Endocrine Physiology & Alterations Flashcards
1
Q
Functions of the Endocrine System
A
- BGLs
- sexual characteristics
- reproduction
- growth and development
- stress response
- overall maintenance of the body’s internal environment
2
Q
What is a hormone?
A
Chemical messenger
3
Q
Hormone regulation
A
- regulated with negative feedback loops
- they circulated through the bloodstream and only affect cells the posses the appropriate receptor
- receptors are ether located on the cell membrane or in the intracellular compartment of the target cell
4
Q
Protein based hormones
A
Examples include
- vasopressin, insulin and growth hormone
- water soluble
- acts as first messengers - they bind to receptors causing intracellular signalling which activates a secondary messenger within the cell
5
Q
Steriod based hormones
A
Examples include
- testosterone and cortisol
- lipid soluble - can cross the cell membrane
- act directly on the nucleus by binding to nuclear receptors
- allow fro rapid response
6
Q
Function of the Hypothalamus
A
exert control over production of hormones in most endocrine organs
releases hormones which bind on the target receptor on the other endocrine gland
7
Q
Pituitary gland
A
anterior and posterior
- connected to the hypothalamus via the the hypothalamus-pituitary-axis
Posterior
- doesn’t produce hormones it secretes them - stimulated by messengers in the nerve fibres
- hormones are made in the hypothalamus, stored in the PPG in Herring Bodies
Anterior
- produces and releases adrenocorticotropic hormone, and stimulates growth, reproduction (FSH, LH, PRL) hormone
- connected by a capillary bed
8
Q
Pineal gland
A
located in the centre of the brain
- produces melatonin
- melatonin regulates wake/sleep patterns and seasonal functions
9
Q
Thyroid gland
A
- one largest endocrine organs
- found below the thyroid cartilage (Adam’s apple)
- regulates the body’s metabolism, production of proteins and response to other hormones
- Thyroid epithelia cells secrete T3 and T4
- Parafollicular cells secrete calcitonin
- Iodine is required for thyroxine and triidothyronine production
10
Q
Parathyroid
A
- located on the posterior of the thyroid gland
- produce parathyroid hormone
- regulate how much calcium is in the bones and blood
- calcium homeostasis is important in muscle and nerve function
11
Q
Thymus
A
- needed for normal immune function
- secretes hormones called humoral factors
- these hormones support the development of the lymphoid system
12
Q
Pancreas
A
- contains both endocrine and exocrine
Hormone produced include:
- alpha cells secrete insulin (increase BGL)
- beta cells secrete insulin (decrease BGL)
- delta cells secrete somatostatin (regulates alpha and beta cells)
- gamma cells, secrete pancreatic polypeptide - regulates endo/exocrine secretion
13
Q
Adrenal gland
A
- located on the superior portion of the kidneys
- several hormones: corticosteriods e.g. cortisol, catecholamines e.g. adrenalin and noradrenaline
- Androgens
- Aldosterone - regulates osmolarity of blood plasma
14
Q
Testes and Ovaries
A
- Testosterone produced in the testicles by Leydig cells
- Testosterone is important in the development of secondary sex characteristics in men and sperm production
- Oestrogen and Progesterone are produced by the ovaries
- They promote the menstrual cycle and the development of secondary sexual characteristics in women
15
Q
Hormonal Balance
A
- may results from elevated or depressed hormones
- may be due to a: faulty feedback loop, dysfunction of the gland, altered metabolism of hormone, non-endocrine production of hormone
16
Q
Alterations in Pituitary function
A
Disorders include:
- syndrome of inappropriate antidiuretic hormone
- sodium is diluted leading to hyponatremia and hypoosmolarity
- Results from a brain injury or from a cancer secreting ADH
- Diabetes Inspidus (low ADH production)
- either results from a neurogenic cause
- insufficient ADH produced or a nephrogenic cause
- lack of response by target cells in the kidney
- either results from a neurogenic cause
17
Q
Acromegaly
A
Abnormal production of growth hormone after the skeleton and other organs finish growing
18
Q
Gigantism
A
Characterised by excessive growth and heigh significantly above average
- caused by excessive GH production in childhood
19
Q
Dwarfism
A
Mainly caused by two disorders
- achondroplasia - autosomal dominant disorder
- growth hormone deficiency
20
Q
Alterations in Thyroid Function
A
- Dysfunction of the thyroid and pituitary (produces thyroid stimulating hormone) gland
- Dysfunction of the hypothalamus (regulates the pituitary via thyrotropin-releasing hormone)
- As we age, TSH also decreases
21
Q
Hypothyroidism
A
Major cause is iodine deficiency
- decreased production of thyroxine and triiodothyronine
Other causes include:
- autoimmune disease
- cold or respiratory infection
- pregnancy
- birth defects
- surgical removal or radiation therapy
Symptoms include:
- Constipation
- Fatigue
- Sensitivity of cold
- Dry skin
- Weight gain
- Depression
- Joint/muscle pain
22
Q
Grave’s Disease
A
Autoimmune disease
- overactive thyroid due to thyroid antibodies binding to the TSH-receptor and stimulating thyroid hormone synthesis, secretion and goiter formation
Patient may have:
- psychiatric problems
- rhythm irregularities
- graves’ ophthalmopathy
- overactive metabolism
23
Q
Thyroid Storm
A
- life threathening
- results from untreated thyrotoxicosis
- may be caused by stress such as trauma or infection
- patients may develop cardiac failure and pulmonary oedema
Symptoms includes:
- agitation
- change in LOC
- confusion
- diarrhea
- fever
- tachycardia
- restlessness
- shaking
- sweating
24
Q
Alterations in Pancreatic Function
A
Diabetes Mellitus
- collection of disorders characterise by glucose intolerancem chronic hyperglycaemia (high BGLs) and alterations in protein, fat and carbohydrate metabolism
Type 1
- Autoimmune (destruction of pancreatic beta cells)
- as a result they produce insufficient amounts of insulin.
- polyuria and polydispia are common
Gestational diabetes - glucose intolerance during pregnancy
Type 2
- related to diet and life style
- insulin is produced but either not in sufficient quantities or the insulin receptors on the cells surface become “blind” or resistant to insulin
25
Alterations in the Adrenal Glands
Disorders of the adrenal cortex are mostly related to excessive production of hormones
- Hypoaldosteronism may be caused by a primary adrenal cortex problem or a secondary production of aldosterone
- symptoms include HTN (due to hypervolaemia), hypokalaemia leading to muscle weakness, and alkalosis
- treatment includes surgery for a adrenal adenoma or an aldosterone antagonist such as spironolactone
Hypercortisolism is usually the result of Cushing Syndrome
- common cause of Cushing's syndrome is exogenous administration of glucocorticoids for asthma, immunosuppression
- Pituitary Cushing's, a benign pituitary adenoma secretes ACTH
- Adrenal Cushing's, excess cortisol is produced by adrenal gland tumours, hyperplastic adrenal glands, or adrenal glands with nodular adrenal hyperplasia
26
Symptoms of Cushing's Mnemonic
Symptoms include:
- Central obesity, collagen fibre weakness
- Urinary free cortisol and glucose increase
- Stiae, supressed immunity
- HTN, hyperglycaemia, hypercortisolism, hypernatremia, hypokalamia, hypercholesterolemia
- Iatrogenic
- Noniatrogenic
- Glucose intolerance, growth retardation
27
Treatment of Cushing's Treatment
- Stop glucorticoid administration
- Remove tumour if present
- Supportive therapy is required for some patients until their normal feedback loop for cortisol production is restored
28
Alterations in Endocrine Function in Respons to Ageing
Endocrine organs undergo:
- atrophy
- vascular changes
- decreased secretion and metabolism of hormones
- decrease in receptor binding
- decrease in intracellular signalling
29
Define a feedback system and explain why endocrine feedback
| mechanisms so are important for maintaining homeostasis.
feedback systems allow for the required levels of hormones to be maintained so as not to results in disease and imbalance
- consist of negative and positive feedback loop
- most are negative feedback loops
TSH - if too much T3 and T4 in blood - feedback to hypothalamus to inhibit the production
30
Describe the common hypothalamic-pituitary disorders and the
| main hormones involved.
- hyper/hypopituitarism
- acromegaly - excessive growth hormone
- prolactin secreting tumours
- Diabetes inspidus due to ADH hypoactivity
- syndrome of inappropriate ADH secretion
- hypothalamic disease may cause deficiencies in any downstream hormone
e. g. TSH, adrenocorticotrophic hormone, beta-endorphin, lutenizing hormone, FSH, MSH
31
Describe two main thyroid and parathyroid disorders and discuss
the main hormones involved.
Graves disease - hyperthyroidism. Autoimmune disorder where thyroid stimulating immunoglobulins bind to the thyroid cells and stimulates the production of too much thyroid hormone
Hastimoto's disease (autoimmune thyroiditis) - inflammation damages the gland leading to decreased thyroid hormone production
- has phase of both hyperthyroidism = excess thyroid hormone production in early disease onset and hypothyroidism = decreased thyroid hormone production
Hyperparathyroidism = excessive PTH and too much calcium in the blood, hypoparathyroidism in not enough PTH and low calcium in the blood
32
ould a goiter occur in both grave’s disease and hashimoto’s
| disease? Why/why not?
Yes, the excess thyroid hormone causes the T cells to mistaking attack the thyroid gland causing inflammation producing excess thyroxine
33
Describe two main adrenal gland disorders including symptoms
| and causes and discuss the main hormones involved.
Cushing's syndrome - too much cortisol
- symptoms include - rapid weight gain, moon face, baldness, buffalo hump, depression and anxiety
- may be due to exogenous administration of glucocorticoids or endogenous pituitary adenoma, adrenal tumours, paraneoplastic cushing's commonly from small cell lung cancer
Addison's disease - too little cortisol
- symptoms include - chronic fatigue, muscle weakness, weightloss, loss of appetite and low BP
- adrenal insufficiency, secondary adrenal insufficiency caused by ACTH deficiency e.g. removal of the pituitary, TB which can destroy adrenal glands, cancer and chronic fungal infection
34
Define diabetes mellitus, and explain how it differs from diabetes
insipidus?
diabetes mellitus is caused by a lack of insulin or insulin resistance whereas diabetes insipidus is caused by the lack of hormone vasopressin (ADH)
patients with both types will fell thirsty and urinate frequently
35
Define metabolic syndrome
Conditions that increase risk of cardiovascular disease and type 2 diabetes
- obesity
- elevated triglycerides (greater than 1.69 mmol/L)
- HTN (> 130/85)
- glucose intolerance
- decreased HDL cholesterol
36
State three chronic complications of diabetes mellitus and describe the
pathophysiological cause.
- Heart and blood vessel disease - excess glucose binds to the blind vessels wall causing thickening and hardening to occur
- Nerve damage - excess glucose can damage the capillaries that nourish the nerves
- Nephropathy - damage to the nephrons (blood vessels are damaged)
- eye damage - blood vessels at the back or the eye balloon into pouches, this can ultimately lead to bleeding and loss of vision
- osteoporosis - diabetes can decrease your bone mineral density and increase your risk of osteoporosis
37
Outline the risk factors/causes, pathophysiology and clinical
manifestations of Syndrome of Inappropriate Anti-diuretic Hormone
Secretion.
- Head injury, pituitary surgery, pulmonary disease and lung tumour
SIADH - increased ADH, causing inability to excrete dilute urine, retention of water, expansion of extracellular volume, dilutional or euvolemic hyponatremia
- clinical manifestations; oligura, weight gain anorexia, N&V, muscle weakness, coma
38
Risk factors/causes and
possible pathophysiology that may lead to the development of Type II
diabetes
genetic and environmental factors
- increased appetite
- decreased exercise
- increased nutrient intake
- increased metabolic efficiency
- increased adiposity - obesity
- low grade inflammation, reactive oxygen species, dyslipidaemia, adipokines, beta cell stress
- insulin resistance - type 2 diabetes
- Beta cell dysfunction - type 2 diabetes
excess glucose production, impaired glucose uptake and utilisation
Beta cells (β cells) are a type of cell found in pancreatic islets that synthesize and secrete insulin and amylin
