Negative Feedback + Diseases

Dehydration: ADH

• Effect: low water concentration in blood

• Gland: hypothalamus produces ADH

• Gland/NS: stored in the posterior pituitary

• Target: kidney - increases water reabsorption by kidneys

• Negative Feedback: increase in water concentration in blood inhibits ADH production

Low Blood Pressure: Aldosterone

• Effect: stimulation of stretch receptors in hearts atria

• Gland: adrenal gland release aldosterone

• Target: Kidney - increases sodium reabsorption resulting in water erabsoprtion

• Negative Feedback: increase in blood pressure inhibits the adrenal glands release of aldosterone

Low Na+ Levels: Aldosterone

• Effect: exercise can lower salt levels

• Gland: adrenal gland releases aldosterone

• Target: Kidney - increases sodium reabsorption

Low Cellular Respiration Rate: Thyroxin

• Effect: low rate detected by hypothalamus

• Gland: hypothalamus produces an anterior pituitary stimulating hormone

• Gland: anterior pituitary produces TSH

• Target: thyroid - secretes thyroxine which stimulates an overall increase in metabolic rates

• Negative Feedback: increased metabolic rates inhibit the hypothalamus and the anterior pituitary

Low Blood Calcium Levels: Calcitonin + Parathyroid

• Effect: low levels detected by the parathyroid glands

• Gland: the parathyroid glands secrete PTH

• Target: Bone cells - release calcium into the blood stream; Kidneys - reabsorb calcium from urine into the blood

• Negative Feedback: increased calcium in the blood inhibits the parathyroid glands

High Calcium Levels: Parathyroid + Calcitonin

• Effect: high blood concentrations detected by the thyroid

• Gland: the thyroid gland secretes calcitonin

• Target: bones - reduces the loos of bone marrow into the blood

• Negative Feedback: low calcium detected by the parathyroid glands

High Levels of Blood Sugar: Insulin + Glucagon

• Effect: high levels detected by the pancreas

• Gland: the pancreas produces insulin

• Target: cells - conversion of glucose into glycogen

• Negative Feedback: high levels of blood sugar triggers pancreas to produce insulin, causing glucose to turn into glycogen

• Negative Feedback: low level of blood sugar triggers pancreas to produce glucagon, this turns glycogen into glucose

Low Levels of Blood Sugar: Insulin + Glucagon

• Effect: low levels detected by pancreas

• Gland: pancreas’ islets of Langerhans produce glucagon

• Target: cells - conversion of glycogen (stored within the liver and muscle) into glucose

• Negative Feedback: low level of blood sugar triggers pancreas to produce glucagon, this turns glycogen into glucose

Stress Levels (Long Term): Cortisol → Sugar

• Effect: detected by hypothalamus

• Gland: hypothalamus releases an anterior pituitary stimulating hormone

• Gland: anterior pituitary gland secretes ACTH

• Gland: Adrenal cortex releases cortisol

• Target: cortisol stimulates conversion of carbs/fats into glucose and suppresses the immune response

• Negative Feedback

Fight or Flight Response (Short Term): Epinephrine/Adrenaline

• Effect: hypothalamus sends a nerve signal to adrenal medulla

• Gland: adrenal medulla releases epinephrine and norepinephrine

• Target: increases cellular metabolism, breathing rate, heart rate and blood pressure (sympathetic nervous response)

• Negative Feedback: lower stress inhibits the sympathetic response

Type 1 Diabetes Mellitus

• Gland: pancreas

• Cause: the immune system destroys the insulin producing cells of the pancreas (often in children)

• Symptoms: low energy levels, poor blood circulation, excessive urination

• Solution: daily insulin injections

Type 2 Diabetes mellitus

• Gland: pancreas

• Cause: insulin receptors on body’s cells stop responding to insulin in adulthood

• Symptoms: low energy levels, poor blood circulation, excessive urination and thirst

• Solution: dietary management

Diabetes Insipidus

• Gland: hypothalamus and posterior pituitary gland

• Cause: damage to either structure produces low amounts of ADH

• Symptoms: excessive urination and extreme thirst

• Solution: medication that reduces water loss

Hyperthyroidism

• Gland: thyroid

• Cause: overproduction of thyroxin

• Symptoms; anxiety, insomnia, heat intolerance, irregular heartbeat, and weight loss

• Solution: mediation, irradiation or removal of thyroid gland

Hypothyroidism

• Gland: thyroid

• Cause: underproduction of thyroxine

• Symptoms:

  • childhood: cretinism (shorter than average with mental delays)

  • adults: slow metabolism, hair loss and excessive weight gain

• Solution: diet and/or synthetic thyroxine

Goitre

• Gland: thyroid

• Cause: lack of iodine. This is a key component of thyroxine. There is no stop signal to the secretion of TSH by anterior pituitary gland

• Symptoms: an enlarged thyroid

• Solution: Diet

Addison’s Disease

• Gland: adrenal cortex

• Cause: a damaged adrenal cortex secretes inadequate amounts of cortisol and aldosterone

• Symptoms: low blood sugar, rapid weight loss and general weakness

• Solution: medication

hGH Deficiencies

• Gland: anterior pituitary gland

• Cause: genetics or a damaged gland

• Symptoms:

  • Childhood - pituitary dwarfism

  • Adult - loss of mass

• Solution: medication

hGH Overproduction

• Gland: anterior pituitary gland

• Cause: genetics or a damaged gland

• Symptoms:

  • Childhood- gigantism

  • Adult - acromegaly

• Solution: medication