7. endocrine system Flashcards

Question

heart as a secondary endocrine organ

Answer 1

The heart is mainly responsible for pumping blood throughout the body, but it also produces hormones involved in regulating cardiovascular and fluid balance: - Atrial Natriuretic Peptide (ANP): The heart produces ANP in response to increased blood volume and pressure. ANP helps lower blood pressure by promoting sodium excretion in the kidneys, leading to water loss and reduced blood volume.

Answer 2

The pineal gland regulates the sleep-wake cycle (circadian rhythm) by secreting melatonin, which is influenced by the amount of light exposure. Melatonin helps promote sleep.

Answer 3

The hypothalamus is a key regulator of the endocrine system. It controls the release of hormones from the pituitary gland through releasing and inhibiting hormones. It also produces oxytocin and vasopressin (ADH), which are stored in and released by the pituitary gland. Additionally, the hypothalamus helps maintain homeostasis by regulating body temperature, hunger, thirst, and the stress response.

Answer 4

The pituitary gland is often referred to as the "master gland" because it controls many other endocrine glands. It is divided into the anterior and posterior lobes: - Anterior pituitary: Secretes hormones that regulate growth, metabolism, and reproduction, including GH, TSH, ACTH, PRL, LH, and FSH. - Posterior pituitary: Stores and releases oxytocin (involved in labour, milk ejection, and social bonding) and vasopressin (ADH, which regulates water balance).

Answer 5

The thyroid gland regulates metabolism through the secretion of thyroid hormones (T3 and T4), which control the rate at which the body uses energy. It also helps in the regulation of growth and development. Calcitonin helps lower blood calcium levels by inhibiting osteoclasts in bones, thus promoting calcium deposition.

Answer 6

The parathyroid glands regulate calcium and phosphate balance in the body. PTH increases blood calcium levels by stimulating osteoclast activity in bones, increasing calcium absorption in the intestines (through vitamin D), and decreasing calcium excretion by the kidneys.

Answer 7

The thymus is primarily involved in the development and maturation of T lymphocytes (a type of white blood cell important for the immune system). The hormone thymosin supports the maturation of T cells, which are essential for adaptive immunity.

Answer 8

The adrenal glands are divided into the adrenal cortex and adrenal medulla: - Adrenal cortex: Secretes cortisol (which regulates stress responses, metabolism, and immune function) and aldosterone (which regulates sodium and water balance, impacting blood pressure). - Adrenal medulla: Produces adrenaline and norepinephrine, which are involved in the "fight or flight" response, increasing heart rate, blood flow to muscles, and blood glucose levels.

Answer 9

The pancreas plays a critical role in regulating blood sugar levels: - Insulin lowers blood glucose by promoting glucose uptake by cells and storage as glycogen. - Glucagon raises blood glucose by stimulating the liver to release glucose. - Somatostatin inhibits the release of insulin and glucagon, helping to regulate overall glucose homeostasis.

Answer 10

The ovaries produce estrogen and progesterone, which regulate the menstrual cycle, support pregnancy, and promote the development of female secondary sexual characteristics (e.g., breast development, widening hips).

Answer 11

The testes produce testosterone, which is essential for sperm production, sexual function, and the development of male secondary sexual characteristics (e.g., facial hair, deeper voice).

Answer 12

infundibulum

Answer 13

hypophysis

Answer 14

1cm 0.5-1g

Answer 15

sphenoid bone

Answer 16

anterior= adenohypophysis posterior= neurohypophysis

Answer 17

hypothalamus

Answer 18

The diencephalon is a region of the brain located between the brainstem and the cerebrum, and it includes several important structures: - Hypothalamus: Responsible for regulating many bodily functions like temperature, hunger, thirst, and hormone production. It plays a key role in controlling the endocrine system by connecting to the pituitary gland and regulating its release of hormones. - Thalamus: Acts as a relay station for sensory and motor signals, transmitting information to the appropriate areas of the cerebral cortex. - Epithalamus: Includes the pineal gland, which is involved in regulating circadian rhythms, and other structures that affect sleep-wake cycles. - Subthalamus: Involved in motor control, particularly in coordination of movements.

Answer 19

- overseas internal body conditions - receives nervous stimuli from receptors throughout body - monitors chemical and physical characteristics of blood - secretes hormones which regulate pituitary function

Answer 20

altered homeostasis -> hypothalamus makes hormones to stimulate pituitary -> affects hormones release from ant/post pituitary

Answer 21

connects hypothalamus & posterior pituitary

Answer 22

neurons - extend through the infundibulum [hypothalamo-hypophysial tract]

Answer 23

hypothalamus makes neurohormones - pass along neurons in tract (hypothalamo-hypophysial tract) - stored in posterior pituitary until needed - released from posterior pituitary when hypothalamus detects need

Answer 24

connects anterior pituitary to hypothalamus

Answer 25

via portal blood vessels - created direct communication

Answer 26

eventually portal blood merges again with general circulation

Answer 27

Tropic hormones are defined as those hormones that work on other endocrine glands. Most tropic hormones are produced by the anterior pituitary in the brain.

Answer 28

tropic hormones

Answer 29

secretory epithelial cells

Answer 30

clumps of secretory epithelial cells surrounded by vascular network

Answer 31

when glands signal to each other in sequence

Answer 32

hypothalamus pituitary thyroid axis top level: hypothalamus - produces 'releasing' hormones to stimulate pituitary intermediate level: pituitary - produces 'stimulating' hormones target gland: thyroid - produces the hormones *feeds back to hypothalamus

Answer 33

lateral to trachea inferior to thyroid cartilage

Answer 34

by isthmus

Answer 35

regulated by TRH (hypothalamus) and TSH (ant. pituitary)

Answer 36

dark red- highly vascularised

Answer 37

Negative feedback is a regulatory mechanism in which the levels of a hormone in the bloodstream are regulated by the hormone itself. When the level of a hormone in the bloodstream is too high, it triggers the release of a different hormone that decreases its production.

Answer 38

it is meant that some consequence of hormonal secretion acts on the secretory cells to provide an augmented drive for secretion. Rather than being self-limiting, as with negative feedback, the drive for secretion becomes progressively more intense. Very few endocrine hormones are regulated by positive feedback loops.

Answer 39

- The internal jugular vein is a major vein that drains blood from the brain, face, and neck. - It runs along the side of the neck and is located lateral (to the side) of the thyroid gland. - The internal jugular vein passes posterior (behind) and lateral to the thyroid gland. It runs in the carotid sheath, a connective tissue structure that also contains the common carotid artery and vagus nerve.

Answer 40

- The submandibular gland is one of the major salivary glands located beneath the lower jaw, near the angle of the mandible (lower jawbone). - It is superior (above) to the thyroid gland and situated anterior (in front of) the neck, below the jaw. - The submandibular gland is not directly related to the thyroid but lies in the same general region of the neck, separated by other structures, like the muscles and blood vessels. The submandibular duct (Wharton's duct) drains saliva into the mouth near the lower teeth, and this duct passes near the anterior aspect of the thyroid gland.

Answer 41

- The common carotid artery is a major artery that supplies blood to the head and neck. It divides into the internal carotid artery (supplying the brain) and the external carotid artery (supplying the face, jaw, and neck). - The common carotid artery runs medial (toward the center) to the thyroid gland and is located deep within the neck, lying within the carotid sheath along with the internal jugular vein and vagus nerve. - The thyroid gland receives blood supply from two main arteries: the superior thyroid artery (branch of the external carotid) and the inferior thyroid artery (branch of the subclavian artery), but the common carotid artery is anatomically important due to its proximity to these vessels.

Answer 42

many follicles (spheres of simple cuboidal epithelial cells) they produce triiodothyronine (T3) and thyroxine (T4) - stored in and released from follicles in response to TSH from pituitary - iodine needed for thyroid hormone synthesis; from diet (seafood, dairy, kelp) parafollicular/C cells produce calcitonin involved in calcium homeostasis

Answer 43

spheres of simple cuboidal epithelial cells

Answer 44

1. triiodothyronine (T3) 2. thyroxine (T4)

Answer 45

TSH from pituitary

Answer 46

iodine from diet (seafood, dairy, kelp)

Answer 47

parafollicular/ C cells

Answer 48

calcium homeostasis (produced by parafollicular/c cells in thyroid)

Answer 49

4 small glands on posterior of thyroid gland make up of: - parathyroid (chief) cells: small, stain darker, produce parathyroid hormone (PTH) - oxyphil cells: large, stain lighter, function unknown

Answer 50

parathyroid hormone (PTH) [parathyroid (chief) cells of parathyroid glands produce PTH; regulate blood calcium levels by producing and releasing parathyroid hormone (PTH)]

Answer 51

darker = parathyroid (chief) cells lighter = oxyphil cells

Answer 52

suprarenal glands

Answer 53

the medulla is the most internal part of the adrenal glands, while the cortex surrounds it and is responsible for producing steroid hormones, and the capsule is the outermost layer protecting the gland.

Answer 54

The right suprarenal gland is typically pyramid-shaped and is located slightly lower than the left adrenal gland, due to the position of the liver on the right side of the body. The left suprarenal gland is generally crescent-shaped and lies above the left kidney, adjacent to the aorta and the spleen.

Answer 55

The medulla is the innermost part of the adrenal gland. It is responsible for producing catecholamines, such as: - Epinephrine (adrenaline): Involved in the "fight or flight" response, increasing heart rate, blood pressure, and energy production. - Norepinephrine (noradrenaline): Works with epinephrine to enhance the body's response to stress and plays a role in regulating blood pressure. The medulla is controlled by the sympathetic nervous system and acts as part of the body’s response to stress, quickly releasing these hormones into the bloodstream in response to stressful situations.

Answer 56

The cortex is the middle layer of the adrenal gland and is responsible for producing a variety of steroid hormones, which are essential for numerous bodily functions. 1. Zona Glomerulosa (outermost layer): Produces mineralocorticoids, primarily aldosterone, which is involved in regulating sodium and potassium levels, and thus plays a role in blood pressure and fluid balance. 2. Zona Fasciculata (middle layer): Produces glucocorticoids, primarily cortisol, which is involved in metabolism, the stress response, immune function, and inflammation regulation. 3. Zona Reticularis (innermost layer of the cortex): Produces androgens (sex hormones, such as dehydroepiandrosterone, or DHEA), which are involved in the development of secondary sexual characteristics and sexual function.

Answer 57

increased cortisol production by adrenal - weight gain, excessive sweating, thin skin caused by: - pituitary tumour - artificially produced with immunosuppressive therapy

Answer 58

1. pituitary tumour 2. artificially produced with immunosuppressive therapy

Answer 59

behind peritoneum between greater curvature of stomach and duodenum (peritoneum= a membrane that lines the inside of your abdomen and pelvis (parietal layer). It also covers many of your organs inside (visceral layer).

Answer 60

15 cm long 85-100g

Answer 61

exocrine: acini produce pancreatic juice, carried in duct to small intestine endocrine: pancreatic islets secrete hormones into circulation - islets of langerhans - regulates nutrient concentration in circulation (insulin and amino acids)

Answer 62

The pancreatic acinar cell is the functional unit of the exocrine pancreas. It synthesizes, stores, and secretes digestive enzymes. Under normal physiological conditions, digestive enzymes are activated only once they have reached the duodenum.

Answer 63

~1 million (distributed along exocrine ducts)

Answer 64

alpha beta delta

Answer 65

produce insulin targets; liver, skeletal muscle, adipose tissue = increased uptake and use of glucose and amino acids

Answer 66

produce glucagon targets; liver = increased breakdown of glycogen, release of glucose into the circulatory system

Answer 67

somatostatin targets; alpha and beta cells = inhibition of insulin and glucagon secretion

Answer 68

delta cells of pancreas some produced in hypothalamus

Answer 69

1. direct membrane - membrane contact 2. (more commonly) by synthesis and release of messengers

Answer 70

1. small chemicals 2. peptides 3. antibodies 4. neurotransmitter 5. hormones

Answer 71

hormones [pass signals from endocrine glands to many other cells around the body]

Answer 72

1. peptide/protein 2. steroid (lipid-derived) 3. amino acid (or fatty acid derivatives)

Answer 73

- peptide hormones are lipophobic - they are water-soluble (hydrophylic) - peptide hormones bind to cell surface receptors - they are inactivated by gastric acid and peptidases *The cell membrane is primarily composed of a lipid bilayer, which is a barrier to water-soluble molecules

Answer 74

cell surface receptors

Answer 75

- gastric acid - peptidases

Answer 76

liver - insulin-like growth factor I pancreas - glucagon - insulin - somatostatin anterior pituitary - adrenocorticotropic hormone (ACTH) - follicle stimulating hormone (FSH) - luteinising hormone (LH) - growth hormone - thyroid-stimulating hormone - prolactin hypothalamus - growth hormone releasing hormone (GHRH) - gonadotropin releasing hormone (GnRH)

Answer 77

- derivatives of cholesterol - water-insoluble (hydrophobic) - transported by carrier proteins - typically lipid-soluble and can be administered via oral route

Answer 78

gonads - progesterone - testosterone adrenal cortex - cortisol - progesterone - aldosterone

Answer 79

- derived from amino acids tyrosine and tryptophan - thyroid hormones behave similarly to steroid hormones (binds to intracellular receptors) - catecholamines behave similarly to peptide hormones (bind to cell surface receptors)

Answer 80

1. tyrosine 2. tryptophan

Answer 81

pineal gland - melatonin neuroendocrine glands (CNS, GI tract) - serotonin adrenal medulla - epinephrine and norepinephrine thyroid gland - triiodothyronine and thyroxine

Answer 82

melatonin (pineal gland) serotonin (neuroendocrine glands; CNS+GI) [amine hormones]

Answer 83

triiodothyronine + thyroxine (thyroid gland) epinephrine + norepinephrine (adrenal medulla) [amine hormones]

Answer 84

cholesterol

Answer 85

1. synthesis of signalling molecule in signalling cell 2. release of signalling molecule by signalling cell 3. transport of signalling molecule to target cell 4. detection of signalling molecule by a specific receptor protein (or in) the target cell 5. change in target cell function triggered by receptor-signal complex 5. inactivation/removal of signalling molecule

Answer 86

1. endocrine 2. paracrine 3. autocrine 4. interaction of proteins expressed on cell surface

Answer 87

- Steroid hormones and thyroid hormones (a type of amine hormone) are lipid-soluble and can enter the target cell to bind to intracellular receptors, affecting gene expression. - Peptide hormones and catecholamines (another type of amine hormone) are water-soluble and must bind to cell surface receptors, triggering signal transduction within the cell. *The solubility of the hormone determines whether it can pass through the cell membrane (lipid-soluble) or must bind to surface receptors (water-soluble).

Answer 88

Direct signalling involves the communication between cells without the need for hormones or neurotransmitters to travel long distances. There are various ways that direct signalling can occur, including through gap junctions (in animal cells) and plasmodesmata (in plant cells). Both of these mechanisms allow for the transfer of molecules between adjacent cells, facilitating communication in a localised, efficient manner.

Answer 89

signalling molecule released by endocrine cell directly into bloodstream and carried to distant target cells (long range)

Answer 90

release of insulin by beta-cells in pancreas, travels in bloodstream and acts on liver, muscle and fat cells

Answer 91

signalling molecule released into extracellular fluid and affect target cells in close proximity to secreting cells (short range)

Answer 92

somatostatin release by pancreatic delta(δ)-cells acts locally; neurotransmission also considered to be a type of paracrine signalling

Answer 93

signalling molecules released into extracellular fluid and affect cells from which they were released; very short range

Answer 94

Juxtacrine signaling is a type of cell communication where signaling molecules, such as Wnt proteins, act locally on adjacent target cells without traveling long distances through diffusion

Answer 95

most neurotransmitters and many growth factors bind to receptors on the cells that release them

Answer 96

endocrine = long range paracrine = short range autocrine = very short range

Answer 97

proteins expressed on the surface of the signalling cell interact with 'receptor' proteins expressed on the surface of the target cell (direct contact)

Answer 98

signalling by T cells in the immune system

Answer 99

- most molecules that affect cell activity or function do not enter cells - they act on membrane-bound receptors and control cell function through 'signal transduction' mechanisms - these receptors often control the production of intracellular molecules that are responsible for 'converting' receptor activation into a change in cell activity - these intracellular molecules are known as 'second messengers'

Answer 100

second messengers

Answer 101

- also known as inotropic receptors - widely expressed on electrically excitable cells e.g. nerve, muscle, etc - binding of signalling molecule (ligand) leads to a conformational change in the receptor that results in opening of a central ion pore - resulting ion flux causes change in the membrane potential - ion flux is driven by the electrochemical gradient for the permeant ions

Answer 102

- many cell-surface receptors are coupled to trimeric signal-transducing G proteins that bind either GTP or GDP - trimeric= composed of three different subunits (α, β, γ) - ligand binding to a G protein-couples receptor activates the associated G protein which, in turn, activates/inhibits a downstream enzyme to generate an intracellular 'second messenger' - G protein activation and complex formation are part of a cycle

Answer 103

composed of three different subunits (α, β, γ)

Answer 104

to trimeric signal-transducing G proteins that bind either GTP or GDP

Answer 105

G proteins are specialized proteins with the ability to bind the nucleotides guanosine triphosphate (GTP) and guanosine diphosphate (GDP)

Answer 106

NH3+ = extracellular COO-= cytoplasmic side all G protein-couples receptors have 7 transmembrane spanning regions with their amino termini (NH3+) on the extracellular side and their carboxy termini (COO-) on the cytoplasmic side of the plasma membrane.

Answer 107

largely determines by which G protein it interacts with GPCRs couples to Gi, inhibit their targets (reduce enzyme activity) Gs, stimulate their targets (increase enzyme activity)

Answer 108

- large and diverse group of membrane receptors - primarily respond to protein mediators consist of - extracellular ligand-binding domain - single transmembrane helix - intracellular domain (often enzymatic) intracellular domain may have - protein kinase or guanylyl cyclase activity - no enzymatic activity but interacts with intracellular effector enzymes via adaptor proteins

Answer 109

- protein kinase or guanylyl cyclase activity - no enzymatic activity but interacts with intracellular effector enzymes via adaptor proteins

Answer 110

A kinase cascade is a series of protein kinases (enzymes that add phosphate groups to other proteins) that phosphorylate one another in a specific sequence. This cascade plays a crucial role in signal transduction, which is the process by which a cell responds to external signals. Kinase cascades amplify and propagate signals within the cell, and they are essential in controlling various cellular processes such as growth, differentiation, metabolism, and apoptosis.

Answer 111

- regulate gene transcription - known as nuclear receptors, through some are located in the cytosol - migrate to the nucleus upon ligand binding - can recognise foreign molecules - induce expression of enzymes that metabolise foreign substances - there are two main classes (I & II)

Answer 112

present in the cytoplasm, form homodimers in the presence of their ligand and migrate to the nucleus. their ligands are mainly endocrine in nature (e.g. steroid hormones)

Answer 113

generally constitutively present in the nucleus and form heterodimers with the RXR their ligands are usually lipids (e.g. fatty acids)

Answer 114

class I= mainly endocrine in nature (e.g. steroid hormones) class II= usually lipids (e.g. fatty acids)

Answer 115

homodimer = class I (in the presence of their ligand) heterodimer= class II (with the RXR)

Answer 116

liganded receptor complexes initiate changes in gene transcription by binding to HREs in gene promoters and recruiting co-activator or co-repressor factors

Answer 117

nuclear receptors the receptor family is the target of approximately 10% of prescription drugs, and the enzymes that it regulates affect the pharmacokinetics of some 60% of all prescription drugs

Answer 118

a single ligand binding to a receptor can trigger a cascade of intracellular events, leading to a massive response from just a small initial signal. efficiency: allows cells to respond strongly to low concentrations of signalling molecules speed: rapidly spreads the signal across the cell control and regulation: enables the fine-tined responses to environmental or physiological changes biological impact: essential for processes like hormone signalling, immune responses, and neurotransmission

Answer 119

People with Addison's disease may need to consume extra salt, particularly in hot weather or during times of stress (like illness or injury), because aldosterone helps the body retain sodium, and its deficiency can cause low blood pressure and dehydration.

Answer 120

1. proteins and polypeptides 2. steroids 3. thyroid hormones 4. catecholamines

Answer 121

1. thyroid hormones 2. catecholamines

Answer 122

- insulin - GH - TSH

Answer 123

Thyroid-stimulating hormone (TSH) is a pituitary hormone that stimulates the thyroid gland to produce and release thyroid hormones (T4 and T3), which regulate metabolism and other bodily functions

Answer 124

- cortisol - oestrogen

Answer 125

- thyroxine

Answer 126

- adrenaline

Answer 127

- steroids - thyroid hormones

Answer 128

- proteins and polypeptides - catecholamines

Answer 129

proteins and polypeptides: - anterior pituitary, posterior pituitary, pancreas, parathyroid steroids: - adrenal cortex, ovaries, testes, placenta thyroid hormones: - thyroid catecholamines: - adrenal medulla

Answer 130

synthesised in advance (often as prohormones that require further processing to be active)

Answer 131

synthesised on demand in a series of reaction pathways from cholesterol

Answer 132

synthesised from tyrosine (iodination)

Answer 133

synthesised from tyrosine (hydroxyl & amine groups only)

Answer 134

commonly stored in vesicles within the cell until the trigger to release

Answer 135

not stored prior to secretion; released upon synthesis

Answer 136

made in advance, stored as colloid in thyroid follicles

Answer 137

stored in secretory vesicles

Answer 138

proteins and polypeptides catecholamines

Answer 139

simple diffusion

Answer 140

transport protein

Answer 141

primarily dissolved in plasma

Answer 142

primarily bound to plasma proteins

Answer 143

primarily bound to plasma proteins

Answer 144

freely dissolved

Answer 145

steroids thyroid hormones

Answer 146

composed of amino acids size ranges from 3AA-> ~200AA

Answer 147

1. Transcription (Gene Activation The mRNA is transcribed from the gene encoding the hormone in the nucleus. 2. Translation The mRNA leaves the nucleus and travels to the rough endoplasmic reticulum (ER) Ribosomes on the rough ER translate the mRNA into a precursor hormone (preprohormone), 3. Modification in the Endoplasmic Reticulum (ER) The preprohormone undergoes initial modifications, such as the cleavage of the signal peptide to form the prohormone (an inactive precursor hormone). 4. Packaging in the Golgi Apparatus The prohormone is then transported to the Golgi apparatus, where it is further processed and packaged into secretory vesicles This vesicle contains the active hormone ready for secretion. 5. Storage The secretory vesicles store the active hormone until it is needed. This hormone remains inactive until the appropriate stimulus triggers its release. 6. secretion When an appropriate stimulus (e.g., a rise in calcium ions, Ca²⁺, or a signaling molecule like cAMP) triggers secretion, the secretory vesicle fuses with the cell membrane, releasing the active hormone into the bloodstream (or onto the target tissue).

Answer 148

Since peptide hormones are water-soluble, they cannot cross the lipid bilayer of the cell membrane. Instead, they act by binding to specific membrane-bound receptors on the surface of the target cells. - The peptide hormone (e.g., glucagon or prolactin) binds to a specific receptor on the cell membrane of the target cell. - The receptor activates a G-protein complex located inside the cell membrane. The G-protein undergoes a conformational change, and the alpha subunit of the G-protein exchanges GDP for GTP, becoming active. - The active G-protein complex activates adenylate cyclase, an enzyme on the inner membrane of the cell. - Adenylate cyclase catalyzes the conversion of ATP to cAMP (cyclic adenosine monophosphate).; cAMP is a second messenger that activates further downstream signaling pathways inside the cell. - cAMP activates protein kinase A (PKA), which in turn activates or inhibits various enzymes and proteins within the cell. - The activation of protein kinases leads to a cellular response, such as changes in metabolism, gene expression, or ion transport. In the case of glucagon, this might lead to the activation of glucose release from the liver into the bloodstream.

Answer 149

the alpha subunit of the G-protein exchanges GDP for GTP, becoming active.

Answer 150

- The active G-protein complex activates adenylate cyclase, an enzyme on the inner membrane of the cell. - Adenylate cyclase catalyzes the conversion of ATP to cAMP (cyclic adenosine monophosphate).

Answer 151

- cAMP is a second messenger that activates further downstream signaling pathways inside the cell. - cAMP activates protein kinase A (PKA), which in turn activates or inhibits various enzymes and proteins within the cell.

Answer 152

Steroid hormones are lipid-soluble, derived from cholesterol, and are synthesized primarily in the adrenal cortex, gonads (testes and ovaries), and placenta. These hormones include glucocorticoids (e.g., cortisol), mineralocorticoids (e.g., aldosterone), sex hormones (e.g., estrogen, testosterone), and progesterone.

Answer 153

The rate-limiting step in steroid hormone synthesis is the transport of cholesterol into the mitochondria. This step is regulated by the enzyme steroidogenic acute regulatory (StAR) protein.

Answer 154

1. Cholesterol as a Precursor: - The synthesis of steroid hormones begins with cholesterol, which can be obtained from the bloodstream or synthesized de novo in cells 2. Movement of Cholesterol: - The rate-limiting step in steroid hormone synthesis is the transport of cholesterol into the mitochondria. This step is regulated by the enzyme steroidogenic acute regulatory (StAR) protein. 3. Conversion to Pregnenolone: - Once inside the mitochondria, cholesterol is converted into pregnenolone, the precursor to all steroid hormones. 4. Further Modification: - Pregnenolone is then converted into different classes of steroid hormones (e.g., cortisol, aldosterone, estrogen, testosterone) through a series of enzymatic steps that vary depending on the specific hormone being synthesized. 5. Binding and Transport: - Once synthesized, steroid hormones are lipid-soluble and can pass through cell membranes. In the bloodstream, they are often bound to carrier proteins (e.g., albumin or sex hormone-binding globulin), which help transport them to target tissues. - Because of their lipid solubility, they can easily diffuse through the cell membrane of their target cells and bind to intracellular receptors in the cytoplasm or nucleus, where they can regulate gene expression and cellular activity.

Answer 155

- cell surface receptor - activate second messenger system - modification of existing proteins

Answer 156

- intracellular receptors; cytoplasm/nucleus - promote/supress gene transcription - synthesis of new proteins

Answer 157

- intracellular receptors; nucleus - promote/ supress gene transcription - synthesis of new proteins

Answer 158

- cell surface receptors - activate second messenger system - modification of existing proteins

Answer 159

Negative feedback aims to bring a variable back to a set point, while positive feedback amplifies the response, often to produce an event (e.g., childbirth).

Answer 160

Blood glucose is regulated by negative feedback. When blood glucose is high, insulin is secreted by the pancreas to lower glucose levels. When blood glucose returns to normal, insulin secretion slows down.

Answer 161

In childbirth, uterine contractions stimulate the cervix to stretch, sending signals to the brain to release oxytocin. Oxytocin increases uterine contractions, which further stretch the cervix, continuing the cycle until the baby is delivered.

Answer 162

Feed-forward control is an anticipatory response where the body prepares for an event before it fully occurs. An example is the morning cortisol surge, where the body releases cortisol in anticipation of the waking state to meet the increased energy demands.

Answer 163

The body responds to changes in plasma volume and osmolarity, which indirectly indicate changes in fluid and electrolyte balance.

Answer 164

Water movement occurs passively by diffusion, and aquaporin channels facilitate water transport across membranes, allowing for rapid adjustment in response to osmotic gradients.

Answer 165

Sodium is the principal extracellular cation. Its regulation is crucial for maintaining fluid balance and proper cellular function.

Answer 166

The hypothalamus contains osmoreceptors that detect changes in blood osmolarity and regulates the release of ADH to control water balance in the body.

Answer 167

ADH promotes water reabsorption in the kidneys, which helps to conserve water and maintain blood volume and osmolarity.

Answer 168

Aldosterone promotes sodium reabsorption in the kidneys, which leads to water reabsorption, helping to regulate blood volume and pressure.

Answer 169

The kidneys respond to ADH by reabsorbing water and to aldosterone by reabsorbing sodium and water, which helps regulate fluid volume and osmolarity.

Answer 170

The RAAS system is activated in response to low blood pressure or low sodium levels. It leads to the release of aldosterone, which promotes sodium and water reabsorption in the kidneys, helping to increase blood volume and pressure.

Answer 171

The purpose of negative feedback is to maintain homeostasis by counteracting changes in a variable (e.g., blood glucose, calcium, osmolarity), ensuring it returns to its normal set point.

Answer 172

When blood glucose levels rise, the pancreas secretes insulin. Insulin promotes the uptake of glucose by cells, which lowers blood glucose levels back to normal, thereby decreasing the secretion of insulin once normal levels are restored.

Answer 173

When blood calcium levels are low, PTH is released by the parathyroid glands. PTH increases calcium reabsorption from the kidneys, bone resorption, and calcium absorption in the intestines, restoring calcium levels back to normal. When calcium levels return to normal, PTH secretion decreases.

Answer 174

The hypothalamus detects changes in blood osmolarity through osmoreceptors. When osmolarity is high (e.g., dehydration), it stimulates the release of ADH from the posterior pituitary to promote water reabsorption in the kidneys, lowering osmolarity back to normal levels, which in turn reduces ADH secretion.

Answer 175

When blood glucose levels are low, glucagon is released by the pancreas to stimulate the liver to release stored glucose (glycogenolysis) into the bloodstream. Once glucose levels rise, glucagon secretion stops, maintaining a stable glucose level.

Answer 176

Positive feedback amplifies a response, whereas negative feedback counteracts changes to return a variable to its set point. Positive feedback usually leads to an event, like childbirth or ovulation, while negative feedback maintains homeostasis.

Answer 177

During labor, uterine contractions stimulate the cervix, which sends signals to the brain to release oxytocin. Oxytocin stimulates stronger uterine contractions, which further stretch the cervix, continuing the loop until the baby is delivered.

Answer 178

As estrogen levels rise during the menstrual cycle, they stimulate the release of luteinizing hormone (LH) from the anterior pituitary. The surge in LH triggers ovulation, and the increased estrogen levels feed back to further increase LH release, leading to the ovulation event.

Answer 179

When a blood vessel is injured, clotting factors are activated, which amplify the response and promote the activation of more clotting factors. This positive feedback loop continues until a blood clot forms and the bleeding is stopped.

Answer 180

The stretching of the cervix during labor activates stretch-sensitive nerve receptors, which signal the brain to release oxytocin. Oxytocin enhances uterine contractions, which in turn increases cervix dilation, causing more oxytocin to be released, creating a loop that amplifies the contractions until delivery.

Answer 181

Feed-forward control is an anticipatory mechanism where the body prepares for a change before it occurs. It allows the body to respond to stimuli in advance of the event, rather than waiting for feedback signals.

Answer 182

The suprachiasmatic nucleus (SCN) in the hypothalamus acts as the body’s internal clock and prepares for the waking state. Before waking, the SCN signals the hypothalamus to release corticotropin-releasing hormone (CRH), which leads to the secretion of adrenocorticotropic hormone (ACTH) and subsequently cortisol, preparing the body for the energy demands of the day.

Answer 183

Feed-forward control allows the body to prepare for stress before it happens. For example, the anticipation of a stressful event can increase cortisol levels ahead of time, ensuring that the body has enough energy to cope with the stressor.

Answer 184

Before exercise, the brain anticipates the increase in demand for oxygen and energy, signaling the release of adrenaline (epinephrine) from the adrenal glands. This prepares the cardiovascular system by increasing heart rate and blood flow, helping the body respond efficiently when exercise begins.

Answer 185

The light-dark cycle influences the suprachiasmatic nucleus (SCN), the body's internal clock. As dawn approaches, the SCN signals the hypothalamus to release CRH, anticipating the increased energy demands of waking and the active state, thereby initiating the release of cortisol in advance.

Answer 186

Negative feedback is more common because it helps maintain stability and homeostasis, preventing excessive or uncontrollable hormonal responses. Positive feedback is used in situations where a rapid and amplified response is needed, such as childbirth or blood clotting.

Answer 187

Multiple feedback loops, both negative and positive, can operate simultaneously within the body to finely adjust hormone levels and physiological processes. This allows for precise regulation of variables such as temperature, blood pressure, and metabolic function

Answer 188

Increased blood osmolarity.

Answer 189

the concentration of dissolved particles, like electrolytes and other chemicals, in the fluid part of your blood, essentially a measure of how concentrated or dilute your blood is

Answer 190

Osmolarity refers to the number of osmoles of solute per liter of solution (Osm/L), while osmolality refers to the number of osmoles of solute per kilogram of solvent (Osm/kg)

Answer 191

It contains osmoreceptors that sense blood osmolarity and regulate the release of ADH.

Answer 192

Aldosterone promotes sodium and water reabsorption in the kidneys in response to signals from the RAAS.

Answer 193

ADH increases membrane permeability to water in the collecting ducts, leading to increased water reabsorption.

Answer 194

They induce natriuresis (sodium excretion) and diuresis (water excretion) by the kidneys.

Answer 195

Osmoreceptors detect increases in plasma osmolality and trigger the sensation of thirst through the hypothalamic thirst center.

Answer 196

Decreased osmolality is detected by osmoreceptors, which suppress further ADH release, contributing to homeostasis.

Answer 197

ADH binds to V2 receptors in the basolateral membrane of collecting tubule cells, activating a cascade that increases water permeability in the collecting duct.

Answer 198

A decrease in blood osmolality suppresses further ADH secretion, maintaining balance in blood volume and osmolarity.

Answer 199

An increase in plasma osmolality stimulates the hypothalamus, leading to the sensation of thirst and the intake of fluids to decrease osmolality

Answer 200

The body lacks dedicated receptors for fluid and electrolyte monitoring, so it regulates fluid balance by responding to changes in plasma volume and osmotic concentration.

Answer 201

Water movement is passive, responding to osmotic gradients through either diffusion or through aquaporin channels.

Answer 202

Changes in dietary intake (fluid and electrolytes) and environmental losses (e.g., sweat, urination) affect the fluid and electrolyte balance.

Answer 203

When dietary gains exceed environmental losses, the body increases fluid and electrolyte content.

Answer 204

The hypothalamus, pituitary gland, kidneys, and adrenal glands are key organs involved in sodium and water balance.

Answer 205

The hypothalamus contains osmoreceptors that sense changes in blood osmolarity and regulates the release of ADH in response to these changes.

Answer 206

The posterior pituitary gland releases ADH in response to signals from the hypothalamus, promoting water reabsorption in the kidneys.

Answer 207

The kidneys regulate excretion or reabsorption of sodium and water based on hormonal signals, responding to ADH for water reabsorption and aldosterone for sodium and water reabsorption.

Answer 208

Aldosterone is secreted by the adrenal glands in response to signals from the RAAS, promoting sodium and water reabsorption in the kidneys.

Answer 209

The hypothalamus senses changes in blood osmolarity and stimulates the thirst mechanism, encouraging fluid intake to restore fluid balance.

Answer 210

ADH, aldosterone, and natriuretic peptides (e.g., ANP) are released in response to physiological changes to regulate water and sodium balance.

Answer 211

The primary stimulus for ADH release is an increase in blood osmolarity (more solutes in the blood).

Answer 212

ADH increases water reabsorption in the kidneys by making the collecting ducts more permeable to water.

Answer 213

When ADH binds to its receptors, aquaporins are inserted into the apical membrane of the collecting duct cells, allowing more water to be reabsorbed into the blood by osmosis.

Answer 214

The increased water reabsorption due to ADH leads to decreased urine production, a process called antidiuresis.

Answer 215

ADH V2 receptors are located on the basolateral membrane of collecting duct cells in the kidneys. When activated, they trigger a signaling cascade that increases aquaporin insertion into the apical membrane.

Answer 216

When ADH binds to V2 receptors, it catalyzes the formation of cAMP, which activates protein kinase A (PKA), leading to the insertion of aquaporins into the membrane.

Answer 217

The functional outcome is the increased permeability of the collecting duct to water, enabling water reabsorption into the blood.

Answer 218

When blood osmolality decreases, osmoreceptors detect the change and suppress ADH secretion, contributing to homeostasis.

Answer 219

Aquaporins inserted into the apical membrane are constantly recycled. When ADH levels decrease, aquaporin endocytosis increases, reducing water reabsorption.

Answer 220

A decrease in blood osmolality suppresses ADH secretion, which reduces water retention and restores homeostasis.

Answer 221

Thirst is stimulated when there is an increase in plasma osmolality or a decrease in plasma volume, leading to fluid intake to restore the balance.

Answer 222

The sensation of thirst leads to fluid ingestion, which dilutes the blood, reducing plasma osmolality back to normal levels.

Answer 223

A decrease in plasma volume (10-15%) is detected by the body, stimulating RAAS and the production of angiotensin II, which enhances thirst sensation.

Answer 224

An increase in plasma osmolality stimulates the hypothalamus to trigger thirst, leading to increased fluid intake to restore balance.

Answer 225

Natriuretic Peptides are released by the heart (atria) in response to increased atrial stretch. They promote sodium excretion (natriuresis) and water excretion (diuresis) by the kidneys.

Answer 226

Aldosterone, in response to RAAS signals, promotes sodium and water reabsorption in the kidneys, helping to increase blood volume and maintain fluid balance.

Answer 227

Fluid and electrolyte regulation helps maintain the volume and osmolarity of body fluids by responding to changes in plasma volume, blood osmolarity, and electrolytes.

Answer 228

The body adjusts sodium and water balance through the action of hormones (ADH, aldosterone), the thirst mechanism, and feedback loops that monitor blood osmolality and volume.

Answer 229

Increased blood osmolarity (more solutes) stimulates the release of ADH, which promotes water reabsorption in the kidneys, while decreased blood osmolarity suppresses ADH secretion.

Answer 230

ADH (Antidiuretic Hormone) helps regulate water balance by promoting water reabsorption in the kidneys. It is secreted more at night to reduce urine production, contributing to less urine output during sleep.

Answer 231

Increased ADH secretion at night reduces urine production by enhancing water reabsorption in the kidneys, particularly in the collecting ducts. This leads to more concentrated urine being excreted.

Answer 232

Nocturnal enuresis, or bedwetting, is the involuntary release of urine during sleep. Disruption or delay in the natural increase in ADH secretion during the night can result in insufficient water reabsorption in the kidneys, leading to increased urine production at night.

Answer 233

Desmopressin is a synthetic form of ADH used to treat nocturnal enuresis by mimicking the effects of ADH, increasing water reabsorption in the kidneys, and reducing urine production at night.

Answer 234

In older adults, the normal diurnal rhythm of ADH secretion may be lost or diminished, which can lead to increased urine production at night (nocturia).

Answer 235

Females may have kidneys that are more sensitive to the effects of ADH, which could influence urinary patterns such as more frequent urination or better regulation of water balance.

Answer 236

Aldosterone regulates sodium reabsorption and excretion in the kidneys.

Answer 237

Aldosterone is synthesized in the zona glomerulosa of the adrenal cortex and acts to increase sodium reabsorption and potassium secretion in the distal convoluted tubule and collecting duct of the kidneys.

Answer 238

Aldosterone secretion is primarily stimulated by decreased blood pressure or blood volume. The renin-angiotensin system is activated, leading to the production of angiotensin II, which stimulates aldosterone secretion.

Answer 239

Decreased blood pressure triggers a decrease in blood flow to juxtaglomerular cells, stimulating the release of renin. Renin converts angiotensinogen to angiotensin I, which is converted to angiotensin II by ACE. Angiotensin II stimulates aldosterone secretion, leading to increased sodium and water reabsorption.

Answer 240

Aldosterone binds to the mineralocorticoid receptor (MR) in the cytoplasm of renal tubular cells. This forms a complex that translocates to the nucleus and initiates transcription for the production of sodium and potassium channels and pumps.

Answer 241

ENaC (Epithelial Sodium Channels) are located on the apical membrane of renal tubular cells. They facilitate sodium reabsorption from the filtrate into the cells, increasing sodium retention in the body.

Answer 242

The Na+/K+ ATPase pump located on the basolateral membrane of renal tubular cells exchanges sodium for potassium, transferring sodium into the bloodstream and potassium into the renal tubule for excretion.

Answer 243

In the DCT, aldosterone promotes sodium reabsorption, which increases blood osmolarity. This elevation in osmolarity stimulates the release of ADH, leading to increased water reabsorption in the collecting ducts.

Answer 244

By increasing sodium reabsorption in the distal convoluted tubule (DCT), aldosterone raises blood osmolarity. This triggers the release of ADH, which promotes water retention, further increasing blood volume.

Answer 245

ADH is released in response to increased blood osmolarity (e.g., dehydration). It increases the permeability of the renal collecting ducts to water, promoting water reabsorption and reducing osmolarity.

Answer 246

ADH increases the permeability of the collecting ducts to water by inserting aquaporins into the luminal membrane. This allows more water to be reabsorbed into the bloodstream.

Answer 247

The combined action of aldosterone and ADH increases sodium and water reabsorption in the kidneys, contributing to an increase in blood volume, extracellular fluid volume, and blood pressure.

Answer 248

Thirst is stimulated by ADH and elevated blood osmolarity, prompting individuals to drink more fluids, which helps restore normal fluid balance and blood osmolarity.

Answer 249

The feedback loop involves aldosterone stimulating sodium reabsorption, which increases blood osmolarity and triggers ADH secretion. ADH enhances water reabsorption, increasing blood volume and blood pressure. Thirst further increases fluid intake, completing the loop.

Answer 250

ADH and aldosterone work together to regulate fluid and sodium balance. ADH promotes water reabsorption when osmolarity is high, while aldosterone increases sodium retention when blood pressure or volume is low, contributing to increased blood volume and osmolarity.

Answer 251

ANP is released by the heart in response to increased blood volume or pressure. It promotes sodium and water excretion in the kidneys, counteracting the effects of ADH and aldosterone, which promote retention.

Answer 252

Angiotensin II stimulates thirst to increase fluid intake and causes vasoconstriction, both of which help raise blood pressure. It also promotes aldosterone secretion to enhance sodium and water retention.

Answer 253

Angiotensin II directly stimulates the thirst center in the brain, leading to increased fluid intake. It also induces vasoconstriction, which raises blood pressure by increasing vascular resistance.

Answer 254

The combined actions of aldosterone (promoting sodium and water retention), ADH (promoting water retention and lowering osmolarity), and ANP (promoting sodium and water excretion) work together to maintain blood pressure, blood volume, and fluid balance, ensuring overall homeostasis.

Answer 255

Zona glomerulosa

Answer 256

Zona reticularis

Answer 257

Cholesterol

Answer 258

Corticosteroid-binding globulin (CBG)

Answer 259

Cytoplasmic glucocorticoid receptor

Answer 260

↑ Gluconeogenesis, ↑ Lipolysis, ↑ Proteolysis

Answer 261

Increases bone resorption

Answer 262

It suppresses it (anti-inflammatory)

Answer 263

CRH → ACTH → Cortisol

Answer 264

Long-term steroids suppress ACTH → adrenal atrophy → poor cortisol response in stress

Answer 265

They didn’t control for time of day; cortisol has a circadian rhythm.

Answer 266

Thyroglobulin with attached T3 and T4

Answer 267

Parafollicular (C) cells

Answer 268

Sodium-iodide symporter

Answer 269

It is oxidised and attached to tyrosine residues on thyroglobulin

Answer 270

Bound to TBG, transthyretin, or albumin

Answer 271

↑ BMR, ↑ CNS maturation, ↑ Heart rate/CO

Answer 272

By upregulating Na⁺/K⁺ ATPase, glucose use, lipolysis

Answer 273

Levothyroxine

Answer 274

By 3 weeks of age

Answer 275

1. Zona glomerulosa → Aldosterone 2. Zona fasciculata → Cortisol 3. Zona reticularis → Androgens (DHEA, androstenedione)

Answer 276

Zona fasciculata

Answer 277

Zona reticularis

Answer 278

Zona glomerulosa

Answer 279

Angiotensin II and potassium (K⁺)

Answer 280

ACTH (Adrenocorticotropic hormone)

Answer 281

Cholesterol

Answer 282

Cholesterol → Pregnenolone → Progesterone → DOC → Corticosterone → 18(OH) corticosterone → Aldosterone

Answer 283

Androstenedione

Answer 284

Corticosteroid-binding globulin (CBG)

Answer 285

Translocates to the nucleus and regulates gene transcription

Answer 286

By stimulating gluconeogenesis in the liver

Answer 287

Increases proteolysis and decreases glucose transport via GLUT4 internalisation

Answer 288

Increases lipolysis and free fatty acid release, reduces glucose uptake and leptin action

Answer 289

Increases gluconeogenesis, glycogen storage, and enhances glucagon/adrenaline response

Answer 290

Decreases insulin secretion

Answer 291

Increases bone resorption

Answer 292

Increases sodium reabsorption and potassium secretion

Answer 293

Regulates stress reactivity, sleep-wake cycle, appetite, and memory

Answer 294

Anti-inflammatory and immunosuppressive

Answer 295

CRH (hypothalamus) → ACTH (pituitary) → Cortisol (adrenal cortex)

Answer 296

Stress (emotional, physical, inflammatory), circadian rhythm, infection, metabolic stress

Answer 297

It inhibits CRH and ACTH release

Answer 298

Constant external cortisol causes suppression of ACTH → adrenal atrophy → no reserve capacity

Answer 299

Severe illness or adrenal crisis due to lack of endogenous cortisol

Answer 300

Hormone replacement (e.g. Addison’s), anti-inflammatory, immunosuppressant

Answer 301

Asthma, eczema, rheumatoid arthritis, IBD, organ transplant rejection

Answer 302

Colloid, primarily composed of thyroglobulin

Answer 303

Cuboidal follicular cells

Answer 304

Calcitonin

Answer 305

~70 tyrosine residues used for thyroid hormone synthesis

Answer 306

In the ER and Golgi of follicular cells

Answer 307

150 micrograms

Answer 308

It is oxidised and incorporated into thyroglobulin to form MIT and DIT

Answer 309

Via monocarboxylate transporters (MCTs)

Answer 310

Thyroid-binding globulin (TBG), transthyretin (TTR), albumin

Answer 311

Converted to T3 inside cells

Answer 312

Nuclear receptors

Answer 313

Initiation of gene transcription

Answer 314

Growth, CNS development, metabolism, BMR, cardiovascular

Answer 315

↑ Na⁺/K⁺ ATPase, ↑ O₂ consumption, ↑ heat production

Answer 316

↑ Glucose absorption, ↑ gluconeogenesis, ↑ glycogenolysis

Answer 317

↑ Heart rate, ↑ cardiac output via β1 receptor upregulation

Answer 318

Crucial for maturation of the central nervous system

Answer 319

Net catabolic

Answer 320

TRH (hypothalamus) → TSH (pituitary) → T3/T4 (thyroid gland)

Answer 321

Negative feedback from circulating T3 and T4

Answer 322

Iodine uptake, thyroglobulin production, T3/T4 release

Answer 323

Often an absent or underdeveloped thyroid gland

Answer 324

1 in 4,000 births

Answer 325

Heel-prick blood spot test on day 5

Answer 326

High TSH (due to lack of T3/T4 negative feedback)

Answer 327

Short stature, cognitive delay, delayed puberty, thickened skin, enlarged tongue, low muscle tone

Answer 328

Levothyroxine

Answer 329

It is converted to T3 in the body

Answer 330

TRH, CRH, dopamine

Answer 331

Adrenaline and noradrenaline

Answer 332

Autoantibodies stimulating the TSH receptor

Answer 333

Lethargy, bradycardia

Answer 334

Levothyroxine

Answer 335

Autoimmune destruction of pancreatic β-cells

Answer 336

It's degraded in the GI tract

Answer 337

SGLT2 inhibitors (e.g. dapagliflozin)

Answer 338

Block ATP-sensitive K+ channels, causing insulin release

Answer 339

They slow gastric emptying and promote satiety

Answer 340

Primary adrenal insufficiency

Answer 341

Hydrocortisone + fludrocortisone ± DHEA

Answer 342

Excess cortisol (from tumour or steroid use)

Answer 343

Ketoconazole

Answer 344

Suppress GnRH, FSH, LH; prevent ovulation

Answer 345

Progesterone

Answer 346

To secrete hormones that regulate physiological processes such as metabolism, growth, reproduction, and mood.

Answer 347

Pineal gland

Answer 348

Oxytocin and vasopressin

Answer 349

Insulin, glucagon, somatostatin

Answer 350

Erythropoietin

Answer 351

Calcium levels in the blood

Answer 352

Thymopoietin

Answer 353

Diffuse toxic goitre (Graves’ disease) and toxic nodular goitre

Answer 354

They inhibit thyroperoxidase, reducing iodination of thyroglobulin.

Answer 355

It is taken up by the thyroid and emits beta radiation that destroys follicular cells.

Answer 356

Treatment of myxoedema coma (severe hypothyroidism)

Answer 357

Autoimmune destruction of pancreatic β-cells

Answer 358

It is a peptide and is degraded in the GI tract if taken orally.

Answer 359

Rapid, short, intermediate, long-acting

Answer 360

To mimic physiological basal and postprandial insulin secretion.

Answer 361

Using recombinant DNA technology in E. coli

Answer 362

↓ hepatic gluconeogenesis, ↑ glucose uptake into muscle, ↓ GI absorption of carbs

Answer 363

AMP-activated protein kinase (AMPK)

Answer 364

Insulin sensitisers; activate PPAR-γ to alter gene expression and improve insulin sensitivity

Answer 365

Pioglitazone, rosiglitazone

Answer 366

Insulin secretagogues

Answer 367

ATP-sensitive K⁺ channels (K_ATP)

Answer 368

Depolarisation → Ca²⁺ influx → insulin secretion

Answer 369

GI hormones that stimulate insulin release; GLP-1 and GIP

Answer 370

Inhibit glucagon, delay gastric emptying, reduce appetite

Answer 371

DPP-4 inhibitors (e.g., sitagliptin); prevent breakdown of GLP-1 and GIP

Answer 372

Subcutaneous injection (due to peptide degradation in GI tract)

Answer 373

Exenatide, liraglutide, semaglutide

Answer 374

Longer duration, weekly dosing, more effective for weight loss

Answer 375

Sodium-glucose co-transporter 2 in the proximal tubule of the nephron

Answer 376

Dapagliflozin, empagliflozin

Answer 377

They may be helpful in heart failure

Answer 378

Primary adrenal insufficiency (↓ cortisol and aldosterone)

Answer 379

Cortisol (hydrocortisone), aldosterone (fludrocortisone), and androgens (DHEA)

Answer 380

Excess cortisol production (endogenous or exogenous)

Answer 381

Ketoconazole (↓ cortisol production), mifepristone (blocks cortisol effects)

Answer 382

Long-term corticosteroid use for inflammatory or autoimmune diseases

Answer 383

Estrogen and progestogen

Answer 384

Progestogen only

Answer 385

Suppress GnRH, FSH, and LH → inhibit ovulation, thicken cervical mucus, reduce implantation

Answer 386

They influence hormone regulation despite not treating a disorder

Answer 387

Hormone replacement therapy

Answer 388

Surgery, radiation, or drugs to block hormone production/action

Answer 389

T1D = insulin deficiency; T2D = insulin resistance ± deficiency

Answer 390

Insulin sensitisers, insulin secretagogues, incretin mimetics, SGLT2 inhibitors

Answer 391

The anterior pituitary, also known as the adenohypophysis, is a glandular tissue that produces and secretes its own hormones. The posterior pituitary, also known as the neurohypophysis, stores and releases hormones produced by the hypothalamus