Physiology 🫁 Flashcards

Question

compare betweeen negative feedback and positive feedback according to incidence and significance

Answer 1

- In which the trophic hormone stimulates the secretion of target gland hormone, which in turn inhibit the trophic hormone secretion - TSH stimulates the secretion of the target gland hormone e.g. thyroxine hormone which in turn inhibits the secretion of trophic gland hormone secreted from the pituitary gland e.g. TSH

Answer 2

- In which the trophic hormone stimulates the secretion of target gland hormone, which in turn stimulate the trophic hormone secretion. - An example of a +ve feed-back loop is that which exists between LH and estrogen 48 hrs before ovulation to induce ovulation

Answer 3

according to the modes of action: **Long loop Feed-Back:** It represents the relationship of trophic anterior pituitary hormones and their target gland hormones. **Short loop Feed-Back:** The inter-relation between pituitary trophic hormones and the hypothalamic releasing and release- inhibiting hormones.

Answer 4

Cytokines are **proteins** produced by various cell types in response to stimuli arising from different physiological and pathophysiological states.

Answer 5

by acting on the endocrine glands and on the hormonally responsive tissues.

Answer 6

**a) Inflammatory cytokines** e.g. interleukin and tumour necrosis factors. **b) Immunomodulatory cytokines** e.g. interferons. **c) Chemokines** e.g. ciliary neurotrophic factors and oncostatin. **d) Growth factors** e.g. platelet derived growth factor, epidermal growth factor

Answer 7

Posterior pituitary is **not a gland but a collection of nerve endings of cell bodies** in the **supraoptic and paraventricular nuclei of the hypothalamus**.

Answer 8

- The crude extract of this posterior lobe is called **pituitrin which contains 2 hormones**: 1. Antidiuretic hormone (ADH), also called vasopressin or pitressin. 2. Oxytocin (or pitocin) hormone.

Answer 9

- The two hormones are **formed in the hypothalamus** and **incorporated into granules with a binding protein (neurophysin).** - **neurophysin-1 for oxytocin and neurophysin-2 for antidiuretic hormone**. - The **granules (or neurosecretory vesicles) pass down** the axons of the **neurohypophyseal tracts** to dilated nerve endings in the posterior pituitary, from which **they enter the blood**

Answer 10

- When a **nerve impulse is transmitted** from the cell body in the hypothalamus down the axon, it **depolarizes the neurosecretory vesicles within the terminal Herring body**. - An **influx of Ca** into the neurosecretory vesicles then results in **hormone enters the closely adjacent capillary**.

Answer 11

1. The **major action of ADH** is on the **distal convoluted tubules** and collecting ducts that are responsible for **reabsorbing free water** from the glomerular filtrate. 2. when administered **systemically in large doses**, ADH causes **contraction of the smooth muscles particularly in the blood vessels** leading to elevation of the blood pressure, **coronary vasoconstriction and intense splanchnic vasoconstriction (control persistent, serious gastrointestinal bleeding)**.

Answer 12

- ADH **binds to V2** (vasopression-2) receptors. - The intracellular **↑cAMP** causes the **insertion of aquaporin-2 (AQP2) water channels in the apical (luminal) membrane**. - **Synthesis of the water channels also is increased**, Removal of ADH removes the water channels from the membrane. - Basolateral membrane has AQP3 and AQP4 channels.

Answer 13

Secretion of ADH is primarily regulated by osmotic and volume stimuli

Answer 14

- The **hypothalamic supraoptic nuclei contain very sensitive osmoreceptors**, being responsive to changes in osmolality of **only 1%** (normal plasma osmolality is 290 m osm/liter). - Minimal rise of plasma osmolality **(dehydration, administration of solutes)** leads to **loss of intracellular water from osmoreceptor neurons and causes ADH release**. As a result, ADH produces reabsorption of most of the water from tubular fluid, in the kidney, while electrolytes continue to be lost into the urine. This effect dilutes the extracellular fluids, returning them to a normal osmotic composition.

Answer 15

- ADH release is also stimulated by a **decrease of 5% to 10% in total circulating blood volume**, Haemorrhage decreases blood volume. - Hypovolaemia is **perceived by a number of pressure (rather than volume) sensors**: 1. Carotid and aortic baroreceptors. 2. Stretch receptors in the walls of the left atrium and pulmonary veins. **Since the pressure receptors normally maintain tonic inhibition of ADH release, hypovolaemia decreases these inhibitory impulses and increases ADH release**. 3. Also, the release of **renin from the juxtaglomerular apparatus** leads to generation of **angiotensin** directly within the brain which **stimulates thirst & mediates the release of ADH**.

Answer 16

- Sulfonylureas used in the treatment of diabetes mellitus - Nicotine - Increased temperature and opiates

Answer 17

Diuretics Cold weather ethanol Chronic water loading

Answer 18

The problem is either - a deficiency of ADH (central form) - a lack of an effect of ADH on the collecting duct (nephrogenic form).

Answer 19

- the individual is forming a large volume of dilute urine (polyuria) along with polydipsia.

Answer 20

polypeptide hormone, released by the paraventricular nuclei of the hypothalamus.

Answer 21

At the target cells, it combines with specific plasma membrane receptors and probably exerts its effects by increasing intracellular Ca++ content.

Answer 22

1. Milk-letting effect 2. Suckling-reflex 3. Powerful contracting action on the uterus 4. Transport of the sperms into the uterus during intercourse 5. Discharge of sperms in male 6. Stimulation of sweat secretion

Answer 23

by stimulation of the myoepithelial cells of the alveoli of the mammary glands.

Answer 24

- potentiated by estrogen - inhibited by catecholamines.

Answer 25

- **Suckling** of the breast by the infant stimulates **touch receptors at the nipple and areola** - which send **afferent impulses into the hypothalamus** to **release both oxytocin and prolactin hormones**.

Answer 26

- by lowering the threshold for membrane depolarization of the myometrial muscles **---------** - It plays an important role in labor, sustained post-partum contractions that help to: 1. **maintain haemostasis** after evacuation of the placenta 2. **involution of the uterus** after delivery.

Answer 27

- potentiated by estrogen - inhibited by progesterone.

Answer 28

By the end of the act of intercourse (or matting), oxytocin is released giving the (orgasm) sensation due to uterine contractions which suck the sperms into the uterus.

Answer 29

Oxytocin leads to discharge of sperms from the seminiferous tubules and epididymis to vas deferens.

Answer 30

from sweat glands at the axillae, nipples, groins and perineum which produce sex attraction especially in animals.

Answer 31

ovoid structure

Answer 32

500 and 600 mg in an adult. | **"not even 1 gm!"**

Answer 33

at the base of the brain in a small cavity called (pituitary fossa or sella tursica)

Answer 34

- which is covered by an extension of the **dura mater (the diaphragma sellae)** through which passes the **pituitary stalk** connecting the gland to the hypothalamus.

Answer 35

accounts for 75% of the weight of the pituitary gland.

Answer 36

it is **dark red colour** is due to the presence of **blood sinusoids in between the secretory cells**.

Answer 37

**Primary:** - GH (somatotropic or somatotropin) - Prolactin (lactogenic or mammotropin) - MSH (melanotropin or **intermedin**) **Trophic:** - TSH (thyrotropin or thyrotropic hormone) - ACTH (corticotrophin) - FSH - LH (in male, it is called interstitial cell stimulating hormone). **Others:** - beta lipoproteins "analgensic"

Answer 38

the adenohypophysis controls, through its trophic hormones, all other endocrine glands except the parathyroid, supra-renal medulla and pancreas.

Answer 39

1. Hypothalamus 2. Negative Feedback 3. Others

Answer 40

- The hypothalamus has a major influence on the release and the synthesis of the anterior pituitary hormones. - This is achieved by: **hypothalamo-hypophyseal portal circulation.** " a path for hormones" - Internal Carotid Artery ---> 2 Superior Hypophyseal Arteries ---> 1st set of capillaries (In Median Eminence & Neural Stalk) ---> Portal Veins ---> 2nd set of capillaries (Sinusoids) (In Anterior Pituitary gland)

Answer 41

The activity of the anterior pituitary is also influenced by the hormones of the target glands: - thyroxin - cortisol - gonadal steroids. ## Footnote Thyroxin, GH -----> -ve FB on anterior pituitary Cortisol, Estrogen ---> -ve Fb on Hypothalamus

Answer 42

Numerous other mechanisms influence the activity of the anterior pituitary such as: - physical and emotional stress "GH" - coitus "FSH & LH" - suckling "Prolactin"

Answer 43

- Growth hormone (GH) is a **protein** hormone secreted from specific **acidophil cells** in the adenohypophysis called somatotrophs which **form 30-40% of the cell population of the gland**.

Answer 44

less than 3 ng/ml.

Answer 45

- Growth Function - Metabolism Function - Others

Answer 46

**Stimulates protein synthesis by:** - Increase amino acid transport through the cell membranes. - Increase of proteins synthesis by ribosomes. - Increase formation of RNA. - Inhibition of protein catabolism

Answer 47

GH has **anti-insulin action:** - decreases glucose uptake by tissues. "which is mediated by hexokinase" - stimulates gluconeogenesis in the liver with more production of glucose. - stimulates the release of glucagon hormone by the pancreas with consequent increase in glycogenolysis in the liver.

Answer 48

- It has powerful **lipolytic** effect thus increasing the blood level of FFA which provides energy during stress conditions particularly hypoglycemia and starvation.

Answer 49

- Marked increase of Ca++ absorption from GIT. - Reduces Na+ , K+ and HPO4 - excretion by kidney

Answer 50

- Growth hormone has **no direct anabolic effects.** - Its growth promoting actions are mediated by a group of **intermediary polypeptide substances called somatomedins.**

Answer 51

polypeptide, formed in the liver, in bone cells, and probably some other tissues.

Answer 52

proinsulin

Answer 53

- **Somatomedins** bind to specific plasma membrane **receptors**. - IGF-I **interacts with target organs** to induce growth. - These receptors can also bind insulin and pro-insulin but with much less affinities. - They may also feedback on the pituitary to inhibit GH secretion.

Answer 54

- In some cases, control of IGF-l can be independent of growth hormone. - For example, in a state of long-term stress (e.g., in starvation) growth hormone increases but IGF-I decreases

Answer 55

- Growth hormone has no direct anabolic effects. - Its growth promoting actions are mediated by a group of intermediary polypeptide substances called somatomedins. - Somatomedins are formed in the liver, in bone cells, and probably some other tissues. - They are structurally similar to proinsulin. - they are called insulin-like growth factors (IGF), of which 2 types have been identified: IGF-I and IGF-II. - IGF-I interacts with target organs to induce growth. - They may also feedback on the pituitary to inhibit GH secretion. - Somatomedins bind to specific plasma membrane receptors. - These receptors can also bind insulin and pro-insulin but with much less affinities. - In some cases, control of IGF-l can be independent of growth hormone. - For example, in a state of long-term stress (e.g., in starvation) growth hormone increases but IGF-I decreases

Answer 56

1. Hypothalamus 2. Others

Answer 57

- GHRH: ↑ GH secretion. - GHIH (somatostatin): ↓ GH secretion.

Answer 58

- Hypoglycemia - ↓FFA - ↑A.A e.g. high protein diet or infusion of arginine **------------** - Starvation - Stress and α-adrenergic agonists - Sleep **------------** - Exercise

Answer 59

- Hyperglycemia - ↑FFA - ↓A.A **-------** - ↑Cortisol - ↑G.H - IGF-1

Answer 60

- Most **(70%)** of the pulsatile release of growth hormone occurs **during slow wave** sleep (stages 3 and 4) and this increases during puberty. - Nocturnal pulses are not suppressed by glucose.

Answer 61

↑ GH secretion - If before union of epiphysis: gigantism - If after union of epiphysis: acromegaly **--------** ↓ GH secretion - In adult: No physical signs but there’s loss of some proteins. - In children: Dwarfism.

Answer 62

Growth-hormone secretion remains pulsatile but nocturnal dominance is lost.

Answer 63

A disease resulting from increased secretion of the growth hormone before the union of the epiphyses

Answer 64

- Marked elongation of different body bones but in a relative proportion (the span =the height). - Overgrowth of soft tissues e.g. the muscles and viscera. - Hyperglycemia and increased metabolic rate - These patients are often mentally subnormal and unless treated, usually die before the age of 20 yrs. - Headache and visual disturbances due to local pressure of the growing tumor on the sella tursica and optic chiasma

Answer 65

- This disease is due to hyper secretion of growth hormone in adults after the epiphyses have fused - The bones become thicker and deformed; the muscles and viscera also enlarge

Answer 66

- Generalized coarsening of the features due to: ➢Thickening of the skin and subcutaneous tissues. ➢Elevated supraorbital ridge ➢The lower jaw protrudes forward (prognathism), and the teeth become widely separated. - Kyphosis due to thickening of the vertebrae. - Raised BMR. - Hyperglycemia, glucosuria and Hypogonadism. - Some patients have defects in the visual fields because of the pressure of the tumor on optic chiasma. - headache and vomiting

Answer 67

requires surgical removal of the tumor or destruction by irradiation.

Answer 68

Deficiency of growth hormone in children

Answer 69

a) Short stature by rapid closure of the epiphyses. b) Retarded growth of soft tissues but mild obesity is common. c) normal mental and sexual growth ## Footnote Treated by adminstrtion of GH

Answer 70

Lactogenic hormone or mammotropin

Answer 71

polypeptide hormone.

Answer 72

similar to growth hormone and human chorionic somatomammotropin (HCS).

Answer 73

- Its normal plasma concentration is about 5 ng/ml in men and 8 ng/ml in women. - Prolactin circulates unbound, and in the basal state the plasma levels are the same in men and women.

Answer 74

1. Prolactin participates in stimulating the development of breast tissue: - Prolactin is not involved in breast development during puberty but is involved in breast enlargement during pregnancy. - After parturition, prolactin stimulates milk synthesis and secretion. 2. Hyperprolactinemia causes hypogonadism **(infertility)**. It disrupts the GnRH-gonadotropin axis but does not affect the basal levels of LH and FSH ## Footnote It affects exocrine gland

Answer 75

- Hypothalamic control - Pregnancy - Suckling - Drugs - Other factors

Answer 76

- The hypothalamus releases both prolactin releasing hormone (PRH) and prolactin release inhibiting hormone (PRIH) which is structurally similar to dopamine. - Section of the pituitary stalk leads to prompt increase in the plasma prolactin level, thus the effect of the hypothalamus is mainly inhibitory.

Answer 77

**(Inhibit prolactin)** Drugs increasing the formation of dopamine or stimulate dopamine receptors: - L-doppa - Apomorphine - bromocriptine

Answer 78

Stimulation of the nipples as by suckling in lactation produces rapid increase of prolactin level through inhibition of PRIH release.

Answer 79

prolactin secretion increases steadily during pregnancy, mediated by the large increase in estrogen.

Answer 80

Increased release in response to rest and during sleep.

Answer 81

- **Postpartum pituitary infarction:** During pregnancy, the pituitary enlarges in response to estrogen stimulation of the lactotrophs, but there is no compensatory increase in vascularity. Thus, following delivery, the pituitary is more susceptible to blood loss and the ensuing hypotension. - Can result in partial or complete pituitary insufficiency.

Answer 82

Thyroxine hormone (T4) was the first to be discovered and constitutes about 90% of the thyroid output.

Answer 83

Although T3 is released in a smaller amount and persists in blood for a much shorter time than does T4, it appears to be the most active hormone at the cellular level, being 3-5 times more active than T4.

Answer 84

The biological effects of T4 are largely a result of its intracellular conversion to T3.

Answer 85

T4 is converted to T3, Some of T4 is also converted to another iodinated tyrosine compound called ‘reverse triiodothyronine (rT3) which has no apparent biological action.

Answer 86

1. Intracellular actions of thyroid hormones (mechanism of action). 2. On the whole body.

Answer 87

T3 and T4 appear to enter the cell freely by passive diffusion where they: - Bind directly to a specific nuclear receptor. - The hormone receptor complex interacts with DNA to stimulate the formation of mRNA ---> increase synthesis of specific proteins ----> increase size and number of mitochondria and ---> increase amount of plasma membrane Na+, K + -ATPase

Answer 88

1. Growth and development 2. Energy metabolism 3. Gastro-intestinal tract 4. Cardio-vascular system 5. Respiratory system 6. Gonads 7. Skeletal muscles 8. Vitamins and drugs 9. Carbohydrate metabolism 10. Protein metabolism 11. Fat metabolism 12. Haemopoietic system

Answer 89

- Thyroid hormones stimulate physical, mental and sexual growth. **Physical growth:** - Has a permissive effect on GH & potentiate the effect of somatomedins. - Eruption & development of teeth. - Closure of fontannels. **Mental growth:** - Growth, development & function of CNS during fetal life & first few years after birth. - Myelination of nerve fibers & development of synapses. **Sexual growth:** - Essential for normal menestrual cycle & spermatogenesis (fertility). - Stimulates milk secretion during lactation.

Answer 90

- Thyroid hormones stimulate the basal metabolic rate, oxygen consumption, heat production, and glucose uptake by cells. - One mg of thyroxin can raise heat production by about 1000 calories.

Answer 91

- inc. glucose absorption from the intestine and glycogenolysis. - inc. appetite and GIT motility.

Answer 92

- inc. heart rate and stroke volume. - The systolic blood pressure is high, while the diastolic remains normal or decreased due to dilatation of the peripheral arterioles which lead to a reduction in the peripheral resistance.

Answer 93

- inc. rate and depth of breathing with a consequent increase in pulmonary ventilation.

Answer 94

- Normal level of thyroid hormones is essential for proper sexual functions. - Thyroid hormones increase sex steroid binding-globulin to decrease the metabolic clearance of estrogen and testosterone. - Both hyper and hypothyroid states lead to infertility.

Answer 95

Normal skeletal muscle function also requires thyroid hormones.

Answer 96

**In physiologic amounts:** - thyroid hormones potentiate the action of insulin and promote glycogenesis and glucose utilization. **In large doses, induce hyperglycemia by:** 1. inc. glycogenolytic effect of epinephrine. 2. inc. gluconeogenesis. 3. inc intestinal glucose absorption.

Answer 97

1. In physiologic amounts, they have protein anabolic effect. 2. While in large doses,they enhance protein catabolism.

Answer 98

- Thyroid hormones stimulate all aspects of lipid metabolism, including synthesis, mobilization and utilization. - They dec. serum TG , phospholipids and cholesterol, mean while they inc. serum FFA and glycerol.

Answer 99

- Thyroid hormones inc. erythropoiesis with increase in RBCs. - They also facilitate the dissociation of O2 from haemoglobin by increasing the amount of 2,3 diphosphoglycerate (DPG) in the RBCs.

Answer 100

1. TSH 2. Thyroid stimulating immunoglobulin (TSI) 3. All types of stress 4. Age 5. Pregnancy 6. Antithyroid agents (Goitrogens) 7. Blood iodine level

Answer 101

TSH has the following effects on the thyroid gland: - Promotes hyperplasia of the gland cells. - Increases its uptake of iodide from the blood. - Stimulates synthesis and release of the thyroid hormones, T3 & T4. **There is a negative feedback mechanism between the plasma levels of the thyroid hormones and the output of TSH. Excess T3 and/or T4 suppresses the release of TSH by acting directly on the thyrotrope cells, and to a lesser extent on the anterior hypothalamus (site of release of TRH).**

Answer 102

TSI acts on the thyroid in a manner similar to TSH but is not affected by the level of T3 and T4 in the blood (no –ve feed back).

Answer 103

e.g exposure to cold environment stimulates the thyroid with consequent increase in metabolic rate and heat production to counteract the effects of low temperature.

Answer 104

Although its effect is small, but there tends to be a decrease in activity with increasing age.

Answer 105

- Thyroid activity increases during pregnancy. - The placenta secretes a hormone called ‘human chorionic gonadotropin’ or HCG which is structurally similar to TSH.

Answer 106

- Such agents interfere with one or more steps in T3 and T4 synthesis. - Deficiency of thyroid hormones leads to a rise in TSH level which results in enlargement of the thyroid gland (goiter). - Primary goitrogens include thiocyanates such as those found in cabbage and inhibit the I - uptake by the thyroid gland.

Answer 107

**Iodine deficiency** → dec. T3&T4 → inc. TSH→ goiter. **Excess iodine (Wolff-Chaikoff) results in:** 1. dec. organic binding of iodine in the gland. 2. dec. proteolysis of thyroglobulin.

Answer 108

This immunoglobulin is produced by lymphocytes in all cases of Grave’s disease (hyperthyroidism).

Answer 109

Primary goitrogens include thiocyanates such as those found in cabbage

Answer 110

Cretinism & myxedema

Answer 111

Hypothyroidism in human infants.

Answer 112

- Retardation of physical , mental& sexual growth. - Low BMR and O2 consumption. - The skin: 1. Yellowish due to carotinaemia. 2. Scaly and thick with scanty coarse hair, due to failure of formation of vitamin A in the liver from carotins. - Facial features: puffy eye lids, Lips are thick and the tongue is swollen (macroglossia). - Abdomen is protuberant (potbelly) & umbilical hernia.

Answer 113

Hypothyroidism in adults.

Answer 114

- Retardation of all mental processes e.g lack of concentration, slow thinking and speech, long reflex time and sleepiness. - Low BMR and O2 consumption leads to: 1. Weight gain. 2. Increased sensitivity to cold weather. - Bradycardia and hypotension. - Skin: becomes yellowish, cold and thicker due to the deposition of a protein substance (myxoedematus tissue) - Increased level of cholesterol

Answer 115

due to excess thyroid hormones secretion resulting from thyroid tumor or over stimulation of the thyroid by TSH or TSI.

Answer 116

- Excessive nervousness and irritability - Increased appetite. - Low serum cholesterol level. - Increased BMR and O2 consumption - The skin: Warm and moist, Hair is fine and silky. - **Ocular signs include:** 1. Characteristic stare with widened palpebral fissure due to upward retraction of upper eye lid. 2. Lid lag phenomenon i.e a delay in the downward movement of the upper eye lid on following a falling object. 3. Exophthalmos (accumulation of exophthalmos producing factor’ which is probably a degradation product of TSH). 4. Failure of convergence.

Answer 117

1. **Characteristic stare** with widened palpebral fissure due to upward retraction of upper eye lid. 2. **Lid lag phenomenon** i.e a delay in the downward movement of the upper eye lid on following a falling object. 3. **Exophthalmos** (accumulation of exophthalmos producing factor’ which is probably a degradation product of TSH). 4. Failure of convergence.

Answer 118

- Goiter means enlargement of the thyroid gland. - It is accompanied by either hypo, or hyperfunction.

Answer 119

1. Goitrogens 2. Iodine deficiency 3. Grave’s disease 4. Nodular goiter 5. Physiological goiter

Answer 120

- These are substances that block synthesis of thyroid hormones, e.g. thiocyanates and thiocarbamides. - They lead to decreased T3 & T4 → increased TSH → increased gland size.

Answer 121

- it leads to decreased T3 & T4 → increased TSH → goiter

Answer 122

due to the presence of TSI which binds to TSH receptors on thyroid cells → diffuse goiter.

Answer 123

Irregular enlargement of the thyroid with varying numbers of discrete nodules, probably due to exposure to stresses.

Answer 124

adolescence and pregnancy.

Answer 125

- inc. synthesis of vitamin A from carotenes in the liver. - Stimulate both the utilization and clearance of all vitamins.

Answer 126

70 - 110 mg / 100ml

Answer 127

**Pancreatic hormones:** - insulin - glucagon - somatostatin - pancreatic polypeptide **Other Hormones:** (All ↑ blood glucose level) - Adrenaline. - Glucocorticoid. - Growth hormone. - Thyroxine.

Answer 128

75% of islet mass

Answer 129

Peptide hormones.

Answer 130

- A **pre-proinsulin** is **first synthesized** on the **ribosomes**. - **23 AA** residue is rapidly **cleared** at the **site of synthesis** to yield a **pro-insulin chain**. - **During its transport from the endoplasmic reticulum and its packaging into granules by the Golgi apparatus**, **pro-insulin** is slowly **cleaved** by trypsin-like and carboxypeptidase-like enzyme. - **The generated insulin and C-peptide** molecules are **stored in the granules** and **released** by exocytosis in **equimolar amounts**. - C-peptide has no known function but because it is not removed by liver , C peptide is a better marker for insulin secretion than insulin itself. - Half life of insulin is 5-8 min , while C peptide is 3-4 times longer

Answer 131

- C-peptide has no known function but because it is not removed by liver , C peptide is a better marker for insulin secretion than insulin itself.

Answer 132

Half life of insulin is 5-8 min , while C peptide is 3-4 times longer.

Answer 133

**On glucose metabolism:** Insulin tends to lower blood glucose level by: - Stimulation of Glycogenesis in the liver and muscles - Inhibition of glycogenolysis - Increasing the glucose uptake by the tissues - Inhibition of gluconeogenesis by decreasing the hepatic uptake of amino acids - Stimulate lipogenesis in adipose tissue **Anabolic action:** - Stimulates the uptake of amino acids by muscle. - Stimulates the rate of protein synthesis, by stimulationg transcription followed by translation. - Anti-catabolic effects i.e. it inhibits proteolysis. - Certain peptides called insulin-like growth factors, have similar amino acid sequences, and cross react with insulin receptors. **Increases cellular uptake of potassium, phosphate , magnesium.** **Increases reabsorption of potassium, phosphate and sodium by renal tubules.**

Answer 134

- CHO Compounds - FFA & Triglycerides - A.A - Gastric inhibitory polypeptide (GIP) - Glucagon & entero-glucagon - K & Ca

Answer 135

- major regulation is the plasma glucose level. - No insulin is secreted below a plasma glucose level of 50 mg. - A half maximum insulin secretory response occurs at a plasma glucose level of about 150 mg. - A maximum response at 300 to 500 mg.

Answer 136

plasma glucose level

Answer 137

- No insulin is secreted below a plasma glucose level of 50 mg. - A half maximum insulin secretory response occurs at a plasma glucose level of about 150 mg. - A maximum response at 300 to 500 mg.

Answer 138

increased FFA & Triglycerides Have little stimulatory effect on insulin release

Answer 139

increased AA like oral protein intake stimulates insulin secretion

Answer 140

- Is the most important of these insulinogogues. - GIP is also called glucose dependent insulinotropic peptide. - It is released by duodenal mucosa in response to drop in pH of the contents and intake of sugars, to stimulate pancreas to release insulin. - When glucose is given orally, a greater insulin response is elicited than when plasma glucose is comparably elevated by intravenous administration.

Answer 141

**Stimulates insulin secretion:** 1. Directly by acting on B-cells (paracrine effect), 2. Indirectly by increasing blood glucose level.

Answer 142

Both are essential for normal insulin responses to glucose

Answer 143

Somatostatin, α-Adrenergic stimuli, Fasting, Diazoxide, Phenytoin

Answer 144

- a polypeptide of 29 AA , formed from pro-glucagon. - The only significant target site for glucogon is liver - skeletal ms is not a target tissue for glucagon.

Answer 145

- alpha cells of the pancreatic islets. - Small intestinal cells : secrete glycentin (glucagon-like peptides).

Answer 146

- Glucagon binds to receptors in cell membrane - Second messenger is cAMP.

Answer 147

1. **Glucagon is a hyperglycemic factor. It increases blood glucose level by:** - It stimulates glycogenolysis through activation of glycogen phosphorylase. - It stimulates gluconeogenesis. - Glucagon has little or no effect on glucose utilization by peripheral tissues. 2. **Stimulate lipolysis** by activation of lipase leading to increase FA which pass to tissue for oxidation. 3. **It decreases hepatic cholesterol synthesis.** 4. **Natriuresis**, by inhibition of renal tubular Na reabsorption. 5. Activation of myocardial adenyl cyclase, causing a moderate **increase of cardiac output.** 6. May act as a local CNS hormone for the **regulation of appetite.**

Answer 148

- Amino acids release insulin and glucagon. - The CHO/protein content of the meal determines the rate of insulin to glucagon release (insulin/glucagon ratio) . - A mixed meal high in CHO releases mainly insulin. - A high-protein meal releases mainly glucagon. This is to protect the individual from the hypoglycemic effects of insulin following a protein meal.

Answer 149

- Hypoglycemia. - Protein meal by amino acids such as arginine and alanine. - ↓plasma F.F.A. - Exercise of sufficient intensity and duration. - Stress.

Answer 150

- Hyperglycemia. - ↑plasma free fatty acids. - Somatostatin. - Local insulin.

Answer 151

It inhibits secretion of insulin and somatostatin via a direct pancreatic effect.

Answer 152

- Results from deficiency of insulin in type 1 diabetes. - insulin resistance in type 2 diabetes.

Answer 153

- Hyperglycaemia - Glucosuria - Polyuria - Polydepsia - Acidosis - weight Loss & asthenia - increased cholesterol & triglycerides

Answer 154

Due to absence of the effects of insulin

Answer 155

- loss of glucose in urine. - This occurs when the blood glucose level becomes higher than the renal threshold (180 mg%).

Answer 156

Intense thirst due to dehydration

Answer 157

Due to osmotic pressure of excreted glucose (osmotic diuresis).

Answer 158

- Due to inhibition of CHO metabolism. - The body depends on the fat metabolism which leads to the accumulation of acetoacetic acid & beta hydroxy-buteric acid.

Answer 159

Due to mobilization of fat and proteins for the supply of energy.

Answer 160

due leads to early development of arteriosclerosis.

Answer 161

- Diagnosis based on glucose intolerance - Hemoglobin A1C - Stress (counter regulatory) hormones

Answer 162

- Not recommended for diagnosing diabetes. - But remain the preferred method for monitoring the effectiveness of diabetes treatment.

Answer 163

In some cases can promote diabetes and, at the very least, aggravate the hyperglycemia of diabetes.

Answer 164

- Glucose intolerance can develop in late pregnancy. - Human placental lactogen (hPL) acts similarly to the stress effects of growth hormone. It decreases the peripheral uptake of glucose. - Most women revert to a normal glucose tolerance following delivery but have a higher risk of developing diabetes later in life .