#Hormones

#Biology

#EndocrineSystem

Adrenaline: A hormone and neurotransmitter secreted primarily by the adrenal glands (near the kidneys) and some neurons in the brain, typically during stressful, exciting, or highly emotional situations. Also known as epinephrine, adrenaline increases heart rate and blood flow to the brain and muscles, allowing the body to react quickly and, if necessary, engage in fight-or-flight.

Cortisol: A hormone produced by the adrenal gland that regulates key physical functions such as balancing blood sugar and dampening inflammation; it also helps the body to cope with stress. Cortisol is released regularly throughout the day, peaking early in the morning and dipping overnight. When faced with a stressful situation, the body releases heightened amounts of cortisol to prevent inflammation and increase glucose reserves in the blood; over time, consistently high levels of cortisol can lead to negative physical and emotional effects, such as worsened immunity.

Dopamine: A neurotransmitter and hormone released by the brain during rewarding activities such as eating, sex, and exercise. Known as a “feel-good” hormone, dopamine contributes to feelings of pleasure and motivates humans (and other animals) to seek out rewarding activities. It also plays key roles in learning, attention, and emotion.

Estrogen: A sex hormone that, while present in both sexes, is largely responsible for female sexual development and functioning. Primarily produced in the ovaries, estrogen helps to regulate menstruation, vaginal functioning, and libido (in both sexes). It’s also vital to brain health, playing a role in emotional regulation, mood disorders, and memory, particularly as age increases and, in women, menopause starts.

Ghrelin: A hormone produced primarily by the gastrointestinal tract—most notably in the stomach—that helps to regulate appetite. When ghrelin is released, appetite increases. Once the body signals that it’s full, ghrelin production slows down; this, along with the increase in the hormone leptin, motivates the person to stop eating. Ghrelin is typically regulated by the body’s circadian rhythm, the timing of the last meal, and blood sugar levels; however, it can be disrupted by factors such as stress and poor sleep, which can lead to dysregulated appetite.

Growth Hormone: A hormone that stimulates growth, cell reproduction, and cell repair. Also known as human growth hormone, or HGH, it is produced by the pituitary gland. Though production continues throughout the lifetime, it ramps up during puberty to increase height, boost muscle mass, and promote bone growth and strengthening. HGH also regulates immune functioning, rejuvenates tissues and organs, and is an essential component of collagen production, which boosts skin and hair health.

Insulin: A hormone produced in the pancreas that regulates metabolism and blood sugar. Insulin is released as the body breaks down carbohydrates into glucose, allowing glucose to enter cells where it is used as energy, and carrying excess glucose to the liver. Those who make very little insulin—or who become resistant to its effects, often due to obesity, metabolic syndrome, or genetics—can develop diabetes.

Leptin: A hormone released by adipose tissue (also known as fat) that works in concert with ghrelin to regulate appetite. When ghrelin is released, hunger increases; leptin is released after food is consumed to signal fullness and discourage additional intake. The body becoming increasingly resistant to leptin’s effects over time is a risk factor for obesity; a condition known as leptin receptor deficiency can also promote obesity (and psychological distress) by triggering near-constant hunger.

Melatonin: A hormone released primarily by the brain’s pineal gland that regulates the body’s sleep-wake cycle. Melatonin levels rise and fall naturally throughout the day, peaking in the evening (to promote feelings of sleepiness before bedtime) and dipping to their lowest levels in the morning. While the melatonin cycle is strongly influenced by the 24-hour cycle of day and night, it can also be affected by food, physical activity, genetics, and travel.

Norepinephrine: A hormone and neurotransmitter released by the brain and the adrenal glands. Among other functions, norepinephrine is critical for the fight-or-flight response. In the brain, it helps regulate attention, alertness, vigilance, and anxiety; in the body, increased levels of norepinephrine speed heart rate, breathing, and blood pressure. Like adrenaline, norepinephrine production increases during stressful or exciting situations.

Oxytocin: A hormone and neurotransmitter produced by the hypothalamus and released by the pituitary gland. Known colloquially as the “love hormone,” oxytocin plays a key role in socializing, romantic relationships, and parent-child bonding, as it is released during group activities, physical contact, sexual stimulation, childbirth, and breastfeeding. Oxytocin can also, however, trigger aggression toward members of the ”out-group.”

Progesterone: A sex hormone primarily implicated in the female reproductive cycle. Though it’s also necessary for male sexual function (as it aids the production of testosterone), progesterone’s main roles are to regulate the menstrual cycle, the development of female sex characteristics, such as breasts, and pregnancy. In women, progesterone is produced in the ovaries and works in concert with estrogen.

Testosterone: A sex hormone that is the main driver of male sexual development and libido; it also plays a smaller role in female sexual functioning. Testosterone is often thought of as a driver of aggression, and though it does play a role in aggression to some degree, it also affects language skills, cognitive functioning, growth, and physical health. Testosterone is produced in the testicles of males and in the ovaries of females.

Vasopressin: A hormone produced by the hypothalamus and released by the pituitary gland that has several physiological functions, including the regulation of blood pressure and circulatory function. Recent research (most notably in animals) suggests that vasopressin may also play a role in disorders like autism, as well as work in concert with oxytocin to promote social bonding.