporal lobes are involved in high-level auditory processing. So The temporal lobe is involved in primary auditory perception, such as hearing, and holds the primary auditory cortex. Here how it work, The primary auditory cortex receives sensory information from the ears and secondary areas process the information into meaningful units such as speech and words. The superior temporal gyrus includes an area (within the lateral fissure) where auditory signals from the cochlea first reach the cerebral cortex and are processed by the primary auditory cortex in the left temporal lobe.
Alright and the visual, The areas associated with vision in the temporal lobe interpret the meaning of visual stimuli and establish object recognition. The ventral part of the temporal cortices appear to be involved in high-level visual processing of complex stimuli such as faces (fusiform gyrus) and scenes (parahippocampal gyrus). Anterior parts of this ventral stream for visual processing are involved in object perception and recognition.
The temporal lobe holds the primary auditory cortex, which is important for the processing of semantics in both speech and vision in humans. Okay so the Wernicke’s area which spans the region between temporal and parietal lobes, plays a key role (in tandem with Broca’s area in the frontal lobe) in speech comprehension. The functions of the left temporal lobe are not limited to low-level perception but extend to comprehension, naming, and verbal memory.
Okay as i said The medial temporal lobes include the hippocampi, which are essential for memory storage, and if there any damage to this area can result in impairment in new memory formation leading to permanent or temporary anterograde amnesia.
4-Fourth Lobe is The Occipital Lobe:
Okay this is the last lobe we are going to talk about, the occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex,and of course its the last of the major four lobes. The primary visual cortex is Brodmann area 17 and it commoly called The V1 which stands for “visual one”,and this located on the medial side of the occipital lobe within the calcarine sulcus.
The occipital lobe in both sides, left and right are smallest of four paired lobes in the human cerebral cortex. The lobe Located in the rearmost portion of the skull, and also this lobe is part of the forebrain. None of the cortical lobes are defined by any internal structural features, but rather by the bones of the head bone that overlie them. Thus, the occipital lobe is defined as the part of the cerebral cortex that lies underneath the occipital bone.
This lobe rest on the tentorium cerebelli, a process of dura mater that separates the cerebrum from the cerebellum. They are structurally isolated in their respective cerebral hemispheres by the separation of the cerebral fissure,okay now lets move to the functions,i know you are tired of hanging with robe, or did you forget that we are inside the human body using imagination, and we imagine our self as the anti-man from the movie, okay just a reminder.
The Occipital lobe Functions:
So this lobe have divided into several functional visual areas, Each visual area contains a full map of the visual world. Although there are no anatomical markers distinguishing these areas (except for the prominent striations in the striate cortex), physiologists have used electrode recordings to divide the cortex into different functional regions.
Okay i’m going to mention one area so i hope its enough. Anyway the primary visual cortex is one of the areas, and it contains a low-level description of the local orientation, spatial-frequency and color properties within small receptive fields. The primary visual cortex projects to the occipital areas of the ventral stream (which is the visual area V2 and visual area V4), and the occipital areas of the dorsal stream which is the visual area V3, visual area MT (V5), and the dorsomedial area (DM).
Alright we are about to finish the episode if you still reading till this point, you are the best, so i need to talk about four points and then we are out here.
The Cerebellum :
The cerebellum in latin language means the little man,and that mean is smaller than the cerebrum, and this a major feature of the hindbrain of all vertebrates.and this one located in the bottom of the brain. We are not going to go deep in details, because there is nothing you want to know unless you really planning on becoming a doctor, and that’s another thing. So we are going to move to the function.
The cerebellum Function:
The cerebellum plays an important role in motor control, and it may also be involved in some cognitive functions such as attention and language as well as in regulating fear and pleasure responses.
The comparative simplicity and regularity of the cerebellar anatomy led to an early hope that it might imply a similar simplicity of computational function,i dont think there any more interesting details so i will just mention the four principles have been identified as important,feedforward processing, divergence and convergence, modularity, plasticity.
There is considerable evidence that the cerebellum plays an essential role in some types of motor learning. The tasks where the cerebellum most clearly comes into play are those in which it is necessary to make fine adjustments to the way an action is performed.
Okay so far we are close to the end, but before i move to next point the i think before the last one, i want to talk about the Cerebrospinal fluid,the Cerebrospinal fluid is clear and colourless fluid that circulates around the brain, within the brain in its ventricular system, and in the central canal of the spinal cord in the subarachnoid space, as well as within some spaces within the brain.There are four ventricles, two lateral ventricles, third ventricle, and fourth ventricle, which all produce cerebrospinal fluid. Most cerebrospinal fluid is created in the choroid plexuses of the ventricles.
So yeah thats what i want to talk about now lets move the next point, there is only three points to go.
The pons is part of the brainstem, and in humans and other bipeds lies between the midbrain (above) and the medulla oblongata (below) and in front of the cerebellum.The pons in humans measures about 2.5 centimetres (0.98 in) in length. And most of it appears as a broad anterior bulge rostral to the medulla. Posteriorly, it consists mainly of two pairs of thick stalks called cerebellar peduncles. They connect the cerebellum to the pons and midbrain
The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.
The Pons function:
The functions of these four cranial nerves (V-VIII) include sensory roles in hearing, equilibrium, and taste, and in facial sensations such as touch and pain, as well as motor roles in eye movement, facial expressions, chewing, swallowing, and the secretion of saliva and tears.
Okay the last point i’m going to talk about is ….,before i do that let me say its over for list–best style for now, i’m going to write in normal style.
The last point i want to talk is the two cells in the brain, so the first one is the Neuron or also known neurone is an electrically excitable cell that processes and transmits information through electrical and chemical signals. These signals between neurons occur via synapses, specialized connections with other cells. Neurons can connect to each other to form neural networks. Neurons are the core components of the brain and spinal cord of the central nervous system (CNS), and of the ganglia of the peripheral nervous system (PNS)
And the last one is the Neuroglia or you can use the “glia ” for short name and easy to read,anyway these are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems. In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells and microglia, and in the peripheral nervous system glial cells include Schwann cells and satellite cells.
Alright everything, i think thats everything you would like to know about the brain, but i’m going to mention the brain functions quick, and i’m going to end the episode.
Yeah, i have to use the list–best style so i will bring it back, to mention that this point need the list-best style in order to make more fun to end the episode.
The First Function is Motor control:
The motor system of the brain is responsible for the generation and control of movement. And Generated movements pass from the brain through nerves to motor neurons in the body, which control the action of muscles,this is how the movements travel in the humans. The corticospinal tract carries movements from the brain, through the spinal cord, to the torso and limbs.The cranial nerves carry movements related to the eyes, mouth and face.
The Second Function is Sensory:
The sensory nervous system is involved with the reception and processing of sensory information. This information is received through the cranial nerves, through tracts in the spinal cord, and directly at centers of the brain exposed to the blood. The brain also receives and interprets the special senses (vision, smell, hearing, and taste). Mixed motor and sensory signals are also integrated.
The Third Function is Regulation:
The brain influences blood pressure and controls the rate of breathing, mainly by centres in the medulla. The vasomotor center of the medulla causes arteries and veins to be somewhat constricted at rest, as well as influencing the heart rate. It does this by influencing the sympathetic nervous system and parasympathetic via the vagus nerve. Information about blood pressure is generated by stretch receptors in the arch of aorta and passed to the brain along the vagus nerve, and about the stretch of the carotid sinus via the a nerve joining with the glossopharyngeal nerve. This information travels up to the solitary nucleus. Signals from here influence the vasomotor nucleus to adjust vein and artery constriction accordingly.
The fourth Function is Language:
Language functions are generally localized to Wernicke’s area and Broca’s area.Wernicke’s area is at the posterior part of the superior temporal gyrus of the dominant half of the brain, and seems to be responsible for creation and interpretation of spoken thought.
The Fifth Function is Lateralization:
Each hemisphere of the brain interacts primarily with one half of the body: the left side of the brain interacts with the right side of the body, and vice versa. The developmental cause for this is uncertain. Motor connections from the brain to the spinal cord, and sensory connections from the spinal cord to the brain, both cross sides in the brainstem.
Visual input follows a more complex rule: the optic nerves from the two eyes come together at a point called the optic chiasm, and half of the fibers from each nerve split off to join the other.The result is that connections from the left half of the retina, in both eyes, go to the left side of the brain, whereas connections from the right half of the retina go to the right side of the brain.
Because each half of the retina receives light coming from the opposite half of the visual field, the functional consequence is that visual input from the left side of the world goes to the right side of the brain, and vice versa. Thus, the right side of the brain receives somatosensory input from the left side of the body, and visual input from the left side of the visual field.
The Sixth Function is Emotion:
Emotions are generally defined as two step multicomponent processes involving elicitation, followed by psychological feelings, appraisal, expression, autonomic responses, and action tendencies.Attempts to localize basic emotions to certain brain regions have been controversial, with some research finding no evidence for specific locations corresponding to emotions, and instead circuitry involved in general emotional processes.
The amygdala, orbitofrontal cortex, mid and anterior insula cortex and lateral prefrontal cortex, appeared to be involved approach related emotions, while weaker evidence was found for the ventral tegmental area, ventral pallidum and nucleus accumbens in incentive salience.Others, however, have found evidence of activation of specific regions, such as the basal ganglia in happiness, the subcallosal cingulate cortex in sadness, and amygdala in fear.
Alright everyone, this is the last point we gonna talk about and its the Executive functions, The Executive functions are an umbrella term for various cognitive processes and sub-processes, that allow for the control of thought and behavior. These functions include the ability to filter information, or attention, the ability to manipulate working memory, the ability to switch tasks, response inhibition, and the ability to determine the relevance of information.
The prefrontal cortex plays a significant role in executive functions. Neuroimaging during tasks testing executive function, such as stroop task and memory tasks, have found that cortical maturation of the prefrontal cortex correlates with executive function in children.Future planning involves activation of the dorsolateral prefrontal cortex, anterior cingulate cortex, angular prefrontal cortex, right prefrontal cortex, and supramarginal gyrus.
Working memory manipulation involves the DLPFC, inferior frontal gyrus, and areas of the parietal cortex. Response inhibition involves multiple areas of the cortex, including the inferior frontal gyrus, and ventrolateral prefrontal cortex. Task shifting doesn’t involve specific regions of the brain, but instead involves multiple regions of the prefrontal cortex and parietal lobe.
Finally we have came to the end of this episode, “The Brain” Episode of the Body parts show, thank you so much for reading, i hope you enjoyed, i will see you in the next post,have an amazing day till then.