human physiology

• Movement

  Significant feature of living beings
• Locomotion

  Voluntary movements resulting in change in place/location
• Reasons for locomotion

  • Search of food
  • Search of mate
  • Search of breeding ground
  • Escape from enemies/predators
• Types of movement/locomotion

  • Amoeboid (involving microfilaments and streaming of protoplasm)
  • Ciliary (involving cilia)
  • Flagellar (involving flagella)
  • Muscular (involving muscles)
• Amoeboid movement

  • Leucocytes
  • Macrophages
  • Amoeba
• Ciliary movement

  • Removing dust particles from trachea
  • Passage of ova through female reproductive tract
  • Maintenance of water current in canal system of sponges
• Flagellar movement

  • Locomotion in Euglena
  • Swimming of spermatozoa
• Muscular movement

  • Movement of limbs, jaws, tongue
  • Running, walking, climbing, flying
• All locomotions are movements but all movements are not locomotion
• Movement in Paramoecium

  • Cilia helps in movement of food through cytopharynx and in locomotion as well
• Movement in Hydra

  • Tentacles are used for capturing of prey and also for locomotion
• Locomotion requires a perfect coordinated activity of muscular, skeletal and neural systems
• Muscle tissue

  Mesodermal in origin
• 40-50% of body weight of a human adult is contributed by muscles
• Properties of muscles

  • Excitability
  • Contractility
  • Extensibility
  • Elasticity
• Cardiac muscle

  Many cardiac muscle cells assemble in branching pattern to form a cardiac muscle
• Classification of muscles

  • Skeletal (striated, voluntary)
  • Visceral (non-striated/smooth, involuntary)
  • Cardiac (striated, involuntary)
• Skeletal muscle

  • Many muscle fibre bundles/fascicles held by fascia (collagenous connective tissue)
  • Each muscle fibre have many parallelly arranged myofibrils/myofilaments
  • Skeletal muscles are primarily involved in locomotion and change in body posture
• Mechanism of muscle contraction/sliding filament theory

  1. Motor neuron releases neurotransmitter acetylcholine at neuromuscular junction

  2. Action potential generated in sarcolemma causes release of Ca2+ in sarcoplasm from SR

  3. Ca2+ binds to troponin, changes its conformation, unmasks active site for myosin binding on actin

  4. Energised myosin (Myosin - ADP+ Pi) binds to actin, forming cross bridge

  5. Cross bridge shortens, pulling thin filaments toward centre of sarcomere, reducing length of I-band

  6. ADP+Pi released from myosin head, new ATP binds, cross bridge broken

  7. ATP hydrolysis on myosin head, cycle repeats until Ca2+ pumped back to sarcoplasmic cisternae
• Reaction time of muscle fibres vary in different muscles
• Repeated activity of muscle leads to accumulation of lactic acid due to anaerobic breakdown of glycogen, causing fatigue
• Skeletal muscle structure

  • Thin filaments make I/Isotropic band-actin, arranged alternately throughout the length of myofibrils
  • Thick filaments make A/Anisotropic band-actin + myosin parallel to each other and to longitudinal axis of myofibris
  • Sarcomere: Functional unit of contraction between 2'Z' lines (elastic fibres)=1A-band +2 half I-band
  • H-zone is non overlapped part of thick filament by thin filaments
• Bones of the axial skeleton

  • Cranium (Frontal, Parietal, Occipital, Ethmoid, Temporal, Sphenoid, Nasal)
  • Facial bones (Mandible, Lacrimal, Maxilla, Zygomatic, others)
  • Hyoid
  • Ear ossicles (Malleus, Incus, Stapes)
  • Vertebrae (Cervical, Thoracic, Lumbar, Sacral, Coccygeal)
  • Ribs (True, False, Floating)
  • Sternum
• Axial skeleton

  • Main framework of trunk
  • Protects spinal cord
  • Supports head
  • Point of attachment of ribs and muscles of back
  • 7th cervical vertebra (atlas) articulates with occipital condyles
  • Neural canal of vertebrae is site from where spinal cord passes
• Ribs

  • Attach dorsally to vertebrae and ventrally to sternum with hyaline cartilage
  • Not directly attached to sternum but to 7th rib with hyaline cartilage (8 to 10 pair)
  • Not connected ventrally (11th and 12th pair)
  • All ribs are bicephalic thin flat bones i.e. they have 2 articulating ends on dorsal side
• Pectoral girdle

  • Scapula, a dorsal triangular flat bone, have elevated ridge/spine, expanded to form acromion process that articulates with clavicle
  • Glenoid cavity in scapula articulates with humerus head to form shoulder joint
• Pelvic girdle

  • Acetabulum, formed by fusion of ilium, ischium and pubis, articulates with femur to form hip joint
  • 2 halves of pelvic girdle meet ventrally to form pubic symphysis containing fibrous cartilage
• Joints

  • Point of contact between bones or bones and cartilages
  • Force generated by muscle is used to carry out movement through joint, where joint acts as fulcrum
• Types of joints (based on major structural forms)

  • Fibrous (joined by dense fibrous connective tissue, no movement)
  • Cartilaginous (joined by fibrous cartilage, limited movement)
  • Synovial (fluid filled synovial cavity between 2 bones, considerable movement)
• Examples of different types of joints

  • Flat skull bones fused end to end via sutures to form cranium (Fibrous)
  • Adjacent vertebrae (Cartilaginous)
  • Humerus & pectoral girdle (Ball and socket joint, Synovial)
  • Knee joint (Hinge joint, Synovial)
  • Atlas & axis (Pivot joint, Synovial)
  • Between carpals (Gliding joint, Synovial)
  • Carpal & metacarpal of thumb (Saddle joint, Synovial)
• Disorders

  • Myasthenia gravis (Affect neuromuscular junction, fatigue, weakening and paralysis of skeletal muscles)
  • Muscular dystrophy (Progressive degeneration of skeletal muscles)
  • Tetany (Rapid spasms in muscle)
  • Arthritis (Inflammation of joints)
  • Gout (Inflammation of joints due to uric acid crystals)
  • Osteoporosis (Decreased bone mass, increased chances of fracture)
• Significance

  As the nerve fibres do not innervate all cells of the body and the cellular functions require continuous regulation, hence the role of endocrine system is integrated with neural system
• Endocrine glands

  Secrete hormones
• Hormones

  Non-nutrient chemicals that act as intercellular messengers, produced in trace amounts, released into blood and transported to target organ
• Organs with diffused tissues and cells

  • Gastrointestinal tract
  • Heart
  • Liver
  • Kidneys
• Pineal gland

  • Located on dorsal side of forebrain
  • Releases melatonin
• Melatonin

  Regulates 24 hour diurnal rhythm (sleep-wake cycle), influences body metabolism, temperature, pigmentation, menstrual cycle and defense capabilities
• Neurohypophysis

  • Releases oxytocin and vasopressin/ADH
• Oxytocin

  Acts on smooth muscles and stimulates their contraction, stimulates vigorous contractions of uterus at childbirth, stimulates milk ejection from mammary glands
• Vasopressin/ADH

  Acts on kidney and stimulates resorption of water and electrolytes by distal tubules, reduces loss of water through urine (diuresis)