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What Part Of The Brain Is The Hypothalamus Located

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What Is The Role Of The Brain Hypothalamus In The Reproductive System

The hypothalamus

What is the role of the brain hypothalamus in the reproductive system? The hypothalamus controls reproduction by regulating the secretory activities of the pituitary gland. In female birds, growth of the ovarian follicles, synthesis of sex steroids, and ovulation are effected, at least in part, by neurohormonally mediated changes in rates of release of pituitary gonadotrophins.

What is the role of the hypothalamus in the reproductive system? The hypothalamus monitors the need for the FSH and LH hormones made and released from the anterior pituitary. In females, FSH and LH cause estrogen and progesterone to be produced. They regulate the female reproductive system which is divided into the ovarian cycle and the menstrual cycle.

What is the role of the brain hypothalamus in the reproductive system in male? Brain centers play a key role in the regulation and control of the reproductive hormones and system. The hypothalamus produces gonadotropin-releasing hormone to regulate the production and release of FSH and LH in the pituitary gland.

What is the main function of the hypothalamus in the brain? The hypothalamus is a small, central region of the human brain formed by nervous fibers and a conglomerate of nuclear bodies with various functions. The hypothalamus is considered to be a link structure between the nervous and the endocrine system, its main function being to maintain the homeostasis of the body.

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What Is The Hypothalamus And What Does It Do

The hypothalamus is a collection of nuclei with a variety of functions. Many of the important roles of the hypothalamus involve what are known as the two H’s: Homeostasis and Hormones.

Homeostasis is the maintenance of equilibrium in a system like the human body. Optimal biological function is facilitated by keeping things like body temperature, blood pressure, and caloric intake/expenditure at a fairly constant level. The hypothalamus receives a steady stream of information about these types of factors. When it recognizes an unanticipated imbalance, it enacts a mechanism to rectify that disparity.

The hypothalamus generally restores homeostasis through two mechanisms. First, it has connections to the autonomic nervous system, through which it can send signals to influence things like heart rate, digestion, and perspiration. For example, if the hypothalamus senses that body temperature is too high, it may send a message to sweat glands to cause perspiration, which acts to cool the body down.

The hypothalamus thus has widespread effects on the body and behavior, which stem from its role in maintaining homeostasis and its stimulation of hormone release. It is often said that the hypothalamus is responsible for the four Fs: fighting, fleeing, feeding, and fornication. Clearly, due to the frequency and significance of these behaviors, the hypothalamus is extremely important in everyday life.

The Cerebellum’s Balancing Act

Next up is the cerebellum. The cerebellum is at the back of the brain, below the cerebrum. It’s a lot smaller than the cerebrum. But it’s a very important part of the brain. It controls balance, movement, and coordination .

Because of your cerebellum, you can stand upright, keep your balance, and move around. Think about a surfer riding the waves on his board. What does he need most to stay balanced? The best surfboard? The coolest wetsuit? Nope he needs his cerebellum!

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Anatomy Of The Hypothalamus

The hypothalamus is found underneath the thalamus and comprises the floor of the third ventricle . The hypothalamus extends downward from the brain into a stalk known as the pituitary stalk , which connects it to the pituitary gland.

It can be divided into three main regions, each containing distinct nuclei and neuron clusters that are assigned various functions: The anterior region of the hypothalamus is known as the supraoptic region.

The supraoptic and paraventricular nuclei can be found here along with many more, smaller nuclei. The supraoptic nucleus functions as the main source of vasopressin, also known as the antidiuretic hormone , which plays a key role in the absorption of salts and glucose and maintaining the concentration of water in the extracellular fluid.

The middle region of the hypothalamus is known as the tuberal region and its primary nuclei are the ventromedial and arcuate nuclei. The ventromedial nucleus controls the appetite and the arcuate nucleus releases the growth hormone-releasing hormone , which stimulates the pituitary gland to produce growth hormone .

Finally, the posterior region of the hypothalamus, called the mammillary region, contains the following major nuclei: the posterior hypothalamic nucleus and mammillary nuclei.

The posterior region of the hypothalamus is also home to a structure called the median eminence. This structure contains many endings of neurosecretory cells .

What Is Amygdala And Hypothalamus

Hypothalamus

Both are structures located within our brain and both are involved in the neural network of aggressive behaviors. The entire system is called the limbic system and is involved in our emotions. However, there are differences as well. The amygdala structure is the emotion center of the brain while hypothalamus is linked with changes in emotional reactivity.

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Ventricles And Cerebrospinal Fluid

Deep in the brain are four open areas with passageways between them. They also open into the central spinal canal and the area beneath arachnoid layer of the meninges.

The ventricles manufacture cerebrospinal fluid, or CSF, a watery fluid that circulates in and around the ventricles and the spinal cord, and between the meninges. CSF surrounds and cushions the spinal cord and brain, washes out waste and impurities, and delivers nutrients.

Control Of Food Intake

Peptide hormones and neuropeptides that regulate feeding

Peptides that increase
Glucagon-like peptide 1

The extreme lateral part of the ventromedial nucleus of the hypothalamus is responsible for the control of food intake. Stimulation of this area causes increased food intake. Bilateral lesion of this area causes complete cessation of food intake. Medial parts of the nucleus have a controlling effect on the lateral part. Bilateral lesion of the medial part of the ventromedial nucleus causes hyperphagia and obesity of the animal. Further lesion of the lateral part of the ventromedial nucleus in the same animal produces complete cessation of food intake.

There are different hypotheses related to this regulation:

  • Lipostatic hypothesis: This hypothesis holds that adiposetissue produces a humoral signal that is proportionate to the amount of fat and acts on the hypothalamus to decrease food intake and increase energy output. It has been evident that a hormoneleptin acts on the hypothalamus to decrease food intake and increase energy output.
  • Gutpeptide hypothesis: gastrointestinal hormones like Grp, glucagons, CCK and others claimed to inhibit food intake. The food entering the gastrointestinal tract triggers the release of these hormones, which act on the brain to produce satiety. The brain contains both CCK-A and CCK-B receptors.
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    Hypothalamic Control Of Fluid And Electrolyte Balance

    To maintain adequate tissue perfusion, the hypothalamus must regulate fluid acquisition through drinking, and control the osmolality and electrolyte content of the blood, as well as the overall blood volume. When there is excess fluid volume, it must regulate diuresis by the kidney. These tasks are under the regulation of the preoptic area, in particular the median preoptic nucleus and organum vasculosum of the lamina terminalis, along the anterior wall of the third ventricle. Drinking behavior is tightly linked with feeding, and with thermoregulation .

    What Is The Thalamus

    Neuroanatomy : Diencephalon, Thalamus & Hypothalamus

    As Ive mentioned, the thalamus is a part of the brain segment called the diencephalon, located between the cerebral cortex and the midbrain. It serves as a bridge between the two, therefore it is closely connected to both.

    It transmits signals between the midbrain and the cerebral cortex, but it also regulates sleep, alertness and wakefulness. When looking at the cross-section of the human brain, the thalamus can be found almost at the very center of the brain, between the frontal lobe and the brain stem.

    It consists of two bulbs, each about 6cm in length, one on each hemisphere of the brain. Since its located so close to the center, where the nerves go out in all directions towards the periphery of the brain, it has the optimal spot for the purpose that it fulfills .

    Its blood flow is facilitated through four branches of the posterior cerebral artery, allowing it just enough oxygen to function. Distinct segments of the thalamus have been discovered, such as the isothalamus or allothalamus, but they vary only slightly in structure and function, and therefore wont be discussed in further detail.

    The distinctive characteristics of the thalamus are:

    • Part of the diencephalon, located between the cerebral cortex and the midbrain, near the center of the brain
    • Transfers information between the cerebral cortex and the midbrain
    • Regulates sleep, alertness and wakefulness
    • Consists of two bulbs on each hemisphere, each around 6cm in length

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    How Does The Brain Work

    The brain sends and receives chemical and electrical signals throughout the body. Different signals control different processes, and your brain interprets each. Some make you feel tired, for example, while others make you feel pain.

    Some messages are kept within the brain, while others are relayed through the spine and across the bodys vast network of nerves to distant extremities. To do this, the central nervous system relies on billions of neurons .

    Brain Stem Keeps You Breathing And More

    Another brain part that’s small but mighty is the brain stem. The brain stem sits beneath the cerebrum and in front of the cerebellum. It connects the rest of the brain to the spinal cord, which runs down your neck and back. The brain stem is in charge of all the functions your body needs to stay alive, like breathing air, digesting food, and circulating blood.

    Part of the brain stem’s job is to control your involuntary muscles the ones that work automatically, without you even thinking about it. There are involuntary muscles in the heart and stomach, and it’s the brain stem that tells your heart to pump more blood when you’re biking or your stomach to start digesting your lunch. The brain stem also sorts through the millions of messages that the brain and the rest of the body send back and forth. Whew! It’s a big job being the brain’s secretary!

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    Causes And Risk Factors

    The most common causes of hypothalamic diseases are injuries to the head that impact the hypothalamus. Surgeries, radiation, and tumors can also cause disease in the hypothalamus.

    Some hypothalamic diseases have a genetic link to hypothalamic disease. For instance, Kallman syndrome causes hypothalamic problems in children, most noticeably delayed or absent puberty, accompanied by an impaired sense of smell.

    Hypothalamus problems also appear to have a genetic link in Prader-Willi Syndrome. This is a condition in which a missing chromosome leads to short stature and hypothalamic dysfunction.

    Additional causes of hypothalamic disease can include:

    • eating disorders, such as bulimia or anorexia
    • genetic disorders that cause excess iron buildup in the body

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    Blood Supply Of Hypothalamus

    Hypothalamus

    Hypothalamus receives blood mainly from the hypophyseal artery, a branch of the anterior cerebral artery. All the blood from the hypothalamus is drained into the hypothalamohypophyseal system of veins and distributed to the pituitary gland. From the pituitary gland, the blood is drained via the hypophyseal vein.

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    Autonomous Processes Regulated By The Hypothalamus

    The autonomous processes regulated by the hypothalamus are key to its ability to control homeostasis. Each of these processes must be maintained at a specific level called the set-point.

    This set-point can be observed to have minimal changes over time, but overall, it will remain largely the same. The main elements that contribute to the set-point are blood pressure, body temperature, the balance of electrolytes and fluids, and body weight.

    Inputs to the Hypothalamus

    In order to properly manage this set-point, the hypothalamus must receive neurological inputs from multiple nervous and endocrine system sources. These sources are:

    • Neurohypophysis: releases hormones such as oxytocin and vasopressin into the blood
    • Area postrema: controls the vomiting reflex
    • Subfornical organ: regulates bodily fluids and processes such as osmoregulation, cardiovascular regulation, and energy maintenance.
    • Vascular organ of lamina terminalis: intake of chemosensory information
    • Median eminence: a neurohemal organ that contains a capillary bed into which hypothalamic nerves send their neuronal transmissions
  • Limbic and olfactory systems: gathering and distribution of olfactory sensory information and the regulation of emotions.
  • Hormones Released by the Hypothalamus

    The hormones released by the hypothalamus include

    The Biggest Part: The Cerebrum

    The biggest part of the brain is the cerebrum. The cerebrum is the thinking part of the brain and it controls your voluntary muscles the ones that move when you want them to. So you need your cerebrum to dance or kick a soccer ball.

    You need your cerebrum to solve math problems, figure out a video game, and draw a picture. Your memory lives in the cerebrum both short-term memory and long-term memory . The cerebrum also helps you reason, like when you figure out that youd better do your homework now because your mom is taking you to a movie later.

    The cerebrum has two halves, with one on either side of the head. Scientists think that the right half helps you think about abstract things like music, colors, and shapes. The left half is said to be more analytical, helping you with math, logic, and speech. Scientists do know for sure that the right half of the cerebrum controls the left side of your body, and the left half controls the right side.

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    How Do You Know If Your Thalamus Is Damaged

    Speech and Cognitive Therapy While thalamus damage primarily causes sensory problems, it can also lead to behavioral and cognitive changes. For example, many patients with a thalamus injury have incorrect speech patterns and can struggle to find the right words. Others display apathy and memory problems.

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    What Could Go Wrong With My Hypothalamus

    Hypothalamus anatomy

    Hypothalamic function can be affected by head trauma, brain tumours, infection, surgery, radiation and significant weight loss. It can lead to disorders of energy balance and thermoregulation, disorganised body rhythms, and symptoms of pituitary deficiency due to loss of hypothalamic control. Pituitary deficiency ultimately causes a deficiency of hormones produced by the gonads, adrenal cortex and thyroid gland, as well as loss of growth hormone.

    Lack of anti-diuretic hormone production by the hypothalamus causes diabetes insipidus. In this condition the kidneys are unable to reabsorb water, which leads to excessive production of dilute urine and very large amounts of drinking.

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    Damage To The Limbic System

    Damage to the limbic system is dependant on which region is affected. Amygdala damage could affect a personâs fear processing , which could result in more risk-taking behaviors and putting themselves in dangerous situations.

    Damage to the hippocampus could lead to deficits in being able to learn anything new, as well as affecting memory.

    Hypothalamus damage can affect the production of certain hormones, including those which can affect mood and emotion.

    Below is a non-exhaustive list of symptoms associated with limbic system damage:

    • Uncontrolled emotions â more aggression, anxiety, and agitation.
    • Olfactory impairments
    • Alzheimerâs disease
    • Movement disorders â Huntingtonâs and Parkinsonâs disease

    A potential treatment for limbic impairments is deep brain stimulation . Successful treatment of some cognitive disorders such as anxiety and posttraumatic stress disorder has come from DBS of the amygdala.

    DBS has also shown to be useful in targeting the nucleus accumbens in relation to drug addiction .

    Similarly, the use of antidepressant medications has shown links with restoring the underlying physiological differences in the limbic system in major depressive disorder .

    Hypothalamic Control Of Stress Responses

    When an animal is under attack, it must reach full arousal, mobilize its energy stores, and be ready either for fight or flight. Reproductive behavior, food foraging, and other non-essential tasks must be inhibited. The signals that regulate this response must come from cognitive and limbic systems that are capable of assessing threats. The paraventricular nucleus plays a key role in stress responses, as it contains most of the neurons that produce corticotropin releasing hormone, which causes release of ACTH and then adrenal steroids. The paraventricular nucleus also contains many of the autonomic control neurons, necessary to cause adrenaline release. However, lateral hypothalamic neurons must be engaged to bring the cortex to a full state of alert wakefulness, as must medial hypothalamic neurons to mobilize energy stores. Stress inhibits sexual behavior, and in some cases may even lead to interruption of pregnancy. Because stress is inherently non-specific, i.e., it can include any stimulus that threatens survival, it may inherently interact with any of the other hypothalamic regulatory systems.

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    Function Of The Hypothalamus

    The function of the hypothalamus is to help regulate your body’s processes and to release hormones. The hormones it makes travel to the anterior pituitary through the blood.

    The hypothalamus can make the following hormones:

    • Dopamine: A brain chemical that influences mood and feelings of reward and motivation
    • Somatostatin: Regulates the gastrointestinal tract and other important bodily functions
    • Oxytocin: Fosters positive feelings of connection and well-being, sometimes called the love hormone
    • Vasopressin: An antidiuretic hormone involved in regulating fluid levels in the body
    • Growth hormone-releasing hormone : Stimulates the release of growth hormone
    • Thyrotropin-releasing hormone : Regulates the release of an important thyroid hormone.
    • Gonadotropin-releasing hormone : Stimulates the production of testosterone
    • Corticotropin-releasing hormone : Helps drive the body’s stress response

    Some of the functions of the hypothalamus include regulating:

    • Hunger and appetite
    • Brain MRI and CT scans

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