Endocrine Glands
1.
Glands are of two types- Exocrine glands
and Endocrine glands.
.Exocrine
glands are duct (having tube) glands- secrete enzymes.
.Endocrine
glands are ductless (tube lacking) glands secrete enzymes.
2.
Hormones are
chemical messengers which are produced at one part of our body and have
influence at some other parts (target organs) of our body.
Characteristics of hormones:
1.
Hormones are always poured or secreted into
blood by endocrine glands.
2.
Hormones always act away from the source of
their secretion.
3.
Hormones are produced in trace quantity but they have wide influence all over our body.
4.
Same hormone produced in different species
will have the same influence.
5.
Hormones cannot be stored in our body but will be excreted after their action.
6.
Hormones regulate physiological process by
chemical means.
7.
Chemically hormones are peptides (insulin),
amine (adrenaline), steroids (testosterone).
8.
Secretion of a hormone less (hypo/under
secretion) or more (hyper/over secretion) leads to some defects in the body.
1.
THYROID GLAND:
Location:
A butterfly shaped gland present below larynx and above
trachea. The two wings of thyroid gland are connected by a bridge like region
called isthmus.
Hormones
secreted: Thyroxine and Calcitonin
Principal
activities of Thyroxine hormone:-
1. Regulate
basal metabolism ( Cellular oxidation resulting in heat production).
2. It
influences general growth of the body, ossification of bones, mental
development and body heat content.
Hypo secretion or under
secretion (Hypothyroidism) of this hormone leads to three defects.
a.
Simple Goiter: Thyroid gland present
below the neck region become swollen.
Symptom: Abnormal
swelling of thyroid gland present below the neck region.
Reason: Lack of iodine
in diet. Iodine helps in the synthesis of thyroxine hormone by thyroid gland.
People live in hilly
plains most commonly suffer from this defect due to iodine gets leached away
from the sloppy soils. Hence the food produced from these crops lack iodine
mineral.
b.
Cretinism: It is a defect caused in child
or at infancy.
Symptoms: Dwarfism, Mental
retardation.
c.
Myxoedema: disease caused in old people. Person become
sluggish. Swelling can be Iseen in face and hands.
Over secretion /Hyper
secretion (Hyperthyroidism) leads to Exophthalmic Goiter.
Symptoms: 1. Eyes
protrude out.
2.
Metabolic and heart beat rate increases.
3.
Shortness of breath
4.
Goiter in the neck.
2.PANCREAS:
This gland acts as both
exocrine and endocrine gland. Pancreas is present below the stomach
region. Pancreas as an exocrine gland it secret enzymes and as an endocrine
gland secrete hormones. Patches of endocrine cells present in pancreas together
known as Islets of Langerhans.
a.
Beta cells of Islets of Langerhans secret Insulin.
Principal activities of
Insulin hormone:
1.
Insulin promotes proper utilization of
glucose by our body cells.
2.
Insulin converts excess glucose present
in blood to glycogen and store it in liver.
b.
Alpha cells of Islets of Langerhans secret Glucagon.
Glucagon converts
glycogen present in liver to glucose and put into blood circulation.
c.
Delta cells of Islets of Langerhans
secrete Somatostatin. This hormone control secretions of both insulin and
glucagon hormones.
