A2 - Unit 1 - Communication and homeostasis Flashcards
Give 4 ways organisms can change their internal environment in order to survive
Blood glucose concentration
Internal temperature
Water potential
Cell pH
Give 4 ways organisms can change their external environment in order to survive
Humidity
External temperature
Light intensity
New or sudden sound
Why is coordination needed in an organism
Organisms have become specialised to perform specific functions, and different cells perform different functions
In order for the organism to work effectively these different functions need to be in coordination
What is homeostasis?
Coordination in order to maintain a relatively constant internal environment
What can cells do during cell signalling??
Transfer signals locally e.g. Between neurones at synapses (signal used is called a neurotransmitter)
Transfer signals across large distances, using hormones e.g. Cells of pituitary glad secrete ADH which acts on the kidneys
How do plants coordinate?
Plant stems grow towards a light source to maximise photosynthesis rate
Achieved through use of plant hormones
Describe the cell body in a neurone
Contains the nucleus surrounded by cytoplasm
Large amounts of ER and mitochondria involved in the production of neurotransmitters
These are chemicals used to pass signals from one neutrons to the next
Describe the dendrons in a neurone
Short extensions which comes from the cell body
Extensions divide into smaller and smaller branches known as dendrites
Responsible for transmitting electrical impulses towards the cell body
Describe the axons in a neuron
Singular elongated nerve fibres that transmit impulses away from the cell body
Fibres can be very long
Transmit impulses from the tips of the toes and fingers to the spinal cord
Cylindrical in shape
Very narrow region of cytoplasm surrounded by a plasma membrane
What are the three types of neurone?
Sensory
Relay
Motor
What is a sensory neurone?
Transmit impulses from a sensory receptor cell to a relay neurone, motor neurone, or the brain
They have one dendron
Carries the impulse to the cell body and one axon which carries the impulse away from the cell body
What is a relay neurone?
Transmit impulses between neurones e.g. Between sensory neurones and motor neurones
Have many short axons and dendrons
What are motor neurones?
Transmit impulses from a relay neurone or sensory neurone to an effector, such as a muscle or a glad
They have a long axon and many short dendrites
What route does the typical nervous response impulse travel?
Receptor- sensory neurone - relay neurone - motor neurone - effector cell
Describe the structure of myelinated neurones
Neurones are covered in a myelin sheath, made of many layers of plasma membrane
Schwann cells produce the thin layers of membrane, growing around the axon many times
Schwann cells stop growing when there’s 20 layers of membrane
Insulating layer
What is the node of Ranvier?
The gaps in the myelin sheath
Allows the electrical impulse to ‘jump’ from one node to the next
Allows the impulse to be transmitted much faster
How does an electrical impulse travelling through an non myelinated neurone differ to a myelinated neurone?
Myelinated, the impulse jumps across the neurone from one node of Ranvier to the other
Non myelinated impulse travels continuously along the nerve fibre much slower
What are the 4 different types of receptor??
Mechanoreceptor
Chemoreceptor
Thermoreceptor
Photoreceptor
Where are mechanoreceptors on the body?
Skin
Where are chemoreceptors on the body?
Nose
Where are thermoreceptor on the body?
Tongue
Where are photoreceptors in the body?
Eye
What is a transducer?
It converts a stimulus into a nerve impulse
What are pacinian corpuscles?
Specific sensory receptors that detect mechanical pressure
Located deep in the skin
Abundant in fingers and soles of the feet