1.
Pituitary gland is controlled by
Correct Answer
A. Hypothalamus
Explanation
The pituitary gland is controlled by the hypothalamus. The hypothalamus is a small region of the brain that plays a crucial role in regulating various bodily functions, including the secretion of hormones. It releases hormones that stimulate or inhibit the release of hormones from the pituitary gland, which is often referred to as the "master gland" because it controls the functions of other endocrine glands in the body. Therefore, the hypothalamus is responsible for controlling the pituitary gland.
2.
Hypothalamus connected to pituitary gland via
Correct Answer
C. Pituitary stalk (infundibulum)
Explanation
The hypothalamus is connected to the pituitary gland via the pituitary stalk, also known as the infundibulum. This connection allows for communication between the hypothalamus and the pituitary gland. The hypothalamus produces releasing and inhibiting hormones that are transported through the pituitary stalk to the anterior pituitary gland. These hormones then stimulate or inhibit the release of various hormones from the pituitary gland, which play a crucial role in regulating various bodily functions. Therefore, the pituitary stalk serves as the pathway for communication and coordination between the hypothalamus and the pituitary gland.
3.
The pituitary gland lies in the
Correct Answer
B. Sella turcica
Explanation
The pituitary gland is located in a bony structure called the sella turcica. This is a depression in the sphenoid bone, located at the base of the skull, behind the bridge of the nose. The sella turcica provides protection and support for the pituitary gland, which is often referred to as the "master gland" because it regulates the functions of other endocrine glands in the body. Therefore, the correct answer is sella turcica.
4.
Which approach does the surgeon take for a pituitary gland surgery?
Correct Answer
D. Trans-sphenoidal
Explanation
The surgeon takes a trans-sphenoidal approach for a pituitary gland surgery. This means that the surgery is performed by accessing the pituitary gland through the sphenoid sinus, which is located behind the nasal cavity. This approach allows the surgeon to reach the pituitary gland without making any external incisions, resulting in a less invasive procedure with fewer complications and a quicker recovery time.
5.
The anterior pituitary arises embryologically as an:
Correct Answer
A. Invagination of the roof of the pharynx (rathke's pouch)
Explanation
The correct answer is invagination of the roof of the pharynx (Rathke's pouch). During embryological development, the anterior pituitary gland originates from an invagination or pouch-like structure called Rathke's pouch, which forms from the roof of the developing pharynx. This invagination gives rise to the anterior pituitary, which plays a crucial role in the secretion of various hormones that regulate growth, reproduction, and other physiological processes in the body. The primitive gut and primitive lung are not involved in the development of the anterior pituitary.
6.
On both sides of the gland, there are sinuses called the Cavernous Venous Sinuses. These sinuses contains nerves & internal carotid artery. Which nerves are located in these sinuses?
Correct Answer
B. Medially: Oculomotor (3), Abducent(6)
Laterally: Opthalmic & Maxillary (5)
7.
Which nerve will be compressed 1st when a pituitary gland enlarges?
Correct Answer
B. Oculomotor
Explanation
Oculomotor is located most medially
8.
In enlargement of a pituitary gland anterior superiorly, the optic nerves will be compressed (temporal half - side view). The patient will not be able to see the sides. What condition is this called?
Correct Answer
C. Bitemporal hemionopia
Explanation
In the enlargement of the pituitary gland anterior superiorly, the optic nerves will be compressed, specifically in the temporal half. This compression leads to a condition called bitemporal hemianopia. Bitemporal hemianopia refers to the loss of vision in the outer (temporal) half of the visual field of both eyes. This condition occurs because the compression affects the optic chiasm, the point where the optic nerves cross over. As a result, the patient will not be able to see the sides of their visual field.
9.
What are the parts of the anterior pituitary?
Correct Answer
A. Pars distalis(pars anterior), Pars tuberalis, Pars intermedia
Explanation
The anterior pituitary is composed of three main parts: Pars distalis (also known as pars anterior), Pars tuberalis, and Pars intermedia. These parts are responsible for producing and releasing various hormones that regulate different functions in the body. The Pars distalis is the largest and most functional part, producing hormones such as growth hormone, prolactin, and adrenocorticotropic hormone. The Pars tuberalis is located around the infundibulum of the pituitary gland and is involved in the regulation of reproductive hormones. The Pars intermedia is a small region between the Pars distalis and Pars nervosa, and it produces melanocyte-stimulating hormone.
10.
Which of the parts of the posterior pituitary is the connection to the hypothalamus?
Correct Answer
C. Infundibular stalk
Explanation
The infundibular stalk is the connection between the posterior pituitary and the hypothalamus. It serves as a pathway for the transmission of hormones produced by the hypothalamus, such as oxytocin and vasopressin, which are then released into the bloodstream from the posterior pituitary. The infundibular stalk also contains blood vessels that supply the posterior pituitary with nutrients and oxygen. Therefore, the infundibular stalk is the correct answer as it plays a crucial role in the communication and regulation between the hypothalamus and the posterior pituitary.
11.
The pars distalis/anterior consists of 2 types of cells:
Correct Answer
chromophils
chromophobes
Explanation
The pars distalis/anterior is a region of the pituitary gland that is composed of two types of cells: chromophils and chromophobes. Chromophils are hormone-secreting cells that can be further classified into acidophils and basophils based on the staining properties of their secretory granules. Acidophils secrete growth hormone and prolactin, while basophils secrete adrenocorticotropic hormone, thyroid-stimulating hormone, and follicle-stimulating hormone. On the other hand, chromophobes are non-secretory cells that appear pale and do not stain well. They are believed to be degranulated chromophils or precursor cells.
12.
Which are the secretory cells of the pars anterior?
Correct Answer
B. Chromophils
Explanation
The secretory cells of the pars anterior are known as chromophils. These cells are responsible for producing and releasing hormones into the bloodstream. They are named chromophils because they can be stained with certain dyes, which helps in their identification. Chromophils include different cell types such as acidophils and basophils, each producing different hormones. These secretory cells play a crucial role in regulating various physiological processes in the body.
13.
There are 2 different type of chromophils (of the pars anterior), the acidophils & basophils. What does the acidophils secrete?
Correct Answer
B. Growth hormones & prolactin
Explanation
The rest are secretions of the basophils. The hormones of the basophils are stimulating hormone, meaning they act on other endocrine organs to stimulate synthesis & secretion of the respective hormones)
14.
What does the pars intermedia (of the anterior pituitary) secrete?
Correct Answer
B. MSH
Explanation
The pars intermedia of the anterior pituitary secretes melanocyte-stimulating hormone (MSH). MSH plays a role in regulating skin pigmentation by stimulating the production and dispersion of melanin in melanocytes. It also has effects on appetite and sexual behavior.
15.
There are 2 types of nuclei in the posterior pituitary. The paraventricular nucleus and the supraoptic nuclue. Which on secretes oxytocin?
Correct Answer
A. Paraventricular
Explanation
Supraoptic secretes ADH
16.
Which are the hormones that are produced from amino acids?
Correct Answer
A. Thyroxine, serotonin
Explanation
Thyroxine and serotonin are hormones that are produced from amino acids. Thyroxine is produced from the amino acid tyrosine, while serotonin is produced from the amino acid tryptophan. These hormones play important roles in regulating various physiological processes in the body. Thyroxine is involved in regulating metabolism, growth, and development, while serotonin is involved in regulating mood, appetite, and sleep.
17.
Which are the hormones produced from lipid? (cholesterol/steroids)
Correct Answer
C. Cortisol & sex hormone
Explanation
Cortisol and sex hormones are produced from lipids, specifically cholesterol. Cholesterol is a precursor molecule for the synthesis of these hormones. Cortisol is a steroid hormone that regulates metabolism and has anti-inflammatory effects. Sex hormones, such as estrogen and testosterone, are also steroid hormones that play a crucial role in sexual development and reproduction. These hormones are synthesized from cholesterol in the adrenal glands and gonads.
18.
Why does steroid hormones (sex hormone & cortisol) & thyroid hormone require carrier proteins to be transported in blood?
Correct Answer
C. It is insoluble in water
Explanation
Steroid hormones, including sex hormones, cortisol, and thyroid hormone, are insoluble in water. This means that they cannot dissolve and be transported freely in the bloodstream. To overcome this issue, carrier proteins are required to bind to the hormones and transport them in the blood. These carrier proteins make the hormones soluble in water and allow them to be effectively transported to their target organs. Therefore, the requirement of carrier proteins is necessary for the transport of steroid hormones in the bloodstream.
19.
Which is responsible for the effects of the hormones to be seen?
Correct Answer
C. CAMP
Explanation
When the hormone binds to the receptor (ligand interaction), the receptor will undergo conformational changes (change shape), which activates G-protein in the cell (which can be stimulatory, Gs, or inhibitory, Gi). Assuming that it is stimulatory, it will cause phosphorylation of GDP to convert to GTP which will bind to the effector (enzyme adenylyl cyclase) coverting ATP to cAMP. cAMP will activate Protein Kinase A which inturn will lead to phosphorylation of intracellular mediators called second messengers (relay message from the hormone) producing intracellular effects.
20.
Which hormone receptors/2nd messengers are protein kinases (phosphorylates intracellular mediators to produce action)
Correct Answer
B. Receptor tyrosine kinase
Explanation
Receptor tyrosine kinases are a type of cell surface receptor that, when activated by binding to a specific ligand, have the ability to phosphorylate intracellular mediators. This phosphorylation event then triggers a cascade of signaling events within the cell, ultimately leading to a specific cellular response. Therefore, receptor tyrosine kinases act as protein kinases by phosphorylating intracellular mediators to produce action.
21.
Which of these hormones have a receptor that is a protein kinase?
Correct Answer
C. Insulin
Explanation
Tyrosine kinase is a protein kinase. The hormones that bind to this receptor are: Insulin, GH, PRL, Oxytocin, Erythropoietin, Growth factors
22.
Which hormone will be able to diffuse thru the cell membrane by simple diffusion?
Correct Answer
B. Steroid hormone
Explanation
Steroid hormones are able to diffuse through the cell membrane by simple diffusion. This is because steroid hormones are lipophilic, meaning they are soluble in lipids. The cell membrane is composed of a lipid bilayer, which allows lipophilic molecules like steroid hormones to pass through easily. In contrast, thyroid hormone and growth hormone are not lipophilic and therefore cannot diffuse through the cell membrane by simple diffusion.
23.
Which hormone has a positive feedback mechanism
Correct Answer(s)
A. Oxytocin
B. LH
Explanation
Oxytocin and LH both have a positive feedback mechanism. Oxytocin is released during childbirth, stimulating contractions which in turn release more oxytocin, leading to stronger contractions. LH is involved in the menstrual cycle, where it stimulates the release of an egg from the ovary. This increase in LH triggers the release of more LH, creating a positive feedback loop. FSH and ADH do not have a positive feedback mechanism.
24.
Growth hormone is controlled by a diurnal rhythm. When during the day GH is high in amount?
Correct Answer(s)
C. During 1st few hours of deep sleep
D. During strenous exercise
Explanation
During the first few hours of deep sleep, growth hormone (GH) is high in amount. This is because GH secretion is known to be highest during the early stages of deep sleep. Additionally, during strenuous exercise, GH levels also increase. Both deep sleep and strenuous exercise stimulate the release of GH, which plays a crucial role in growth and repair of tissues in the body.
25.
When during the day ACTH & Cortisol are high in amount?
Correct Answer
B. Last few hours before waking up
Explanation
During the last few hours before waking up, ACTH (adrenocorticotropic hormone) and cortisol levels are high. This is because the body naturally produces higher levels of these hormones in the early morning to help wake up and prepare for the day ahead. The increase in ACTH stimulates the release of cortisol from the adrenal glands, which helps regulate metabolism, blood pressure, and the body's response to stress.
26.
The endocrine system depends on hormone-receptor interaction by 2 types
of receptors: extracellular and intracellular. Extracellular will
require a cascade of 2nd messengers to relay it’s message inside the
cell, however intracellular directly binds to DNA to produce it’s
intended actions.Which hormone binds to intracellular receptors?
Correct Answer
B. Testosterone
Explanation
Steroid hormones, because they are lipid soluble and diffuse thru the cell membrane thru simple diffusion.
27.
Which nuclei of the hypothalamus stimulates the anterior pituitary?
Correct Answer
A. Parvocellular neuron (small neuron)
Explanation
Magnocellular neuron stimulates the posterior pituitary
28.
In which part of the brain does the parvocellular neurosecretory neurons (paraventricular, supraoptic & arcuate) project into, before releasing peptides into the blood vessels to stimulate the synthesis and secretion of hormone from the anterior pituitary?
Correct Answer
D. Median eminence
Explanation
The parvocellular neurosecretory neurons project into the median eminence before releasing peptides into the blood vessels. The median eminence is a part of the hypothalamus located at the base of the brain. It serves as a gateway for the release of hormones into the bloodstream. The peptides released by the parvocellular neurosecretory neurons stimulate the synthesis and secretion of hormones from the anterior pituitary gland.
29.
Tropic hormones are those that act on target endocrine gland to promote hormone secretion. Which of these is not a tropic hormone (act on exocrine gland)?
Correct Answer
E. Prolactin
Explanation
Prolactin is not a tropic hormone because it does not act on a target endocrine gland to promote hormone secretion. Instead, it acts on the mammary glands in the breasts to stimulate milk production. Tropic hormones, such as thyroid hormone, LH, GH, and FSH, target specific endocrine glands to regulate the secretion of hormones from those glands.
30.
All glycoprotein hormones (TSH, LH, FSH) consist of alpha & beta
subunits. However, the alpha subunit is also present in the a placental
glycoprotein hormone. Therefore
it’s action is similar to LH.Which of these is the placental hormone?
Correct Answer
C. Human chorionic gonadotrophin (hCG).
Explanation
The question states that the placental glycoprotein hormone has a similar action to LH, which suggests that the placental hormone is also involved in reproductive functions. Among the given options, human chorionic gonadotrophin (hCG) is the only hormone that fits this description. Progesterone and estrogen are not glycoprotein hormones, while LH and FSH are not placental hormones. Therefore, the correct answer is human chorionic gonadotrophin (hCG).
31.
The hormones of the posterior pituitary are synthesized as a larger precursor molecule in the cell bodies of the neurons of the hypothalamus. The precursor molecule of the vasopressin is:
Correct Answer
A. Prepropressophysin
Explanation
preprooxyphysin is the precursor molecule for oxytocin
32.
The ADH will increase water reabsorption at which part of the nephron?
Correct Answer
A. DCT & CD
Explanation
The correct answer is DCT & CD. ADH, or antidiuretic hormone, increases water reabsorption in the distal convoluted tubule (DCT) and collecting duct (CD) of the nephron. This hormone is released by the pituitary gland in response to low blood volume or high blood osmolality. By increasing water reabsorption in the DCT and CD, ADH helps to concentrate urine and conserve water in the body.
33.
Which receptor does ADH bind to to increase the water channels in the Collecting Duct (aquaporins)?
Correct Answer
B. V2 receptor
Explanation
ADH (antidiuretic hormone) binds to the V2 receptor to increase the water channels in the Collecting Duct (aquaporins). The V2 receptor is located on the basolateral membrane of the cells in the Collecting Duct. When ADH binds to the V2 receptor, it activates a signaling pathway that leads to the insertion of aquaporins into the apical membrane of the cells. This allows for increased reabsorption of water from the urine back into the bloodstream, leading to water conservation and concentrated urine production.
34.
Besides increasing water reabsorption in the distal nephron, what is the other function of ADH?
Correct Answer(s)
A. Inhibit renin release
C. Increase vasoconstriction
D. Stimulate ACTH secretion from anterior pituitary (synergy with CRH)
E. Glycogenolysis in liver (glycogen b/d)
Explanation
ADH, also known as antidiuretic hormone or vasopressin, has multiple functions in addition to increasing water reabsorption in the distal nephron. It inhibits renin release, which helps regulate blood pressure by reducing the production of angiotensin II. ADH also increases vasoconstriction, narrowing the blood vessels and further contributing to blood pressure regulation. Additionally, it stimulates ACTH secretion from the anterior pituitary gland, working in synergy with CRH (corticotropin-releasing hormone) to regulate the release of cortisol. Finally, ADH promotes glycogenolysis in the liver, breaking down glycogen into glucose and increasing blood sugar levels.
35.
What stimulates ADH secretion?
Correct Answer(s)
A. Mental/Physical stress
B. Nausea/Vomiting
D. Nicotine
Explanation
Increased plasma osmolality will stimulate release of ADH. Alcohol inhibits ADH secretion.
36.
What happens where there is excess in vasopressin?
Correct Answer
C. SIADH
Explanation
SIADH stands for Syndrome of Inappropriate Antidiuretic Hormone secretion. It occurs when there is an excess of vasopressin, also known as antidiuretic hormone (ADH), in the body. Vasopressin is responsible for regulating the body's water balance by controlling the amount of water reabsorbed by the kidneys. In SIADH, there is an abnormal increase in vasopressin production, leading to excessive water retention in the body. This can result in dilutional hyponatremia, where the concentration of sodium in the blood becomes abnormally low. Symptoms may include nausea, vomiting, headache, confusion, seizures, and even coma.
37.
What happens where there is deficiency in vasopressin?
Correct Answer
A. Diabetes insipidus
Explanation
When there is a deficiency in vasopressin, it leads to a condition called diabetes insipidus. Vasopressin, also known as antidiuretic hormone (ADH), is responsible for regulating the amount of water reabsorbed by the kidneys. In diabetes insipidus, the body is unable to properly regulate water balance, leading to excessive urination and thirst. This condition is different from diabetes mellitus, which is characterized by high blood sugar levels, and SIADH (syndrome of inappropriate antidiuretic hormone secretion), which involves excessive release of vasopressin. Dehydration can occur as a result of the excessive urination in diabetes insipidus.
38.
What is the complication of SIADH?
Correct Answer(s)
A. Oedema formation
C. Hypertension
Explanation
The complication of SIADH is oedema formation and hypertension. SIADH, or Syndrome of Inappropriate Antidiuretic Hormone secretion, is a condition where the body produces too much antidiuretic hormone, leading to water retention and dilutional hyponatremia. The excessive water retention can cause fluid to accumulate in the tissues, leading to oedema formation. Additionally, the increased fluid volume can also lead to increased blood pressure, resulting in hypertension.
39.
What are the actions of prolactin?
Correct Answer(s)
B. Milk synthesis
C. Milk secretion
Explanation
the rest are actions of oxytocin
40.
Which of the following are the actions of oxytocin?
Correct Answer(s)
A. Uterine contraction
B. Assistance in parturition
C. Milk ejection
D. Sperm transport (ejaculation)
Explanation
Oxytocin is a hormone that is produced in the hypothalamus and released by the pituitary gland. It has several actions in the body, including uterine contraction, which helps during labor and childbirth. It also assists in parturition, or the process of giving birth. Oxytocin is also responsible for milk ejection, or the release of breast milk from the mammary glands. Additionally, oxytocin plays a role in sperm transport during ejaculation.
41.
Besides the ant & post pituitary hormones is the intermediate lobe, which does release it’s own hormones as well. The hormone, pro-opiomelanocortin (POMC) in the intermediate lobe will be hydrolysed into different hormones.Which of the following are the hormones secreted from the intermediate lobe?
Correct Answer(s)
B. ACTH
C. MSH
Explanation
Therefore, ACTH have MSH activity as well (hyperpigmentation in excess, pallow in deficiency)
42.
In pituitary tumour, the pituitary stalk will be compressed. Which of the following is the side effect of the compressed pituitary stalk?
Correct Answer
C. Prolactinemia
Explanation
Prolactinemia is a side effect of a compressed pituitary stalk. The pituitary gland plays a crucial role in regulating hormone levels in the body, including the hormone prolactin. When the pituitary stalk is compressed, it can disrupt the normal functioning of the pituitary gland, leading to an increase in prolactin levels. This condition is known as prolactinemia. Prolactinemia can cause various symptoms such as irregular menstrual periods, breast milk production in non-pregnant women, and decreased libido in both men and women.
43.
The growth hormone is synthesized by the somatotropes. It is a single polypeptide with disulphide linkages. How many disulphide linkages does the GH have?
Correct Answer
B. 2
Explanation
The growth hormone (GH) is synthesized by the somatotropes and is a single polypeptide with disulphide linkages. The correct answer is 2.
44.
When GH binds to a cell surface receptor (receptor no.1), it will pull
another cell surface receptor (receptor no. 2) and binds with it,
causing dimerization of 2 GH receptors, forming a dimeric complex. The
GH-dimeric receptor complex associates with and activates the JAK-2
protein (a tyrosine kinase) causing phosphorylation of the receptor and
autophosphorylation of JAK-2 on tyrosine residues. This event will
activate a number of signal pathways:
Correct Answer(s)
A. State protein activation & gene transcription
B. MAP kinase pathway activation
D. PI 3 kinase pathway activation
E. PLC activation, production of diacylglycerol & protein kinase C activation
Explanation
When GH binds to the dimeric receptor complex, it activates the JAK-2 protein, which leads to phosphorylation of the receptor and autophosphorylation of JAK-2 on tyrosine residues. This activation event triggers the activation of multiple signal pathways. The MAP kinase pathway is activated, which regulates gene transcription and protein activation. The PI 3 kinase pathway is also activated, which plays a role in cell survival and growth. Additionally, the activation of PLC leads to the production of diacylglycerol and the activation of protein kinase C, which are involved in various cellular processes.
45.
Secretion of growth hormone is regulated & stimulated by:
Correct Answer(s)
A. Metabolic fuels
B. Stress
C. Sleep & exercise
E. High amino acid & fatty acid
Explanation
hyperglycemia inhibits growth hormone secretion
46.
The growth effect of the growth hormone is mediated by insulin-like growth factors
(IGF/Somatomedins –Mediate), which are a family of growth promoting proteins produced by liver cells. It is
produced when GH binds to it’s receptors. There are 4 IGFs. Which one of the following is the active IGF for growth?
Correct Answer
A. IGF-1
Explanation
The growth effect of the growth hormone is mediated by insulin-like growth factors (IGF/Somatomedins – Mediate), which are a family of growth promoting proteins produced by liver cells. IGF-1 is the active IGF for growth as it is produced when GH binds to its receptors.
47.
It is structurally similar to proinsulin (insulin-like). IGF is also
originally known as ‘sulfation factor’.Why was it known as a 'sulfation factor'?
Correct Answer
C. Incorporate suphate into cartilage
Explanation
IGF (Insulin-like Growth Factor) was known as a 'sulfation factor' because it incorporates sulphate into cartilage. This means that IGF plays a role in the process of adding sulphate molecules to cartilage, which is important for the growth and maintenance of cartilage tissue.
48.
Growth hormone effects are seen in:
Correct Answer(s)
A. Cartillage growth
B. Linear & width bone growth
C. Organ growth
D. Muscle growth
Explanation
Growth hormone affects various aspects of growth in the body. It promotes cartilage growth, which is essential for the development and maintenance of bones and joints. It also stimulates linear and width bone growth, contributing to overall skeletal growth and development. Additionally, growth hormone plays a role in organ growth, ensuring proper development and functioning of organs. Lastly, it stimulates muscle growth, aiding in the increase of muscle mass and strength.
49.
Besides growth effects, what are other effects of growth hormone ?
Correct Answer(s)
A. Protein synthesis
B. Increased glycogen synthesis in liver (for storage, from increased glucose), Increase hepatic glucose production (glyconeogenesis), Decrease tissue glucose uptake (more glucose in blood), Decreased rate of glycolysis (not used)
C. Promotes lipolysis, reduce TG snthesis, increase oxidation of free FA in liver when taken into tissue (form ketone bodies)
D. Stimulate production & release of IGFs in liver
E. Prolactin-like effect, stimulate mammary gland (lactogenesis)
Explanation
Protein synthesis: resembles actions of insulin
Carbohydrate metabolism: Oppose effect of insulin -> prolonged administration of GH will result in diabetes mellitus
Lipid metabolism: GH favours usage of FA as fuel. Therefore, glucose remains high/conserved.
Mineral metabolisme
Promotes positive Calcium, Magnesium & Phosphate balance.
Bone growth:
* Promotes growth of long bones at epiphyseal plates in growing children.
* Promotes appositional/ acral growth in adults.
Causes retention of Na+, K+ & Cl-
Prolactin-like effect
Due to it’s similar structure, it can bind to lactogenic receptors. Causes stimulation of mammary gland (lactogenesis).
50.
Hyposecretion of Growth hormone.Which type of condition corresponds to these findings?-Low GH-Low IFG-1-Responds to GH stimulation
Correct Answer
A. GH- deficient dwarfs
Explanation
GH-deficient dwarfs: Eventhough it responds to GH normally, but there is no GH. No GH, no IGF-1. Even in hypoglycemia, GH levels will fail to increase.
Pygmies: They lack IGF-1 eventhough there is normal GH. This is because IGF-1 is not produced when GH binds to GH receptor. Therefore, there is no growth. They have a post-GH receptor defect.
Laron type dwarfs: They have high amounts of GH, but it cannot bind to the GH receptor. They lack functional hepatic GH receptors.
Therefore, pygmies & Laron type dwarfs are due to target organ resistance.