Endocrine System Flashcards
What does the endocrine system include?
Hypothalamus, Pituitary, Thyroid, Parathyroids, Adrenals, Pancreas, Ovaries, Testes, Pineal gland
What are hormones?
Made in gland(s) or cells, transported by blood, activate physiological response at distant target tissue receptors
What functions do hormones control?
- Control of enzymatic reactions
- Transport of ions or molecules across cell membranes
- Gene expression and protein synthesis
- Exert effects at very low concentrations
- Bind to target cell receptors
- Half-life indicates length of activity
What are tropic hormones?
Act on other endocrine glands, control of hormone secretion
What are non-tropic hormones?
Act on effector organs, e.g., thyroid, adrenals, pancreas
What are the types of hormones based on their structure?
- Peptide hormones
- Steroid hormones
- Amine hormones
What are peptide hormones?
Large, inactive preprohormones that undergo post-translational modification to become active hormones
What is the half-life of peptide hormones?
Short half-life
What are steroid hormones derived from?
Cholesterol
How do steroid hormones act?
Activate DNA for protein synthesis, slow-acting, longer half-life
What are amine hormones derived from?
One of two amino acids: Tryptophan or Tyrosine
What are the main features of peptide hormones?
- Hydrophilic (water soluble)
- Can travel freely in the blood
- Cannot enter the cell (need a membrane receptor)
- Use second messenger systems
What is the process of peptide hormone synthesis?
mRNA -> Ribosome -> Preprohormone -> Prohormone -> Active hormone
What is the role of the receptor-hormone complex in steroid hormone action?
Binds to DNA and activates or represses genes
What is negative feedback in hormonal control?
Self-regulates hormone levels, turns off response homeostatically
What factors can affect hormone secretion?
- Emotional state
- Disease state
- Stress
- Diet, sleep
- Body cycles (circadian rhythm, menstrual cycle)
What is hyposecretion?
Too little hormone is secreted
What is hypersecretion?
Too much hormone is secreted
What are the causes of primary hyposecretion?
- Gland abnormality
- Genetic factors
- Dietary issues
- Chemical/toxic influences
- Autoimmune diseases
What is secondary hyposecretion?
Gland is normal but too little hormone is secreted due to decreased tropic hormone
What does synergism in hormone interactions mean?
Multiple stimuli produce effects that are more than additive
What is permissiveness in hormone interactions?
Need second hormone to get full expression of the first hormone
What is antagonism in hormone interactions?
Pairs of hormones with opposing effects
What is a deficiency?
A lack of a necessary substance or hormone in the body
What are the symptoms of deficiency?
Varies depending on the hormone or substance involved
What causes hypersecretion?
Tumours, immunologic factors, primary and secondary hypersecretion
Define primary hypersecretion.
Too much hormone is secreted due to abnormality within the gland
Define secondary hypersecretion.
Excessive stimulation from outside the gland causes oversecretion
What is the role of the hypothalamus?
Controls the anterior pituitary and maintains homeostasis
What are hypothalamic releasing and inhibiting hormones?
Hormones that stimulate or inhibit anterior pituitary hormones
What effect does Thyrotropin-Releasing hormone (TRH) have?
Stimulates release of TSH
What effect does Corticotropin-Releasing hormone (CRH) have?
Stimulates release of ACTH
What does Gonadotropin-releasing hormone (GnRH) stimulate?
Stimulates release of FSH and LH
What is the effect of Growth-hormone releasing hormone (GHRH)?
Stimulates release of growth hormone
What is the role of Growth-hormone inhibiting hormone (GHIH)?
Inhibits release of growth hormone and TSH
What does Prolactin-releasing hormone (PRH) do?
Stimulates release of prolactin
What is the function of Prolactin-inhibiting hormone (PIH)?
Inhibits release of prolactin
What hormones are stored in the posterior pituitary?
Oxytocin and ADH
What is the function of oxytocin?
Stimulates uterine contractions and promotes milk ejection
What does ADH (Vasopressin) do?
Increases water reabsorption in kidney and decreases urine output
What is diabetes insipidus?
Condition characterized by low ADH leading to excessive polyuria
What are the symptoms of diabetes insipidus?
Hypotension, dizziness, constipation
What are the treatments for diabetes insipidus?
Vasopressin replacement
What does the anterior pituitary secrete?
6 peptide hormones, 5 of which are tropic
What are gonadotropins?
FSH and LH, hormones that promote egg and sperm production
What does Thyroid-secreting hormone (TSH) promote?
Promotes secretion of thyroid hormones
What is the function of Adrenocorticotropic hormone (ACTH)?
Promotes cortisol secretion from the adrenal cortex
What does prolactin act on?
Mammary glands for breast development and milk production
What is the effect of Growth Hormone (GH)?
Stimulates liver to release IGFs and promotes growth
What metabolic effects does Growth Hormone have?
Increases fatty acids in blood and blood glucose
What factors influence growth?
- Genetics
- Adequate diet and sleep
- Freedom from chronic disease and stress
- Normal levels of growth-influencing hormones
What is the role of the pineal gland?
Secretes melatonin and influences body clock and antioxidant activity
What is Seasonal Affective Disorder (SAD)?
A type of depression related to changes in seasons
Fill in the blank: GH hyposecretion leads to _______.
Dwarfism
Fill in the blank: GH hypersecretion before growth plates close leads to _______.
Gigantism
Fill in the blank: GH hypersecretion after growth plates close leads to _______.
Acromegaly
What structures are included in the endocrine system?
Hypothalamus, Pituitary, Thyroid, Parathyroids, Adrenals, Pancreas, Ovaries, Testes, Pineal gland
The endocrine system is responsible for hormone production and regulation.
What are the two hormones produced by the thyroid gland?
Thyroid hormone (TH) and Calcitonin
TH includes T3 and T4, which are crucial for metabolism.
What is the largest pure endocrine gland?
Thyroid gland
The thyroid gland plays a significant role in metabolism and energy regulation.
What is required for the synthesis of thyroid hormones?
Iodine
Iodine is essential for the production of T3 and T4 hormones.
What is hyperthyroidism?
Excessive thyroxine production
Symptoms include tachycardia, nervousness, hyperactivity, weight loss, and exophthalmus.
What autoimmune condition is associated with hyperthyroidism?
Grave’s disease
Treatment may include medication, radiation, and surgery.
What are the symptoms of hypothyroidism?
Cold and lethargic, weight gain, brittle hair and nails, mental sluggishness
Treatment typically involves thyroid hormone replacement.
What is cretinism?
Low thyroid hormone in the first 2 years of life
It leads to severe mental impairment and low muscle tone.
What is a simple goiter?
Enlargement of the thyroid gland
Can be due to hypo- or hyperthyroidism and may cause dyspnea and dysphagia.
What does calcitonin do?
Lowers blood calcium levels
Released when blood calcium is high, it decreases gut absorption, increases kidney excretion, and promotes bone absorption.
What hormone do parathyroid glands secrete?
Parathyroid hormone (PTH)
PTH acts to increase blood calcium levels.
What is the role of Vitamin D in calcium regulation?
Stimulates calcium and phosphate absorption from the intestine
Activated by PTH and can be synthesized from cholesterol.
What is hyperparathyroidism?
Increased blood calcium levels
Symptoms include kidney stones, bone weakness, and hyperactivity of the heart.
What is Addison’s disease?
Hypoadrenalism resulting in decreased adrenal hormones
Symptoms include weight loss, nausea, muscle weakness, and low blood pressure.
What does cortisol do?
Increases blood glucose and plays a role in stress adaptation
It is known as the ‘stress hormone’ and has anti-inflammatory effects.
What are the three phases of the stress response?
Alarm Phase, Resistance Phase, Exhaustion Phase
Each phase has distinct physiological responses to stress.
What is Cushing’s syndrome?
Increased cortisol levels
Symptoms include hyperglycemia, weight gain, and poor immune function.
What triggers the release of insulin?
High blood glucose levels
Insulin facilitates glucose uptake into cells and reduces blood glucose levels.
What is Type I Diabetes Mellitus?
Insulin-dependent diabetes, autoimmune disorder
It typically requires daily insulin injections for management.
What is the main controller during the absorptive state after eating?
Insulin
It helps move nutrients into cells and promotes storage.
What are the symptoms of diabetes mellitus?
Frequent urination, thirst, hunger
High blood glucose levels lead to glucose spilling into urine.
What is glucagon’s role in blood glucose regulation?
Increases blood glucose levels
It promotes gluconeogenesis and glycogenolysis when blood glucose is low.
What hormone is secreted by the adrenal medulla?
Epinephrine
It plays a role in the sympathetic nervous response.
What is the primary function of aldosterone?
Increases sodium reabsorption in the kidneys
It is part of the RAAS system and helps control blood pressure.
What are the primary actions of insulin?
Facilitates glucose uptake, promotes glycogen formation
Also enhances cellular uptake of fatty acids and amino acids.
What is insulin?
A hormone that regulates blood sugar levels
Insulin is produced by the pancreas and plays a crucial role in glucose metabolism.
What is Diabetes Mellitus Type II characterized by?
Low insulin response and gradual onset
Type II Diabetes is more common in adults, especially those over age 40.
What factors contribute to Type II Diabetes?
- Obesity
- Decreased sensitivity of cells to insulin
- ‘Wearing out’ of islets of Langerhans
These factors lead to poor insulin regulation and secretion.
How can Type II Diabetes be managed?
Through diet and exercise
Managing lifestyle can help control insulin secretion and improve sensitivity.
What occurs in early Type II Diabetes?
Poor response to insulin with high insulin levels
Patients need diet control and exercise to re-sensitize to insulin.
What happens in late Type II Diabetes?
Beta cells become dysfunctional and insulin levels drop
Patients may require insulin injections at this stage.
What are some complications of Diabetes Mellitus?
- Long-term tissue damage
- Atherosclerosis
- Diabetic retinopathy
- Kidney damage
- Neuropathies
- Heart disease
- Gestational diabetes in pregnancy
These complications can arise from uncontrolled diabetes over time.
What are the reproductive hormones affected by Diabetes Mellitus?
Testosterone, Estrogen, and Progesterone
These hormones play significant roles in sexual function and reproductive health.
What effects does testosterone have?
- Puberty to death
- Sperm production
- Motility/number
- Secondary sex characteristics
- Sex drive
- Hair growth
- Muscle maintenance
Testosterone is crucial for male reproductive health.
What effects do estrogen and progesterone have?
- Menstrual cycle regulation
- Increased fat
- Increased water retention
- Breast development
- Bone deposition
- Mucous production
These hormones are key to female reproductive health and menstrual cycles.
Fill in the blank: Type II Diabetes is more common in _______.
adults
This type of diabetes typically manifests later in life.
True or False: Insulin injections are always beneficial for patients with early Type II Diabetes.
False
Insulin injections can further desensitize patients in the early stages.
