B10.2(shorter) Flashcards
Why is the investigation and treatment of the brain difficult?
- it can be easily damaged or destroyed
- it is a complex and delicate organ
- certain membranes prevent drugs from reaching the brain
Why is homeostasis important?
Homeostasis is important because certain conditions are required for the body to function correctly and if they aren’t met, the body could fail
Why are reflex actions important?
Reflex actions aid survival by preventing harm to the body.
what’s the motor neurone?
type of neurone transmits a signal from the central nervous system to an effector such as a muscle
what’s the sensory neurone?
type of neurone transmits a signal from a sense organ to the central nervous system
Which part of the nervous system is not involved in producing reflex actions?
the brain
Where can receptor cells be found?
- Skin
- Ears
- Eyes
- Nose
What type of signal are neurotransmitters?
Chemical
What type of organ is the eye?
A sense organ
What type of neurones are found in the CNS?
Relay
What type of lens can treat hyperopia?
Convex lens, which converge the light rays so they can be focused on the retina
What stimuli are the receptors of the eye sensitive to?
Light intensity and colour
What methods are used by scientists to determine brain function?
- MRI scans
- electrical stimulation of the brain
- studying patients with brain damage
What is the white outer layer of the eye called?
Sclera
What is the role of the CNS?
To receive information from receptors and coordinate a response
What is the nervous system?
The nervous system is a system that allows all the parts of the body to communicate with each other, enabling humans to react to their surroundings and to coordinate their behaviour.
What is the medulla?
concerned with unconscious activities such as controlling the heartbeat,movement of gut and breathing
What is the ideal human body temperature?
37 degrees C
What is the CNS (Central Nervous System) made up of?
Brain and spinal cord
What is myopia?
Short-sightedness or myopia usually occurs when the lens of the eye is too curved. As a result, light is focused in the retina so images appear blurry.
What is hyperopia?
Long-sightedness usually occurs when the lens of the eye is too flat. This causes light to focus behind the retina, making images appear out of focus
What is homeostasis?
Homeostasis is the maintenance of a constant internal environment to maintain optimum conditions for function
What is cerebral cortex?
Part of the brain mainly concerned with intelligence, memory and language
What is an effector?
Muscles or glands that bring about a response to the stimulus that has been received
What is accomodation?
The alteration of the lens’ shape in order to focus on near or distant objects
What is a synapse?
A synapse is the gap at the junction of two neurones.
What is a stimuli?
A stimuli is a change in the environment
What is a reflex?
A reflex is a rapid automatic response to a stimulus
What is a reflex arc?
The neurological and sensory mechanism that controls a reflex
What is a negative feedback loop?
A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback.
What is a motor neurone?
A neurone that carries electrical imuplses from the CNS to effectors
What is a coordination centre?
Areas that receive and process from the receptors, sending out signals to coordinate a response
What does the nervous system use to help body parts communicate?
Electrical impulses
What are the risks of lens replacement?
- cataract
- infections
- retinal damage
What are the receptors in the eye sensitive to?
- light intensity
- colour
What are relay neruones?
A relay neuron allows sensory and motor neurons to communicate with each other. They are found in the CNS.
What are receptors?
Cells that detect changes in the internal or external environment
What are neurotransmitters?
Chemicals that diffuse across synapses and bind to receptors on the next neurone
What are nerves?
Bundle of hundred/thousand neurones
What are nerve cells called?
Neurones
What are cells that carry electrical impulses called?
Neurones
Stimulus response order
stimulus>receptor>SN>CNS>MN>effector>response
Stages of a reflex arc
stimulus>receotor>SN>RN>MN>effector>response
draw the eye
label
label brain
brain
How does the eye focus on a nearby object?
- cilliery muscles contract
- suspensory ligaments lossen
- lens becomes thicker and more curved light rays refract strongly
How does the eye focus on a faraway object?
- colliery muscles relax
- suspensory ligaments tighten
- lens becomes thinner light rays are refracted weakly
How does shivering cause the body temperature to rise?
Respiration allows muscles to contract. It is an exothermic process, so heat energy is released.
How can myopia be treated?
Using glasses with a concave lens, which spreads out light rays so they can be focused on the retina
Factors that affect human reaction time
- Caffeine
- Age
- Fitness
- Fatigue
- Distraction
Examples of reflex actions
- Blinking
- Sneezing
- Dropping hot objects
Examples of homeostasis in the human body
- Body temperature
- Water levels
- Blood glucose levels
Examples of coordination centres
Brain, spinal cord or pancreas
Example of negative feedback loop in the body
Body temperature is controlled by the hypothalamus in your brain, and if your body gets too hot, your body begins to sweat to try and reduce it. However if the body gets too cold, it begins to shiver to try and raise the temperature.
Diagram of electrical impulse being transmitted through a synapse
Diagram of a nerve cell (neurone)
Diagram of a negative feedback loop
- conditions in a body change from a certain point
- corrective mechanisms switched off
- condition return to set point
- corrective mechanism activated
- change detected
Describe the strucutre and function of the ciliary muscles and suspensory ligaments
CM and SL hold lens in place and control shape
Describe the structure and function of the sclera
- tough outer layer of eye which protects internal structure
Describe the structure and function of the retina
light sensitive layer found at back of eye/ stimulates retina cells resulting impulses sent back to brain
Describe the structure and function of the optic nerve
connects eye to brain. carries impulses to brain so image can be visualised
Describe the structure and function of the iris
- muscle which controls size of the pupil by contracting and relaxing. allows eye to adjust to bright and dim lighting
Describe the structure and function of the cornea
transparent layer at front of eye
lets light into eye and allows light to be focused on retina
Describe how the iris alters the size of the pupil in both dim and bright lighting
- bright light circular muscles contract and radial muscles relax avoid damage
- dim light circular muscles contract and radial contract. pupil larger so more light can enter
3 components of the body’s automatic control system
- Receptors
- Effectors
- Coordination centres
2 types of contact lenses
hard -rigid material, last a long time and must be kept sterile
soft - flexible material, last for a shorter time and more comfortable
2 main functions of structures found within the eye
- adaptation to dim light
- focusing on near or distant objects
