2.5 Homeostasis & Nervous System Flashcards
Define Homeostasis
Homeostasis is the regulation of the internal conditions of a cell or organism, in order to maintain the optimum conditions for function, in response to internal and external changes
Homeostasis maintains the optimal conditions for ____________ and all ____________
Homeostasis maintains the optimal conditions for enzyme action and all cell functions
What are 3 conditions controlled by homeostasis?
- Body Temperature
- Water levels (in body)
- Blood Glucose concentration
What happens if the body temperature is too high?
If the body temperature is too high, enzymes would denature, which would cause many reactions to stop
What happens if the body temperature is too low?
If the body temperature is too low, enzyme activity would slow down
What happens if the water levels are not controlled?
If the water levels are not controlled, cells could gain or lose water by osmosis, causing the cells to swell or shrink
What happens if the blood glucose concentration falls?
If the blood glucose concentration falls, less glucose will be available for respiration so less energy is available for cell activities (like active transport)
What are automatic control systems?
Automatic Control Systems is the way the body detects and responds to changes in the external environment
Name 2 Automatic Control Systems
- Nervous System
- Endocrine System
What do all biological control systems include?
- Receptors
- Coordination Centres
- Effectors
What is a stimulus?
A stimulus is a change in the environment
What are Receptors?
Receptors are the cells that detect stimuli
What are Coordination Centres?
Coordination Centres are the areas that recieve and process the information from the receptors
What are Effectors?
Effectors are the muscles or glands that carry out responses to restore the body conditions to optimum levels
What does the nervous system enable humans to do
The nervous system enables humans to:
- React to their surroundings
- Coordinate their behaviour
What are the 2 parts of the nervous system?
- CNS - Central Nervous System
- PNS - Peripheral Nervous System
What does the CNS consist of?
The brain and the spinal cord
What does the PNS consist of?
All of the nerves in the body
Give 2 adaptations of the structure of the nervous system
- Neurones have a very long axon which makes it faster and more efficient compared to having multiple neurone cells
- The axon is insulated by a fatty myelin sheath which allows electrical impulses to travel quickly and efficiently
Explain the pathway of the nervous system
- When the stimulus is detected, the information from the receptors is sent along the neurones as electrical impulses
- It travels along the neurones until it reaches the CNS, which is the brain or the spinal cord
- The CNS coordinates a response and sends it to the effectors, which is a muscle or gland that carries out the response
Reflex actions are ____________ and ______
Reflex actions are automatic and rapid
Why are reflex actions automatic and rapid?
They do not involve the conscious part of the brain
Why do reflex actions happen rapidly?
Reflex actions happen rapidly to help minimise or avoid danger or harm
Explain the stages in the Reflex Arc
- The stimulus is detected by a receptor
- The sensory neurone sends electrical impulses to the CNS, which is the spinal cord via the relay neurone
- The relay neurone connects the sensory and motor neurones and is found in the CNS
- An electrical impulse is carried along the motor neurone to the effector
What are synapses?
Synapses are the junctions or gaps between neurones
Size of synapses
Synapses are incredibly small
What are neurotransmitters?
Neurotransmitters are chemical messengers that are released from the vesicles
What do neurotransmitters do?
Neurotransmitters diffuse across the synaptic gap and bind with the receptor molecules on the postsynaptic membrane
