B5 : Seneca ACTIVE Flashcards
What is Homeostasis
Homeostasis describes all of the processes that happen in a cell or organism to maintain (keep) optimal conditions
This is needed to respond to changes in the internal and external environment.
Enzyme Functioning
Because humans are organisms that live in a changing environment, we must regulate our body’s internal conditions to make sure our enzymes and cells function well.
Denaturing
If conditions are not optimal, then our enzymes can denature (change shape).
This reduces their ability to catalyze (speed-up) metabolic reactions (chemical reactions in organisms).
Why do humans need to regulate the internal conditions of the body
Humans must regulate their body’s internal conditions to make sure that enzymes and cells function well
What are the internal conditions of the body that have to be regulated
. Internal body temperature
. Water levels
. Urea concentration
. Blood sugar levels
. Carbon dioxide levels
What three parts make up control systems
Coordination centers
Receptors
Effectors (muscles or glands)
Coordination centers
Coordination centers receive and process information arriving from receptor cells.
Receptors
Receptor cells detect changes in the environment.
Effectors
(muscles or glands) that carry out responses to stimuli (events or things) that help to restore optimum levels.
What is the Negative Feedback Loop
. An internal condition changes
. Change is detected
. Corrective mechanisms are activated
. internal conditions return to normal
. corrective mechanisms are deactivated
What is Positive Feedback
Positive feedback is the opposite of negative feedback. It makes a small change even bigger
How does the nervous system protect organisms from harm
The nervous system protects organisms from harm by responding to changes in the environment.
It does this by coordinating communication between different parts of organisms
What is the Nervous System made up of
. The brain
. The Spinal cord
. Neurones
The Brain
The brain is one of the components (parts) of the central nervous system (CNS).
The CNS coordinates the response of effectors.
Effectors are muscles or glands that act in response to a change in the internal or external environment.
The Spinal Cord
The spinal cord is the other component (part) of the CNS. It is also important in coordinating the response of effectors to changes in the environment.
Neurones
Neurones (nerve cells) carry electrical impulses (signals) between receptors, the central nervous system (CNS) and effectors.
What are Synapses
Synapses are gaps between neurones, and can be found at each junction of a reflex arc. Nerve impulses need to travel across synapses:
Arrival at the Synapse
The electrical impulse reaches the end of the neurone before the synapse.
This triggers the release of chemicals called neurotransmitters.
Passing on the Impulse
The neurotransmitters diffuse (move down a concentration gradient) across the synapse.
The neurotransmitters bind to receptors on the next neurone.
The presence of the neurotransmitter causes the production of an electrical impulse in the next neurone.
What are reflexes
Reflex actions allow us to respond to dangerous situations rapidly and automatically. Reflex actions do not involve conscious thought
What are some examples of reflexes
. Sneezing
. Blinking
. Dropping hot objects
How does the central nervous system respond to stimuli
Via the reflex arc
What are the components of the reflex arc
. Stimulus
. Receptor
. Neurones
. Effector
. Response
Stimulus
A stimulus can be any change in the environment to which the body needs to respond.
The stimulus is detected by a receptor.
Receptor
Receptors are found all over the body.
They detect the change in the environment and initiate (start) a signaling process within the body.
The signal is picked up by a neurone (nerve cell).
What are the three types of Neurone
. Sensory Neurone
. Relay Neurone
. Motor Neurone
Sensory Neurone
carries the signal in the form of an electrical impulse to the central nervous system (CNS)
Relay Neurone
relays the electrical impulse from the sensory neurone to the appropriate motor neurone
Motor Neurone
another type of nerve cell that carries the electrical impulse from the CNS to an effector
Effector
a muscle or gland that brings about an action in response to the change in the internal or external environment.
Response
The response can be any action that helps the organism to avoid the harmful situation.
How do we investigate human reaction times
Hold a ruler vertically from one end. The test subject should have their thumb and finger either side of the ruler at the 0cm mark.
Drop the ruler. The subject should try to catch it between their thumb and forefinger as fast as possible.
Note down the distance from the 0cm mark that the ruler travels before the subject catches it.
Use a table to convert this distance into a reaction time.
Repeat the experiment on a subject who has just had a coffee, or who has just done exercise.
Compare reaction times.
What are the factors that can affect human reaction time
. Exercise
. Caffeine
Why are reflex actions important?
They let us react to dangerous situations quickly and automatically
What is the Brain
The brain is a very complex organ that controls all conscious and unconscious thoughts in order to keep an organism alive
Brain damage
The brain is delicate, complex, and not well understood.
Therefore, the treatment of brain damage and brain disease is difficult
Brain function
The brain is made up of millions of interconnecting neurones (nerve cells).
Different regions of the brain are responsible for coordinating (organizing) different functions.
What are the three parts of the Brain
. Cerebral cortex
. Cerebellum
. Medulla
Cerebral cortex
This part is responsible for conscious thought (e.g. memory, language and intelligence).
Cerebellum
This part is responsible for the muscle coordination.
The cerebellum is important for movement, posture, balance and speech.
Medulla
This part is responsible for unconscious activities (e.g. breathing and heartbeat).
What are ways of researching the Brain
. MRI scanners
. Electrical stimulation
. Brain damage
MRI scanners
MRI stands for Magnetic Resonance Imaging.
MRI scanners have allowed us to learn which areas of the brain are active during different activities, such as moving, speaking and listening.
Electrical stimulation
Electrical stimulation has also allowed us to treat certain disorders of the brain.
Because the nervous system communicates using electrical impulses, electrical stimulation is used to help treat conditions such as Parkinson’s disease (causes tremors).
Brain damage
By studying patients with brain damage, where part of their brain doesn’t function, neuroscientists have been able to link particular regions of the brain to particular functions.
What are the components that make up the eye
. Retina
. Optic Nerve
. Sclera
. Cornea
Retina
Packed with receptor cells, which are sensitive to both the brightness (light intensity) and the colour of light
Optic nerve
Transmits visual information, in the form of electrical impulses, from the retina to the brain
Sclera
The white of the eye; the opaque protective outer layer
Cornea
The transparent frontal portion of the eye responsible for refracting light
What is the anatomy of the inside of the eye
. Pupil
. Iris
. Suspensory ligaments
. Ciliary muscles
The retina is full of ________ cells, which are sensitive to both the brightness and the _____ of light.
receptor, color
What is accomodation
The process of the lens in your eyes changing shape to focus on an object
How does the focus point change to close things
Ciliary Muscles contract
Suspensory Ligaments loosen
Lens becomes thicker and rounder allowing in significant refraction of light rays
How does the focus point change to distant things
Ciliary Muscles relax
Suspensory Ligaments tighten
Lens become flatter and thinner resulting in minor refraction of light rays
Which structure controls our eyes’ adaptation to different light levels?
Iris
What are the two eye defects
Myopia (short - sightedness)
Hyperopia (long - sightedness)
Myopia (short-sightedness)
Myopia happens when rays of light focus in front of the retina.
Hyperopia (long-sightedness)
Hyperopia happens when rays of light focus behind the retina.
What is thermoregulation
Control of the Body Temperature
What receptors detect temperature changes
Receptors on skin - Monitor the temperature at the surface of the body
Receptors in the Brain - Monitor the internal body temperature as blood flows through the brain.
How does our body change if it is too cold
. Muscle contractions increase (shivering)
. Hairs stand on end
. Blood vessels constrict reducing blood flow to capillaries (vasoconstriction)
How does our body change if it is too hot
. Sweat is released from sweat glands under the skin
. Hairs lie flat
. Blood vessels dilate to allow more blood to enter capillaries that pass close to the skin surface (vasodilation).
Sweating
Sweat glands release water, which covers the skin.
Heat energy from the body is transferred to this water 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.
Shivering
When we are too cold, muscles start to contract automatically. This makes us shiver.
This process requires energy, which is generated through respiration.
Respiration produces heat, which warms us up.
What happens to our body hair when it is too cold
When we are too cold, the hair erector muscle contracts, causing the hair to stand on end (which pull on the skin giving you goosebumps).
When all the hairs are standing on end, they trap an insulating layer of air around the body.
What happens to our body hair when it is too hot
When we are too hot, the hair erector muscle relaxes, causing the hair to lie flat.
What happens to our blood vessels when it is too hot
If we are too hot, then the muscular walls relax.
This is called vasodilation.
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 happens to our blood vessels when it is too cold
If we are too cold, then the muscular walls contract.
This is called vasoconstriction.
This reduces the blood flow to the skin surface and heat energy is kept inside the body.
Blood flow in Ducks
They have evolved to decrease the blood flow to their feet.
This blood is also cooled so that less heat is lost to (conducted away by) the cold water when it reaches the ducks’ feet.
