Homeostasis and response (Seneca) Flashcards
Homeostasis describes all of the …
processes that happen in a cell or organism to maintain (keep) optimal conditions.
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.
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.
If conditions are not optimal, then our enzymes can …
denature (change shape).
If conditions are not optimal, then our enzymes can denature (change shape).
This reduces their ability to …
catalyse (speed-up) metabolic reactions (chemical reactions in organisms).
Humans must regulate their body’s internal conditions to make sure that enzymes and cells function well. The conditions that need to be regulated are:
- Internal body temperature
- Carbon dioxide levels
- Water levels
- Blood sugar levels
- Urea concentration (in urine)
Control systems use both …
nervous and chemical responses.
Control systems use both nervous and chemical responses. Control systems are made up of three parts:
- Receptors
- Coordination centres
- Effectors (muscles or glands)
Effectors (muscles or glands) carry out responses to …
stimuli (events or things) that help to restore optimum levels.
Coordination centres receive and process …
information arriving from receptor cells.
Receptor cells can (function) …
detect changes in the environment
When our internal conditions are optimal, the body does not need to …
respond
If an internal condition changes and is no longer optimal, this ——— is detected and the body works to counteract (reverse) the change and return conditions to the optimum.
stimulus
If an internal condition changes and is no longer optimal, this stimulus is detected and the body works to …
counteract (reverse) the change and return conditions to the optimum.
Positive feedback is the opposite of negative feedback. It makes a small change …
even bigger.
An example of positive feedback in the body is the …
release of oxytocin (hormone), which increases the number of contractions during childbirth.
Lactic acid can cause …
muscle fatigue and soreness.
During anaerobic respiration glucose is broken down into …
lactic acid.
A person suffering from a condition called ———- cannot sweat.
anhidrosis
When a person sweats, heat is …
released which cools the body down.
Effectors carry out responses to ———— to help restore optimal levels.
stimuli
The nervous system protects organisms from …
harm by responding to changes in the environment.
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.
The nervous system is made up of:
- The brain
- The spinal cord
- The neurones (nerve cells)
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 is the other component (part) of the CNS. It is also important in …
coordinating the response of effectors to changes in the environment.
Neurones (nerve cells) carry …
electrical impulses (signals) between receptors, the central nervous system (CNS) and effectors.
What another name for neurones?
nerve cells
What are synapses?
Synapses are gaps between neurones and can be found at each junction of a reflex arc.
What does the CNS stand for?
Central nervous system
What are neurotransmitters?
Neurotransmitters are chemicals that diffuse across synapses and bind to receptors on the next neurone.
Define a reflex action.
A reflex action is an unconscious response
that allows a person to respond to a dangerous situation
automatically and rapidly via a reflex arc.
What are the components of a reflex arc?
- Stimulus.
- Receptor.
- Neurones.
- Effector.
- Response.
What type of signal are neurotransmitters?
Chemical
What terms describe a reflex action?
- unconscious
- fast
- automatic
Nerve impulses need to travel across synapses:
- Arrival at the synapse
- Passing on the impulse
The electrical impulse reaches the end of the neurone before the …
synapse.
The electrical impulse reaches the end of the neurone before the synapse.
This triggers …
the release of chemicals called neurotransmitters.
The neurotransmitters diffuse (move down a concentration gradient) across the synapse.The neurotransmitters bind to …
receptors on the next neurone.
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.
At each junction of the ——— arc, there is a synapse.
reflex
Some examples of reflexes are:
- Sneezing
- Blinking
- Dropping hot objects
Reflex actions do not involve …
conscious thought.
The nervous system responds to stimuli (events or things) via a …
reflex arc.
The different parts of a reflex arc are:
- Stimulus
- Receptor
- Neurones
- Effector
- Response
A stimulus can be …
any change in the environment to which the body needs to respond.
The stimulus is detected by a …
receptor
Receptors are found …
all over the body.
Receptors are found all over the body.
They detect the …
change in the environment and initiate (start) a signalling process within the body.
The signal is picked up by a …
neurone (nerve cell).
There are three types of neurone (nerve cell):
- the sensory neurone
- the relay neurone
- motor neurone
The sensory neurone, which …
carries the signal in the form of an electrical impulse to the central nervous system (CNS).
The relay neurone (in the CNS) relays …
the electrical impulse from the sensory neurone to the appropriate motor neurone.
The motor neurone is another type of nerve cell that …
carries the electrical impulse from the CNS to an effector.
If the reaction time is reduced this means it takes …
less time to react.
—————— are factors that could affect human reaction time
Caffeine and exercise
Caffeine and exercise are factors that could affect human reaction time. Their effect can be tested by …
dropping and catching a ruler.
The steps in the practical procedure for reaction time are:
- 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.
In a ruler-drop experiment examining the effect of caffeine on human reaction time, what is the dependent variable?
the subject’s reaction time.
In a ruler-drop experiment examining the effect of caffeine on human reaction time, what is the independent variable?
whether or not the subject has had caffeine or exercised.
A synapse is a ——— between neurones.
junction
Neuromuscular junctions are a specialised type of …
synapse between a neuron and a muscle.
The brain is a very complex organ that …
controls all conscious and unconscious thoughts in order to keep an organism alive.
The brain is made up of …
millions of interconnecting neurones (nerve cells).
Different regions of the brain are responsible for …
coordinating (organising) different functions.
The brain is (describe) …
delicate, complex, and not well understood.
The brain is delicate, complex, and not well understood.
Therefore, the treatment of brain damage and brain disease is …
difficult
The brain is made up of ——— main parts.
three
The brain is made up of three main parts. They are:
- Cerebellum
- Medulla
- Cerebral cortex
Cerebellum is responsible for …
the muscle coordination.
The cerebellum is important for …
movement, posture, balance and speech.
Medulla is responsible for …
unconscious activities (e.g. breathing and heartbeat).
The Cerebral cortex is responsible for …
conscious thought (e.g. memory, language and intelligence).
————— has also allowed us to treat certain disorders of the brain.
Electrical stimulation
Electrical stimulation has also allowed us to …
treat certain disorders of the brain.
————- (scientists who study the brain) have been working for many years to understand how the brain works.
Neuroscientists
Because the nervous system communicates using electrical impulses, ————— is used to help treat conditions such as Parkinson’s disease (causes tremors).
electrical stimulation
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.
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.
What type of signals does the nervous system use to communicate?
Electrical impulses
Some of the techniques used in neuroscience are:
- Electrical stimulation
- MRI scanners
- Studying brain damage
Your retina is full of receptor cells, which are sensitive to …
both the brightness (light intensity) and the colour of light.
Retina scanning looks at the …
pattern of blood vessels in your retina to identify you
The Retina is Filled with …
receptor cells, which are sensitive to both the brightness (light intensity) and the colour of light.
Optic nerve transmits (sends) …
Visual information, in the form of electrical impulses, from the retina to the brain.
The cornea is …
The transparent frontal portion of the eye responsible for refracting light.
The iris controls …
pupil diameter and the quantity of light reaching the retina.
The pupil is …
hole in the centre of the iris, through which light passes.
Suspensory ligaments is a …
ring of fibres that connect ciliary muscles to the lens.
Ciliary muscles are a …
ring of smooth muscle that changes the shape of the lens to focus light.
What is the name of the muscle that can change the shape of the lens, which the eye uses to focus light?
Ciliary
How many key structures are found in the eye?
8
Key features of the eye:
- ciliary muscles
- iris
- suspensory ligaments
- pupil
- cornea
- sclera
- optic nerve
- retina
The sclera is the …
white of the eye and the opaque protective outer layer of the eye.
The cornea is the…
transparent frontal portion of the eye responsible for refracting light.
The optic nerve …
Transmits (sends) visual information (as electrical impulses) from the retina to the brain.
Accommodation is the process of …
changing lens shape in order to focus on an object as its distance from the eye changes.
The iris controls how our eyes adapt to different light levels by controlling the size of the pupil. If there is too much light, the iris …
decreases the pupil size to reduce the amount of light that reaches the retina.
Myopia happens when …
rays of light focus in front of the retina.
Hyperopia happens when …
rays of light focus behind the retina.
Both myopia and hyperopia can be treated using ————————-. Contact lenses and laser eye surgery can also correct these issues.
glasses fitted with lenses that refract light rays to allow the image to form on the retina
Both myopia and hyperopia can be treated using glasses fitted with lenses that refract light rays to allow the image to form on the retina. ——————— can also correct these issues.
Contact lenses and laser eye surgery
What is another name for long-sightedness?
Hyperopia
What is another name for short-sightedness?
Myopia
When our eyes focus on a close object, which structures undergo these changes?
- the lens thicken and rounded
- ciliary muscles contract
- suspensory ligaments loosen
Our body temperature needs to be kept as close to ——— as possible.
37°C
Receptors on the surface of the —— monitor the temperature at the surface of the body.
skin
Receptors in the ————— of our brain (called the hypothalamus) monitor the internal body temperature as blood flows through the brain.
thermoregulatory centre
Receptors in the thermoregulatory centre of our brain (called the hypothalamus) monitor …
the internal body temperature as blood flows through the brain.
Our body temperature needs to be kept as close to 37°C as possible. If your body 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).
Our body temperature needs to be kept as close to 37°C as possible. If your body is cold:
- Muscle contractions increase, causing shivering.
- Hairs stand on end.
- Blood vessels constrict to reduce blood flow in capillaries (vasoconstriction).
—— means that something is related to blood vessels.
Vaso
Vaso means that something is …
related to blood vessels.
Vasodilation means …
Blood vessels dilate to allow more blood to enter capillaries
Vasoconstriction means …
Blood vessels constrict to reduce blood flow in capillaries
Sweat glands release water, which covers the …
skin
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.
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.
When we are too cold, muscles start to …
contract automatically. This makes us shiver.
When we are too cold, muscles start to contract automatically. This makes us shiver.
This process requires …
energy, which is generated through respiration.
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.
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.
When we are too hot, the hair erector muscle …
relaxes, causing the hair to lie flat.
What is the technical term for body temperature control?
Thermoregulation
In what region of the brain are the receptors that detect internal body temperature?
Thermoregulatory centre
When we are too cold, muscle ———- increase, causing us to shiver.
contractions
The endocrine system coordinates the …
body’s response to changes in the environment using chemical messengers (hormones).
The optic nerve transmits visual information from the 1. to the 2.
- retina
- brain.
Hormones are released by ——– into the bloodstream, where they travel to target organs.
glands
Hormones are released by glands into the ————-, where they travel to target organs.
bloodstream
The ovaries produce oestrogen, which …
controls puberty and is one of the main hormones in the regulation of the menstrual cycle.
The ovaries produce ———–, which controls puberty and is one of the main hormones in the regulation of the menstrual cycle.
oestrogen
The ———- produce oestrogen, which controls puberty and is one of the main hormones in the regulation of the menstrual cycle.
ovaries
The ——— produces insulin and glucagon, both of which are involved in regulating blood glucose levels.
pancreas
The pancreas produces —————–, both of which are involved in regulating blood glucose levels.
insulin and glucagon
The pancreas produces insulin and glucagon, both of which are involved in …
regulating blood glucose levels.
The ——– are situated above each kidney.
two adrenal glands
The two adrenal glands are situated …
above each kidney.
Adrenal glands produce ———–, which triggers the ‘fight or flight’ response when an organism is presented with a dangerous situation.
adrenaline
Adrenal glands produce adrenaline, which …
triggers the ‘fight or flight’ response when an organism is presented with a dangerous situation.
————- produce adrenaline, which triggers the ‘fight or flight’ response when an organism is presented with a dangerous situation.
Adrenal glands
Thyroid gland is in …
our neck .
Thyroxine regulates …
our metabolism, heart rate and temperature.
Thyroid gland releases …
thyroxine.