Chemical coordination
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Transcript of Chemical coordination
CHEMICAL COORDINATION
“ It is the type of coordination present between the cells or different organs within the body of multicellular organisms. In this kind of coordination a group of cells releases specific chemicals, which regulates the activities of other cell of the body.”
Endocrine system
ENDOCRINE SYSTEM
DEFINITION Endocrine glands are organs in the
body that produce hormones which are released directly into the bloodstream. Together these glands make up the endocrine system, which performs essential functions like regulating metabolism, growth and reproduction.
INTRODUCTION Endocrine derives from the Greek words endo
meaning inside, within, and crinis for secrete Chemicals are released by these glands(hormones)
hormone derived from Greek word which means ‘to excite’
The field of study dealing with the endocrine system and its disorders is endocrinology, a branch of internal medicine.
In animals glands are of two types Exocrine gland: release products (enzymes) into
DUCTS› Ex) Sweat, digestive juices
Endocrine glands:– directly to bloodstream; NO DUCTS› Ex) Hormones
Features of endocrine gland: their ductless nature their vascularity, the presence of intracellular vacuoles or granules
storing their hormones.
Endocrine system vs. nervous system
Endocrine system Effects are slow to
initiate Response are
prolonged (few hrs to week)
HORMONES released in blood stream
Nervous system Effects very fast
and quick Responses are short
lived. NEUROTRANSMITTERs
travel through neurons released in synaptic cleft
CHEMICAL CLASSIFICATION OF HORMONES
1. Peptide/ Protein2. Steroid3. Amine (modified amino acids e.g. Thyroxine, Epinephrine,
Norepinephrine) PEPTIDE HORMONE
May occur as short chain of amino acids e.g., ADH, Oxytocin
Or occur as long chain amino acid e.g. Glucagon, Insulin, Prolactin
Not lipid soluble Received by receptors external to the cell membraneSTEROID HORMONE They are lipid soluble Diffuse easily through the membrane
Hormone Actions
PEPTIDE HORMONE › React with specific receptors
outside the cell› This triggers an enzyme
reaction with lead to the formation of a second messenger (cAMP).
› cAMP can produce specific intracellular functions: Activates cell enzymes Change in membrane
permeability Promote protein synthesis Change in cell metabolism Stimulation of cell secretions
Hormone Actions Steroid Hormones
› Pass through the cell membrane› Binds to specific receptors› Then enters the nucleus to bind
with the DNA which then activates certain genes (Direct gene activation).
› mRNA is synthesized in the nucleus and enters the cytoplasm and promotes protein synthesis for: Enzymes as catalysts Tissue growth and repair Regulate enzyme function
Endocrine Glands Hypothalamus Pituitary
› Anterior lobe› Posterior lobe
Thyroid gland Parathyroid
glands Adrenal Glands
› Cortex› Medulla
Islets of Langerhans
Gonads› Ovaries› Testes
Pineal gland Thymus others
Hormonal Communication
Hypothalamus Neuroendocrine organ Central part of brain
attached by numerous nerves to pituitary gland
Weight is about 4g(human) Control the pituitary gland
by producing chemicals (releasing/stimulating or inhibiting hormones)
Maintains homeostasis(heart rate, body temperature, water balance, and the secretions of the pituitary gland)
Pituitary gland(Hypophysis)
Pea size gland hang from the base of brain by stalk (infundibulum) loge in the bone of skull, weigh is about 5gm
In past considered as master gland but it itself under the control of hypothalamus
It consists of a hormone-producing glandular portion
Have two lobes1.Anterior pituitary (Adenohypophysis)2.Posterior pituitary (Neurohypophysis)
Anterior pituitary –hypothalamus
(Adenohypophysis) It Secretes six regulating
hormone (tropic hormone)
1. Thyroid stimulating hormone (TSH)
2. Adrenocorticotropic hormone (ACTH)
3. Follicle stimulating hormone (FSH)
4. Luteinizing hormone (LH)
5. Growth / somatotropin hormone (GH /STH)
6. Prolactin
7. Melanocyte stimulating hormone (MSH)
Anterior P. Homeostatic Imbalances
Growth /Somatotropin
hormone (GH) It is a non- trophic,anabolic
hormone which simulates the growth of all body tissue specially skeletal muscles ,bone and cartilage.
Control protein synthesis and general metabolism
Imbalances 1. Hyperseretion in childhood
produces gigantism2. Hyperseretion after adult-hood
produces acromegaly3. Hypo secretion in childhood
produces dwarfism
Posterior Pituitary or Neurohypophysis
Neurohypophysis It does not synthesize hormones, however, it stores and releases two hormones produced by the neurosecretory cells of the hypothalamus
• It is an extension of hypothalamus
• Antidiuretic hormone (ADH)
• Oxytocin
Pituitary—Posterior lobe Oxytocin
› Stimulates smooth muscle contraction of uterus at labour
› Stimulates mammary glands during lactation.
Antidiuretic H.› Stimulates water
reabsorption in collecting ducts.
› Decreases urine output
› Hypo secretion of ADH produces diabetes insipidus
› Excessive thirst and urination
Thyroid Gland Located at the base of neck in
front of trachea Bilobed and butterfly shaped Weigh about 25-40gm Composed of follicles which
produce 1. Thyroxine (TetraiodothyronineT4)2. Triiodothyronine (T3) 3. Calcitonin
Both T3 and T4 are important in controlling metabolism and are essential for normal physical growth and mental development.
Calcitonin causes excess blood calcium to be deposited in bones.
Homeostatic imbalances
Hypothyroidism results› Myxedema (in adults)lethargy,
weight gain, dry- skin, hair loss, cold intolerant, confused and depressed.
› Goiter—low intake of iodine in diet
› Cretinism (in children)mental retardation,dwarfism,lack of sexual maturity.
Hyperthyroidism results› Graves disease (enlargement
of overall gland along with
› Exopthalamic goiter(excess accumulation of fat and mucus in eye orbit)
Parathyroid GlandsTwo pairs of pea-sized
glands embedded on the surface of thyroidWeigh about 0.05g-0.3gParathyroid hormone (PTH)Antagonistic to CalcitoninStimulated by falling Ca2+
in blood and inhibited by rising blood Ca2+
Stimulates osteoclasts to free Ca2+ from boneStimulates Ca2+ uptake
from intestine & kidney
Pancreas Consists of two major types
of secretory tissues which reflects its dual function › Exocrine gland
secretes digestive juice
› Endocrine gland releases hormones
Patches of pancreatic cells (Islets of Langerhans) secretes› Insulin from beta cells in
response to high blood glucose level
› Glucagon from alpha cells in response to low blood glucose level
Adrenal gland/ suprarenal gland
Triangular structure located at the top of kidney
Weight of each gland is 5gm Have two parts1. Adrenal medulla 2. Adrenal cortex Adrenal cortex produces three
kinds of steroid hormones Glucocorticoid(cortisol) Mineralocorticoid (aldosterone) Small amount of sex hormone
(Androgens).
Adrenal cortex Cortex› Activity stimulated by ACTH› Controls prolonged responses by
secreting corticosteroids.1. Glucocorticoid(Cortisol)
regulate glucose metabolism and the immune system.
2. Mineralocorticoids(Aldosterone) regulate salt and water balance
3. Gonad corticoids(Androgens)development of secondary sexual
characteristics in male like growth of facial hair and deepening of voice.
It is produced in both sexes and its excessive secretion in females causes masculinization i.e,appearance of beard
Adrenal Cortex Imbalances
Hyper secretion leads to Cushing’s Disease Weight gain Hypertension Reduced sex drive Diabetes Depression/inability to think clearlyHypo secretion leads to Addison’s DiseaseFatigue, weakness, loss of appetite Weight loss Gastrointestinal problems (nausea, vomiting, etc.) Darkening of the skin Low blood pressure and low blood sugar
Adrenal Medulla Medulla
› The adrenal medulla mediates short–term responses under the influence of sympathetic nervous system.
› It secretes two emergency hormones under stress conditions to bring about fight or flight response.
Epinephrine(adrenaline) increases blood glucose, heart
beat, breathing rate and metabolic rate.
directs blood to the heart, brain, and skeletal muscles.
Norepinephrine (noreadrenaline) Works like epinephrine Sustains blood pressure
Pancreas Homeostatic ImbalancesDiabetes
TYPE I Diabetes Beta cells are destroyed by
lymphocytes as a result of autoimmune disorder.
No insulin is produced.TYPE II (Diabetes mellitus) Insulin is produced Target cells lose insulin
receptors Excess glucose excreted in
urine As a result of fat
metabolism ketone bodies accumulates in bloodBlood Level Regulation in Diabetics
Thymus gland
It is present in the upper part of chest behind the breast bone.
It consists of two lobes that join infront of trachea.
It secretes a hormone, Thymosin, which stimulates the development and differentiation of T lymphocytes after they leave the thymus.
It plays a role in regulating the immune system by stimulating other kinds of immune cells.
Pineal gland It is a tiny cone-shaped
body located in diencephalon (fore brain)
It secretes Melatonin which› Influences growth and
development of gonads› Controls Day/night cycles› Timing of sleep, body
temperature, appetite› Participates in setting the
body’s clock
Gonads Ovaries
› Estrogens› Maintains female reproductive cycle› Development of secondary sexual characters› Progesterone› Preparation and maintenance of uterus for the
development of embryo Testes
› Testosterone› Stimulates bones and muscles growth› Development of secondary sexual characters