Endocrine system Flashcards
What do hormones regulate?
- Growth
- Metabolism
- Sexual development and function
What do endocrine glands secrete?
Hormones
Is hormone action rapid or prolonged?
Prolonged
Where are endocrine gland secretions released?
Into the bloodstream
What is the general role of substances secreted by endocrine glands?
Help in the regulation and maintenance of physiological events such as metabolism, menstrual flow, and reproductive functioning
What do exocrine glands secrete?
Enzymes
Is the activity of enzymes short or long term?
Short term
Where are exocrine secreted substances released?
Directly over the target site or tissue
What is the general role of exocrine glands?
They are glands of external secretion, for example:
- Sweat
- Saliva
- Digestive enzymes
What do the hypothalamus and pituitary monitor?
Chemical and physical characteristics of blood
- BP
- Nutrients
- Hormones
- Water content
What are the two main reasons the hypothalamus will stimulate the pituitary gland?
- Deviation in homeostasis
- Developmental changes are required
What response is initiated by the pituitary when there is a deviation in homeostasis?
Increase in cellular activity
What response is initiated by the pituitary for developmental changes?
Release of hormones from the anterior and posterior pituitary gland
What type of hormones are secreted by the anterior pituitary gland? List them.
Tropic hormones
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Luteinising hormone (LH)
- Follicle-stimulating hormone (FSH)
- Prolactin
- Growth hormone (GH)
What makes up most of the posterior pituitary gland?
Nerves that have their cell bodies in the hypothalamus
What does the posterior pituitary gland store and release when stimulated?
Oxytocin and anti-diuretic hormone (ADH)
What are the two primary functions of the thyroid gland?
- Secretion of thyroid hormones
- Secretion of calcitonin
How many parathyroid glands do humans have?
Four
True or false: each parathyroid gland is richly vascularised
What do the parathyroid glands both produce and secrete?
Parathyroid hormone
The adrenal gland includes which two endocrine organs?
- Adrenal medulla
- Adrenal cortex
The adrenal glands are two organs, one surrounding the other: name which is the inner and outer organ.
- Adrenal medulla is the inner organ
- Adrenal cortex is the outer organ
What type of hormone is seceted by the adrenal medulla?
Provide three examples.
Catecholamines
- Adrenaline
- Noradrenaline
- Dopamine
What type of hormone is secreted by the adrenal cortex?
Steroid hormones
What mechanism do the adrenal medulla hormones mostly work to prepare?
Sympathetic response (fight or flight)
What two corticosteroid subgroups of hormones are produced by the adrenal cortex?
- Glucocorticoids
- Mineralocorticoids
What two control centres regulate the release of corticosteroid hormones from the adrenal cortex?
- Hypothalamus
- Pituitary gland
Release of corticosteroid hormones from the adrenal cortex is mediated by signals triggered by which organ?
The kidney
What glucocorticoids are released by the adrenal cortex?
- Hydrocortisone
- Corticosterone
What is the function of hydrocortisone?
- Regulates how the body converts fats, proteins, and carbohydrates to energy
- Regulates BP and cardiovascular function
What is the function of corticosterone?
Works with hydrocortisone to regulate immune responses and suppress inflammatory reactions
What is the principle mineralocorticoid secreted by the adrenal cortex?
Aldosterone
What regulates aldosterone release?
RAAS
True or false: the pancreas is comprised of two glands mixed together into one organ
What kind of cells make up most of the first functional component of the pancreas, endocrine or exocrine?
Exocrine
What kind of cells make up most of the second functional component of the pancreas, endocrine or exocrine?
Endocrine
What is the purpose of the first functional component of the pancreas?
Produce and release enzymes into ducts to assist digestion
What is the purpose of the second functional component of the pancreas?
Blood glucose level homeostasis, including release of hormones insulin and glucagon.
The second functional component of the pancreas (endocrine) is comprised of a number of small islands of cells. What is this region called?
Islet of Langerhans
The Islet of Langerhans inclues for types of cells involved in BGL regulation; name them.
- Alpha
- Beta
- Delta
- Gamma
What are the three derivative hormome types? Provide examples of each.
-
Lipid derived
- Mostly derived from cholesterol
- Primary class of lipid-derived hormones is steroid hormones
- Steroid hormones are usually ketones and alcohols
-
Amino acid derived
- Derived from amino acids tyrosine and tryptophan
- Examples include thyroxine, adrenaline, and noradrenaline
-
Peptide derived
- Includes oxytocin and ADH
Production and release of hormones is primarily controlled by what kind of feedback?
Negative feedback
Name the three mechanisms involved in hormone release and describe the stimuli for each one
-
Humeral
- Control of hormone release in response to changes in ECF
-
Hormonal
- Control of hormonal release in response to other hormones
-
Neural
- Control of hormone release in response to direct stimulation by the nervous system
True or false: a hormone can have a generalised effect on a variety of cells
Hormones affect specific tissue cells
What are the specific tissue cells affected by hormones called?
Target cells
What particular feature do target cells have and what two places may they be located?
- Receptors
- Either on the plasma membrane of the cell or within the cell so that hormones can bind
Describe the process of homeostasis involving the endocrine system
Variable (factor being regulated) → Stimulus (input to respond to) → Receptor (response to stimulus) → Afferent pathway (carries information to control centre) → Control centre (assesses the nature of the stimulusm, compares it to the set point, and determines the response) → Set point (reference value that must be maintained) → Efferent pathway (carries responses generated by control centre) → Effector (carries out action to achieve the desired response)
How does negative feedback work?
Shuts off or reduces the intensity of the original stimulus
What is the most common homeostatic control mechanism?
Negative feedback
How does positive feedback work?
Enhances the original stimulus (this is harder for the body for control)
Insulin is released by ____ cells located in the ____.
Beta cells in the Islets of Langerhans (in the pancreas)
What is the effect of insulin on blood glucose cellular uptake?
Insulin hastens uptake by the cells
How does insulin facilitate glycogenesis?
By turning glucose into glycogen so it can be stored in the liver
(id est, not in the blood)
When is the stimulus causing insulin release reduced?
Once BGL levels return to normal
Glucagon is released by ____ cells located in the ____.
Alpha cells located in the Islets of Langerhans/pancreas
What is the effect of glucagon?
Causes the liver to release its storage of glycogen as glucose back into the blood
What is the term for release of glycogen storage as glucose?
Glycogenolysis
What is characteristic of IDDM?
Pancreatic beta cell destruction with absolute insulin deficiency
What is pancreatic beta cell destruction with absolute insulin deficiency usally associated with?
Autoimmune damage
IDDM is usually diagnosed between age ____ to ____.
5 to 20
True or false: IDDM requires life-line insulin injections
True
What is the classical presentation of IDDM?
- Polyuria
- Polydipsia
- Polyphagia
- Unexplained weight loss
NIDDM is characterised by…
Peripheral insulin resistance and inadequate insulin secretion by pancreatic beta cells
Which diabetes is significantly more common than the other, IDDM or NIDDM?
NIDDM
NIDDM is generally associated with what three factors?
- Poor lifestyle
- Poor diet
- Obesity
Describe the likely presentation of NIDDM
- Polyuria
- Polydipsia
- Polyphagia
- Blurred vision
- Lower extermity paraesthesia
- Balanits/yeast infection
What is the definition of gestational diabetes?
Glucose intolerance with onset or first presentation/regocnition duing pregnancy
Describe the pathophysiology of gestational diabetes
The placenta produces hormones that encourage foetal growth and development
↓
These hormones block insulin action
↓
Insulin resistance
True or false: gestational diabetes requires aggressive treatment to prevent morbidity and mortality
True
Diabetic treatment regimens are designed for what goal?
Avoid high and low levels of glucose and insulin
What can NIDDM patients generally use to manage their condion?
Combination of diet control, oral hypoglycaemic medicaitons
True or false: insulin is not requred for NIDDM mx
False - it doesn’t require lifelong injections like IDDM, but some NIDDM cases may require insulin
What is gluconeogenesis?
Metabolic pathway that results in generation of glucose from non-carbohydrate sources such as lactate, glycerol, and glucogenic amino acids
What is glycogenolysis?
The process by which glycogen in the liver is converted into glucose to be released into the blood
What is lipolysis?
Breakdown of lipids involving hydrolysis of triglycerides into glycerol and free fatty acids
What are the four diabetic emergencies?
- Hypoglycaemia
- Hyperglycaemia
- Diabetic ketoacidosis (DKA)
- Hyperosmolar hyperglycaemic non-ketotic syndrome (HHNS)
What is the definition of hypoglycaemia?
Reduction of plasma glucose concentration; BGL <4mmol)
Hypoglycaemia is usually seen in patients with what condition?
IDDM
List some of the causes of hypoglycaemia
- IDDM
- Insulin OD
- Insulin administration not followed by a timely meal
- Change in diabetic medication
- Pt has overexerted themselves
What are some common symptoms of hypoglycaemia?
- Tachycardia with bounding pulse
- Irritability/combative behaviour
- Pale/cold/clammy skin
- BGL <4mmol
- ALOC
- Behaviour mimicking CVA or intoxication
- Weakness
- Headache
- Lack of coordination
- Seizure activity
Describe the mx of hypoglycaemia
- Encourage self-administration of oral glucose if pt is conscious
- IV glucose 10% if pt is ALOC
- Use glucagon if unable to obtain IV access
List some causes of hyperglycaemia
- Not using enough insulin or oral hypoglycaemics
- Not injecting insulin properly or using expired insulin
- Infection
- Injury
- Poor diet choices
- Stress
- Certain medications (steroids)
What are the early signs of hyperglycaemia?
- Polyuria
- Polydipsia
- Blurred vision
- Fatigue
- Headache
What are the late signs of hyperglycaemia?
- Sweet smelling breath
- N+V
- SOB
- Dry mouth
- Weakness
- Confusion
- Coma
- Abdo pain
What is diabetic ketoacidosis?
An acute life-threatening complication of diabetes; it is a disordered metabolic state characterised by hyperglycaemia, ketoacidosis, and ketonuria
DKA occurs as a consequence of…
Absolute relative insulin deficiency that is accompanied by an increase in counter regulatory hormone (glucagon, cortisol, GH, adrenaline)
Describe the pathophysiology of DKA
Note: big process, don’t panic.
Marked insulin deficiency and release of catecholamine hormone
↓
Adrenaline blocks any residual insulin action and stimulates glucagon secretion
↓
The insulin deficiency combined with excess glucagon decreases peripheral glucose utilisation and increases gluconeogenesis
↓
Gluconeogenesis exacerbates hyperglycaemia
↓
Hyperglycaemia causes osmotic diuresis and dehydration characteristic of the ketoacidotic state
↓
The insulin combined with excess glucagon also activates ketogenic machinery
↓
Insulin deficiency stimulates lipoprotein lipase (breakdown of adipose stores)
↓
Increase in free fatty acids
↓
Ketone bodies are formed when free fatty acids reach the liver
↓
If the rate of ketone body formation exceeds the rate they are used in peripheral tissues, ketonaemia and ketouria develop
↓
If dehydration compromises the urinary secretion of ketones it results in system metabolic ketoacidosis
Summarise the pathophysiology of DKA
- Hyperglycaemia of DKA evolves through accelerrated gluconeogenesis, glycogenolysis, and decreased glucose utilisation
- Hyperglycaemia-induced osmotic diuretics leads to dehydration, hyperosmolarity, electrolyte loss, and subsequent decrease in glomerular filtration
- Ketone bodies occur when free fatty acids are converted in the liver
List some of the causes of DKA
- Inadequate insulin dise
- Failure to take insulin
- Infection
- Increased stress (trauma, surgery)
- Increased dietary intake
- Decreased metabolic rate
- Significant emotional stress
Describe the common presentation of DKA
- Slow onset (12-48 hours)
- Diuresis
- Dry mucous membranes
- Polyuria
- Polydipsia
- Acidosis
- Kussmaul respirations
- Sweet-smelling breath
Describe the mx of DKA
- Confirm hyperglycaemia
- General cares
- IV access
- Fluid therapy
What is a hyperosmolar hyperglycaemic non-ketotic state (HHNS)?
A life-threatening diabetic emergency mainly seen in NIDDM patients that’s less common than DKA
HHNS is more common in which pt group?
Elderly
HHNS is characterised by…
Hyperglycaemia
Hyperosmolarity
Dehydration
PN: significant ketoacidosis
HHNS develops from…
Sustained hyperglycaemia which produces a hyperosmolar state followed by a hyperosmolar state
What two symptoms do most HHNS pts commonly present with?
Severe dehydration
Neurological deficit
List the causes of HHNS
- Increased insulin requirements (stress, infection, trauma, burns, AMI)
- Cardiac disease
- Renal disease
- Age
Describe the common presentation of HHNS
- Very gradual onset
- Polyuria
- Polydipsia
- Postural syncope
- Dry mucous membranes
- Tachycardia
- Lethargy
- Confusion
- Coma
Describe the mx of HHNS
General symptom mx
Name three disorders of the thyroid gland
- Hyperthyroidism/thyrotoxicosis
- Hypothyroidism
- Thyroid storm
What is hyperthyroidism/thyrotoxicosis?
Excessive production of thyroid hormone by the thyroid gland overstimulates metabolism and exacerbates the effect of the sympathetic nervous system
List some causes of hyperthyroidism
- Thyroiditis (inflammation)
- Grave’s disease
- Toxic thyroid adenoma
- Toxic multinodular goitre
- Excess iodine
- Tumours of the ovaries/testes/thyroid gland
Which is the more common cause of hyperthyroidism, the entire gland overproducing the hormone, or overproduction by a single nodule (hot nodules)?
The entire gland overproducing the hormone
True or false: hyperthyroidism can be symptomatic or asymptomatic
List some symptoms of hyperthyroidism/thyrotoxicosis
- Weight loss
- Anxiety
- Heat intolerance
- Hair loss
- Muscle aches
- Weakness
- Fatigue
- Hyperactivity
- Irritability
- Exophthalmos
What is thyroid storm?
An acute life-threatening hypermetabolic state induced by excessive relesae of thyroid hormones in an individual with hyperthyroidism; it is the most extreme state of hyperthyroidism
True or false: thyroid storm can be the initial presentation in children and especially neonates with hyperthyroidism
What are thyroid storm symptoms related to?
Severely exaggerated effects of thyroid hormones due to increased release or intake (less common) of thyroid hormone
What are some possible causes of thyroid storm?
- Severe undertreated hyperthyroidism
- Infection associated with hyperthyroidism
- Trauma
- Surgery
- Severe emotional stress
- Stroke
- DKA
- CHF
- PE
Symptoms of thyroid storm include…
- Tachycardia
- AF
- Hypertension
- Cardiac failure
- Arrhythmias
- Hyperpyrexia
- Sweating
- Shaking
- Abdo pain
- Agitation
- Restlessness
- Confusion
- Diarrhoea
- Seizures
- Coma
What is hypothyroidism?
A common disorder where the thyroid gland doesn’t produce enough thyroid hormone
What is primary hypothyroidism?
Inadequate function of the thyroid gland itself
What is secondary hypothyroidism?
Inadequate stimulation by TSH from the pituitary gland
What is tertiary hypothyroidism?
Inadequate release of thyrotropin releasing hormone from the hypothalamus
What is the most common cause of primary hypothyroidism?
Iodine deficiency
What is the most common cause of hypothyroidism in areas of the world that have adequate dietary iodine?
Hashimoto’s thyroiditis (autoimmune disease)
What are the symptoms of hypothyroidism?
- Poor ability to tolerate cold
- Fatigue
- Constipation
- Depression
- Weight gain
- Goitre
- Myxoedema coma (extreme hypothyroidism causing symptoms related to slowing functions of multiple organs)
Describe hypothyroidism mx
Rx symptoms of myxoedema coma (bradycardia, hypoventilation, hypothermia) and transport to hospital
What are two significant disorders of the adrenal gland?
Cushings syndrome and Addison’s disease
What is Cushing’s syndrome?
Hypersecretion of corticosteroid by the adrenal glands
What can cause Cushing’s syndrome?
- Adrenal gland tumour
- Corticosteroid administration
- Pituitary tumour causing enlargement of both adrenal glands
What are some signs and symptoms of Cushing’s syndrome?
- Increase in proportion of body fat to limbs (rapid weight gain)
- Depression
- Irritability
- Muscle atrophy
- Hirsuteness (excessive hair growth)
- Psychosis (extreme cases)
What is Addison’s disease?
A long term endocrine disorder in which the adrenal glands do not produce enough steroid hormone; it is primary adrenal insufficiency and hypocortisolism
Addision’s disease arises from problems with the adrenal gland when…
Insufficient cortisol (steroid hormone) is produced
What two things can cause Addison’s disease?
- Tuberculosis
- Immune damage to adrenal glands
What are the symptoms of Addison’s disease?
- Fatigue
- Light-headedness
- Difficulty standing
- Muscle weakness
- Fever
- Weight loss
- Anxiety
- GIT symptoms
- Personality changes
- Joint pain
- Salt cravings
- Hypotension
What is an Addisonian crisis? Describe what occurs.
Medical emergency severe adrenal insufficiency during which the adrenal glands cannot increase production of corticosteroid hormone to help the body cope with stress
What can cause Addisonian crisis?
- Stress (emotional or physical)
- Illness/infection
- EtOH intoxication
- Hypothermia
What are the symptoms of Addisonian crisis?
- Sudden pain in legs/lower back/abdomen
- Severe V+D
- Dehydration
- Hypotension
- Syncope
- Hypoglycaemia
- Confusion, psychosis
- Lethargy
- Hyponatraemia
- Hyperkalaemia
- Hypercalcaemia
- Seizures
Describe mx of Addisonian crisis
- General cares
- IV hydrocortisone
- Fluid therapy
- Hypoglycaemia rx if indicated
What are the indications for hydrocortisone?
- Moderate or severe asthma
- Acute exacerbation of COPD
- Severe allergic reaction or anaphylaxis
- Symptomatic adrenal insufficiency
What are the contraindications for hydrocortisone?
KSAR
What are the precautions for hydrocortisone?
Hypertension
What are the side effects of hydrocortisone?
Nil
What is the adult dosage of hydrocortisone for symptomatic adrenal insufficiency?
100mg IV* or IM, single dose only
*Note: IV administration is slow push over one minute
*Note: presentation is 100mg vial that is reconstituted with 2mL sodium chloride 0.9% or water for injection*
