module 3.2 - BIOLOGY

• Exocrine Glands


  • Also known as duct glands
  • Secretions are released through a duct outside the body
  • Salivary - saliva
  • Sebaceous - sweat
  • Mammary - milk
  • Lacrimal - tears
• Endocrine System

  • Communication system that uses glands to convey messages by releasing hormones into the bloodstream
  • Hormones are chemical messengers released into the bloodstream that influence mood, cognition, appetite, and many other processes and behaviors
• Pituitary Gland


  1. Known as the "master gland"

  2. Secretes human growth hormone and influences all other hormone-secreting glands
• Human Growth Hormone (HGH)


  • Responsible for the growth and repair of all cells in the body
• Thyroid Stimulating Hormone (TSH)


  • Influences the thyroid gland for the release of thyroxine, its own hormone. TSH is also called Thyrotropin
• Adrenocorticotropic Hormone (ACTH)

  • Influences the adrenal gland to release of Cortisol or the "stress hormone". ACTH is also known as corticotropin
• Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH)


  • Collectively known as Gonadotropins, LH and FSH control the sexual and reproductive characteristics in males and females
• Effects of undersecretion of HGH

  • Dwarfism in children
• Prolactin (PRL)

  • Produces milk in the breast. The secretion is increased during and just after pregnancy
• Melanocyte-Stimulating Hormone (MSH)


  • Involved in the stimulation of the production of melanin by skin and hair
• Oxytocin


  • Involved in reproduction and parental behavior. Stimulates contractions of the uterus in childbirth
• Vasopressin


  • Controls the levels of water in the body; acts as antidiuretic
• Effects of undersecretion of vasopressin

  • Diabetes Insipidus
• Effects of oversecretion of vasopressin

  • Syndrome of Inappropriate ADH (SIADH)
• Pineal Gland

  Endocrine gland located near the base of the cerebrum. Plays a role in biological rhythms and secretes melatonin
• Irregularities in Melatonin Secretions

  • Disrupted Sleep Patterns
  • Insomnia and Sleep Disorders
  • Daytime Fatigue and Impaired Cognitive Function
  • Mood Disturbances
  • Weakened Immune Function
  • Increased Risk Of Chronic Health Conditions
  • Potential Role in Mental Health Disorders
• Thyroid Gland

  Endocrine gland found in the neck; regulates growth and metabolism. Produces Thyroxin (T4) and Triiodothyronine (T3) responsible for regulating metabolism
• Effects of Hypothyroidism

  • Fatigue, weight gain, cold sensitivity, depression, dry skin and hair, constipation
• Effects of Hyperthyroidism

  • Weight loss, rapid heartbeat, heat intolerance, anxiety, irritability, tremors, sleep disturbance
• Effects of Congenital Hypothyroidism (Cretenism)


  • Int
• Hypothyroidism symptoms

  • Fatigue
  • Weight gain
  • Cold sensitivity
  • Depression
  • Dry skin and hair
  • Constipation
• Hyperthyroidism symptoms


  • Weight loss
  • Rapid heartbeat
  • Heat intolerance
  • Anxiety and irritability
  • Tremors
  • Sleep disturbance
• Congenital Hypothyroidism (Cretenism) symptoms

  • Intellectual disability
  • Growth retardation
  • Delayed motor skills
  • Coarse facial features
  • Umbilical hernia
  • Poor muscle tone
• Parathyroid Gland

  • The parathyroid glands produce a hormone called parathyroid hormone
  • They control calcium levels in the bloodstream to make the calcium levels generally very stable
  • This is important to ensure the nervous system and the body’s muscles can work properly, and also that bones remain strong
• Parathyroid Gland disorders

  • Hyperparathyroidism /Hypercalcaemia - oversecretion of parathyroid
  • Hypocalcaemia - undersecretion of parathyroid leading to low blood calcium level
• Pancreas


  • The pancreas controls the level of blood sugar in the body by secreting insulin and glucagon
  • Insulin lowers down sugar level in the blood
  • Glucagon increases sugar level in the blood
• Pancreas disorders

  • Diabetes mellitus - under secretion of insulin
  • Hypoglycemia - or low blood sugar; over secretion of insulin which causes a person to feel hungry all the time and often become overweight as a result
• Gonads

  • The gonads are the sex glands, including the ovaries in the female and the testes in the male
  • Males produce sperm cells through a process called spermatogenesis, females produce egg through the process called oogenesis
  • They do not control all sexual behavior, though. In a very real sense, the brain itself is the master of the sexual system—human sexual behavior is not controlled totally by instincts and the actions of the glands as in some parts of the animal world, but it is also affected by psychological factors such as attractiveness
• Female Gonad Hormones

  • Estrogens - Group of female sex hormones essential for reproduction and the development of the female reproductive system
  • Progesterone - Hormones that prepare the uterus for conception, regulate changes in the uterus during the menstrual cycle, aid ovulation, and stimulate gland development for the production of milk during pregnancy
• Gonad Disorders in Females

  • Hypogonadism in Females - can cause delayed puberty, lack of menstruation, hot flashes, and breast discharge
  • Menstrual Disorders - usually caused by imbalances in estrogen and progesterone or related to an overactive or underactive thyroid. Symptoms include abnormally early or late onset of puberty, amenorrhea, severe cramps, menorrhagia, irregular periods, PCOS, and PMS and PMDD
• Male Gonad Hormones

  • Testosterone (Androgen) - responsible and essential for increased growth of bone and muscle, growth of body hair, developing broader shoulder, voice deepening, and growth of the penis
  • Androstenedione - Hormones that act as a precursor to estrogens and testosterone
  • Inhibin - Hormones that inhibit the release of FSH and thought to be involved in sperm cell regulation
• Effects of male sex hormones

  • Increased growth of bone and muscle
  • Growth of body hair
  • Developing broader shoulders
  • Voice deepening
  • Growth of the penis
• Androstenedione


  • Hormones that act as a precursor to estrogens and testosterone
• Inhibin

  • Hormones that inhibit the release of FSH and are involved in sperm cell regulation and development
• Hypogonadism in Males is the undersecretion of male sex hormones. Symptoms include erectile dysfunction, male infertility, delayed puberty, development of breast tissue (gynecomastia), body hair loss, depression or reduced energy, osteoporosis (loss of bone), and low sex drive
• Adrenal glands functions

  • Regulate metabolism
  • Regulate immune system
  • Regulate blood pressure
  • Regulate response to stress and other essential functions
• Adrenal insufficiency (Addison’s disease) occurs when adrenal glands don’t produce enough hormones. Symptoms include fatigue, cravings for salty foods, lethargy, muscle weakness, low mood, and irritability
• Adrenal Medulla

  • Controls hormones that initiate the flight or fight response
  • Main hormones secreted include epinephrine (adrenaline) and norepinephrine (noradrenaline) which increase heart rate, force of heart contractions, blood flow to muscles and brain, relax airway smooth muscles, and assist in glucose metabolism
• Adrenal Cortex


  • Produces more than 30 different hormones called corticoids (steroids)
  • Cortisol (Glucocorticoids) helps control body's use of fats, proteins, and carbohydrates, suppresses inflammation, regulates blood pressure, increases blood sugar, and can decrease bone formation
  • Aldosterone (Mineralocorticoids) regulates blood pressure and certain electrolytes
  • Androgens cause male sexual development, affect muscle mass, sex drive, and sense of well-being
• Adrenal Gland Disorders

  • Cushing Syndrome
  • Hyperaldosteronism
  • Pheochromocytoma