Endocrine - Pituitary Hormone-1 Flashcards
What are the structural difference between the adenohypophysis and neurohypophysis?
- Adenohypophysis: Consists of glandular tissue.
- Neurohypophysis: Consists of neural tissue and pituicytes (glial cells)
What is the function of adenohypophysis and neurohypophysis?
- Adenohypophysis: Produces and secretes hormones in response to
hypothalamic signals. - Neurohypophysis: Stores and releases hormones produced by the
hypothalamus.
What is the regulation of the adenopophysis nd neurohypophysis?
- Adenohypophysis: Regulated by hypothalamic releasing and inhibiting
hormones via the hypophyseal portal system (Hypothalamus-pituitary axis). - Neurohypophysis: Directly controlled by nerve signals from the
hypothalamus
What are the hormones released from the anterior pituitary?
*somatotropin
*prolactin
*corticotropin
*thyrotropin
*gonadotropin
What are the hormones released by the posterior pituitary?
*oxytocin
*ADH
What are the local effects of pituitary tumour?
*headaches
*visual disturbances
What do pituitary tumours do?
*can over produce or under produce hormones
*slowly grow over time
*mostly benign
What does the hypothalamus do in terms of GH?
- Growth Hormone-Releasing Hormone (GHRH): Stimulates the
secretion of GH from the anterior pituitary. - Somatostatin (SS): Inhibits the secretion of GH from the anterior pituitary
What does the anterior pituitary do in terms of GH?
- In response to GHRH, acidophilic cells in the anterior pituitary secrete GH.
- GH is then released into the bloodstream in a pulsatile manner.
What does the liver do to feedback from the anterior in terms of GH?
Liver: GH stimulates the liver to produce Insulin-like Growth Factor 1 (IGF-1),
which has growth-promoting effects on almost every cell in the body,
especially bone and muscle
What is the positive regulation of the GH?
GHRH: Released from the hypothalamus, stimulates GH secretion from the
anterior pituitary.
What is the negative regulation of the GH?
- Somatostatin (SS): Released from the hypothalamus, inhibits GH secretion.
- IGF-1: Produced in response to GH, provides negative feedback to both the
hypothalamus and the pituitary gland to decrease GH production
What are the direct effects on metabolism from GH?
*increase blood glucose
*increase gluconeogensis (liver)
*increase protein synthesis (muscle)
*decrease glucose uptake in muscle
*increases lipolysis (adipose)
*decrease glucose uptake in adipose tissue
What is the indirect growth effect from GH?
increase hypertrophy (cell size)
*increase protein synthesis
*increase hyperplasia (cell number, cell division)
*increases linear skeletal growth
Describe how sleep affects GH release
GH release peaks during deep sleep stages (slow-wave sleep).
*Sleep quality and duration significantly influence GH secretion.
*Poor sleep quality or disorders can impair GH release
Describe how exercise affects GH release?
High-intensity and longer-duration exercises stimulate substantial GH release.
*Both resistance and aerobic exercises can increase GH levels, with resistance training
typically having a more pronounced effect.
*GH levels peak shortly after exercise and gradually return to baseline.
*Regular training can enhance the GH response to exercise
What are the different types of GH deficiency?
*congenial deficiency
*acquired deficiency
*idiopathic deficiency
What are the causes and symptoms of congenital GH deficiency?
*Causes: Genetic mutations or structural issues in the baby’s brain that affect the
development or function of the pituitary gland.
*Symptoms: Poor growth and short stature from birth, delayed puberty, and, in some
cases, hypoglycaemia in infants
What are the causes and symptoms of acquired GH deficiency?
Causes: Damage to the pituitary gland or hypothalamus due to injury, infection, tumour,
surgery, or radiation therapy.
*Symptoms: Stunted growth if occurring in children, reduced muscle mass, increased fat
mass, decreased energy levels, and poor quality of life in adults
What are the causes and symptoms of idiopathic GH deficiency?
*Causes: Unknown cause; no identifiable genetic, structural, or acquired reasons.
*Symptoms: Similar to congenital and acquired GH deficiency, including short stature,
delayed growth, and other metabolic issues
What are the treatment options of GH deficiency?
*GH replacement therapy
*monitoring and support
What are some side effects to gigantism/ acromegaly?
- coarsening of facial features
- enlarged hands and feet (arthritis)
- headaches, vision disturbance
- sleep apnoea, general tiredness
- hypertension, cardiomegaly
- glucose intolerance (diabetes)
- irregular or loss of periods (females); impotence
(males) - bowel polyps
What are the treatment options for excess GH disorders?
*reduce GH levels/block GH action
*surgical removal of the tumour (transsphenoidal surgery) or (stereotactic radio surgery/gama knife)
*radiotherapy
What are the functions and effects of thyroxine (T4)?
- Function: Serves as a prohormone and is converted into T3 in peripheral tissues
*Effects: Influences metabolism, heart rate, and body temperature.
It also plays a role in growth and development
What is the structure and regulation of thyroxine?
- Structure: Contains four iodine atoms *Regulation: Controlled by Thyroid-Stimulating Hormone (TSH) from
the anterior pituitary
What are the structure and function of Tri-iodothyronnie (T3)?
- Structure: Contains three iodine atoms.
- Function: The active form of thyroid hormone, much more potent
than T4
What is the conversion and effects of T3?
- Conversion: Produced both directly by the thyroid gland and from
the conversion of T4 in the liver and other tissues. - Effects: Regulates metabolic rate, enhances oxygen consumption,
stimulates protein synthesis, and influences neural development
What is the source, function and regulation of calcitonin?
- Source: Produced by the parafollicular cells (C cells) of the thyroid
gland. - Function: Lowers blood calcium levels.
- Regulation: Secretion is stimulated by high blood calcium levels
What is the source, function and regulation of the parathyroid hormone?
- Source: Produced by the parathyroid glands, which are small glands
located on the posterior surface of the thyroid gland. - Function: Raises blood calcium levels.
- Regulation: Secretion is stimulated by low blood calcium levels.
What are the functions of T3?
*basal metabolic rate (BMR)
= sugar, fat and protein metabolism
*growth and development
=CNS development
*synergistic effect with SNS
=adrenergic receptors
= physiological effects
What are the causes of thyroid hormone disease?
- Iodine Deficiency: The most common cause worldwide.
- Graves’ Disease: Causes diffuse enlargement of the thyroid.
- Hashimoto’s Thyroiditis: Can lead to thyroid enlargement.
- Thyroid Nodules: Growth of lumps (cancerous) within the thyroid.
What are the symptoms to thyroid disease?
*visible swelling in the neck
*difficulty swallowing or breathing (if large)
What are the causes of hypothyroidism?
- Hashimoto’s Thyroiditis: An autoimmune disorder where the immune
system attacks the thyroid gland. - Iodine Deficiency: Lack of iodine in the diet, necessary for thyroid hormone
production. - Surgical Removal: Partial or complete removal of the thyroid gland.
- Radiation Therapy: Damage to the thyroid from radiation treatments.
- Medications: Certain medications can affect thyroid function
What are the symptoms to hypothyroidism?
BMR - decrease in body core temp
- decrease in sweating
-decrease in thermal discomfort
- weight gain
- constipation
CNS
- depression, confusion, poor memory and concentration
-growth deficiency
-dry skin, hoarse voice, menstrual issues
CVS - decrease in HR, MAP
What is the treatment to hypothyroidism?
- Thyroid Hormone Replacement Therapy: Synthetic thyroxine (T4) is
administered to restore normal hormone levels
What are the causes of hyperthyroidism?
*grave’s disease
*thyroid nodules
*thyroiditis
*excessive iodine intake
*pituitary adenomas
What are the symptoms of hyperthyroidism?
BMR - increased body temp
increased sweating
increased heat intolerance
increased appetite
weight loss and diarrhoea
CNS - anxiety, emotions, restlessness
CVS - increase in HR, MAP (palpation)
What are some causes for Grave’s disease?
*autoimmune mechanism
*genetic factors
*environmental triggers
What are the symptoms of grave’s disease?
1.Thyroid-Related Symptoms:
* Hyperthyroidism: Symptoms include weight loss, heat intolerance,
increased appetite, sweating, and tremors.
* Goitre: An enlarged thyroid gland, which may cause a visible swelling in the
neck.
2.Ophthalmopathy (Graves’ Orbitopathy):
* Exophthalmos: Bulging of the eyes due to inflammation and tissue swelling
behind the eyes.
* Eye Irritation: Dryness, redness, tearing, and sensitivity to light.
* Double Vision: Due to swelling and fibrosis of the eye muscles.
* Severe Cases: Compression of the optic nerve can lead to vision loss.
3.Cardiovascular Symptoms:
* Palpitations, rapid heartbeat (tachycardia), and atrial fibrillation.
4.Neurological Symptoms:
* Anxiety, irritability, and tremors.
5.Reproductive Symptoms:
* Irregular menstrual cycles or amenorrhoea in females, and erectile
dysfunction in males.
What are the functions of prolactin?
*stimulation of lactation = milk production and lactogenesis
*breast growth and development
= mammary gland development and during pregnancy
What can high prolactin cause?
- High Levels of Prolactin: Elevated prolactin levels can inhibit the release of
Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus. - Effect on Reproductive Function: This inhibition can lead to decreased
secretion of luteinising hormone (LH) and follicle-stimulating hormone
(FSH), which can cause disruptions in the menstrual cycle in women and
reduce fertility in both women and men.
Clinical Implications: Conditions causing high prolactin levels, such as
prolactinomas (prolactin-secreting pituitary tumours), can lead to symptoms such
as amenorrhoea, galactorrhoea (excessive or inappropriate production of milk),and infertility.
