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Flashcards in Human Biology Deck (49):

Levels of Organisation in the Human Body flowchart

Systems -> Organs -> Tissues -> Cells


Humans are a ______________ organism. What does this mean?

Multicellular. This means we are made up of many cells


How do your systems work together to keep you alive?

Your digestive system breaks down nutrients and your circulatory system delivers these. Your respiratory system provides oxygen and removes carbon dioxide. The excretory system removes wastes that can be toxic


What is homeostasis?

Homeostasis is the maintenance of a constant internal environment of the body or part of the body in varying conditions.


What is a stimulus-response model?

Changes in the internal environment are detected by receptors. The message is then communicated to the effectors correct this change. This is described as the stimulus-response model


Stimulus Response Model flowchart

Stimulus - Receptor - Control Centre - Effector - Response


What are receptors?

Receptors identify changes inside and outside your body. They are located in sense organs such as your eyes, ears, nose, tongue and skin. Different types of receptors respond to particular stimuli.


What is the control centre?

The control centre is the central nervous system (brain & spinal chord). A message in the form of a nerve impulse travels there


What are effectors?

Effectors are muscles or glands that receive messages from the central nervous system. Their response depends on the original stimulus.


What is negative feedback?

Negative feedback occurs when the response is in the opposite direction to the stimulus.


How does glucose levels involves negative feedback?

If an increase in blood glucose levels have been detected by receptors, the pancreas releases insulin which lowers blood glucose levels.


What is positive feedback?

Response goes in the same direction. Eg. Mechanoreceptors in nipple detect baby sucking, message is transferred to the CNS (spinal chord) then to the muscles lining the milk glands to respond by secreting milk.


What do Neurons contain?

Nucleus, cell organelles, cytosol and a cell membrane


What are the three main parts of a neuron?

Cell body, dendrites and an axon


What is the axon part of a neuron covered with?

Myelin sheath


What is a myelin sheath

It is a white insulating substance that helps speed up conduction of the message through the neuron


What is a synapse?

Gap between the Neurons


What is the central nervous system ?

The central nervous system is the brain and spinal chord


What is the peripheral nervous system?

The peripheral nervous system is the nerves that connected the central nervous system to the rest of the body.


Where are photoreceptors found and what do they respond to?

in the eye and they respond to light


Where are mechanoreceptors located and what do they respond to?

in the ear and they respond to sound.


Where are chemoreceptors found and what do they respond to?

found in the nose and on tongue, respond to chemicals


Where are thermoreceptors located and what do they do?

found in skin, respond to temperature.


What does the endocrine system do?

Releases hormones into the bloodstream which target a specific cell leading to a response.


How does the endocrine and nervous system work together?

The endocrine system secretes hormones into bloodstream. These hormones affect the development of the nervous system.


What do sensory neurons do?

Carry impulses generated by the stimulus to the central nervous system


What do interneurons do?

Carry the impulses through the central nervous system


What do motor neurons do?

Take messages away from the central nervous system


What is another name for sensory neurons?

Afferent neurons


What is another name for internuerons

Connector or relay neurons


What is another name for motor neuron?

Efferent neuron


What is the node of ranvier?

a gap in the myelin sheath of a nerve


What are hormones?

chemical substances produced by glands and circulated in the blood. Hormones have specific effects in the body.


What are neurons?

Neurons are nerve cells


What are neurotransmitters

Chemical released from the axon terminals into the synapse between your nerve cells during a nerve impulse


How does the message from the stimulus travel from neuron to neuron?

When the nerve impulse reaches the axon terminal, neurotransmitters move across the synapse and bind to receptors of the next neuron and converts into nervous impulse.


What are reflex actions?

Reflex actions involve only a few Neurons and involve no conscious thought. The message goes from the receptor to the spinal chord then to the effector.


What do poisons do?

They block the production and action of neurotransmitters at synapses. Interfering with the transference of a message can cause spasms or even paralysis.


What are pain receptors?

Enable you to respond to chemicals released by damaged cells. They are not found in the brain.


How do you smell?

Gaseous molecules from the air are breathed in through your nose. Then dissolved into mucus in the hairs of the cochlea and the message is sent to the olfactory nerve then to your brain


What is the pupil?

Black opening in the middle of the eye. Light comes through this opening.


What is the cornea

The cornea is a clear white covering over the outside of the eye. It helps the eye focus like a lens on a camera.


What is the iris?

The iris is the part of your eye that has color. It gets bigger and smaller to let in different amounts of light.


What is the aqueous humour?

The aqueous humor is clear water-like substance that keeps your eye clean. It also provides nutrition.


What is the lens?

The lens bends light. This helps the eye see close up and far away things.


What is the vitreous humour?

The vitreous humor is clear water-like substance in the back of your eye.


What is the retina

The retina has nerve cells called rods and cones that detect light. It is in the back of your eye.


What is the optic nerve?

The optic nerve carries electrical signals from your retina to your brain so you can see.


What are rods and cones?

Rods allow you to see black & white in dim light. Cones are responsible for colour vision