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What is nervous tissue?
Nervous tissue is specialized to react to stimuli and to conduct impulses to various organs in the body which bring about a response to the stimulus.
Nerve tissue are all made up of specialised nerve cells called neurons
Neurons are easily stimulated and transmit impulses very rapidly.
A nerve is made up of many nerve cell fibres (neurons) bound together by connective tissue.
Types of neurons
sensory (or afferent) neurons
motor (or efferent) neurons
Inter neurons
Structure of a Motor Neuron
Classification of Neurons
Unipolar Neurons.
• Sensory neurons single process or fibretwo main branches (axon and dendrite)
Multipolar Neurons.
• Motor neuronsnumerous cell processes (an axon and many dendrites)multipolar neurons
Bipolar neurons
• Bipolar neurons dendrite at one end and an axon at the other
Functions of Nerve Tissue
• Nervous tissue allows an organism to sense stimuli in both the internal and external environment.
• The stimuli are analysed and integrated to provide appropriate, co-ordinated responses in various organs.
• The afferent or sensory neurons conduct nerve impulses from the sense organs and receptors to the central nervous system
• Autonomic motor or efferent neurons transmit impulses to the involuntary muscles and glands.
What is the characteristics of muscle tissue?
Contractility
• Only one action: to shorten
• Shortening generates pulling force
Excitability
• Nerve fibers cause electrical impulse to travel
Extensibility
• Stretch with contraction of an opposing muscle
Elasticity
• Recoils passively after being stretched
Types of Muscle TissueSkeletal
• Attach to and move skeleton• 40% of body weight• Fibers = multinucleate cells (embryonic cells fuse)• Cells with obvious striations• Contractions are voluntary
Cardiac: only in the wall of the heart
• Cells are striated• Contractions are involuntary
(not voluntary)
Smooth: walls of hollow organs• Lack striations• Contractions are involuntary (not voluntary)
Skeletal muscle
Epimysium: surrounds whole muscle
Perimysium is around fascicle
Endomysium is around each muscle fiber
Skeletal Muscle
• Each muscle: one nerve, one artery, one vein– Branch repeatedly
• Attachments– One bone to another– Cross at least one movable joint– Origin: the less movable attachment– Insertion: is pulled toward the origin– Usually one bone moves while the
other remains fixed– In muscles of the limb, origin lies
proximal to the insertion (by convention)
– Note: origin and insertion may switch depending on body position and movement produced
Skeletal muscle
• Fibers (each is one cell) have striations
• Myofibrils are organelles of the cell: these are made up of filaments
• Sarcomere– Basic unit of
contraction– Myofibrils are long
rows of repeating sarcomeres
– Boundaries: Z discs (or lines)
This big cylinder is a fiber: 1 cell
-an organelle
BONE● What is bone?● ~ hard, whitish tissue that makes up the skeletal system
of vertebrates.● Fetuses have cartilages in the shape of future bones
which convert into bones at a later stage ;● a) from the center (earlier stage)● b) from growth plates at the end of bones (later stage)● Babies are born with 300 bones● The bones fuse as they age● An average adult has 206 bones (after fusing)
Bone Growth● Cartilages in the shape of future bones are formed.
● Osteoblasts penetrate cartilage to form bone.
How ?● Osteoblasts deposit osteoids which contain sites for Calcium
Phosphate crystal production.
● The production and deposition of these mineral crystals give bone it's hard and strong structure.
● Blood vessels develop
● Osteoclasts reshape the bone – forms a central cavity
● Central cavity contains the bone marrow.
● New cartilage is formed at the growth plate which is placed at the end of the bone.
● The cartilages are turned into bone by osteoblasts
● Process continues until the growth plate 'closes', leaving no more room for growth.
How do bones elongate?
● Damage to growth plate due to trauma.
● Illnesses that damage growth plate
● Growth Hormone deficiency
● Growth Hormone (Acromegaly is a result when access GH is produced. Bones continue to grow)
● Estrogen
● Testosteron.
Hormones involved in bone growth?
What can halt growth of bones?
Thank You