SSC Biology Human Physiology Human Physiology

Introduction

• The food that we consume must be broken down into simpler absorbable forms so that they can be easily absorbed and transported to various parts of our body through blood. This task is accomplished by the digestive system.

• Dental formula for adult human

\[\frac{Upper\,\,jaw}{Lower\,\,jaw}=\frac{IC\,PmM}{IC\,PmM}=\frac{2123}{2123}\]

• Digestion of Food

• Vitamin required by the body

• Inorganic Elements in the Human Diet

• Marasmus is produced by a simultaneous deficiency of proteins and calories. In Marasmus, protein deficiency impairs growth and replacement of tissue proteins; extreme emaciation of the body and thinning of limbs results, the skin becomes dry, thin and wrinkled. Growth rate and body weight decline considerably.
• K washiorkar is produced by protein deficiency unaccompanied by calorie deficiency. Like marasmus, kwashiorkor shows wasting of muscles, thinning of limbs, failure of growth and brain development.

Human Respiratory System

• Human Respiratory System
• Human respiratory system consists of external nostrils, nasal cavity, nasopharynx, larynx, trachea, bronchiole and lungs.
• Transport of gases
• 97% of oxygen is transported from the lungs to the tissues in combination with haemoglobin, \[(Hb+{{O}_{2}}\to Hb{{O}_{2}}\]oxyhaemoglobin). 3% is transported in dissolved condition by the plasma.
• There are three ways of transport of\[C{{O}_{2}}\].
• 5%-7% (approximately) of \[C{{O}_{2}}\]is transported, being dissolved in the plasma of blood.
• \[C{{O}_{2}}\]react with the water to form carbonic acid \[{{H}_{2}}C{{O}_{3}}\] by the enzyme carbonic anhydrase (present in RBC).
• \[C{{O}_{2}}\] reacts with amine radicals \[N{{H}_{2}}\] of haemoglobin molecule and forms a carbamino-haemoglobin \[HbC{{O}_{2}}\] molecule. Nearly 23% of \[C{{O}_{2}}\] is transported through this mode.
• Disorders of respiratory system
• Bronchial Asthma: It is characterised by the spasm of smooth muscles of the wall of bronchiole.
• Emphysema: It is an inflation of bronchiole, which results into loss of elasticity of these parts.
• Occupational Lung Disease: It is caused because of the exposure of potentially harmful substances persuntion in the environment, where people work. Two common occupational diseases are - silicosis and asbestosis.

Blood Groups

• ABO grouping: It is based on the presence or absence of two surface antigens on the RBCs namely A and B,

Table: Blood Groups and Donor Compatibility

• Rh Grouping: Another antigen, the Rh antigen are also observed on the surface of RBCs of majority of humans (\[R{{h}^{+}}\]individuals). A special case of Rh incompatibility has been observed between \[R{{h}^{-}}\] bloods of a pregnant mother with \[R{{h}^{+}}\] blood of foetus.

Circulatory Pathways

• The circulatory patterns are of two types -
• Open circulatory system is present in arthropods and molluscs in which blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses. Annelids and chordates have a closed circulatory system in which the blood pumped by the heart is always circulated through a closed network of blood vessels. All vertebrates possess a muscular chambered heart. Fishes have a 2-chambered heart with an atrium and a ventricle. Amphibians and the reptiles (except crocodiles) have a 3-chambered heart with two atria and a single ventricle, whereas crocodiles, birds and mammals possess a 4-chambered heart with two artia and two ventricles.

• Heart Beat and Pulse
• The human heart beats at the rate of about 72-80 per minute in the resting condition.

• Electrocardiograph
• ECG is the graphic record of electronic current produced by the excitation of cardiac muscles.
• A normal electrocardiogram is composed of a P wave, QRS complex and T wave. P wave indicate the depolarisation of the atria. QRS complex expresses the ventricular depolarisation. T wave indicate an repolarization of ventrcle.

• Disorders of Circulatory System
• Hypertension

A continuous or sustained rise in arterial pressure is known as hypertension. High blood pressure compels heart to work excessive and then can tend to congestive heart disease.

• Atherosclerosis
• In this, calcium salts precipitated with cholesterol of the forming or formed opaque making the wall of arteries stiff and rigid and is referred to as the hardening of the arteries. It may lead to heart attack and death.

Excretion

• Excretion
• The process of excreting ammonia is -Ammonotelism. Kidney plays a minor role in the elimination of ammonia e.g., teleost fishes, tadpoles, aquatic soft bodied invertebrates. Organism undergoing ammonotelism are called ammonotelic.
• The process of excreting urea is - Ureotelism. Examples are mammals, many terrestrial adult amphibians and cartilaginous fishes (shark).
• The process of elimination of uric acid is –Uricotelism Examples are land snails, insects, birds and many reptiles.
• Each kidney has nearly one million complex tubular structures called nephrons, which are the functional units of kidney. These filter the blood to produce urine.

• Disorders of the Excretory System
• Malfunctioning of kidneys can lead to accumulation of urea in blood, a condition called uremia, which is highly harmful and may lead to kidney failure.
• In such patients, urea can be removed by a process called hemodialysis. Blood drained from a convenient artery is pumped into a dialysing unit called artificial kidney.
• Renal calculi: Stone or insoluble mass of crystallized salts (oxalates, etc.) formed within the kidney.
• Glomerulonephritis: Inflammation of glomeruli of kidney.

Skeletal System

• Axial Skeleton: Skeleton which occurs in the mid axial or longitudinal part of the body.

(i) Skull is made up of 29 bones. It is composed of

• Cranium (8 bones): Frontal - 1; Parietal - 2; Occipital -1; Temporal - 2; Sphenoid -1; Ethmoid -1.
• Facial bones (14 in number): Nasal - 2; Maxillae - 2; Zygomatic - 2; Lacrymals - 2; Mandibles - 1; Inferior turbinals - 2; Vomer - 1; Palatines - 2. Hyoid Tongue bone – 1
• Ear ossicles (6 bones) : Malleus -2; Incus - 2; Stapes-2.

(ii)  Vertebral column: 33 in babies, 26 in adults. Grouped into 5 categories: Cervical - 7; Thoracic -12; Lumber - 5; Sacral - 5; Coccygeal - 4 (fused in adults).

(iii) Sternum: Composed of 3 parts \[\to \] Manubrium, body of sternum and xiphoid process.

(iv) Ribs: They are twelve pairs. First seven pairs are true ribs. The 8th, 9th and 10th ribs are called false ribs or vertebrochondrial ribs. The last 11th and 12th pairs are called floating ribs.

• Appendicular Skeleton: Present laterally or attached to the axial skeleton.

(i) Girdles: 2 types - pectoral and pelvic.

• Pectoral girdle: made of two parts - clavicle and scapula.
• Pelvic girdle: made of three bones - ilium, pubis andischium.

(ii)  Limb bones: Hind limbs and fore limbs - both made up of 30 bones each.                   .

• Fore limbs: Humerus (1); Radius-Ulna (2); Carpals (8); Metacarpals (5); Phalanges (14); Phalanges formula = 2, 3, 3, 3, 3. Hind limbs: Femur (1); Tibia-Fibula (2); Patella (1); Tarsals (7); Metatarsals (5); Phalanges (14).

• Joints
• A joint is a location at which two bones make contact and is essential for all types of movements, involving the bony parts of the body.

Synovial Joints - Movable Joints: They are characterized by the presence of a closed space or cavity between the bones.

• This kind of joint are classified into six major categories.

-   Plane (gliding joint): Present between carpals. Only sliding motion in all direction is allowed.

-   Hinge joint: Present between Knees joint

-   Pivot joint: Present between atlas and axis

-   Saddle joint: Present between carpal and metacarpal

-   Ball and Socket joint: Present between humerus and pectoral girdle.

• Disorders of Muscular and Skeletal System
• Myasthenia gravis - Autoimmune disorder. It affects neuromuscular transmission.
• Muscular dystrophy - Progressive skeletal muscle weakness, defects in muscle proteins, the death of muscle cells and tissue.
• Rheumatoid Arthritis: Inflammation of synovial membrane.
• Osteoarthritis: Degeneration of articular cartilage.
• Gout: Caused by excess formation of uric acid and their deposition in the joints.
• Osteoporosis: Low bone mass, increased fragility and proneness to fracture.

• Neural Control and Coordination
• The neural system is the control system of the body which consists of highly specialized cells called neurons.
• A neuron consists of main cell body and cytoplasmic processes arising from it.

The human brain is divisible into three parts:

• Forebrain: It comprises the olfactory lobes, cerebrum and diencephalon, Cerebrum is the largest and complex part. It consists of the left and right hemispheres connected by a bundle of myelinated fibres, called corpus callosum. The outer layer of the cerebrum is called the cortex.
• Diencephalon: The main parts of the diencephalon are epithalamus, thalamus and hypothalamus.
• The hypothalamus is the highest centre of autonomic nervous system. It governs emotional reactions and exercise control over sleep mechanism.
• Midbrain: It is formed of corpora quadrigemina and cerebral peduncles. Cerebral penduncles. Are bundles of fibres connecting the cerebral cortex with other parts of brain and Spinal cord?
• Hind brain: It comprises of:

-  Cerebellum: It controls the balance and posture of the body.

-  Pens varolii - The pons is concered with maintenance of normal rhythm of respiration.

-  Medulla oblongata - Medullary centres (reflex centres) are present for controlling the functions of important organs, e.g., cardiac centres (heart), respiratory centre, vasomotor centre (for regulating diameter of blood vessels) and reflex centres (for swallowing, vomiting, peristalsis, secretion and activity of alimentary canal, salivation, coughing etc.)

• Chiemical Coordination in Animal (Hormones)

• Pancreas
• Located posterior to stomach, close to duodenum.
• Endocrine Pancreas: Consists of islets of Langerhans. The islet of Langerhans have two main types of cells.

ENDOCRINE PANCREATIC SECRETIONS:

• Testes

Function: Produces a group of hormones called androgens mainly testosterone.

• Androgen regulates the development, maturation and functions of the male accessory sex organs.

• Ovary

Functions: Ovary produces one ovum during each menstrual cycle. It produces 2 groups of steroid hormones called.

(i)   Estrogen

(ii)  Progesterone

• Stimulating growth and activities of female secondary sex organs.
• Supports Pregnancy.
• Also regulates female sexual behaviour.
• Production of milk.

• Reproduction
• It is the ability of living organisms to produce a new offspring similar to themselves.
• The major reproductive events in human beings are

(i) Gametogenesis - Formation of gametes.

(ii) Insemination - Transfer of sperms into female genital tract.

(iii) Fertilisation - Fusion of male and female gametes leading to formation of zygote.

(iv) Implantation - Formation and development of blastocyst and its attachment to the uterine wall.

(v) Gestation - Embryonic development; gestation is the time from conception to birth.

(vi) Parturition - Delivery of baby (the process of birth).