NCERT Solutions for Class 11 Biology Chapter 22 Chemical Coordination and Integration to Study online or Free download in PDF form. Download CBSE Solutions Based on latest NCERT Books updated for new academic session.
NCERT Solutions for Class 11 Biology Chapter 22
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Chemical Coordination and Integration: Solutions
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Important Notes on Chemical Coordination & Integration
- Two types of hormones released are
- Releasing hormones: Simulate secretion of pituitary hormones, e.g., Gonadotropin releasing hormone stimulates pituitary gland to synthesise gonadotrophins.
- Inhibiting hormones: Inhibit secretions of pituitary hormones, e.g., Somatostatin inhibits secretion of growth hormone.
- Has two lobes on either side of trachea interconnected by isthmus (connective tissue).
- Composed of follicles and stromal tissues.
- Follicular cells synthesis thyroxine (T4) and tri-iodothyronine (T3).
- Iodine is necessary for normal functioning in of thyroid.
- Located on dorsal side of heart and aorta.
- Secrete peptide hormones called Thymosins which play role in differentiation of T-lymphocytes (help in cell mediated immunity.)
- Thymosins also produce antibodies and provide humoral immunity.
- Immunity of old people usually becomes weak as thymus gets degenerated with age.
- Present on back side of thyroid gland. Each lobe of thyroid gland has its one pair.
- Secrete peptide hormone called parathyroid hormone (PTH) which increases calcium levels in blood so called hypercalcemia hormone.
- PTH stimulates bone resorption, and reabsorption of calcium from blood and reabsorption of calcium by renal tubules, thus increasing blood Ca++ level.
- Located in bony cavity called as sella tursica.
- Attached to hypothalamus by a stalk.
- Divided anatomically into: Adenohypophysis and Neurohypophysis.
- Hormones released from hypothalamic neurons reach anterior pituitary through portal system.
- Posterior pituitary is under neural control of hypothalamus.
Two major causes
- Primary adrenal insufficiency where our immunity system mistakes adrenal for an antigen and tries to damage it.
- Secondary adrenal insufficiency-when pituitary gland can’t produce ACTH.
A pair of testis composed of seminiferous tubules and interstitial cells is present in the scrotal sac of males. Leydig cells (interstitial cells) produce androgens (mainly testosterone) which regulate development and maturation of male accessory sex organs, formation of secondary sex characters and play stimulatory role in spermatogenesis. Male sexual behaviour (libido) is influenced by androgens.
Hormones secreted by tissues which are not endocrine glands
- Heart: Atrial wall secrets Atrial Natriuretic factor (ANF) which decreases blood pressure by dilation of the blood vessels.
- Kidney: Juxtaglomerular cells secretes erythropoietin which stimulates erythropoiesis (RBC formation).
- Gastro-intestinal tract: it secrets four peptide hormones.