- One heartbeat lasts about 0.85 seconds and includes atrial contraction, ventricular contraction, and relaxation of all chambers.
- The first sound "LUBB" is caused by the closure of tricuspid and bicuspid valves at the start of ventricular contraction.
- The second sound "DUP" is due to the closure of semilunar valves at the start of ventricular relaxation.
- Smaller animals and newborns have faster heart rates because of higher metabolism and heat loss.
- The full sequence of contraction and relaxation in a heartbeat is called the cardiac cycle.
Definitions [26]
Define muscle.
Muscles are long bundles of contractile tissue, which has a fixed end (Origin) and a movable end which pulls some other part.
Define with examples: Carnivores
The organisms which feed upon other animals and animal products.
Examples - tiger, lion, cat, etc.
Define digestion.
It is the breaking down of complex insoluble food components into simple soluble substances.
Define with examples: Omnivores
The organisms which feed on all kinds of plant and animal food are called omnivores.
Examples - Cockroach and human beings.
Define with examples: Autotrophs
These are the organisms which prepare organic food in their body from simple inorganic materials like carbon dioxide, water, etc.
Example - green plants and certain protests.
Define with examples: Herbivores
The organisms that feed on plants only are termed as herbivores.
Examples - sheep, cow, goat, etc.
Define the following term:
Peristalsis
Peristalsis is the rhythmic contraction and relaxation of the muscles of the alimentary canal that pushes the food along the gut.
Define the following term :
Pylorus
Pylorus is the passage at the lower end of the stomach that opens into the duodenum.
Define the following term :
Omnivore
Omnivores are organisms that consume both plants and animals.
Define the following term:
Assimilation
Absorption of substances which are built into other compounds in the organisms.
Define the following term:
Kilocalorie
A kilocalorie is a unit of energy. It is the energy required to raise the temperature of 1 kg of water by 1 Celsius.
Define the following term:
Egestion
Egestion — The process of removal of the undigested food from the body is defined as egestion.
Define the following term:
Digestion
Digestion — The process of breaking the food into smaller and simpler substances so that they can be easily used by the body is called digestion.
Define the following term:
assimilation
Assimilation — The process of using the digested food by the body is called assimilation.
Define the term ‘digestion’.
The process of converting complex food substances into simpler and smaller units so that they can be easily utilised by the body is defined as digestion.
E.g. proteins are converted to amino acids.
Define homodont dentition.
Homodont dentition is a dental condition where an animal possesses a set of teeth that are all of the same type and have a similar shape or morphology.
Define with examples: Heterotrophs
The organisms which cannot prepare their own food and depends on ready-made food synthesized by green plants are called heterotrophs.
Examples - animals and human beings.
Define the term nutrition.
The process by which all organisms obtain or synthesize their food and convert it into simpler substances, so that it can be absorbed and utilized by the cells of the body is called nutrition.
Define the Circulatory system.
The circulatory system is a transport system moving substances throughout our body with the help of blood.
Define the Veins.
Veins are the blood vessels that carry deoxygenated (impure) blood from the body cells to the heart.
Define the Arteries.
Arteries are the blood vessels in which oxygenated blood is going away from the heart to all parts of the body.
Define the following term:
Blood
Blood is a fluid that circulates in the heart, arteries, capillaries, and veins of vertebrate animals. It transports nutrients and oxygen throughout the body and removes waste.
Definition: Cardiac Cycle
The complete sequence of events that occurs during one heartbeat, including contraction and relaxation of the atria and ventricles, is called the cardiac cycle.
Define the following term:
Kidney
Kidneys are the primary excretory organs, eliminating nitrogenous wastes (chiefly urea) from the blood and throwing it out in the form of urine.
Define the following:
Excretory organs
During different metabolic activities taking place in our body, the body produces many substances of which some are useful and some are useless.
If retained in the body the unwanted substances may become poisonous and cause much harm and in severe cases, even death. The organs which remove these unwanted and toxic substances from the body are called excretory organs.
Define the following:
Excretion
During different metabolic activities taking place in our body, the body produces many substances, of which some are useful and some are useless.
The process of removing useless and harmful metabolic waste substances is called excretion.
The process of removal of chemical wastes (Mainly Nitrogenous) from the body is known as ''excretion''. It plays an important role in maintaining the homeostatic (steady-state) condition of the body.
Key Points
Key Points: Axial Skeleton
- The axial skeleton has 80 bones and forms the main axis of the body (head and trunk).
- It includes the skull, vertebral column, ribs and sternum.
- Skull has 22 bones → 8 cranial (protect the brain) and 14 facial (form the face); also includes the hyoid bone and ear ossicles (malleus, incus, stapes).
- The vertebral column has 26 vertebrae and protects the spinal cord; the first vertebra is the atlas.
- The vertebral column is divided into cervical (7), thoracic (12), lumbar (5), sacral (1 fused) and coccygeal (1 fused) regions.
- Ribs are 12 pairs → 7 true ribs, 3 false ribs, and 2 floating ribs.
- The rib cage (ribs + sternum + thoracic vertebrae) protects vital organs like the heart and lungs.
Key Points: Appendicular Skeleton
- The appendicular skeleton includes bones of the limbs and their girdles. Each limb has 30 bones.
- Upper limb - Humerus, Radius, Ulna, 8 Carpals, 5 Metacarpals, 14 Phalanges.
- Lower limb - Femur, Patella (kneecap), Tibia, Fibula, 7 Tarsals, 5 Metatarsals, 14 Phalanges.
- Pectoral girdle - Clavicle + Scapula; glenoid cavity of scapula articulates with humerus → shoulder joint.
- Pelvic girdle - two coxal bones, each formed by fusion of ilium + ischium + pubis; the acetabulum articulates with the femur.
- The two pelvic halves are joined by the pubic symphysis (fibrous cartilage).
Key Points: Human Digestive System
- Digestion is the conversion of complex food into soluble forms that can be absorbed into the blood.
- The digestive system has two main components: the alimentary canal (mouth to anus) and associated digestive glands.
- The alimentary canal is a long muscular tube about 9 m in adults, including mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
- Salivary glands, liver and pancreas are accessory digestive glands that open into this canal and secrete juices needed for digestion.
- Different organs of the digestive system act in sequence; each stage of digestion occurs in a specific organ that performs a specialised mechanical or chemical role.
Key Points: Circulation of Blood in the Heart
- The cycle begins with atrial contraction (atrial systole) while the ventricles are relaxed; blood flows easily from atria into ventricles through open cuspid valves.
- As ventricles contract (ventricular systole) and atria relax, pressure closes the cuspid valves, preventing blood from flowing back into the atria.
- Chordae tendinae, attached to papillary muscles, hold the cuspid valve flaps in place and prevent their inversion during ventricular contraction.
- Blood is pushed out of the ventricles into the pulmonary artery and aorta through semilunar valves, which open under pressure from below.
- When ventricles relax again, blood tends to return, but the semilunar valves fill and close, preventing backflow into the heart.
Key Points: Blood
- Blood is a fluid connective tissue made of plasma (55%) and formed elements (RBCs, WBCs, platelets).
- Plasma contains water, proteins, electrolytes, hormones, and waste products.
- RBCs transport oxygen and carbon dioxide, WBCs help in immunity, and platelets help in blood clotting.
- Blood is slightly alkaline (pH ~7.4) and maintains proper physiological balance (homeostasis).
- Blood helps in the transport of nutrients, wastes, and hormones, and also regulates body temperature.
Key Points: Heart Beat
Key Points: Human Excretory System
- The human excretory system consists of a pair of kidneys, two ureters, a urinary bladder and a urethra.
- Kidneys are dark red, bean-shaped, retroperitoneal structures located from the 12th thoracic to the 3rd lumbar vertebra. Size: 10-12 cm × 5-7 cm × 2-3 cm; weight: 150 g (males), 135 g (females).
- Ureters are narrow tubular structures made of transitional epithelium that carry urine from the kidneys to the urinary bladder.
- The urinary bladder is a pear-shaped, hollow, muscular organ in the pelvic cavity, lined by transitional epithelium, and acts as a reservoir of urine.
- Two sphincters exist between the bladder and the urethra: the internal sphincter (involuntary, detrusor muscles) and the external sphincter (voluntary, striated muscles).
- The urethra is a canal-like structure that opens to the exterior via the urethral orifice, much longer in males than in females.
- The aorta supplies oxygenated blood to the kidneys; the inferior vena cava carries deoxygenated blood away from the kidneys.
Concepts [14]
- Human Organ System
- The Human Skeletal System
- The Human Skeleton: Axial Skeleton
- The Human Skeleton: Appendicular Skeleton
- Muscular System
- Muscles and Its Types
- Human Digestive System
- Parts of Respiration
- Blood Circulatory System
- Circulation of Blood in the Heart (Functioning of Heart)
- Blood
- Heart Beat
- Concept of Sense Organs
- Human Excretory System
