lgse 3012
DESCRIPTION
nervous tissue,muscle tissue,bone growthTRANSCRIPT
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