TISSUE ORGANISATION
Tissues are formed when structurally and functionally similar cells combine.
Advanced multicellular organisms have tissue that can organize and regulate the organism's response
to their environment.
1. Connective tissue: for binding, support, transport, communication between organs
• Areolar loose connective tissue is underneath the skin and provides elasticity to the skin.
• Fibrous connective tissue forms the tendons (attaches muscle to bone).
• Adipose tissue stores fat to be used as energy later on, to retain body heat, and to protect
digestive organs.
• Bones provide the structural framework and protect important organs (e.g., ribcage
around heart, skull around brain).
• Cartilage gives bones flexibility and definite shape, as well as eases joint movement.
• Blood is the only system that helps communication and connection within the body, and
due to its fluid nature, it can communicate with every single cell in the body.
2. Muscle tissue: active contractile tissues that produce force and create locomotion or
movement within the internal organs.
• Three types:
o Smooth or visceral muscles: with the
internal, visceral organs (stomach, lungs,
reproductive system, etc.).
o Cardiac muscles (striated): with the heart.
o Striated or skeletal muscle: attached to
the skeleton.
Visceral
Cardiac
Skeletal
Function
involuntary
involuntary
voluntary
Appearance
smooth
striated
striated
3. Nervous tissue: composed of neurons + neuroglial cells.
• Neurons: conduct transmission of messages in the form of electric currents / nerve
impulses.
• Neuroglial cells: are the support cells for neurons; provide nutrients, remove toxins,
create a good environment and protect them from pathogens.
• Nervous system:
o Central Nervous System (CNS): brain + spinal cord; control center of the body;
decision making center.
o Peripheral Nervous System (PNS): nerves + sensory organs; acts as a pathway;
sensory organs collect stimuli (external or internal), send it to the brain to make a
decision, and then tells your body how to react.
NEURON STRUCTURE
• Cell body / soma
• Dendrites: receive information (stimuli) in the form of nerve impulses.
• Axon: insulated tail of the cell; pathway for the nerve impulse to travel through.
• Myelin sheath: protection for the impulse traveling down the axon; protects the current by
preventing it from getting lost to surrounding areas and instead ensures it follows the
pathway.
• Nodes of Ranvier: unmyelinated areas along the axon which make transmission faster by
making the impulse jump from node to node.
• Terminal button / synaptic button: vesicles containing neurotransmitters.
• Neurotransmitter: chemical secretion that helps communication.
• Synapse: communication site between two neurons.
o Chemical synapse: neurotransmitters are released for communication of impulses.
o Electrical synapse: both neurons have direct communication through electrical currents
(e.g., organs like the brain, heart, etc., rely on electrical synapses because we can't wait
