Topic 3 Flashcards
Define and explain:
Tolerance limit
Tolerance limit is the range of environmental conditions that an organism requires to survive.
If the conditions fall outside of the TL, than the organism will either not survive, or must have mechanisms to maintain its own internal environment.
Explain:
How cells regulate their internal fluid composition
All cells are surrounded by tissue fluid which remains constant.
Cells are able to maintain solute balance through active and passive transport through their membrane
Describe:
Selective responses
Sudden changes tend to be detected while subtle changes are not. Selected changes are responded to, such as moth hormones compared to human hormones.
Describe:
Limiting factors
Factors that affect the tolerance limit, such as oxygen level, Light avalibility, Temperature and Mineral composition.
The limiting factor tends to be the one that is least in abundance
Describe and explain:
Stimulus and response, also the mechanism
A stimulus is any change in the internal or external environment. The stimulus is detected by a receptor which transmits a message in the form of a nerve impulse or hormone. The message is received by an effector which brings about a response.
Describe and explain:
The role of sensory receptors and process of detection to reaction
To detect stimuli. Responding to the intensity, duration and location. They send nerve impulses to the central nervous system where it is processed. CNS sends an impulse along motor neurons which signal effectors.
Describe:
The role of effectors
Is a muscle or gland that carries out a response.
Describe:
Regulation of human internal environment
Cells require pH, Temperature, Osmotic balance and oxygen concentration. A build up of waste, urea, needs to be removed. Sensory receptors initiate homeostatic control mechanisms.
Describe:
Homeostatic control mechanisms
Self-regulating mechanisms, about negative feedback, resulting in a constant flux.
Because of this, Homeostasis involves a stimulus response and negative feedback model
Describe and Explain:
Negative feedback
Where the stimulus results in a feedback that negatively inhibits the initial stimulus.
As the stimulus increases, the response increases to inhibit the stimulus.
Maintenance of a stable internal environment is homeostasis, homeostatic control mechanisms achieve this.
Describe:
Central nervous system
Consists of the brain and spinal chord. Detects internal changes in the brain, recieves stimuli from periferal nerves, process information and send nerce impulses to relevant tissues and organs to repond
Describe:
Peripheral nervous system
Consists of nerves outside of the brain and spinal chord. Connects CNS to parts of the body.
Somatic nervous system, is voulentay nerves. Autonomic nervous system, is invoulentary nerves.
ANS is divide into sympathetic and parasympathetic nervous system. (SN is fight or flight)
Describe:
Cells that make up the nervous system
Neurons and Glial cells. Such as Schwann cells. These provide structural and metabolic support to neurons.
Explain:
Nerve cell mechanisms and similarities, structure
Cell body; Axon and dendrites. In series with gaps between called synapses. Nerve travels through the axon as electric. Neurotransmitters cross the synaptic cleft and transfer the impulse to the next neuron, from axon terminal, to dendrite.
describe:
Structure and function of sensory neurons
Sensory detect stimuli as touch, light, chemical via specialized nerve endings as receptors, triggering an impulse along sensory neurons.
They are unipolar as the cell body only has one “process”extending from it.
Describe:
Structure and function of interneurons
Located in the brain and spinal chord. Recieve from sensory and transmit to motor.
Are multipolar, have many ‘processes’ extending from the cell body.
Describe:
Structure and function of motorneuron
Carry from CNS to effectors. Resulting in movement or sectretion
Are multipolar, have many ‘processes’ extending from cell body.
Describe:
Structure of a nerve pathway from receptor to effector.
RECEPTOR detects STIMULUS, triggering NERVE IMPULSE along SENSORY NEURONS towards SPINAL CHORD in CNS. along nerve fibers in spinal chord as interneurons. Impulse is processed in brain and sent back, goes along MOTOR NEURON, carried to an EFFECTOR resulting in a response.
