Co-ordination and response Flashcards
What is homeostasis?
- the maintenance of constant internal conditions in response to the internal and external environment
What happens if conditions are not optimal in the body?
-enzymes denature resulting in their ability to catalyse chemical reactions slower
What are the 5 processes for homeostasis?
- water levels
- blood sugar levels
- internal body temp
- CO2 levels
- urea concentration
What is a stimulus + 2 examples?
- a change in environmental conditions that brings about a response.
- Sunlight and temperature are examples
What is the receptor?
-detect stimuli
What is the effector + 2 examples?
- carry out responses to stimuli that help to restore optimum levels
- muscles and glands
What is the difference between positive and negative phototropisms?
- positive=plant grows towards the light
- negative=plant grows away from light source
What is the difference between positive and negative geotropisms?
- positive=grow against gravity
- negative=grow in direction of gravity
What does light cause the auxins to do?
-concentrate on the darker side of the shoot tip and spread down the root=cells on darker side grow faster
What does gravity cause the auxins to do?
- to concentrate on the lower side of the root
- auxins inhibit growth on the lower side=grows slower
What are the stages in the reflex arc?
-
What are the stages of nerves transmitted?
-receptors>sensory neuron>synapse>relay neurone>synapse>brain>motor neurone>effectors
What is the synapse?
-gaps between neurones that nerve impulses must travel across (they can only do so in one direction)
How are neurotransmitters produced?
-electrical impulse reaches the end of the neurone before the synapse which triggers the release of chemicals called neurotransmitters
What do neurotransmitters do?
- diffuse across the synapse and bind to receptors on the next neurone.
- The presence of the neurotransmitter causes the production of an electrical impulse in the next neurone
What is the nervous system made up of?
-brain, spinal cord, neurones
stages of reflex arc.
-receptor>sensory neurone>spinal cord>synapse>relay neurone>synapse>motor neurone>effector
What are the purpose of reflex actions?
- allow us to respond to dangerous situations rapidly and automatically. For reflex actions, the nervous system responds to stimuli via a reflex arc
What is the purpose of a receptor?
-detect the change in the environment and initiate a signalling process within the body
What do the 3 types of neurone do?
- sensory neurone=electrical impulse to spine
- relay neurone=in the spine. Relays the electrical impulse from the sensory neurone to the appropriate motor neurone
- motor neurone=electrical impulse to effector
Role of optic nerve.
-Transmits visual information, in the form of electrical impulses, from the retina to the brain
Role of cornea + what is it.
-The transparent frontal portion of the eye responsible for refracting light
What is the retina?
-Filled with receptor cells, which are sensitive to both the brightness (light intensity) and the colour of light
What is the pupil?
-hole in the centre of the iris through which light passes to get to the retina
Role of iris.
-controls pupil diameter and therefore, the quantity of light reaching the retina
What is the sclera?
-white of the eye and the opaque protective outer layer of the eye
What is the role of the cornea?
-the transparent frontal portion of the eye responsible for refracting light
What is accommodation?
- the process of the lens in your eye changing shape to focus on an object as it’s distance from the eye changes
- done by suspensory ligaments + ciliary muscle
How do we focus on close objects?
-ciliary muscles contract + suspensory ligaments loosen=lens becomes thicker and rounder resulting in significant refraction of light rays
How do we focus on far away objects?
-relaxation of ciliary muscles, suspensory ligaments loosen= lens becomes thinner and flatter resulting in minor refraction
What is the hypothalamus?
-Receptors in the thermoregulatory centre of our brain which monitor the internal body temperature as blood flows through the brain
What does thermal regulation control?
-body temp
How does shivering warm us up?
- When we are too cold, muscles start to contract automatically. This makes us shiver.
- This process needs energy, which is generated through respiration.
- Respiration produces heat, which warms us up
How does sweating cool us down?
- Sweat glands (in the middle layer of skin, called the dermis) release sweat, which covers the outer layer of skin (the epidermis).
- Heat energy from the body is transferred to the water in this sweat and, when it has enough energy, it evaporates.
- As it evaporates, it takes the heat energy with it. This lowers the average temperature of the body
What is vasoconstriction?
- when muscular walls contract because we are too cold
- this reduces blood flow to the skin surface and heat energy is kept inside the body
What is vasodilation?
- muscular walls relax when we are too hot
- This allows more blood to enter and flow through capillaries close to the skin surface.
- The excess heat energy is transferred to the surroundings
What is meant by vasodilation?
-Blood vessels dilate to allow more blood to enter capillaries
What is meant by vasoconstriction?
-Blood vessels constrict to reduce blood flow in capillaries
