B10 Flashcards
What are the conditions inside your body called?
The internal environment
Why is it important to keep your internal environment constant?
So your organs can work correctly
What are the 3 conditions of the internal environment that need to be balanced?
Water and ions
Blood sugar
Temperature
How does your body detect a change in the internal environment?
Sense organs form part of the nervous system and contain many specialised cells called receptors. If a receptor detects a stimulus (change) then it sends an electrical impulse to a sensory neurone. The electrical impulse travels along the sensory neurone to the CNS, which makes sense of the electrical impulse and sends impulses to the effectors (muscles/glands) via the motor neurones
What are 5 examples of types of receptors/ sense organs and what do they detect?
Eye - Light
Ear - Sound + Balance
Tongue - Chemicals
Nose - Chemicals
Skin - Touch, Temperature, Pressure, Pain
The nervous system uses…
whereas
Chemical responses use…
The nervous system uses electrical impulses to send signals through the neurones
WHEREAS
Chemical responses use the hormonal system and chemical messengers carried in the bloodstream
List factors that determine the nervous system
Electrical signal
Transferred by neurones
Effectors are muscles or glands
Type of response is muscle contraction or secretion
Rapid response speed
Short duration (until nerve impulses stop)
List factors that determine the hormonal system?
Chemical signal
Transferred by the bloodstream
Effectors are target cells in particular tissues
Type of response is a chemical change
Slower response speed
Long duration (until hormone is broken down by the liver)
What are the 2 types of reflex actions?
Voluntary and Reflex
What are key factors of a voluntary reflex?
You have control over
Happens consciously
Intentional
Effectors are muscles or GLANDS
Nerve impulses always reach the brain
Action initiated by the brain
Can be learnt
Takes longer
What are key factors of a reflex?
You have no control over
Happens subconsciously
Unintentional
Effectors are muscles
Nerve impulses don’t reach the brain
Action initiated by muscle receptor
Can’t be learnt
Why are reflex actions important?
They help protect us from danger and harm
Name some examples of reflex actions
Pulling away if we touch something hot/cold
Coughing
Blinking
Breathing
What is the reflex arc?
The sense organ, sensory neurone, relay neurone, motor neurone and effector organ which brings about a reflex action
What is a synapse?
The connection between two neurones
How do synapses work?
1) An impulse arrives at the end of the presynaptic neurone
2) Vesicles move forward and fuse with presynaptic membrane
3) Neurotransmitter is releases into the synaptic cleft
4) Neurotransmitter diffuses across synaptic cleft
5) Neurotransmitter attaches to receptors on postsynaptic membrane
6) This triggers an impulse along the postsynaptic neurone
7) The neurotransmitter is recycled/destroyed once an impulse is sent
What is the brain responsible for?
Complex behaviours. Everything you do
What is the brain?
The swollen end of the spinal cord that controls and coordinates the entire nervous system
What is the brain made of?
Billions of interconnected neurones
What are the different regions of the brain?
Cerebral cortex
Cerebellum
Spinal cord
Medulla
Pituitary gland
Hypothalamus
What does the Cerebral Cortex do?
Responsible for consciousness, intelligence, memory and language
What does the Cerebellum do?
Responsible for muscle coordination and movement
What does the Medulla do?
Controls unconscious activities like breathing and heartbeat
What does the Pituitary Gland do?
aka “Master Gland” Responsible for regulating many bodily functionsand controlling the activity of other glands
List the main components of the eye
Sclera
Cornea
Iris
Pupil
Lens
Ciliary Muscles
Suspensory Ligaments
Retina
Fovea
Optic Nerve
Blind Spot
Aqueous and Vitreous Humours
What is the function of the Sclera?
Tough, supporting wall of the eye
What is the function of the Cornea?
Protective, transparent out layer in front of eye that refracts light into the eye
What is the function of the Iris?
Contains muscles that can control the diameter of the pupil and how much light enters the eye
What is the function of the Lens?
Disc shaped structure that thickens/flattens to focus the light and imagine onto the retina
What is the function of the Ciliary Muscles and Suspensory Ligaments?
Controls the thickness of the lens
What is the function of the Retina?
Surface that the image lands on that has receptors to detect light and colour
What is the function of the Optic Nerve?
It carries impulses from the receptors on the retina to the brain
What is the Blind Spot?
The part of the retina where the optic nerve is, so there isn’t any receptors in that area so the eye doesn’t detect any light there
What is the function of the Aqueous and Vitreous Humours?
Liquid that maintains the shape of the eye
What are the muscles called that control the iris?
Circular and Radiant
In bright light what happens to the iris?
The radial muscles relax, and the circular muscles contract, causing the pupil to get smaller
In dim light what happens to the iris?
The radial muscles contract, and the circular muscles relax, causing the pupil to dilate
What is Accommodation?
The process of changing the thickness of the lens
To focus on objects nearby the lens must…
Get thicker. The ciliary muscle contracts and the suspensory ligaments loosen
To focus on objects far away, the lens must…
Flatten. The ciliary muscles relaxes, and the suspensory ligaments tighten
What is myopia?
Short-sightedness. Can see objects close up but not far away. The light rays are focused on an area in front of the retina
What can myopia be caused by?
Lens being too curved
Eye being too long
How to correct myopia?
Wearing concave glasses that spreads the light before it enters the eye so it focuses on the retina
What is Hyperopia?
Long sightedness. Can see objects far away but not close up. The light rays are focuses on an area behind the retina
What can Hyperopia be caused by?
Lens being too flat
Eye being too short
How to correct Hyperopia?
Wearing convex glasses that bends light rays together before they enter the eye so they focus on the retina
