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Chapter-22
Chemical Coordination & Integration
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Coordination - Integration of function between different organs of body.
Endocrine gland- Ductless gland secreting hormone.
Hormone- intercellular messengers in trace amounts.
Hypoglycemia- low blood glucose level.
Hyper glycemia- high blood glucose level.
Diabetes mellitus- loss of glucose through urine.
Glycogenesis- conversion of glucose into glycogen.
Introduction:
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Chemical coordination is through hormones.
Hormones act on target tissue.
Hormones & neural system together control & coordinate the body physiology.
Endocrine Glands & hormone:
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Ductless glands.
Secretions having hormones are directly poured into blood.
Hormones are non- nutrient chemicals acting as inter-cellular messenger& are produced in
trace amounts.
Human Endocrine System:
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Consist of-Endocrine Glands & diffused tissues or cells.
Main glands are-Pituitary, Pineal, Thyroid, Adrenal,
Pancreas, Parathyroid, Thymus & Gonad others are organs:
Hypothalamus, Gastro-intestinal tract, Liver, Kidney, and
Heart.
The Hypothalamus:
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Basal part of fore brain.
Cell groups- called nuclei release hormones of two types-
Location of endocrine glands
1-Releasing Hormones- stimulate secretion of pituitary hormones e.g.GnRH.
2-Inhibiting Hormones- inhibit the release of Pituitary
hormones.
e.g. Somatostatin.
 These hormones act on anterior pituitary.
Pituitary (with Hypothythalamus)
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The Pituitary Gland:
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Placed in Sella Tursica
Two parts- (1) Adenohypophysis having two regions –pars distalis & pars intermedia
(2) Neurohypophysis
Hormones of Pars distalis-
Hormones
Growth Hormone (GH)
Prolactin (PR)
Thyroid Stimulating Hormone(TSH)
Adrenocorticotropic Hormone(ACTH)
Luteinising Hormone(LH)
Follicle Stimulating Hormone(FSH)
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Function
Controls body growth. Low secretion –
dwarfism High secretion –Gigantism.
Controls growth of mammary gland & milk
formation
Synthesis & secretion of thyroid hormone
Stimulates synthesis & secretion of
glucocorticoids of Adrenal cortex
In males synthesis & secretion of androgens.
In females induces ovulation.
Growth & development of ovarian follicles
Pars-intermedia- produces only one hormone- Melanocyte Stimulating Hormone (MSH).
MSH regulates Melanin pigmentation of skin.
Hormones of NeurohypophysisHormones
Oxytocin(birth hormone)
Vasopressin(Antidiuretic Hormone ADH)
Function
Acts on smooth muscles, uterus wall
contraction during child birth, milk ejection.
Stimulates resorption of water & electrolytes
by kidney.
The Pineal Gland: On dorsal side of brain.
Hormone
Melatonin
Function
Regulates 24-hour rhythm of body &
influences temperature, metabolism,
pigmentation, menstrual cycle, body
defence.
Thyroid Gland
Thyroid Gland:
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Two lobes in gland joined with isthmus.
Present on either side of trachea.
Hormone
Tetraiodothyronine or Thyroxin(T4) &
Triiodothyronine(T3)
Thyrocalcitonin
Function
Regulate basic metabolic rate, support RBC
formation
Regulate blood calcium level.
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Parathyroid Gland:
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Present on back side of Thyroid gland two in each lobe.
Secrete one hormone - Parathyroid hormone which
increases blood Ca++ level.
Thymus gland:
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Parathyroid Gland
Present on dorsal side of Heart & aorta.
Secrete Thymosins hormone.
Thymosins regulate T- Lymphocyte differentiation (Cell mediated immunity) & promote
antibody formation (Humoral immunity).
Thymus degenerates in old people.
Adrenal Gland:
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Present at anterior part of each kidney.
Has two parts- outer cortex & central- medulla.
Hormone
Adrenaline or epinephrine
& Noradrenalin or Norepinephrine (Emergency
Hormone)
Aldosterone
Cortisol
Androgenic steroids
Function
Increase alertness, pupilary dilation,
piloerrection sweating etc, increase
heart beat, rate of respiration,
breakdown of glycogen into glucose.
Balance of water & Electrolytes in
body ,blood pressure,
Metabolism of carbohydrates,
antiinflamatory reactions & suppress
immune response.
Growth of axial, pubic & facial hair.
Pancreas:
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Composite or mixed gland.
Islet of Langerhans part is endocrine.
Lack of insulin leads in to Diabetes Mellitus.
Hormone
Glucagon(from α cells)
Insulin
Function
Glycolysis, increase blood glucose level
Glycogenesis,Cellular uptake & utilisation of
glucose
Testis:
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Present in scrotal sac.
Leydig cells of testis produce androgens mainly Testosterone.
Androgens regulate maturation & functioning of male sex organs, muscular growth, growth
of facial & axial hair, aggressiveness, low pitch voice, spermatogenesis & libido.
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Ovary:
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Produce two groups of hormones-Estrogens & Progesterone.
Estrogens regulate many actions viz. growth & function of female secondary sex organs,
growth of ovarian follicles, high pitch voice, growth of mammary glands & sexual behaviour
in females.
Progesterone supports pregnancy & stimulates milk secretion.
Hormones of Heart, Kidney & Gastrointestinal Tract:
Organ
Heart
Kidney
Gastrointestinal Tract
Hormone
Atrial Natriuretic Factor
Erythropoetin
Gastrin
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Secretin
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Cholecystokinin(CCK)
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Gastric Inhibitory
Peptide(GIP)
Growth Factor
Several other non endocrine
tissues
Function
Reduces blood pressure.
Formation of RBC.
Stimulates secretion of HCl
& Pepsinogen in stomach.
Secretion of water &
bicarbonate ions from
pancreas.
Secretion of pancreatic juice
& bile juice.
Inhibits gastric secretion &
motility.
Growth, repair& regeneration
Mechanism of Hormone Action:
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Hormones bind to hormone receptors of target tissue cells.
Protein hormones bind to membrane bound receptors & steroid & thyroid hormones bind to
intracellular receptors & make hormone- receptor complex.
Former generates second messengers viz.cAMP, IP3, Ca++ & later interact with genome.
Above messengers or genome affects the cellular physiology giving required result.
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