BIOLOGY 1 Marks Question

Goitre is characterised by an abnormal enlargement of the thyroid gland due to the deficiency of thyroxin hormone in the body.

Parathyroid: The parathyroid gland secretes a hormone known as the parathyroid hormone.

Atrium: The walls of the atrium secrete atrial natriuretic factor.

Androgens: It regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra etc. Androgens mainly testosterone stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice etc. It stimulates spermatogenesis and formation of mature sperms and also influences male sexual behaviour. These hormones also produce synthetic effects on protein and carbohydrate metabolism.

Pancreas: Hormones secreted by the pancreas are insulin and glucagon.

Ovary: The hormone secreted by the ovary includes estrogen and progesterone.

Hormones	Target gland
Corticotrophin (ACTH)	Adrenal.

Hormones	Target gland
Gonadotrophins (LH, FSH)	Ovary, Testis.

Thyroid: The thyroid gland secretes three hormones namely, thyroxin, triiodothyronin, and calcitonin.

Hormones	Target gland
Thyrotrophin (TSH)	Thyroid.

Testis: The hormone secreted by the testis is testosterone.

Kidney: The hormone secreted by kidney is erythropoietin.

Progestational hormone: Progesterone.

Cretinism is characterized by stunted growth in the baby due to the deficiency of thyroid hormone in the body.

Insulin and Glucagon: These hormones are secreted by pancreas and helps in regulation of glucose level in body. Insulin plays a major role in the regulation of glucose homeostasis. It acts mainly on hepatocytes and adipocytes (cells of adipose tissue), and enhances cellular glucose uptake and utilisation. It also stimulates conversion of glucose to glycogen (glycogenesis) in the target cells. Glucagon plays an important role in maintaining the normal blood glucose levels. Glucagon acts mainly on the liver cells (hepatocytes) and stimulates glycogenolysis resulting in an increased blood sugar (hyperglycemia). It also stimulates the process of gluconeogenesis which also contributes to hyperglycemia.

Thymus: Hormones secreted by the thymus are thymosins.

Hypercalcemic hormone: Parathormone hormone (PTH)

Gonadotropic hormones: Luteinising hormone (LH) and follicle-stimulating hormone (FSH)

Estrogens: It produce wide ranging actions such as stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development. Estrogens also regulate female sexual behaviour.

Thymosins: It play a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. It also promotes production of antibodies to provide humeral immunity.

Hyperglycemic hormone: Glucagon. Hypoglycemic hormone: Insulin.

Blood pressure-lowering hormone: Atrial natriuretic factor (ANF)

Hormones	Target gland
Hypothalamic hormones	Pituitary.

Androgens: Testosterone and androsterone. Oestrogens: β-oestradiol.

Diabetes mellitus is characterized by abnormally high glucose levels in the blood due to the deficiency of hormone, called insulin.

G-I tract: The hormones secreted by the G-I tract are Gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP).

Hormones	Target gland
Melanotrophin (MSH)	Melanocyte.

Insulin is a hypoglycemic hormone, as:

1. It stimulates uptake and utilisation of glucose by hepatocytes and adipocytes.
2. It stimulates glycogenesis, i.e. conversion of glucose into glycogen

The nerve fibres do not innervate all cells of the body, but the cellular functions need to be continuously regulated; hence, coordination by endocrine system is necessary.

1. Gluconeogenesis is the process of formation of glucose from fatty acids.
2. Glucagon and glucocorticoids stimulate it.

Oestrogen secreted by granulosa cells of developing ovarian follicle.

Pancreas; Islets of Langerhans.

It is a form of hyperthyroidism. Enlargement of thyroid gland, protrusion of eyeballs, increased basal metabolic rate and weight loss are its symptoms.

Atrial wall of human heart secretes a peptide hormone called atrial natriuretic factor which decreases blood pressure by dilation of the blood vessels.

Erythropoiesis is the process of red blood cells formation or production (erythro = red, poiesis = to form). It occurs almost exclusively in the red bone marrow. When blood oxygen drops, kidneys produce ERYTHROPOIETIN, a hormone which stimulates erythropoiesis, and speeds red blood cells formation. Presence of more red blood cells = more oxygen-carrying capacity. It has been seen that athletes use commercial erythropoietin or EPO to stimulate RBC production and improve their performance.

Hormones are defined as non-nutrient chemicals, which are produced in trace quantities and act as intercellular messengers.

Melanocyte stimulating hormone:

1. It is synthesised in the pars intermedia of adenohypophysis.
2. It acts on the melanocytes of skin and regulates the pigmentation of the skin.

Glycogen concentration decreases as it is broken into glucose.

Androgen (testosterone).

Sella tursica.

Glycogen concentration decreases as adrenalins stimulates glycogenolysis, i.e., breakdown of glycogen into glucose.

Underproduction of hormones by the adrenal cortex alters carbohydrate metabolism. This leads to acute weakness and fatigue. This is called Addison's disease.

Hypothalamus, neurosecretory cells or nuclei.

Cortisol and testosterone are chemically steroid in nature.

Adrenaline and noradrenaline are secreted in response to emergency situations. They help prepare the body to fight with emergency. Hence, they are also called as emergency hormones.

Melatonin maintains circadian rhythm of the body.

By stimulating the breakdown of glycogen.

1. Follicle-stimulating hormone.
2. Luteinizing hormone.

Epinephrine.

Thyrocalcitonin (TCT).

Since ADH stimulates the reabsorption of water and electrolytes by the distal tubules and thereby prevents diuresis i.e., excess loss of water in urine, it is also known as antidiuretic hormone.

Tetraiodothyronin and Triiodothyronine.

Progesterone supports pregnancy and helps in formation of alveoli in mammary glands for storage of milk.

Doctor intends to measure vasopressin hormone. This hormone increases the reabsorption of water by the kidney. Deficiency of this hormone decreases the reabsorption of water and thus leads to formation of excessive dilute urine resulting in constant thirst and low blood pressure.

Corticotropin.

1. Glucagon is a hyperglycemic hormone as it increases the level of blood glucose, i.e. hyperglycemic by:

1. Stimulating glycogenalysis (breakdown of glycogen) in the liver cells.
2. Stimulating gluconeogenesis.
3. Reducing the cellular uptake and utilization of glucose.

2. Prolonged hyperglycemia leads to diabetes mellitus.

It is manifested as:

1. Loss of glucose in the urine.
2. Formation of certain harmful compounds, called ketones, which are also excreted is the urine.

• Outer layer - Zona glomerulosa
• Inner layer - Zona reticularis

1. ANF is secreted from the atrial wall of the heart.
2. It reduces blood pressure by widening the lumen of arteries.

Cortisol is responsible for the suppression of immune response. Chemically it is a steroid.

1. Follicle stimulating hormone from anterior pituitary.
2. Luteinising hormone from anterior pituitary.
3. Catecholamines (adrenaline and nor-adrenaline) from adrenal medulla)
4. Aldosterone (a mineralocorticoid) from adrenal cortex.
5. Cholecystokinin from gastrointestinal tract.

CAMP, DG and IP, act as secondary messengers in hormone action.

Melatonin; pineal gland.

Deficiency in the secretion of vasopressin (ADH) leads to the disorder known as diabetes insipidus.

Mineralocorticoids.

Somatostatin inhibits the secretion of growth hormone from anterior lobe of pituitary gland.

Hormones produced by some non-endocrine tissues are called growth factors.

Progesterone.

Ovaries are absent in male and testes are absent in female.

Heart produces Atrial Natriuretic Factor (ANF) which promotes renal sodium excretion and lowers blood pressure.

Nuclear receptor (present inside the nucleus of a cell) acts as intracellular hormone receptor.

Thyroid gland is the largest endocrine gland and pituitary gland is the smallest endocrine gland.

Diabetes mellitus.

Pancreas.

Any substance, usually of hypothalamic origin, capable of accelerating the rate of secretion of a given hormone by the anterior pituitary gland.

Thymosin.

As the nerve fibres do not innervate all the cells of the body and cellular functions need to be regulated in a continuous manner. So, to regulate this, coordination, endocrine system (chemical and hormonal coordination) is necessary.

Hypothalamus.

1. The two regions of the adenohypophysis are:

• Pars distalis.
• Pars intermedia.

2. Pars distalis secretes growth hormone, follicle stimulating hormone, prolactin, etc.
3. Pars intermedia secretes only one hormone, melanocyte-stimulating hormone (MSH).

Since they are secreted in response to stress of any kind and emergency situation, they are called emergency hormones.

Second messenger regulates the metabolism of a cell, which results in many physiological effects.

Second messenger (e.g. cAMP) acts as intracellular hormonal mediator delivering information inside the target cells. This activates appropriate cellular enzyme system by cascade effect which stimulates the cell machinery to perform its specialized function.

Cortisol. It is a steroid.

Vasopressin.

1. It is the disorder caused by the underproduction of aldosterone and glucocorticoids by adrenal cortex.
2. The carbohydrate metabolism is affected leading to extreme weakness and fatigue.

Diabetes insipidus; it is caused by deficiency of vasopressin.

Dwarfism.

The hormone responsible for diurnal rhythm of our body is melatonin. The source of its secretion is pineal gland.

If a young tadpole is injected with thyroxine hormone, it will lead to metamorphosis due to which it develops into a complete young frog.

Hepatocytes (liver cells) and adipocytes (cells of adipose tissue).

Hyperglycemia refers to an increased level of blood glucose; it leads to diabetes mellitus.

1. The hypothalamic hormones reach the anterior pituitary through a portal circulation.
2. The hormone to the posterior pituitary pass through the axons and are stored in the axon terminals.

Melanocyte stimulating hormone (MSH)

1. Pars intermadia.
2. Prolactin.

1. Gigantism.
2. Acromegaly.

Parathyroid hormone.

Thyroid gland also secretes a protein hormone called thyrocalcitoni’n (TCT) which regulates the blood calcium levels. TCT is secreted by ‘C’ cells of thyroid glands. TCT is a hypocalcaemic hormone which lower the blood calcium level by increasing calcium deposition in the bones, so checks osteoporosis.

Thyrocalcitonin; it is secreted by the parafollicular cells of thyroid.

Adreno-corticotropic hormone.

1. Sella tursica.
2. Somatostatin.

Deficiency of ADH can lead to diminished ability of the kidney to conserve water leading to water loss and dehydration. This disease is known as Diabetes insipidus.

Pituitary gland.

Testosterone hormone is responsible for urge of sex in males.

The corticoids secreted by adrenal cortex which regulate the carbohydrate metabolism of the body, are called glucocorticoids, e.g. cortisol.