19.3 Hormones of Heart, Kidney and Gastrointestinal Tract
Easy NEET Notes (Line-by-Line Explanation)
Introduction
Original Idea:
Some tissues other than endocrine glands also secrete hormones.
Easy Explanation:
- We usually study hormones secreted by endocrine glands like pituitary, thyroid, adrenal etc.
- But some other organs and tissues also produce hormones.
- These hormones help in regulating important body functions.
Hormones of Heart
Atrial Natriuretic Factor (ANF)
Line:
“The atrial wall of our heart secretes a peptide hormone called atrial natriuretic factor (ANF).”
Explanation:
- The atria are the upper chambers of the heart.
- Their walls produce a hormone called ANF.
- ANF is a peptide hormone (made of amino acids).
Function of ANF
Line:
“ANF decreases blood pressure.”
Explanation:
- ANF helps to lower high blood pressure.
- It maintains normal blood circulation.
Line:
“When blood pressure is increased, ANF is secreted which causes dilation of blood vessels.”
Explanation:
- When BP becomes high:
- Heart releases ANF.
- ANF relaxes and widens blood vessels.
- Widening of blood vessels is called vasodilation.
Result
Line:
“This reduces the blood pressure.”
Explanation:
- Wider blood vessels allow blood to flow easily.
- Hence blood pressure decreases.
NEET Quick Fact
- ANF → Secreted by atrial wall of heart
- Function → Lowers blood pressure
Hormones of Kidney
Erythropoietin (EPO)
Line:
“The juxtaglomerular cells of kidney produce a peptide hormone called erythropoietin.”
Explanation:
- Special kidney cells called juxtaglomerular cells produce EPO.
- EPO is also a peptide hormone.
Function
Line:
“Erythropoietin stimulates erythropoiesis (formation of RBC).”
Explanation:
- EPO stimulates bone marrow to make more RBCs.
- RBC = Red Blood Cells.
- RBCs carry oxygen in blood.
NEET Quick Fact
- Hormone → Erythropoietin (EPO)
- Source → Kidney
- Function → RBC formation
Hormones of Gastrointestinal Tract (GIT)
Introduction
Line:
“Endocrine cells present in different parts of the gastrointestinal tract secrete four major peptide hormones.”
Explanation:
- Digestive tract also contains hormone-secreting cells.
- These cells produce important digestive hormones.
Four Major GIT Hormones
- Gastrin
- Secretin
- Cholecystokinin (CCK)
- Gastric Inhibitory Peptide (GIP)
1. Gastrin
Line:
“Gastrin acts on gastric glands and stimulates secretion of hydrochloric acid and pepsinogen.”
Explanation:
- Gastrin acts on stomach glands.
- It increases:
- HCl secretion
- Pepsinogen secretion
Importance:
- HCl helps digestion and kills germs.
- Pepsinogen helps protein digestion.
NEET Quick Fact
- Gastrin → Stimulates HCl and pepsinogen secretion
2. Secretin
Line:
“Secretin acts on the exocrine pancreas and stimulates secretion of water and bicarbonate ions.”
Explanation:
- Secretin acts on pancreas.
- It increases release of:
- Water
- Bicarbonate ions (HCO₃⁻)
Importance:
- Bicarbonate neutralizes acidic food coming from stomach.
NEET Quick Fact
- Secretin → Increases bicarbonate-rich pancreatic juice
3. Cholecystokinin (CCK)
Line:
“CCK acts on both pancreas and gall bladder.”
Explanation:
- CCK affects:
- Pancreas
- Gall bladder
Function
Line:
“Stimulates secretion of pancreatic enzymes and bile juice.”
Explanation:
- Pancreas releases digestive enzymes.
- Gall bladder releases bile juice.
Importance:
- Helps digestion of fats, proteins, and carbohydrates.
NEET Quick Fact
- CCK → Stimulates pancreatic enzymes + bile release
4. Gastric Inhibitory Peptide (GIP)
Line:
“GIP inhibits gastric secretion and motility.”
Explanation:
- GIP slows down stomach activity.
- It reduces:
- Gastric juice secretion
- Stomach movements
Importance:
- Helps proper digestion and prevents overactivity of stomach.
NEET Quick Fact
- GIP → Inhibits stomach secretion and movement
Growth Factors
Line:
“Several other non-endocrine tissues secrete hormones called growth factors.”
Explanation:
- Many tissues produce growth factors.
- These are hormone-like substances.
Function
Line:
“These factors are essential for normal growth and repair/regeneration.”
Explanation:
- Growth factors help:
- Tissue growth
- Healing
- Repair of damaged tissues
19.4 Mechanism of Hormone Action
Hormone Receptors
Line:
“Hormones produce effects by binding to specific proteins called hormone receptors.”
Explanation:
- Hormones act only on target cells.
- Target cells have special proteins called receptors.
Important Point
- Hormone + Receptor = Response
Types of Receptors
1. Membrane-bound Receptors
Line:
“Receptors present on cell membrane are called membrane-bound receptors.”
Explanation:
- These receptors are present on cell surface.
- Mostly used by peptide hormones.
2. Intracellular Receptors
Line:
“Receptors present inside the target cell are called intracellular receptors.”
Explanation:
- Located inside cytoplasm or nucleus.
- Steroid hormones usually use these receptors.
Nuclear Receptors
Line:
“Mostly nuclear receptors (present in nucleus).”
Explanation:
- Many intracellular receptors are present in nucleus.
- They control gene activity.
Hormone-Receptor Complex
Line:
“Binding of hormone to receptor leads to formation of hormone-receptor complex.”
Explanation:
- Hormone joins receptor.
- Together they form a hormone-receptor complex.
Specificity of Receptors
Line:
“Each receptor is specific to one hormone only.”
Explanation:
- One receptor recognizes only one particular hormone.
- Like lock and key mechanism.
Final Effect
Line:
“Hormone-receptor complex formation leads to biochemical changes.”
Explanation:
- Complex activates chemical reactions inside cells.
- This changes metabolism and cell activity.
NEET Most Important Table
| Hormone | Source | Main Function |
|---|---|---|
| ANF | Heart atria | Lowers blood pressure |
| Erythropoietin | Kidney | RBC formation |
| Gastrin | Stomach | HCl & pepsinogen secretion |
| Secretin | Small intestine | Bicarbonate secretion |
| CCK | Small intestine | Pancreatic enzymes & bile release |
| GIP | Small intestine | Inhibits gastric activity |
Super Quick Revision
- ANF → decreases BP
- EPO → RBC formation
- Gastrin → ↑ HCl
- Secretin → ↑ bicarbonate
- CCK → ↑ pancreatic enzymes & bile
- GIP → inhibits stomach activity
- Hormones act through receptors
- Receptors are highly specific
 |
| Easy NEET notes explaining hormones of heart, kidney, gastrointestinal tract and mechanism of hormone action. |
CBSE Class 11 Biology Questions
Chapter: Hormones of Heart, Kidney & Gastrointestinal Tract + Mechanism of Hormone Action
Multiple Choice Questions (MCQs)
1. Atrial Natriuretic Factor (ANF) is secreted by:
A. Ventricle wall
B. Atrial wall
C. Kidney tubules
D. Liver cells
Answer:
B. Atrial wall
2. ANF helps in:
A. Increasing blood sugar
B. Increasing blood pressure
C. Decreasing blood pressure
D. RBC destruction
Answer:
C. Decreasing blood pressure
3. Erythropoietin is secreted by:
A. Liver
B. Pancreas
C. Kidney
D. Heart
Answer:
C. Kidney
4. Erythropoietin stimulates:
A. Digestion
B. Erythropoiesis
C. Ovulation
D. Milk secretion
Answer:
B. Erythropoiesis
5. Gastrin stimulates secretion of:
A. Insulin
B. Bile juice
C. HCl and pepsinogen
D. RBCs
Answer:
C. HCl and pepsinogen
6. Secretin acts on:
A. Gall bladder
B. Exocrine pancreas
C. Kidney
D. Heart
Answer:
B. Exocrine pancreas
7. Cholecystokinin (CCK) stimulates:
A. Insulin secretion
B. Pancreatic enzymes and bile juice
C. RBC formation
D. Blood clotting
Answer:
B. Pancreatic enzymes and bile juice
8. GIP inhibits:
A. RBC formation
B. Gastric secretion and motility
C. Blood pressure
D. Milk secretion
Answer:
B. Gastric secretion and motility
9. Hormone receptors are:
A. Lipids
B. Carbohydrates
C. Specific proteins
D. Enzymes only
Answer:
C. Specific proteins
10. Intracellular receptors are mostly present in:
A. Cell membrane
B. Cytoplasm only
C. Nucleus
D. Golgi body
Answer:
C. Nucleus
Very Short Answer Questions (1 Mark)
1. What is ANF?
Answer:
ANF is a peptide hormone secreted by the atrial wall of the heart that lowers blood pressure.
2. Name the hormone secreted by kidney that stimulates RBC formation.
Answer:
Erythropoietin.
3. What is erythropoiesis?
Answer:
Formation of red blood cells.
4. Name the hormone that stimulates bile secretion.
Answer:
Cholecystokinin (CCK).
5. What are hormone receptors?
Answer:
Specific proteins present on target cells that bind hormones.
Short Answer Questions (2–3 Marks)
1. Explain the role of ANF in blood pressure regulation.
Answer:
- ANF is secreted by the atrial wall of the heart.
- It is released when blood pressure increases.
- ANF causes dilation of blood vessels.
- This reduces blood pressure.
2. Write functions of erythropoietin.
Answer:
- Secreted by juxtaglomerular cells of kidney.
- Stimulates erythropoiesis.
- Increases RBC production in bone marrow.
- Helps in oxygen transport.
3. Differentiate between membrane-bound and intracellular receptors.
| Membrane-bound Receptors | Intracellular Receptors |
|---|---|
| Present on cell membrane | Present inside cell |
| Mostly bind peptide hormones | Mostly bind steroid hormones |
| Act through second messengers | Directly affect gene expression |
4. Write functions of gastrin and secretin.
Answer:
Gastrin:
- Stimulates HCl and pepsinogen secretion.
Secretin:
- Stimulates secretion of bicarbonate ions and water from pancreas.
Long Answer Questions (5 Marks)
1. Describe hormones secreted by gastrointestinal tract and their functions.
Answer:
The endocrine cells of gastrointestinal tract secrete four major peptide hormones:
1. Gastrin
- Acts on gastric glands.
- Stimulates secretion of HCl and pepsinogen.
2. Secretin
- Acts on exocrine pancreas.
- Stimulates secretion of water and bicarbonate ions.
3. Cholecystokinin (CCK)
- Acts on pancreas and gall bladder.
- Stimulates secretion of pancreatic enzymes and bile juice.
4. Gastric Inhibitory Peptide (GIP)
- Inhibits gastric secretion and motility.
These hormones regulate digestion efficiently.
2. Explain mechanism of hormone action.
Answer:
- Hormones act on target tissues through receptors.
- Receptors are specific proteins present on target cells.
- Hormones bind with receptors forming hormone-receptor complex.
- Receptors are of two types:
- Membrane-bound receptors
- Intracellular receptors
- Hormone-receptor complex causes biochemical changes in target cells.
- This changes metabolism and produces physiological response.
Assertion and Reason Questions
1.
Assertion (A):
ANF lowers blood pressure.
Reason (R):
ANF causes dilation of blood vessels.
Answer:
Both A and R are true and R is the correct explanation of A.
2.
Assertion (A):
Erythropoietin is secreted by kidney.
Reason (R):
It stimulates RBC formation.
Answer:
Both A and R are true and R is the correct explanation of A.
3.
Assertion (A):
GIP increases gastric motility.
Reason (R):
GIP inhibits gastric secretion.
Answer:
A is false but R is true.
4.
Assertion (A):
Hormone receptors are specific.
Reason (R):
One receptor binds only one hormone.
Answer:
Both A and R are true and R is the correct explanation of A.
Fill in the Blanks
- ANF is secreted by the ______ wall of heart.
Answer:
atrial
- Erythropoietin stimulates formation of ______.
Answer:
RBCs
- Gastrin stimulates secretion of ______ acid.
Answer:
hydrochloric
- Secretin stimulates secretion of bicarbonate ions from ______.
Answer:
pancreas
- Hormones bind with specific proteins called ______.
Answer:
receptors
Match the Columns
| Column A | Column B |
|---|---|
| 1. ANF | a. RBC formation |
| 2. Erythropoietin | b. Lowers blood pressure |
| 3. Gastrin | c. HCl secretion |
| 4. CCK | d. Bile secretion |
Answers:
1 → b
2 → a
3 → c
4 → d
Statement-Based Questions
1. Identify the correct statements:
- ANF increases blood pressure.
- EPO stimulates RBC formation.
- Secretin stimulates bicarbonate secretion.
- GIP increases gastric motility.
Options:
A. 1 and 2
B. 2 and 3
C. 1 and 4
D. 3 and 4
Answer:
B. 2 and 3
2. Which statements are correct regarding hormone receptors?
- They are specific proteins.
- Present only in blood.
- Intracellular receptors are often nuclear receptors.
- One receptor binds many hormones.
Answer:
Statements 1 and 3 are correct.
Case Study Questions
Case Study 1
A patient is suffering from high blood pressure. Doctors found increased secretion of a peptide hormone from the atrial wall of the heart.
Questions:
1. Name the hormone.
Answer:
ANF
2. What is its function?
Answer:
It lowers blood pressure by dilating blood vessels.
3. Which chamber of heart secretes this hormone?
Answer:
Atrium
Case Study 2
A person has low RBC count. Doctors observed deficiency of a kidney hormone.
Questions:
1. Name the hormone.
Answer:
Erythropoietin
2. What is its function?
Answer:
Stimulates RBC formation.
3. Which cells secrete it?
Answer:
Juxtaglomerular cells of kidney.
Important NEET/CBSE One-Liners
- ANF → decreases blood pressure
- EPO → stimulates erythropoiesis
- Gastrin → stimulates HCl secretion
- Secretin → increases bicarbonate secretion
- CCK → stimulates pancreatic enzymes and bile juice
- GIP → inhibits gastric secretion
- Hormone receptors are highly specific
- Hormone + receptor → hormone-receptor complex
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