Chapter 12: The Muscular System & Digestive System in Human Beings
1) 20 Important Words & Meanings (Meanings only in Hindi)
Muscleसिकुड़ने-ढीला होने वाली रेशों की गठान, जो हरकत कराती है।
Tendonमजबूत रेशेदार पट्टी जो मांसपेशी को हड्डी से जोड़ती है।
Ligamentरेशेदार ऊतक जो दो हड्डियों को जोड़कर जोड़ (joint) बनाता है।
Skeletal Muscleहड्डियों से जुड़ी स्वैच्छिक (इच्छानुसार) मांसपेशी।
Smooth Muscleआंत, रक्तवाहिनी जैसी भीतरी अंगों की धीमी, अनैच्छिक मांसपेशी।
Cardiac Muscleहृदय की मांसपेशी जो लगातार स्वतः धड़कती है।
Bicepsऊपरी भुजा के आगे का मांसपेशी समूह जो कोहनी मोड़ता है।
Tricepsऊपरी भुजा के पीछे का मांसपेशी समूह जो कोहनी सीधी करता है।
Postureशरीर की बैठने-खड़े होने की सही स्थिति।
Digestionखाद्य का घुलनशील व सरल रूप में बदलना व रक्त में अवशोषण।
Alimentary Canalमुख से गुदा तक भोजन चलने वाली लंबी नली।
Peristalsisग्रासनली/आंत की धीमी तरंगीय हरकत जो भोजन आगे बढ़ाती है।
Enzymeरासायनिक क्रिया तेजी से कराने वाला प्रोटीन (उत्प्रेरक)।
Ptyalin (Salivary Amylase)लार का एन्जाइम जो स्टार्च को माल्टोज़ में बदलता है।
Bileयकृत (लिवर) का रस; वसा को छोटे कणों में तोड़ता है।
Pancreatic Juiceअग्न्याशय का रस जिसमें ट्रिप्सिन, लाइपेस, एमाइलेज होते हैं।
Villiछोटी आंत की उंगली जैसे उभार, जिनसे भोजन का अवशोषण होता है।
Acidityअम्ल (HCl) अधिक बनने से पेट में जलन/खट्टी डकार की समस्या।
Addictionहानिकारक पदार्थों की आदत जो स्वास्थ्य बिगाड़ती है।
Appendixबड़ी आंत के आरंभ से जुड़ा छोटा भाग; पाचन के लिए जरूरी नहीं।
2) Important Notes (Quick Revision)
- Muscles are bundles of fibres that contract & relax to create movement, posture and body shape; >600 muscles form ~40% of adult body mass.
- Attachment: Muscles are attached to bones via tendons; movement occurs at joints when one group contracts and the opposite group relaxes (e.g., biceps & triceps).
- Control: Voluntary muscles (skeletal) work by will; Involuntary muscles (smooth & cardiac) work automatically for vital functions (breathing, circulation, digestion).
- Types: Skeletal (voluntary, body movement); Cardiac (heart, involuntary, ~$70\\ \\text{beats/min}$); Smooth (stomach, intestine, vessels—slow, involuntary).
- Care: Strong, efficient muscles need protein + carbohydrate rich diet, regular exercise, and correct posture to avoid vertebral/muscle problems.
- Digestion = conversion of food to soluble form and absorption into blood. Alimentary canal length ~$\\approx 9\\ \\text{m}$.
- Main parts: Mouth → Pharynx → Oesophagus → Stomach → Small intestine (~$6\\ \\text{m}$) → Large intestine (~$1.5\\ \\text{m}$) → Rectum → Anus; glands: Salivary glands, Liver (bile), Pancreas (pancreatic juice).
- Teeth: Incisors (cut), Canines (tear), Premolars & Molars (grind). Enamel is hard (calcium salts).
- Key juices & roles: Saliva—ptyalin converts starch → maltose; Gastric juice—HCl (acidic), pepsin (proteins), mucus (protects lining); Bile—alkaline, emulsifies fats; Pancreatic juice—trypsin (proteins→amino acids), lipase (fats→fatty acids+glycerol), amylase (carbs→simple sugars); Intestinal juice—completes digestion to glucose, amino acids, fatty acids+glycerol.
- Absorption: Mainly in small intestine via villi; Large intestine absorbs water; undigested matter exits via anus.
- Health risks: Tobacco/alcohol/smoking harm mouth, pharynx, stomach & intestines; cause inflammation, ulcers, cancer—avoid completely.
| Organ/Gland | Secretion | Digestive Function |
|---|---|---|
| Salivary glands (mouth) | Saliva (Ptyalin) | Starch $\\to$ Maltose |
| Gastric glands (stomach) | Gastric juice: HCl, Pepsin, Mucus | Food acidic; proteins breakdown; lining protection |
| Liver (bile) & Gall bladder (stores bile) | Bile (alkaline, bile salts) | Neutralizes acid; emulsifies fats |
| Pancreas | Pancreatic juice: Trypsin, Lipase, Amylase | Proteins $\\to$ amino acids; Fats $\\to$ fatty acids+glycerol; Carbs $\\to$ simple sugars |
| Small intestine | Intestinal juice | Completes digestion; absorption through villi |
3) 20 Important One-Word/Line Questions (Answers 1–2 lines)
- What attaches muscle to bone?Tendon.
- Which muscles are under our will?Voluntary (skeletal) muscles.
- Heart muscles are called?Cardiac muscles (involuntary).
- Biceps function?Flex (bend) the elbow.
- Triceps function?Extend (straighten) the elbow.
- Movement of food in oesophagus?Peristalsis.
- Enzyme in saliva?Ptyalin (salivary amylase).
- Strongest outer tooth layer?Enamel.
- Gastric juice acid?Hydrochloric acid (HCl).
- Liver secretion aiding fat digestion?Bile.
- Pancreatic enzyme for fats?Lipase.
- Small intestine length (approx.)?$\\approx 6\\ \\text{m}$.
- Large intestine length (approx.)?$\\approx 1.5\\ \\text{m}$.
- Alimentary canal total length?$\\approx 9\\ \\text{m}$.
- Where is water absorbed?Large intestine.
- Main absorption structures in small intestine?Villi.
- Teeth that cut food?Incisors.
- Teeth that tear food?Canines.
- Teeth that grind food?Premolars and Molars.
- Average heart beats per minute?$\\approx 70\\ \\text{beats/min}$.
4) 20 Very Short Answer Questions (1–2 lines)
- Define ‘organ system’.A group of organs working together for a major body function (e.g., digestion).
- Why do skeletal muscles work in pairs?One contracts while the antagonist relaxes to produce controlled movement.
- Name the muscle type in intestine.Smooth muscle (involuntary).
- Function of mucus in stomach?Protects inner lining from HCl and enzymes.
- Which organ stores bile?Gall bladder.
- Name the three parts where food doesn’t get digested but moved/processed.Oesophagus (movement), large intestine (water absorption), rectum (storage).
- State one posture rule for healthy back.Sit/stand with straight back; avoid hunching.
- Which enzyme begins protein digestion?Pepsin (in stomach).
- What does bile do to fats?Emulsifies large fat globules into small droplets.
- Write one cause of acidity.Excess HCl or irregular/spicy food causing reflux.
- Which habit harms digestive organs?Tobacco chewing/smoking/alcohol consumption.
- Name any two salivary gland locations.In front of ears (parotid), below tongue (sublingual).
- What moves food in oesophagus?Peristaltic waves of smooth muscle.
- Where does most absorption occur?Small intestine via villi.
- Which teeth are adapted for grinding?Premolars and molars.
- Name a nutrient needed for muscle repair.Proteins.
- Name an enzyme in pancreatic juice that acts on carbohydrates.Amylase.
- Voluntary muscle example.Biceps or quadriceps.
- Involuntary muscle example.Cardiac muscle or intestinal smooth muscle.
- One benefit of regular exercise for muscles.Increases strength and efficiency of muscle fibres.
5) 20 Short Answer Questions (about 2–3 lines each)
- Explain how biceps and triceps coordinate to move the forearm.To bend the elbow, biceps contract and triceps relax; to straighten, triceps contract and biceps relax—paired action around the joint.
- Differentiate voluntary and involuntary muscles with one example each.Voluntary work by will (skeletal—biceps). Involuntary work automatically (smooth—intestine; cardiac—heart).
- State two roles of the liver in digestion.Produces bile to emulsify fats and neutralize acidity; also stores glucose as glycogen (energy reserve).
- How does the stomach prepare food for the small intestine?Churns food; mixes HCl, pepsin, mucus; converts food to semi-solid acidic chyme for slow release to small intestine.
- What is peristalsis and where does it occur?Wavelike contractions of smooth muscles that push food along; occurs in oesophagus and intestines.
- Why is enamel the hardest part of the body?It contains dense calcium salts and minerals making it highly resistant to wear.
- List the digestive juices entering the small intestine and their one-line action.Bile—emulsifies fats; Pancreatic juice—acts on proteins, fats, carbs; Intestinal juice—completes digestion to absorbable units.
- Why should posture be correct while sitting?To avoid undue stress on vertebrae and back muscles, preventing pain and long-term spinal issues.
- How do harmful habits affect the digestive tract?Tobacco/alcohol inflame mouth, pharynx, stomach and intestines, causing ulcers and raising cancer risk.
- State the function of villi.They increase surface area to absorb glucose, amino acids, fatty acids and glycerol into blood/lymph.
- Write the four types of teeth and one function of each.Incisors—cut; Canines—tear; Premolars—grind; Molars—grind thoroughly.
- What protects the stomach from its own acid?Mucus layer lining the stomach forms a protective coat; adequate blood supply helps repair.
- Why is the large intestine important though it doesn’t digest food?It absorbs water and salts and compacts undigested residue for egestion.
- Give two dietary tips for strong muscles.Include protein sources (pulses, milk, eggs) and adequate carbohydrates; hydrate well.
- Name the enzyme that begins carbohydrate digestion and where it acts first.Ptyalin in saliva; starts in the mouth during chewing.
- What are cramps?Painful, uncontrolled contractions of muscles (often skeletal) due to fatigue, dehydration, or electrolyte imbalance.
- How does the pancreas assist digestion?Secretes pancreatic juice with trypsin, lipase and amylase into the small intestine for protein, fat and carbohydrate digestion.
- Why must food be chewed properly?Increases surface area for enzymes; mixes food with saliva for easier swallowing and better digestion.
- State two involuntary activities involving smooth muscles.Peristalsis in intestine; regulation of blood vessel diameter.
- Why is regular exercise good for cardiac muscles?Improves heart efficiency, circulation and endurance, supporting all organs including digestive system.
6) Textbook Exercise – Perfect Answers (Chapter 12)
Q1) Fill in the blanks with the right word.
- (a) The process of digestion starts from the mouth.
- (b) Eyelids have involuntary muscles. (Blinking is largely reflex/automatic.)
- (c) Production of blood cells is not a function of the muscular system. (That is a bone marrow function.)
- (d) Muscles of the heart are cardiac muscles.
- (e) Pushing forward the food that has been chewed is the function of the oesophagus.
Q2) Find a match for me.
| Group ‘A’ | Matches from Group ‘B’ |
|---|---|
| (1) Cardiac muscles | (b) we never feel tired (work continuously) |
| (2) Are brought about by muscles | (d) chewing movements of jaws |
| (3) Pepsin | (e) enzyme of the gastric juice |
| (4) Cramps | (c) uncontrolled and painful contraction of muscles |
| (5) Skeletal muscles | (a) always function in pairs |
Q3) Who is telling a lie?
- Tongue: Lie — taste-buds detect not only sweet but also salty, sour, bitter and umami.
- Liver: True — it is the largest gland in the body.
- Large intestine: Lie — it is about $\\approx 1.5\\ \\text{m}$ long, not $7.5\\ \\text{m}$.
- Appendix: Lie — digestion is possible without the appendix.
- Lung: True — lungs excrete $\\mathrm{CO_2}$ and water vapour (excretion).
Q4) Give reasons.
- Food becomes acidic in the stomach: Gastric glands secrete HCl which acidifies food and activates pepsin.
- Cardiac muscles are involuntary: They contract rhythmically on their own (myogenic) and are not under conscious control.
- Intoxicating substances should not be consumed: They damage mouth, pharynx and gastrointestinal tract, cause inflammation, ulcers and cancer; harmful to overall health.
- Your muscles should be strong and efficient: For posture, joint stability and movement; weak muscles lead to pain and vertebral problems.
Q5) Answer the following.
(a) Types of muscles: By control—Voluntary and Involuntary; By structure/function—Skeletal (voluntary), Smooth (involuntary), Cardiac (involuntary).
(b) Cause and effect of acidity: Excess gastric acid or reflux irritates stomach/oesophagus; leads to burning sensation, nausea, sour belching; chronic cases may cause ulcers.
(c) Types of teeth & functions: Incisors—cut; Canines—tear; Premolars—grind; Molars—grind thoroughly.
Q6) Sketch and label a diagram of the digestive system and describe it.
Description: Food enters via mouth (teeth chew; saliva with ptyalin acts) → pharynx → oesophagus (peristalsis) → stomach (HCl, pepsin, mucus; churning; chyme) → small intestine (bile from liver, pancreatic juice from pancreas, intestinal juice; completes digestion and absorbs via villi) → large intestine (water absorption) → rectum → anus (egestion).
✅ Stay healthy: eat balanced meals, chew well, keep great posture, and say NO to tobacco & alcohol.