Biology Ka4 Flashcards
What is homeostasis?
The maintenance of a constant internal body environment
What do enzymes control?
All the functions of a cell (metabolism)
What internal conditions are controlled by enzymes?
Water content of the body.
Blood glucose concentration.
Body temperature.
What is water concentration controlled by?
Osmosis
The concentration of water in your blood should be the same as what?
The salt concentration in your cells
What controls the amount of water in your body?
The kidneys by producing urine or sweat
What controls the concentration of urine?
Nerves and hormones.
The body controls the level of blood with what?
Hormones secreted by the pancreas.
What lowers blood glucose?
Insulin
What raises blood glucose?
Glycogen
Mammals and birds keep a __?
Constant body temperature
What does the body do to warm up?
Shivers, hairs stand on end, sweating stops
What does the body do to cool down?
Sweats, hairs lie flat, blood supply to skin drops
What systems work together to maintain a constant body temperature?
Nervous and hormone systems
What is the endocrine system?
Slower but acts for longer. Carried in blood to all organs, affects target organ only
What do the receptors do?
Detects a stimulus (either the level of something is too high or too low )
What does the coordination centre do?
Receives and processes the information, then organises a response
What does the effector do?
Produces a response which counteracts the change and restores the optimum level
What are the stages of the control system?
Stimulus, receptor, coordination centre, effector
What are the types of receptors?
Light (eyes) Sound (ears) Change in position (ears) Taste (tongue) Smell (nose) Touch, pressure, pain, temp (skin)
How does water leave the body?
Through the lungs, skin, kidneys (urine)
How do excess ions leave the body?
Kidneys (urine)
What are the internal conditions of the body which must be controlled?
Water content, ion content and temperature
Why is it important to keep the body temperature constant?
To keep the body at a temperature at which enzymes work best
Explain what happens when a sensory receptor detects a stimulus
The info is sent as an electrical impulse along special cells called neurons. They stretch to make the connections. The impulse travels along the neurone until it reaches the central nervous system. The cells that do this are the sensory neurones.
What are nerves?
A bundle of hundreds of thousands of neurons
What are the three neurons?
Relay neurones
Sensory neurones
Motor neurones
What are neurones covered with?
A fatty layer called myelin sheath that acts as an insulator and speeds up the transmission of the impulse but is not continuous
What are the cells called that travel along the neuron until it reaches the central nervous system?
The sensory neurones
What does the nervous system let u do?
Take in information from your surroundings and respond in the right way
What are reflexes?
Automatic responses
Why are reflexes important?
Because they take care of basic body functions and protect you from harm
What are reflex actions?
Automatic and rapid responses to stimuli
What are some examples of reflex actions?
Breathing and moving the food through your gut
It takes the nervous impulse less time to travel a distance along a neurone then is does for the arm to start moving. Explain why
The diffusion of the chemicals are much slower and the impulse has to cross two synapses
What are the steps of the nervous system ?
Stimulus ➡️ receptor ➡️ sensory neurone ➡️ coordinator (CNS) ➡️ motor neurone ➡️ effector ➡️ response
Explain how the nervous system works
The receptor sends an impulse along a sensory neurone as a result of a change in the environment (stimulus). The coordinator (CNS) processes the info. It sends impulses down motor neurones. The impulses from the motor neurones stimulate the effectors to create a response.
Explain how synapses work
Neurones do not directly touch each other, there are junctions between them called synapses which form gaps. A chemical called a neurotransmitter releases and diffuses across the gap. When the chemical hits the receptors on the other side, the electrical impulse continues. Synapses mean impulses can only travel one way along the neurones
Where are relay neurones found?
In the spinal cord
Explain the reflex actions when pricking your finger on a pin
Stimulus = drawing pin Receptor = pain Coordinator = sensory, relay, motor neurones Effector = muscles to hand Response = withdrawing hand
Label the reflex arc (on paper)
.
A bee is flying towards a mans eye. What is the reflex in steps
Light receptor in eye ➡️ sensory neurone ➡️ relay neurone ➡️ motor neurone ➡️ eyelid muscle ➡️ blinking
Explain what happens when a receptor detects a stimulus
The receptor detects a change in the environment. The information is sent to the CNS where the information is processed and a response is created as an electrical impulse down a sensory neurone to a gap called a synapse to the relay neurone. It passes through to the other end of the relay neurone, along the other gap to the motor neurone. It is then sent to the effector the response is produced
