How to write an essay on Pathophysiology of depression

How to write an essay on Pathophysiology of depression

The pathophysiology of depression is not clearly understood. However, it is believed that the disruption in the levels of different hormones and neurotransmitters in the body causes depression. Depression is believed to be caused by changes in the receptor neurotransmitter relationships in the limbic system, amygdala, and hippocampus (Abdullah et al., 2019). Norepinephrine and serotonin are believed to be the primary neurotransmitters involved in the pathophysiology of depression. Serotonin plays a role in tryptophan depletion. This is a situation where there is an acute dietary manipulation lowering the transient effect of serotonin in the brain. Impairing serotonin functioning causes the clinical symptoms of depression. The exact effect of norepinephrine is not clearly understood. However, higher levels of these hormones have been associated with various clinicopathologic. Dopamine is also a type of neurotransmitter significant in the pathophysiology of depression. It is responsible for the transmission of messages to the nerve cells. Dopamine plays a role in how individuals feel pleasure. Abnormal dopamine concentration is linked to various signs and symptoms of depression, such as aggressiveness, hallucinations and low motivation. Excess dopamine is responsible for various behavioral symptoms such as hallucinations, aggression, nausea, and vomiting. These symptoms are common in individuals suffering from depression. Melatonin also causes the pathophysiology of depression. Melatonin regulates the circadian rhythm and controls sleep. High levels of melatonin concentration reduce energy levels.  Reduced energy levels contribute to a feeling of depression. It also lowers one’s mood leading to the development of a depressive state in an individual.

Effects of depression on appetite

Depression affects an individual’s appetite. Not eating much and eating too much can be signs of depression. Depression causes a feeling of sadness for two weeks or longer and interferes with the ability of an individual to function daily (Abdullah et al., 2019). The most common sign of depression is a change in eating habits. Some individuals lose their appetite, while others have an increased appetite for food. Change in eating habits is caused by fatigue and lack of pleasure from activities. These symptoms are common in depression. Many individuals lose both interest and energy causing them to lose interest in eating. Other individuals may lose interest in cooking or simply lack the energy to prepare food. The other symptom of depression is nausea.  Individuals experiencing nausea may choose to avoid talking food leading to a reduced appetite. Reduced appetite leads to reduced weight.

In some cases, a feeling of worthlessness or sadness may cause individuals to overeat. Emotional eating is commonly caused by depression. It is a condition whereby eating is not related to physical hunger but instead emotional hunger. When individuals eat in response to emotional hunger, they are soothed by food as it leads to changes in the brain’s chemical balance, producing a feeling of fullness. Increased appetite is characterized by weight gain.

Clinical findings of depression

The clinical findings in individuals with depression include sleep disturbance and troubles with concentration. Sleep disturbance is a common sign in individuals with major depressive disorder. It results from abnormal  time of sleep cycles, reduced slow-wave sleep, and reduced latency of rapid eye movements.  The mechanism of sleep regulation is crucial in the analysis of the pathophysiology of major depressive disorders. The suprachiasmatic nucleus (SCN) plays a crucial function in regulating  sleep and wakeful state. In individuals with depression, there is diminished production of melatonin. Additionally, individuals with depression have suppressed electrical activity in the SCN, interfering with sleep and wakefulness in individuals. Depression leads to loss of concentration.  It has become a part of the negative feedback cycle in depression. Individuals with depression often are preoccupied with negative thoughts, lose their appetite, lose sleep and feel hopeless. All these symptoms affect the ability of an individual to concentrate.

The action of thyroid hormone

Thyroid hormones have profound effects on various physiological processes of the body (Ross et al., 2019). These processes include growth, development, and metabolism. Thyroid hormone plays a vital role in metabolism.  It stimulates diverse metabolic activities in most body tissues hence regulating the basal metabolic rate. The effect of increased metabolic rate is to increase body heat production. This increases the body’s oxygen consumption and the rate of ATP hydrolysis.  Few specific effects of metabolic activity of the thyroid hormone include carbohydrate and lipid metabolism.  Thyroid hormone facilitates fats mobilization leading to increased concentration of fats in the plasma. They also enhance fatty acid oxidization in many tissues.  Thyroid hormone also determines the concentration of triglycerides and cholesterol in the body.  Finally, the thyroid hormone regulates carbohydrate metabolism.

Thyroid hormone is vital in the normal growth of children and young adults. Various studies indicate that thyroid deficiency results in growth retardation. This is because the hormones have a growth-promoting effect. The hormones stimulate the production of growth factors. It also affects the concentration of gonadotropic hormones and somatostatin while increasing their tissue activity.

 Negative feedback loop of thyroid function.

The thyroid-stimulating hormone regulates the synthesis of the thyroid hormones from the anterior pituitary. The binding of thyroid-stimulating hormone to the receptors enhances all the processes necessary to synthesize thyroid hormone, including synthesis of thyroglobulin, thyroid peroxidase, and iodide transporter. The strength of thyroid hormones increases its release rate into the general circulation hence stimulating numerous physiological functions. The thyroid gland is part of the hypothalamic-pituitary-thyroid axis. The axis controls the secretion of thyroid hormone through a classical negative feedback mechanism. The thyroid releasing hormones stimulates the thyroid-stimulating hormone from the anterior pituitary, which further stimulates the release of thyroid hormones.  As the concentration of the thyroid hormone increases in the blood, both the thyroid releasing hormones and the thyroid-stimulating hormones are inhibited, causing a shutdown in the thyroid releasing epithelial cells. Later on, when the levels of thyroid hormones decay, the negative feedback mechanism fades, and the system is initiated in another cycle. Numerous factors in the human system influence thyroid secretion from the epithelial cells. These factors include exposure to cold in young individuals.


Hypothyroidism causes numerous health problems, including heart disease, infertility, joint pain, and obesity (Razyj et al., 2018). It is caused when the body produces or secrets insufficient amount of thyroid hormones. Hypothyroidism leads to numerous signs and symptoms. Hypothyroidism causes fatigue. Fatigue results from the diminished metabolic rate. Energy production requires a sufficient concentration of thyroid hormones in body cells and tissues. Diminished levels lower the production of energy, causing an individual to feel week and tired.

Hypothyroidism increases the sensitivity of an individual to cold. With hypothyroidism, the metabolic rate is reduced, leading to cutaneous vasoconstriction. Cutaneous vasoconstriction makes the patient feel cold even during warm temperatures (Leung et al., 2019). Hypothyroidism also causes constipation. Hypothyroidism also affects the absorption of water from the colon—hypothyroidism results in an increased water absorption rate, which leads to constipation. Additionally, hypothyroidism also slows the gastric metabolism causing fecal impaction. Fecal impaction is one of the main causes of constipation.

Hypothyroidism causes dryness of the skin—the dryness results from diminished eccrine gland secretion caused by diminished thyroid hormone circulation. According to studies, hypothyroidism also reduces the rate of sweating, making the skin dry. Hypothyroidism causes weight gain. When the thyroid glands secrete fewer hormones, the metabolism rate slows down. Slowing the metabolic rate means that the excess calories are not burnt off quickly, leading to weight gain. The weight gain is normally extreme. Hypothyroidism causes elevated blood cholesterol levels. A low level of thyroid hormones reduces the metabolism of cholesterol in the liver. Less low-density lipoprotein is metabolized, leading to increased levels in the blood. Hypothyroidism causes muscle weakness. Muscle weakness is due to the reduced metabolism in the muscles.

Hypothyroidism causes impaired memory. Low levels of thyroid hormones diminish the cognitive functioning of the brain. This results in cognitive symptoms, including difficulty concentrating and memory problems (Leung et al., 2019). Finally, hypothyroidism leads to thinning of the hair. When thyroid hormone secretion and synthesis are disrupted, all the processes in the body are disrupted, including the development of the hair at the root.  The hair falls out and is not replaced by new growth leading to hair thinning across the scalp and other body areas.


Ross, D., Cooper, D., & Mulder, J. (2019). Diagnosis of and screening for hypothyroidism in nonpregnant adults. UpToDate7893(21), 1-24.

Leung, A. K., & Leung, A. A. (2019). Evaluation and management of the child with hypothyroidism. World Journal of Pediatrics15(2), 124-134.

Razvi, S., Jabbar, A., Pingitore, A., Danzi, S., Biondi, B., Klein, I., & Iervasi, G. (2018). Thyroid hormones and cardiovascular function and diseases. Journal of the American College of Cardiology71(16), 1781-1796.

Abdullah, I., Hassan, T. H. A., Abdulaziz, S. A., Mousa, A. B., Safiah, B. A., Maryam, M. A., … & Zainab, M. A. A. (2019). Literature review on pathogenesis and treatment of depression. Depression9, 10.

Related Posts:

Translate »