Chemical Coordination And Integration

(A) Pineal- (ii)Melatonin

The pineal gland is a small endocrine gland attached to the roof of the third ventricle of the forebrain. The pineal gland secretes Melatonin which is an amine hormone.

(B) Thyroid-(iv). Tetraiodothyronine

Thyroid gland is the largest gland in the body which is located on either side of the trachea. It is composed of follicular cells which produce two hormones that are Thyroxin or Tetraiodothyronin(T₄) and Triiodothyronine(T₃).

(C) Ovary -(iii.) Estrogen

Ovary is the part of the female reproductive system which secretes various female hormones. Estrogen is one of them.

(D) Adrenal medulla- (i) Epinephrine

Adrenal medulla is a modified part of the sympathetic system. Two major types of hormones synthesized by this which are Epinephrine and Norepinephrine.

Oxytocin is the hormone which is not secreted by the anterior pituitary. Oxytocin is secreted by the posterior pituitary, it is responsible for uterine contractions at the time of child birth and also for the release of milk from the mammary gland.

Adrenalin and noradrenalin are the hormones which are secreted by the adrenal medulla. They are responsible for this restlessness because during emergency or stress conditions, these hormones increase the fight and flight responses. Hence they are also called emergency hormones. They tend to increase the heart rate as well as the blood pressure.

Aldosterone is a steroid hormone secreted by the adrenal cortex. Aldosterone is a mineralocorticoid which regulates homeostasis of mineral ions, namely sodium ions and potassium ions and helps in the maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure.

Thymosin is responsible for-

• Differentiation of T.lymphocytes

• Promote maturation of T.cells

Whereas other hormones are responsible for the other activities mentioned like

(a). Raising of blood sugar level glucagon is responsible (b). Raising of blood calcium level parathyroid gland is responsible

(d). Decrease in blood RBC: erythropoietin hormone

Generally first messenger is a hormone that causes the production of secondary messenger like-cAMP, cGMP ,Diacyl glycerol calcium etc.

Leydig cells produce a class of hormones called androgen. Leydig cells are present in connective tissue between the seminiferous tubules.

Corpus luteum secretes a hormone called progesterone which is a steroid hormone. It is responsible for the endometrium development.

Cortisol is a hormone which is secreted by adrenal gland. It helps in increasing glucose metabolism. While other mentioned glands produce other hormones like-

• Pancrease- Insulin , Glucagon.

• Thyroid-Triiodothyronne(T₃),Thyroxine(T₄),Calcitonin.

• Adrenal-Epinephrine,norepinephrine,glucocorticoids(cortisol),mineralocorticoids.

• Thymus- thymosin.

Melatonin appears to contribute to the setting of the body’s biological clock. More melatonin is produced in darkness as compare to light thus promoting sleep. Melatonin secretion increases up to 10 times during the night and then the level falls during the day. That’s how melatonin maintains the normal sleep-wake cycle.

Protein hormones bind to specific molecules that are located on plasma membrane to form a complex.

A. Epinephrine-( iv). Increases heart beat

Epinephrine during stress or emergency condition increases blood flow to the heart, liver, muscles etc which increases systolic blood pressure thus heart beat increases.

B. Testosterone-( i). Stimulates muscle growth

Testosterone is a male gonadal hormone. It stimulates muscular growth, facial hair etc. It has a protein called anabolic which promotes bone growth and that’s why more muscular physique in males.

C. Glucagon –(iii). Breakdown of liver glycogen content

Glucagon is a hormone secreted by pancreas which acts on hepatocytes to induce glycogenolysis and gluconeogenesis. It breakdown liver glycogen content to raise blood glucose level.

D. Atrialnatriuretic factor- (ii). Decrease in blood pressure

When blood flow increases to the atria of heart than it causes the release of Atrialnatriuretic factor. This factor causes vasodilationand thus decreases the blood pressure.

Thymosin is the hormone which is secreted by thymus gland and help in maturation and differentiation of T-lymphocytes or T-cells. While the other mentioned hormones Vitamin D, parathyroid hormone and thyrocalcitonin plays an important role in balancing the body calcium.

Liver is the largest gland of body. The structural and functional unit of liver is hepatic lobule, which is roughly hexagonal in shape. It is not divided into medullary and cortical region while the other mentioned options ovay, adrenal and kidney are divided into central meduallary and cortical region.

When the thyroid is deficient it causes the disease called hypothyroidism like cretinism, Goitre, Myxederma but Exophthalmosis is caused by Thyroid enlargement.

Ovaries are absent in male. It secretes different types of female hormones- estrogen, progesterone, inhibin and relaxin. Testes are absent in female. It secrete male sex hormone androgen, the principal of androgen is testosterone which stimulates spermatogenesis.

These are the layers of Adrenal gland. Zonaglomerulosa is outermost which envelop the other layers. Middle layer is Zona fasciculate and innermost layer is Zonareticularis.

• Outer layer -Zonaglomerulosa

• Middle layer-Zona fasciculate

• Inner layer- Zonareticularis

Formation of RBCs is called Erythropoisis. Erythropoitin hormone is responsible for erythropoiesis which is a glycoprotein hormone secreted by the kidney. The secretion of erythropoietin and production of RBCs is stimulated when the amount of oxygen is lower than normal.

Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH). Anterior pituitary consist of two portions that is pars ditalis and pars intermedia. Pars distalis secretes 6 hormones while pars intermedia secrete only one hormone called Melanocyte stimulating hormone.

Thyroid gland is endocrine gland which produce calcitonin hormone which is a peptide hormone and secreted by parafollicular cells of the thyroid gland. This hormone decreses the plasma calcium concentration by decreasing the movement of calcium from bones.

Thymosin

It helps in maturation of T- cells and differentiation of T-cells. It retards the aging process and plays an important role in regulating the immune system by stimulating other kinds of immune cells as well and also responsible for growth during childhood.

secondary messenger like cAMP acts as interacellular hormone which diliver the information as intracellular to the target cells. It activates the appropriate cellular enzyme system where the specific hormone stimulated responses takes place.

a. True

Reason:

• Gastrointestinal tract- gastrin, secretin, cholecystokinin(CCK) and gastric inhibitory peptide.

• Kidney- rennin, erythropoietin

• Heart- atrialnatriuretic factor.

b. True.

Reason:

1. Growth hormone

2. Prolactin

3. Thyroid stimulating hormone

4. Follicle stimulating hormone

5. Leuteinizing hormone

6. Adrenocorticotropic hormone

c. False

Reason:

T. lymphocytes provide cell mediated immunity and B- lymphocytes provide humoral immunity which is a type of adaptive immune system.

d. True

Reason:

Insulin is the hormone which is secreted by pancreas gland which control the amount of glucose in blood but in case of insulin resistance our body cells don’t respond normally to insulin and glucose can’t enter the cells and it build up in blood and leads to diabetes mellitus.

Doctor intends to measure vasopressin hormone because this hormone increases the reabsorption of water by the kidney and deficiency of this hormone decreases reabsorption of water and thus leads formation of excessive urine which results in constant thirst and low blood pressure.

(a) Insulin is a protein hormone.

(b) TSH is secreted from the anterior pituitary.

(c) Adrenaline is an emergency hormone.

(d) Adrenal gland is located on the anterior part of the kidney.

a-iv, b-i, c-ii, d-iii.

Explanation:

a. Oxytocin- (iv). Peptide

Oxytocin is a peptide hormone. Oxytocin is secreted by posterior pituitary gland and this hormone is responsible for secretion of milk from mammary gland.

b. Epinephrine- (i). Aminoacid derivative

Epinephrine is a amine hormone which is secreted by adrenal gland. This hormone is also known as emergency hormone which act during stress and emergency which increases the blood glucose level in body by increasing blood flow.

c. Progesterone- (ii). Steroid

Progesterone is a steroid hormone which is secreted by ovary. It is mainly female hormone which is responsible for pregnancy and is also known as pregnancy hormone.

d. Growth hormone- (iii). Protein

Growth hormone is a protein hormone which is secreted by hypothalamus which helps in regulating the body growth.

In males, LH stimulates the synthesis and secretion of hormone called Androgen from Testes. The principal of androgen is testosterone which stimulates the spermatogenesis and responsible for the growth and development of male accessory sex organs. Which stimulates

• muscle growth

• growth of facial hair

• axillary hair

• aggressiveness

• low pitch of voice

• bone growth

• muscle growth

In females LH induce ovulation, on the day of ovulation follicle repture and release secondary oocyte under the influence of LH. LH promotes the development of corpus luteum.

Hormone which have to interact with membrane bound receptor, do not bind itself for that it require secondary messenger like (cAMP) whichact as intracellular hormonal mediator which diliver the information inside the target cell. It activate the appropriate cellular enzyme system where the specific hormone stimulated responses takes place. Secondary messenger are cAMP, cGMP, diacyglycerol, inositoltriphosphate, phospoinositides, calcium etc.

(a) Goiter

Reason: when thyroid gland is enlarged it causes diseases Goiter which is due to overstimulation of thyroid gland. When thyroid gland stimulates excessive thyroid hormone that is TSH or TSI than it causes Goiter.

(b) It is caused due to the deficiency of iodine in the diet that results in hyperthyroidism and enlargement of the thyroid gland commonly called Goiter in which thyroid hormone hormone form excessively.

(c) Hypothyroidism during pregnancy causes-

• Defective development and maturation of the growing baby leads to stunted growth (cretinism)

• Mental retardation

• Low intelligence quotient

• Abnormal skin

Jet lag is a temporary sleep disorder among air travellers who rapidly travel across time zones. Jet lag occurs as a result of the slow adjustment of the body clock to the destination time. Melatonin is a hormone which is responsible for sleep-wake- cycle which is secreted by pineal gland and are stimulated by darkness and suppressed by light.Melatonin secretion increases up to 10-fold during the darkness of night and then fall to low levels during the light of day. Melatonin levels are higher in children and decline with age in adult. So melatonin is the hormone which is responsible for this biological system discomfort.

Cortisol is a steroid hormone which is secreted by adrenal cortex that produce anti- inflammatory responses and suppresses the immune response.

Functions of cortisolare:

• Stimulates gluconeogenesis

• Stimulates lipolysis and proteolysis

• Inhibit cellular uptake

• Helps in maintaining cardio-vascular system

• Helps in maintaining kidney function

• Stimulates RBCs production

Thymosin is a hormone secreted by thymus gland which play a major important role in development of immune system, but with the increasing age thymus gland degenerated or in the old people thymus gland starts to degenerate and thus thymosis hormone produce less, hence the old people have weak immune system.Thymosin is responsible for the differentiation maturation and development of T-lymphocytes and T-cells which provides cell- mediated immunity. So thymosin is the important hormone that play an important role in immune system but with age thymus gland starts to degenerate and thus old people have weak immune system.

Hypothyroidism during pregnancy causes-

• Defective development and stunted growth( cretinism).

• Mental retardation

• Low intelligence quotient.

• Abnormal skin

• Low concentration of blood calcium level.

• Neurons and muscle fibers depolarized

• Oxytocin hormone from pituitary gland is responsible for this response.

• Oxytocin hormone is protenious in nature.

• Oxytocin hormone is the hormone which stimulates the release of milk from the mammary gland by causing surrounding cells to contract.

• When the infant starts feeding breast stimulates the posterior pituitary to produce the oxytocin hormone and oxytocin hormone stimulates the milk secretion.

• Oxytocin also cause contraction of smooth muscles of uterus to expel the fetus outside the body of the mother.

• So on fondling by calf, the cow gave sufficient milk because calf touches activate the oxytocin hormone which it stimulates milk secretion.

a. Pancreas is the gland and hormone is Insulin which is responsible for this condition. Insulin is the hormone which decreases the level of glucose in blood by increasing the rate as which glucose is transported out of blood into the cell. When insulin is not produced adequately glucose uptake is hampered and hence glucose starts appearing in urine along with ketone bodies.

b. Hepatocytes and adipocytes cells are the main cells on which insulin act. Insulin allow muscles, liver and fat cells to take up this glucose.

c. This condition causes diabetes mellitus. Diabetes mellitus is a condition in which the body does not produce enough insulin hormone which results high level of sugar in blood.

It can be controlled and treated by managing following parameters:

• Keep blood glucose level near to normal.

• Maintain cholesterol and triglyceride level near to normal level.

• Maintain normal blood pressure.

• Insulin pills injections should be taken to maintain insulin level.

• Gene therapy is required if needed.

• Thyroid gland and parathyroid gland are responsible for maintaining calcium homeostasis.

• Both of the glands are antagonist with each other.

• As Calcitonin which is peptide hormone secretes from thyroid gland response to high calcium level in the blood.

• Calcitonin decreases plasma calcium concentration by decreasing mobilization of calcium from bones.

• Whereas parthyroid gland which secretes parathyroid hormone increases calcium level in blood.

• Bone tissue acts as astrongreservoiur for calcium and PTH stimulates the removal of calcium from bone to increase level in blood.

• It increases the reabsorption of calcium by renal tubules of kidney.

• PTH is a hypercalcemic hormone. i.e it increases the blood calcium level.

Fig: show the difference between the mechanism of action of a protein and steroid hormone.

Hypothalamus is a super master endocrine gland as it secretes hormones that regulate the synthesis and secretion of pituitary gland which is master gland. The hypothalamus is connected to the anterior lobe of pituitary gland by hypophysial portal veins. The hormones secreted by hypothalamus are:

1.) Adrenocorticoicotropic releasing hormone (ARH) or corticotrophin releasing hormone- It stimulates the anterior lobe of the pituitary gland to secrete its adrenocortiotropic hormone (ACTC)

2.) Growth hormone releasing hormone (GHRH)- It stimulates the anterior lobe of the pituitary gland to release its growth hormone.(GH)

3.) Thyrotropin releasing hormone (TRH)- It stimulates the anterior lobe of pituitary gland to secrete its thyroid stimulating hormone (TSH) or thyrotropin.

4.) Growth hormone inhibitory hormone (GHIH)-This hormone is called somatostatin (SS). It inhibits the secretion of growth hormone from the anterior lobe of the pituitary gland.

5.) Gonadotropin releasing hormone (GnRH)- It stimulates the anterior lobe of the pituitary gland to secret two gonadotropic hormone. Follicle stimulating hormone and luteinising hormone (LH).

6.) Prolactin inhibitory hormone (PIH)-It inhibits the secretion of prolactin from the anterior lobe of pituitary gland.

7.) Prolactinrelasing hormone (PRH)- It stimulates the anterior lobe of the pituitary gland to secrete its prolactin hormone.

8.) MSH releasing hormone (MSHRH) – It stimulates the intermediate lobe of the pituitary gland to secrete its melanocyte stimulating hormone (MSH).

9.) MSH Inhibitory hormone (MSHIH)- It inhibits the secretion of melanocytes stimulating hormone from the intermediate lobe of the pituitary gland.