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Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) The Endocrine System Glands are modified epithelium which produces certain secretions. TYPES OF GLANDS: Exocrine Gland/Duct Gland Secretions of these Glands are carried to the site of action through fine ducts. E.g.: Salivary Gland Endocrine Gland/Ductless Gland Secretions of these Glands are carried to the site of action through blood. E.g.: Thyroid Gland Heterocrine Gland/Dual Gland These Glands are both Exocrine and Endocrine in function E.g.: Pancreas [Insulin-ENDO ; Pancreatic juice-EXO] Secretions of Endocrine Glands-HORMONES HORMONES: Special chemicals secreted by Endocrine Glands, which are directly poured into the BLOOD and are carried to the site of action, called Target Organ. CHARECTERISTICS OF HORMONES: o o o o o o They are Proteins, specific in function and specific in target Secreted in LOW concentration, if in excess it is excreted through urine Hypo or Hyper secretion causes diseases Hormones act as chemical messengers. They are secreted by living cells/tissues or organs called glands. They are secreted in very small quantities by glands. They act upon specific cells, tissues, or organs called the target sites. They are generally slow in action, but have long lasting effects. They either accelerate or inhibit a reaction. PITUITARY GLAND (A.K.A MASTER GLAND) Location: Below Hypothalamus in the Forebrain. Pituitary Gland id divided into 3 lobes: o Anterior Lobe o Inter-mediate Lobe o Posterior Lobe ANTERIOR PITUITARY LOBE: o Some of the Hormones of Anterior Pituitary Lobe are called Tropic Hormones o Tropic Hormones: Hormones which stimulates other Endocrine Glands to produce their secretions. 1 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) E.g.: TSH, ACTH, FSH, and LH o Thyroid Stimulating Hormone (LHT): Stimulates Thyroid Gland to produce its secretions. o Adreno-Cortico Tropic Hormone (ACTH): Stimulates Adrenal Cortex to secrete its hormones o Follicle Stimulating Hormone (FSH): Stimulated in both MALES & FEMALES It maintains the growth and development of GRAAFIAN follicle. In Males- Spermatogenesis (Production of Sperms) In Females- Maturation of Follicle (Production of Ovum) Testis Leydig cells (Interstitial cells) Secrete androgens, mainly testosterone Testosterone plays a role in spermatogenesis and development of male secondary sexual characters. Ovary It secretes two hormones. Estrogen Secreted by Graafian follicle, it regulates the development of female secondary sexual characters. Progesterone Secreted by corpus luteum, it acts on mammary glands and helps in milk secretion. o Luteinizing Hormone (LH): It helps in secretion of Androgens from Testis. It also induces Ovulation from GRAAFIAN follicle. In Males, it stimulates secretion of male hormone Testosterone. In Males, it also called INTESTITIAL CELL STIMULATING HORMONE. In Females, it stimulates secretion of female hormone Progesterone. Progesterone Secreted by corpus luteum, it acts on mammary glands and helps in milk secretion. GROWTH HORMONE/SOMATOTROPIN Functions Regulates NORMAL growth & development of the body. Of GH Helps in Ossification of Bones. Hypo-secretion: a. Dwarfism in children1. Stunted physical growth Hyper-secretion: a. Gigantism in children1. Abnormal growth in height b. ACROMEGALY in adults1. Elongation of Bones of Limbs 2. Bones of Jaw protrude 2 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) PROLACTIN Stimulates MAMMARY glands to produce the secretions after the birth of a child. ONLY in FEMALES POSTERIOR PITUITARY LOBE: ANTI-DIURETIC HORMONE [ADH]/VASOPRESSIN] Functions It stimulates reabsorption of water by CONVOLUTED tubules. Of ADH It regulates the water levels in Urine. Hypo-secretion: a. Diabetes insipidus1. Watery urine without Glucose 2. Person feels thirsty & tired OXYTOCIN (The Feel Good Hormone) Simulates forceful contraction of Uterine wall (wall of the Uterus) during child birth. It also helps in Milk ejection. THYROID GLAND Location: Below larynx on either sides of trachea Function: Secretes two Hormones, 1. Thyroxin 2. Calcitonin 1. Thyroxin: Functions (of Thyroxin): Controls Cell Division & its differentiations Controls BMR (Basal Metabolism Rate) Controls Metabolism of Carbohydrates, Proteins & Fat Decides the onset of puberty in young Males and Females Hypo-secretion: a. Cretinism in children1. Stunted physical and mental growth b. Myxoedema in adults1. BMR falls 2. Swelling in the Neck 3. Swelling in different parts of the body 4. Tiredness 3 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) Hyper-secretion: a. Exophthalmic Goitre1. Rate of Heart Beat, Breathing increases 2. Eyeballs seem to bulge out 3. Rate of Oxidation of food increases 4. Person becomes irritable Simple Goitre: Caused due to the deficiency of Iodine in diet. Hence, Thyroxin secretion isn t normal. Symptoms: 1. BMR falls 2. Weakness 3. Exhaustion 4. Swelling in the neck due to enlargement of Thyroid Gland 5. Lower Thyroxin levels may also lead to Infertility 2. Calcitonin: Functions: 1. Regulates Calcium Metabolism in the body 2. Regulates Mobilization of Calcium ion from BONES to BLOOD ADRENAL GLAND Location: A pair of Adrenal Glands one above each Kidney (Like CAP) Internally, Adrenal Gland is divided into two parts: (a) Outer Cortex - It secretes hormone called corticoids. * * Corticoid such as glucocorticoid regulates carbohydrate metabolism. Example includes cortisol. Corticoid such as mineralocorticoid maintains the sodium potassium level in blood and tissue. Example includes Aldosterone. (b) Inner Medulla - It secretes ADRENALINE (epinephrine) and NORADRENALINE (norepinephrine). These are collectively called as 4 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) CATECHOLAMINES. These hormones are also called EMERGENCY hormones. CORTEX- Stimulated by ACTH to secrete its hormones. Cortex is divided into 3 layers: Outer Layer Middle Layer Inner Layer 5 Outer Layer Secretes a group of hormones called MINERALORTICOIDS E.g.- Aldosterone Maintains ionic concentration of Blood, i.e., concentration of Na (Sodium) ion, K (Potassium) ion and Ca (Calcium) ion. Hypo-secretiona. Addison s Disease 1. Low Na level in blood 2. Low BP 3. Low Blood Sugar level 4. Weakness 5. Nausea 6. Vomiting 7. Bronze Pigmentation Hyper-secretiona. Conn s Syndrome/Aldosteronism 1. Kidney failure 2. High Blood Sugar level 3. High Na level in blood Middle Layer Secretes a group of hormones called GLUCOCORTICOIDS E.g. : Cortisol & Cortisone Function: Regulates Carbohydrates, Protein & Fat metabolism in the body. These hormones are also called Anti-Stress Hormone Hypo-secretion- Stress Hyper-secretiona. Cushing s Syndrome 1. Rise in Blood volume 2. Rise in BP 3. Rise in Blood Sugar level 4. Obesity Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) Inner LayerSecrete a group of hormones called SEX-CORTICOIDS E.g.: Androstenedione Secrete both in males & females Function: Requires for maintaining secondary sexual characters in males and females. [Facial Hair (boys) |Breasts (Girls)] Hyper-secretiona. Adrenal Virilism 1. In males-Enlargement of Breasts In females- Hoarse voice & appearance of Facial hair MEDULLA- Secretes Adrenaline (epinephrine) also called EMERGENCY hormones. Prepares the body for emergencies like, Increased rate of Heart beat Increased rate of Breathing Increased Blood Sugar level Decreased Blood Supply to skin PANCREAS Location: Below the stomach in the loop of duodenum It is a Heterocrine Gland, the Pancreas have both Endocrine and Heterocrine Gland Endocrine part of Pancreas Islets of Langerhans Islets of Langerhans has three types of cells: ALPHA cells BETA cells DELTA cells ALPHA cells- secrete Glucagon. Hyperglycemia Increased blood glucose level Glucagon is a hyperglycaemic hormone. Function of Glucagon: Converts Glycogen to Glucose BETA cells- secrete Insulin Hypoglycaemia Decreased blood glucose level Insulin is a hypoglycaemic hormone. Functions of Insulin: Converts Glucose to Glycogen. Helps the cells in the uptake of Glucose and its utilization. 6 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) Hypo-secretion of Insulina. Diabetes mellitus 1. Frequent urination 2. Person feels thirsty 3. Person feels hungry 4. Muscle wasting 5. Overtime this condition affects Kidney, Eyes, Nervous System, Heart Hyper secretion of Insulin- COMA, due to nerve cell starvation. DELTA cells- secretes Somatostatin Function of Somatostatin: Regulates the functioning of Glucagon & Insulin INSULIN SHOCK- If a diabetic person has taken the insulin injection but has not eaten his food properly, it results in INSULIN SHOCK. Symptoms: 1. Dizziness/Blackout 2. Sweating 3. Disorientation due to nerve cell starvation Reason: Person s glucose level falls below normal Treatment: The person has to be administered orally. HYPOTHALAMUS: Contains NEUROSECRETORY cells that produce hormones Hormones regulate the synthesis and secretion of pituitary glands. Two types of hormones are released. Releasing hormones Stimulate pituitary gland to release hormones Inhibiting hormones Inhibit pituitary gland from releasing hormones PINEAL GLAND It secretes a hormone called melatonin. It also regulates the rhythm of body. FEEDBACK MECHANISM * * * * 7 Hypothalamus is considered to be a link between Nervous System & Endocrine System, as it controls the functioning of Pituitary Gland. Between Hypothalamus and Pituitary Gland is present a Portal System called Hypophyseal Portal System. Hypothalamus produces two secretions which pass via the portal system to reach Pituitary Gland. These secretions are: a. RELEASING factor b. INHIBITING factor E.g.- If the level of Thyroxin in blood is more than normal Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101 Biology: Endocrine System (NOTES) by Srikrshna P | Helpline for ICSE Students (Class 10) 8 Visit us @ http://icsehelpline101.wordpress.com | Connect @icsehelpline101
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