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.