NCERT Class 11 Biology Chapter 22 Notes Chemical Coordination And Integration- Download PDF Notes

NCERT Class 11 Biology Chapter 19 Notes Chemical Coordination and Integration discuss the control of physiological processes in the human body through hormones. These NCERT notes offer a well-structured and compact summary of important concepts such as endocrine glands, hormones, modes of action, feedback control, and the functions of the hypothalamus, pituitary, thyroid, adrenal, pancreas, and gonads in homeostasis.

New: Get up to 90% Scholarship on NEET/JEE Coaching from top Coaching Institutes

NEET Scholarship Test Kit (Class 11): Narayana | Physics Wallah | Aakash | ALLEN

Browse: NEET papers with solutions | Most scoring concepts for NEET

This Story also Contains

1. NCERT Class 11 Biology Chapter 19 Notes
2. Most Important Questions Class 11 Biology Chapter 22 Chemical Coordination And Integration
3. Approach to Solve Questions of Class 11 Biology Chapter 22
4. Chapter-Wise NCERT Class 11 Notes Biology

These NCERT Class 11 Biology Notes break down complicated topics in an easy-to-understand format and are perfect for rapid revision before CBSE Board exams and competitive exams such as NEET. Students can effectively solidify their concepts using NCERT Solutions and downloadable PDF notes. For better learning, download the NCERT Notes for Class 11 Chapter 19 PDF and learn anywhere, anytime.

Also, students can refer to:

• NCERT Solutions for Class 11 Biology Chapter 22 Chemical Coordination and Integration
• NCERT Exemplar for Class 11 Biology Chapter 22 Chemical Coordination and Integration

NCERT Class 11 Biology Chapter 19 Notes

To maintain homeostasis and to regulate various functions of the body, the nervous system, as well as the endocrine system, plays a very important role. Both the systems control and coordinate at different parts of the body, however, there are some basic differences. The nervous system acts rapidly in a fraction of a second but its response in a muscle lasts for only a few milliseconds. On the other hand, the hormones released from the endocrine system take much more time.

Endocrine Glands And Hormones

• Endocrine glands are called ductless glands since they do not have ducts.
• The secretions of these ductless glands are known as hormones.
• These hormones are produced only in small amounts in the human body to facilitate many functions like transport between cells.
• They function as intracellular messengers.

Human Endocrine System

The endocrine glands constitute the endocrine system.

Fig.1.1 Location of Endocrine Glands

The Hypothalamus:

It forms the basal part of the diencephalon, the forebrain. The hypothalamus has nuclei. It contains neurosecretory cells called nuclei, which produce hormones. The function of the nuclei is the regulation of the secretions of pituitary hormones. Hormones of the hypothalamus are:

1. Releasing hormones: It stimulates the secretions of pituitary hormones.

2. Inhibiting hormones: It inhibits the secretions of pituitary hormones.

The Pituitary Gland

• It is present in sella tunica ( bony cavity ) and is attached to the hypothalamus by a stalk (Figure 1.2).

Fig.1.2. Representation of Pituitary and Hypothalamus

It is classified into adenohypophysis and neurohypophysis. The adenohypophysis has two portions, pars distalis, and pars intermedia. The major features are discussed below:

1. The pars distalis region produces several hormones like growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH).

2. Melanocyte stimulating hormone ( MSH ) is produced by Pars intermedia.

• Oxytocin and vasopressin are stored and released by neurohypophysis.

• Hyper-secretion of GH causes gigantism(abnormal growth of the body) and lower secretion of GH results in pituitary dwarfism(stunted growth).

• Oxytocin causes vigorous contraction of the uterus at the time of childbirth. It also causes milk ejection from the mammary gland.

• Vasopressin( antidiuretic hormone) acts in the kidney. It helps in the reabsorption of water and electrolytes by the distal tubules and hence reduces the loss of water through urine (diuresis).

• A disorder affecting the synthesis or release of ADH causes water loss and dehydration. It is called Diabetes Insipidus.

The Pineal Gland

• It is present on the dorsal side of the forebrain and secretes melatonin which helps in the regulation of a 24-hour (diurnal) rhythm of our body.

The Thyroid Gland

• The thyroid gland consists of two lobes that are present on either side of the trachea (Figure 1.3).

• Isthmus is the point of interconnection between two lobes (a thin flap of connective tissue).

• The thyroid gland synthesizes two hormones, tetraiodothyronine or thyroxine (T4 ) and triiodothyronine (T3 ).

• Iodine deficiency results in hypothyroidism and enlargement of the thyroid gland commonly called goitre.

• Hypothyroidism causes stunted growth (cretinism) and mental retardation.

Fig.1.3 Diagrammatic View of Position of Thyroid Gland

Parathyroid Gland

• Parathyroid glands are four in number.

• They are present on the backside of the thyroid gland.

• The parathyroid glands secrete parathyroid hormone (PTH) which is a peptide hormone.

• Its secretion is controlled by the circulating levels of calcium ions.

• PTH stimulates the process of bone dissolution/ demineralisation.

Fig.1.4. Diagrammatic View of Position of Parathyroid Gland

Thymus

• It is a lobular structure present between the lungs behind the sternum

• It helps in the development of the immune system and secretes the peptide hormones called thymosins which helps in the differentiation of T-lymphocytes.

Adrenal Gland

• There is a pair of adrenal glands at the anterior part of each kidney (Figure 1.5 a).

• The gland consists of two types of tissues. The centrally located tissue is called the adrenal medulla, and the outside adrenal cortex is present. (Figure 1.5 b).

• The deficiency of hormones causes acute weakness and fatigue leading to a disease called Addison’s disease.

Figure 1.5 Diagrammatic Representation of (a) Adrenal Gland Above Kidney (b) Section Showing Two Parts of The Adrenal Gland

• The adrenal medulla synthesizes two hormones adrenaline/epinephrine and noradrenaline/ norepinephrine. These are commonly called catecholamines.

• Adrenaline and noradrenaline are called emergency hormones or hormones of Fight or Flight because they are secreted in response to stress emergencies.

Pancreas

• The pancreas is a mixed gland (Figure 1.1) that acts as both exocrine and endocrine glands.

• The endocrine part is called ‘Islets of Langerhans’.

• α-cells and β-cells are types of cells in the Islet of Langerhans The α-cells produce glucagon, while the β-cells secrete insulin.

Testis

• One pair of the testis is present in the scrotal sac in males.

• It acts as a primary sex organ and an endocrine gland.

• It contains seminiferous tubules and stromal or interstitial tissue.

• Leydig cells or interstitial cells are present in the intertubular spaces that produce androgens, mainly testosterone.

• Androgens maintain the functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, etc., and promote muscular growth, growth of axillary and facial hair, low pitch of voice, etc.

Ovary

• A pair of ovaries are located in the abdomen in females (Figure 1.1).

• It is the primary female sex organ.

• It produces two groups of steroid hormones called estrogen and progesterone.

• Estrogens regulate female sexual behaviour and progesterone supports pregnancy.

Hormones of Heart, Kidney, and Gastrointestinal Tract

• The heart contains an atrial wall that produces a hormone called atrial natriuretic factor (ANF). ANF causes dilation of the blood vessels, which decreases blood pressure.

• Erythropoiesis is stimulated by erythropoietin, which is the juxtaglomerular cells of the kidney.

• Gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide(GIP) are the four major types of peptide hormones secreted by endocrine cells of the GI tract.

• Many other non-endocrine tissues secrete hormones called growth factors, which are important for the normal growth of tissues and their repair/regeneration.

Mechanism of Hormone Action:

• When a hormone binds to its receptor, it forms a hormone-receptor complex (Figure 1.6a, b).
• Hormone-receptor complex formation leads to the development of certain biochemical changes in the target tissue.
• Hormones can be classified into different groups based on their chemical nature:

(i) Peptide, polypeptide, protein hormones - insulin, glucagon, pituitary hormones, hypothalamic hormones, etc.

(ii) Steroids - cortisol, testosterone, estradiol, and progesterone

(iii) Iodothyronines- thyroid hormones

(iv) Amino-acid derivatives - epinephrine.

Subject-Wise NCERT Exemplar Solutions

• NCERT Exemplar Class 11 Solutions
• NCERT Exemplar Class 11 Maths
• NCERT Exemplar Class 11 Physics
• NCERT Exemplar Class 11 Chemistry
• NCERT Exemplar Class 11 Biology

Figure 1.6 Representation of The Mechanism of Hormone Action

Most Important Questions Class 11 Biology Chapter 22 Chemical Coordination And Integration

This chapter focuses on the endocrine system, hormones, and their roles in regulating physiological processes. Below are key MCQS with explanations to help grasp critical concepts.

Q1. Which gland secretes the hormone that regulates calcium and phosphorus metabolism?
A. Thyroid
B. Parathyroid
C. Adrenal
D. Pancreas

Answer:
The parathyroid gland secretes parathyroid hormone (PTH), which regulates calcium and phosphorus levels in the blood.
Hence, the correct option is B. Parathyroid

Q2. Where is the pineal gland located?
A. Base of the brain
B. Neck region
C. Abdomen
D. Thoracic cavity

Answer:
The pineal gland is located at the dorsal side of the forebrain (epithalamus) and secretes melatonin to regulate circadian rhythms.
Hence, the correct option is A. Base of the brain

Q3. Which hormone is secreted by the adrenal medulla?
A. Cortisol
B. Aldosterone
C. Epinephrine
D. Thyroxine

Answer:
The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine, which trigger the "fight or flight" response.
Hence, the correct option is C. Epinephrine

Q4. What is the primary function of glucagon?
A. Lowers blood glucose
B. Raises blood glucose
C. Regulates calcium levels
D. Promotes protein synthesis

Answer:
Glucagon, secreted by pancreatic alpha cells, increases blood glucose by stimulating glycogen breakdown in the liver.
Hence, the correct option is B. Raises blood glucose

Q5. Which hormone deficiency causes diabetes insipidus?
A. Insulin
B. Glucagon
C. Vasopressin (ADH)
D. Oxytocin

Answer:
Vasopressin (ADH) deficiency leads to diabetes insipidus, causing excessive urination and thirst.
Hence, the correct option is C. Vasopressin (ADH)

Q6. Which gland is called the "master gland"?
A. Hypothalamus
B. Pituitary
C. Thyroid
D. Adrenal

Answer:
The pituitary gland controls other endocrine glands and is termed the "master gland".
Hence, the correct option is B. Pituitary

Q7. What distinguishes exocrine glands from endocrine glands?
A. Presence of ducts
B. Hormone secretion
C. Location in the body
D. Size of the gland

Answer:
Exocrine glands (e.g., salivary glands) have ducts, while endocrine glands (e.g., thyroid) release hormones directly into the bloodstream.
Hence, the correct option is A. Presence of ducts

Q8. Which hormone is responsible for uterine contractions during childbirth?
A. Prolactin
B. Oxytocin
C. Estrogen
D. Progesterone

Answer:
Oxytocin, secreted by the posterior pituitary, stimulates uterine contractions and milk ejection.
Hence, the correct option is B. Oxytocin

Q9. What is the role of melatonin?
A. Regulates blood pressure
B. Controls sleep-wake cycles
C. Stimulates growth
D. Manages stress response

Answer:
Melatonin, secreted by the pineal gland, regulates circadian rhythms (sleep-wake cycles).
Hence, the correct option is B. Controls sleep-wake cycles

Q10. Which disorder results from hypothyroidism in adults?
A. Cretinism
B. Myxedema
C. Graves’ disease
D. Addison’s disease

Answer:
Myxedema is caused by hypothyroidism in adults, leading to fatigue, weight gain, and cold intolerance.
Hence, the correct option is B. Myxedema

Subject Wise NCERT Solutions

• NCERT Solutions for Class 11 Mathematics
• NCERT Solutions for Class 11 Chemistry
• NCERT Solutions for Class 11 Physics

• NCERT Solutions for Class 11 Biology

Approach to Solve Questions of Class 11 Biology Chapter 22

To answer Chemical Coordination And Integration questions well, adopt this easy-to-follow approach:

1. Understand the function of endocrine glands and hormones in controlling body functions.
2. Learn about the functions and sources of key hormones such as insulin, thyroxine, and adrenaline.
3. Compare neural and hormonal control about speed and duration.
4. Learn about the action of protein and steroid hormones on target cells.
5. Practice sketching endocrine glands and hormone feedback mechanisms from the NCERT.

Chapter-Wise NCERT Class 11 Notes Biology