Endocrine System Flashcards
What is the main difference between the endocrine system and the nervous system in terms of communication?
The endocrine system relies on hormones which acts chemical messages to provide a more sustained and long-term control in every type of cell in the body whereas the nervous system is fast acting and focused on specific areas or glands
What is relationship between liver, kidneys and hormones?
Most home and circular around the entire body in the bloodstream where they affect their target cells, circulating hormones or inactivated by the liver and excreted by the kidneys if someone suffers liver or kidney failure hormones may build up in the blood
Explain endocrine paracrines and autocrines
Types of Chemical Signaling – Flashcard Format
- Endocrine Signaling
• Definition: Hormones are released into the bloodstream and travel to distant target cells.
• Example: Insulin from the pancreas regulates blood sugar levels throughout the body.
• Key Feature: Long-distance communication via the bloodstream. - Paracrine Signaling
• Definition: Chemical messengers act on nearby cells within the same tissue.
• Example: Nitric oxide (NO) released by endothelial cells causes nearby blood vessels to dilate.
• Key Feature: Local communication, affecting neighboring cells. - Autocrine Signaling
• Definition: A cell releases signals that act on itself to regulate its own activity.
• Example: Immune cells (T-cells) release interleukins to stimulate their own proliferation.
• Key Feature: The cell signals itself,
What type of molecules are hormones and give examples?
Hormones are either amino acid based molecules (proteins) or steroids
Steroids include sex hormones made by the gonads (ovaries and testes) and hormones in the adrenal cortex
List the functions of hormones in our everyday lives
Control metabolic rate, regulation of blood sugar, the amount of salt and water and body fluids
Hormones are most active during puberty where endocrine system releases sex hormones from the gonads
Explain negative feedback using insulin and glucagon as an example
Negative Feedback – Insulin & Glucagon Example
- What is Negative Feedback?
• Definition: A control mechanism where the body counteracts a change to maintain homeostasis.
• Purpose: Prevents extreme fluctuations in physiological conditions. - Blood Sugar Regulation via Insulin & Glucagon
✅ When Blood Sugar is Too High (After Eating)
• Stimulus: Increased blood glucose levels.
• Sensor: Pancreas (β-cells in Islets of Langerhans) detect high glucose.
• Response:
• Insulin release → promotes glucose uptake by cells.
• Liver stores glucose as glycogen.
• Effect: Blood glucose lowers back to normal.
✅ When Blood Sugar is Too Low (Fasting/Exercise)
• Stimulus: Decreased blood glucose levels.
• Sensor: Pancreas (α-cells in Islets of Langerhans) detect low glucose.
• Response:
• Glucagon release → stimulates the liver to break down glycogen into glucose.
• Glucose is released into the blood.
• Effect: Blood glucose rises back to normal.
- Why This Matters
• Keeps blood sugar stable (~70-110 mg/dL).
• Prevents hyperglycemia (too high) & hypoglycemia (too low).
• Diabetes (Type 1 & 2) results from impaired insulin regulation.
What is the key defences between exocrine and endocrine glands?
Exocrine vs. Endocrine Glands – Simple Flashcard Format
- Exocrine Glands
• Use ducts to release substances outside the body or into body cavities.
• Secrete: Sweat, saliva, digestive enzymes.
• Examples: Sweat glands, salivary glands, pancreas (for digestion). - Endocrine Glands
• No ducts, release hormones into the bloodstream.
• Secrete: Insulin, adrenaline, thyroid hormones.
• Examples: Thyroid, adrenal glands, pancreas (for blood sugar control).
List all endocrine glands
Pituitary – thyroid – parathyroid – adrenal – hypothalamus – pancreas – ovaries – testes
What are the three ways which endocrine glands can be stimulated?
Hormonal – endocrine glands can be stimulated by other hormones
Humoral – stimulation changes in the level of certain ions and nutrients in the blood
Neural – in some cases of nerve fibre stimulate hormone release for example adrenaline
Is the hormones produced by the anterior lobe of the pituitary gland?
Growth hormone – also known as somatotrophic hormone as it stimulates somatic cells to stimulate growth in bones and muscles
Thyroid stimulating hormone – stimulated thyroid gland to secrete thyroxine
Adrenocorticotrophic hormone – ACTH stimulates the adrenal cortex to produce glucocorticoids hormones
Follicle stimulating hormone – controls imitation of ovarian follicles and oestrogen production in females and sperm in the males
Luteinising hormone (LH) – also known as interstitial cell stimulating hormone which stimulates the ovaries and leads to the formation of corpus Luteum which produces the hormone progesterone. In men the hormone causes the interstitial cells between the seminiferous tubules to secret androgens (male hormones)
Prolactin – controls production of milk from mammary glands
Explain the posterior glands its functions
Some hormones are made in the hypothalamus and stored in the posterior pituitary until needed and the following hormones are released in response to impulses from the hypothalamus
Antidiuretic hormone or vasopressin controls water balance of the body affecting water absorbed by the kidney tubes
Oxytocin – stimulates contractions of the smooth muscle in the uterus during the process of giving birth
Which endocrine gland stores large surprise if it’s Secretary products up to 100 day supply of the two hormones it makes
The thyroid gland is the only endocrine gland that stores large supplies of the Secretary products thyroxine and calcitonin
What is the role of the thyroid gland?
The thyroid glands and thyroid hormones act in regulation of metabolism
They stimulate protein synthesis – increase cellular respiration of glucose and fatty acids used for ATP production – they increase breakdown of fats – increase cholesterol exclusion reducing blood cholesterol
Explain the thyroxine negative feedback loop
The hypothalamus produces a releasing factor that affects the anterior pituitary
The anterior pituitary produces thyroid stimulating hormone TSH that is then released into the blood
The thyroid gland produces thyroxine in response to TSH which feeds back to the hypothalamus and the pituitary gland suppressing the production and release of TSH
Explain the function of calcitonin and where is released
Calcitonin decreases the levels of calcium in the blood by inhibiting the action of osteoclasts meaning more calcium can be deposited into the bones
It is controlled by the thyroid gland
Explain the function of calcitonin and where is released
Calcitonin decreases the levels of calcium in the blood by inhibiting the action of osteoclasts meaning more calcium can be deposited into the bones
It is controlled by the thyroid gland
Explain the role of the parathyroid gland and it’s importance
The parathyroid gland of 4P shaped glands located close to the thyroid gland
It produces a parathormone hormone which is essential in controlling calcium magnesium phosphate ions in the body, increasing the number and activity of osteoclasts working opposingly to calcitonin (thyroid hormone)
PTH is released when calcium levels become too low as this can cause impulses to be delivered to the muscle at such a rapid rate muscles going to uncontrollable spasms called tetanic contractions open (tetanus)
PTH stimulates bone destruction by osteoclast to break down the bone matrix releasing calcium into the blood
Explain the structure and role of the adrenal cortex
The adrenal cortex is split into the Central adrenal medulla and the outer adrenal cortex
The medulla is a modified part of the autonomic nervous system that produces the hormone adrenaline and the neurotransmitter noradrenaline
Release of adrenaline causes fight of flight response speeding up heart rate and blood flow to the heart and the big skeletal muscles of the limbs while decreasing blood flow to the digestive system
The adrenal cortex is stimulated by adrenalCoricotrophic hormone which is produced in the anterior pituitary gland to produce three classes of hormones known as corticosteroids.
Mineralocorticosteroids, glucocorticoid and sex hormones
Explain the three types of hormones produced by the adrenal cortex versus the adrenal medulla
The adrenal cortex
Mineralocorticoids – home and regulate a balance of mineral ions, e.g. all aldosterone which affects reabsorption of water in the Renal tubes
Glucocorticoids – include cortisone and cortisol support normal cell metabolism and help body cope with long-term stress by adjusting blood glucose levels
Sex Hormones – although oestrogen and testosterone reproduce in their ovaries and testes respectively small amounts of both are producing the adrenal cortex which helps development and function of sex organs
Adrenal medulla
Produces and increase hormone adrenaline and neurotransmitter no adrenaline which have an important role in the nervous system
What is the normal level of glucose in the blood?
80 to 100 mg glucose/100 ml of blood swag
Describe the pancreas exocrine and endocrine function
The cell cells of the exocrine pancreas produce digestive enzymes which are secreted into the duodenum
The endocrine pancreas produces two different hormones, insulin and glucagon affecting glucose in the blood . The islet of Langer hands or islet cells..
Beta cells make insulin increasing blood glucose level alpha cells make glucagon decreasing blood glucose level
Give us step-by-step of what would happen to your body during hypoglycaemia and hyperglycaemia
Step-by-Step Body Response to Hyperglycemia (High Blood Sugar) vs. Hypoglycemia (Low Blood Sugar)
- Hypoglycemia (Low Blood Sugar Response) – Step by Step
- Detection of Low Blood Sugar
• Stimulus: Blood glucose drops below ~70 mg/dL (e.g., fasting, exercise, excess insulin).
• Detection: Alpha cells in the pancreas sense the low glucose. - Pancreas Responds – Glucagon Release
• Pancreas releases glucagon from alpha cells into the bloodstream. - Liver Increases Glucose Production
• Glucagon stimulates the liver to:
• Break down glycogen into glucose (glycogenolysis).
• Make new glucose from amino acids & fats (gluconeogenesis).
• Effect: Glucose is released into the blood → blood sugar increases. - Muscle & Fat Adaptations
• Muscles reduce glucose uptake to conserve sugar for the brain.
• Fat cells break down triglycerides into fatty acids for energy (lipolysis). - Increased Protein Breakdown & Synthesis for Energy
• Proteolysis: Muscles release amino acids for gluconeogenesis.
• Protein synthesis shifts towards making glucose-regulating enzymes. - Brain Response to Low Glucose
• Adrenal glands release epinephrine (adrenaline) to boost glucose release.
• Cortisol (from adrenal cortex) enhances gluconeogenesis & reduces glucose uptake by less essential tissues. - Negative Feedback – Restoring Blood Sugar
• Once blood glucose returns to normal (~70-110 mg/dL):
• Glucagon secretion stops.
• Insulin is released in small amounts to regulate sugar use. - Hyperglycemia (High Blood Sugar Response) – Step by Step
- Detection of High Blood Sugar
• Stimulus: Blood glucose rises above ~110 mg/dL (e.g., after eating, diabetes).
• Detection: Beta cells in the pancreas sense high glucose. - Pancreas Responds – Insulin Release
• Pancreas releases insulin from beta cells into the bloodstream. - Insulin Lowers Blood Sugar in Three Ways
✅ 1. Glucose Uptake by Cells
• Insulin binds to receptors on muscle & fat cells, increasing glucose absorption.
✅ 2. Glycogenesis (Glucose Storage in Liver & Muscles)
• Insulin signals the liver & muscles to store glucose as glycogen.
✅ 3. Fat Storage & Protein Synthesis Increase
• Insulin promotes fat storage (lipogenesis) & protein synthesis for tissue repair.
- Brain Response to High Glucose
• Brain uses glucose as fuel, but excess sugar can cause oxidative stress & inflammation. - Negative Feedback – Restoring Blood Sugar
• Once blood glucose returns to normal (~70-110 mg/dL):
• Insulin secretion stops.
• Glucose uptake & storage slow down.
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List and explain hyper and hypo secretion of hormones from the pituitary gland
Growth hormone when hyper secreted leads to gigantic ism in children or acromegaly and adults
Hyposecretion can lead to one form of dwarf
Hypo secretion of antidiuretic hormone leads to large quantities of very dilute urine and excess dust and his condition known as diabetes insipidus
What is a GOITRE?
This is an enlargement of the thyroid gland which is more common in women than men up to 9% of the population have goitre.
It occurs in both hyper secretion and hypo secretion and can be caused by a lack of iodine in the diet so there isn’t enough to produce thyroxine. The thyroid glands become hyperactive and attempt to make more hormone.
It can be treated with iodide salt
Explain the three diseases of the thyroid gland
Goitre which is enlargement of the thyroid gland which can cause breathing difficulties and can occur in the hyper or hypo secretion
Hyperthyroidism common affecting 2 to 5% of all females at some .5 times more likely in women than men common cause is graves disease and immune disorder – symptoms, bulging eyeballs, heavy perspiration and weight loss
Hypothyroidism is 14 times more common than women than men and is usually caused by disease of the thyroid itself produces many symptoms such as lethargy fatigue weight gain and slowness. What are the symptoms may include dry hair bradycardia dry skin sluggish reflexes
Explain hyper and hypoparathyroidism
As the parathyroid secretes parathormone which is responsible for increasing osteoclast action to release calcium.
Hyper – increase in calcium from bones – osteoporosis and bone fracture
Hypo – low blood calcium increased excitability to central nervous system muscle spasms or tetany
Describe the hyper hypo secretion of the adrenal glands
Hyper secretion of the adrenal glands result in Cushing syndrome which results in the patient having the characteristics of moon face and children may stop growing
Hypo is rare but leads to Addison’s disease patient show general weakness, low blood pressure, anorexia, dehydration, muscle wasting depression GI disorders increase skin pigmentations
Explaining hypo secretion of the pancreas
In cases where the pancreas produces little unknown insulin this cause causes type one diabetes known as insulin dependent diabetes mellitus
If the pancreas loses ability to produce insulin overtime or the body stops responding, this condition is referred to as a non-insulin-dependent diabetes mellitus or type two diabetes
Both results in hyperglycaemia which leads to access glucose in the urine which takes water with it which leads to extreme thirst weight loss dehydration drowsiness loss of energy as protein proteins in factor to consume these fuels in a can eventually lead to coma and death
Knowing the posterior pituitary gland produces vasopressin which is responsible for controlling water balance in the body how do you treat an overactive pituitary?
Using analog is of vasopressin to suppress diabetes insipidus
How do you treat an underactive thyroid and how do you treat an overactive thyroid?
An underactive thyroid levothyroxine is used to replace natural thyroxine
An overactive thyroid gland may be treated with medicines that stop the thyroid producing thyroxine
Beta blockers may be used to relieve symptoms until the treatment medication begins to work
Radio iodine may be used to destroy part of the thyroid gland shrinking and reducing the hormone it can produce
In circumstances, it may be removed completely by surgery
What causes Cushing’s disease and how do we treat it as well as Addison’s disease?
Cushing’s disease is a hyperactive adrenal gland whereas Addison’s disease is an underactive gland?
The cause of Cushing’s disease is often a tumour on the adrenal or pituitary gland surgery or radiotherapy are often used to remove the tumour
Addison’s disease is treated with replacement hormones
What diseases does a hyperactive or hypoactive pancreas lead to? And how can they be treated?
Type one diabetes which is largely genetic and known as incident dependence diabetes where the pancreas produces little to know insulin a recommended insulin
In type two diabetes many cases losing weight meal planning increasing exercise levels can reduce or eliminate symptoms however oral medication is taken by 60 to 70% of people with type 2 to control hyperglycaemia
Metformin inhibits the breakdown of glycogen to glucose in the liver
Sulphonylureas and GLP-1 agonist increased insulin production and released from beta cells in the pancreas
Glitazones make body cells more sensitive to insulin
Acarbose slows rate of complex carbohydrate breakdown in the digestive system, reducing the peak glucose that follows after a meal how is not common to use as a side effects are uncomfortable
Drugs are often use combination
A gastric bypass or laparoscopic gastric band can be used if patients cannot maintain healthy weight
