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Secretory glands of the brain, also known as neuroendocrine glands, are specialized structures that secrete hormones directly into the bloodstream. These hormones affect various organs and tissues throughout the body and play a vital role in maintaining homeostasis. They help regulate important physiological functions such as growth, metabolism, sleep, reproduction and response to stress. The primary secretory glands of the brain are the  pituitary gland  and the  pineal gland.  These glands are located within the central nervous system but also act as  endocrine organs.  They are directly or indirectly controlled by the  hypothalamus  and are involved in the production and secretion of hormones that regulate body functions like stress response, reproductive cycles, circadian rhythms and metabolic activity. 1. Pituitary Gland (Hypophysis) The pituitary gland is a small  pea-shaped  endocrine gland located at the base of the brain in a bo...

Neurotransmission is the process by which neurons communicate with each other. It occurs mainly through two types:  chemical neurotransmission  and  electrical neurotransmission.  Both types serve the same basic function, that is, to transmit signals between neurons, but they differ in their mechanisms. These are two essential modes of  synaptic transmission  in the nervous system. Chemical Neurotransmission Chemical neurotransmission is the predominant form of signal transmission between neurons, involving the release and reception of neurotransmitters (chemical messengers). When an action potential reaches the presynaptic terminal of a neuron, it triggers the opening of voltage-gated  calcium channels,  allowing calcium ions (Ca²⁺) to enter the presynaptic neuron. This influx of calcium ions facilitates the fusion of synaptic vesicles with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft. The neurotransmitters then d...

SAQ 1 a) Write the name of two glands are the main secretary gland of brain. The brain is not only the central organ of the nervous system but also contains two major secretory glands that are directly involved in endocrine functions. These are: Pituitary gland (Hypophysis) Pineal gland (Epiphysis cerebri) These glands are part of the neuroendocrine system, which links the brain and hormonal regulation. They help in maintaining homeostasis, regulating growth, metabolism, stress response, sleep cycle, reproduction and many other vital processes. 1. Pituitary Gland: The Master Gland The pituitary gland is called the "master gland" because it controls the activity of almost all other endocrine glands in the body. It is located at the base of the brain, in a bony cavity called the sella turcica of the sphenoid bone. It is connected to the hypothalamus by a stalk called the infundibulum, which carries signals from the brain to control hormone secretion. The pituitary gland has ...

When GABA is inhibited in the brain, it leads to a neurological condition called  epilepsy.  This happens because GABA normally controls brain activity by stopping too much nerve signalling. When GABA is not working properly, the brain loses its balance and nerve cells start becoming overactive. This overactivity can lead to  seizures,  which is the main feature of  epilepsy. Seizures  are sudden, uncontrolled electrical disturbances in the brain that can cause changes in behavior, movements, feelings, or consciousness. They may last from a few seconds to minutes and can be caused by epilepsy, fever, head injury, or other neurological conditions. Seizures vary in type and severity. Step-by-Step Explanation: How GABA Inhibition Leads to Epilepsy To understand how epilepsy is caused by inhibiting GABA, we can break the process into simple steps. These steps explain what GABA normally does, what changes happen when it is blocked and how those changes result in...

Dopamine is a crucial neurotransmitter in the brain that plays a significant role in controlling motor functions, emotional responses and reward pathways. It is involved in regulating mood, movement and several other physiological processes. However, when there is an imbalance in dopamine secretion or its activity, it can lead to several neurological and neuropsychiatric disorders. An increase in dopamine activity is linked to certain disorders, where excessive dopamine levels in specific brain regions can lead to abnormal behaviors and symptoms. Here are two neurological disorders closely associated with increased dopamine secretion: 1. Tourette Syndrome Tourette Syndrome (TS) is a neurological disorder characterized by repetitive, involuntary movements (motor tics) and sounds (vocal tics). It often begins in childhood and can persist into adulthood. In individuals with Tourette Syndrome, there is evidence of increased dopamine activity, particularly in the  basal ganglia,  a...

One of the best-known neurotransmitters that shows both neuromodulatory and inhibitory functions is  GABA (Gamma-Aminobutyric Acid).  It is a major chemical messenger in the central nervous system (CNS) and plays a vital role in regulating brain activity. GABA is unique because it not only participates in fast synaptic transmission as an inhibitory neurotransmitter but also acts more broadly as a neuromodulator that controls the excitability of entire neural circuits. 1. GABA as a Neuromodulator As a neuromodulator, GABA works at a slower and more widespread level than fast synaptic transmission. Instead of targeting a single postsynaptic neuron, it can influence large groups of neurons or entire regions of the brain. Neuromodulatory action of GABA usually happens through GABA-B receptors, which are metabotropic and linked with second messenger systems. Through these pathways, GABA can regulate the activity of other neurotransmitter systems like: Glutamate (main excitatory neu...

The hormone that is called the sleep hormone is  Melatonin.  It is a naturally occurring hormone in the human body that controls the sleep-wake cycle, also known as the  circadian rhythm.  Melatonin is secreted by the  pineal gland,  which is a small, cone-shaped endocrine gland located deep in the brain, near the centre, just above the cerebellum and behind the third ventricle. Melatonin secretion is directly controlled by the amount of light the eyes receive. When the environment becomes dark, the retina sends signals to a special region in the hypothalamus known as the  suprachiasmatic nucleus (SCN).  This SCN then sends nerve signals to the pineal gland, which begins to release melatonin into the bloodstream. The rise in melatonin levels at night makes a person feel sleepy and relaxed, preparing the body for sleep. During the daytime, especially in the presence of sunlight or artificial light, melatonin secretion is stopped. This is why melato...

The brain is not only the central organ of the nervous system but also contains two major secretory glands that are directly involved in endocrine functions. These are: Pituitary gland (Hypophysis) Pineal gland (Epiphysis cerebri) These glands are part of the neuroendocrine system, which links the brain and hormonal regulation. They help in maintaining homeostasis, regulating growth, metabolism, stress response, sleep cycle, reproduction and many other vital processes. 1. Pituitary Gland: The Master Gland The pituitary gland is called the  "master gland"  because it controls the activity of almost all other endocrine glands in the body. It is located at the base of the brain, in a bony cavity called the sella turcica of the sphenoid bone. It is connected to the  hypothalamus  by a stalk called the  infundibulum,  which carries signals from the brain to control hormone secretion. The pituitary gland has two main lobes: i. Anterior Pituitary (Adenohypophysis)...

SAQ 1 i) The resting membrane potential is created due to: a) Buildup of the negative ions in the cytosol along the inside of the membrane. b) The separation of positive and negative electrical charges along both sides of the plasma membrane. c) Difference in charge across the membrane of the cell. d) All of the above. Answer: d) All of the above ii) Which of the following factor/s contribute to the resting membrane potential of the cell? a) Unequal distribution of ions in the ECF and cytosol b) Activity of Na⁺/K⁺ ATPases c) Most anions cannot leave the cell d) all of the above Answer: d) All of the above iii) The extracellular fluid (ECF) has high concentration of positively charged sodium ions and negatively charge chloride ions. a) True b) False Answer: a) True iv) Intracellular fluid (ECF) in contact with the cell membrane is positively charged with high concentration of potassium ions, phosphate ions and anionic proteins. a) True b) False Answer: a) True v) Usually, sodium ion...