Responding to the environment: Humans Flashcards
What does the pupillary reflex do?
regulates the amount of light that enters the eye
What is astigmatism?
An irregular curvature of the CORNEA or LENS of the eye
What is the retina?
inner layer of the eye
contains light-sensitive rod and cone cells
What makes up the PNS?
12 pairs of cranial nerves
31 pairs of spinal nerves
How do organisms respond to stimuli in the environment allowing us to survive?
in a series of events
How do sesory recpeptors respond to simuli?
They initiate the transmission of nerve impulses via the sensory nerves
What are nerotransmitters released from?
Vesicles in the pre-synaptic neuron
What does a damaged spinal cord result in?
paralysis (immediate loss of the ability to move)
loss of feeling below the fracture
What is a synapse?
A gap between the two neurons over which an impulse is transmitted
The brain is the ___ of the spinal cord
large anterior end
Expliain, in detail, the process of how one hears sound
- pinna collects sound waves
- passed down auditory canal
- cause eardrum to vibrate
- cause the hammer anvil and stiuup to vibrate (amplifying vibrations)
- pass from stirrup through oval window
- pass into the inner ear (cochlea)
- create waves in the fluid within the inner ear
- waves stimulate hair cells of organ of Corti
- stimulus converted into a nerve impulse
- impulses transmit along auditory nerve to cerebrun
- cerebrum interprets nerve impulses as sound
- waves travel out round window into eustachian tube (which eases pressure in cochlea)
What is the leading cause of visual lloss amoung adults aged 55 years and older?
cataracts
What kind of matter makes up the outer layer of the spinal cord?
White matter
What are reflex actions?
Actions that the body has no voluntary control over.
This includes sneezing an blinking
What is the structure of a sensory neuron?
One branch which acts as a dendrite and another branch that acts as an axon
What is the middle ear filled with?
air
What can the ANS be divided into?
The symapathetic nervous system
AND
the parasympathetic nervous system
What is the most important function of the PNS?
Reflex actions
What is the conjunctiva?
thin transparent membrane lining cornea and eyelids
protects the front of the eye
What is the cornea?
round
transparent
allows light into the eye
refracts light rays so they focus on the retina
Explain the 5 stages of a reflex arc
- The receptor detects stimulus and generates a nerve impulse
- The sensory neuron conducts impulses from receptor to CNS
- The connector neuron conducts impulses from sensory neuron to motor neuron
- The motor neuron conducts impulses from CNS to effector
- The effector brings about an action in response to the stimulus
What can motor neurons also be called?
Efferent neurons
If you are short-sighted, is light focused in front of or behind of the retina?
In front of
What happens to the eye in dim light?
circular muscle relaxes
pupil dilates
What is the optic nerve
Sends electrical impulses from the rods and cones of the retina to the cerebrum
Here, interpretation of the image will take place
What are axons often immediately surrounded by?
A fatty myelin sheath
What is a connector neuron?
A neuron that uccurs between sensory and motor neurons in the CNS.
Connector neurons are found in reflex arcs
Does the parasympathetic nervous system increase or decrease blood pressure?
decreases blood pressure
Why does the myelin sheath break down when someone has MS (multiple sclerosis)?
The body’s immune system attacks the meylin sheath, causing it to break down
How are impulses conducted across a synapse?
- Nerve impulses travel along axon to synaptic knob
- Vesicles release neurotransmitter into synaptic cleft
- neurotransmitter becomes attached to membrane of adjacent dendrite
- neurotransmitter is broken down by enzymes atttached to post-synaptic membrane
- neurotransmitter diffuses across synaptic cleft
What is the yellow spot?
area in the centre of the retina at the back of the eyeball
filled with cone cells (colour vision)
sharpest and most detailed image forms here
rod cells (black & white vision) found around the sides of the eye
How many nerves does the PNS contain?
12 pairs of cranial nerves
31 pairs of spinal nerves
What is the part of the spinal cord with a bulge called?
Dorsal root ganglion
Where is a grommet placed?
into an opening in the eardrum
What does a grommet do?
drains fluid from the middle ear
helps to keep air pressure in the middle ear equal to the air pressure in the environment
What does the CNS consist of?
Brain
Spinal cord
What is the aqueous humous?
It enables the front of the eye to keep its bulging shape
separates the cornea from the lens
What does the pinna do?
directs sound waves towards the eardrum
What are the meninges located?
Inside the skull
AND
Inside the vertebrae
What kind of matter mainly makes up the inner layer of the spinal cord?
Grey matter
(in a H shape)
What is a grommet?
A small metal or plastic tube
What is the pre-synaptic neuron (axon) filled with?
neurotransmitters
What does the auditory canal do?
produces wax (cerumen)
transmits sound waves to eardrum
What would not be maintained without coordinated responses?
Homeostasis
What part of the body does Alzheimer’s disease affect?
The brain
What is the vitreous humour?
a transparent, jelly-like substance
- keeps the eyeball spherical in shape.
- plays a role in the distribution of gases and nutrients around eye
What does the auditory nerve do?
passes information from the cochelea to the brain
The brain interprets the nerve impulses as sound
What do the ciliary body and ciliary muscles do when using far vision?
What happens to the suspensory ligaments?
Ciliary body and ciliary muscles contract
suspensory ligaments become taut
How can doctors regenerate damagted nerve tissue in the CNS?
There is no way of regenerating damaged nerve tissue in the CNS
What is short-sightedness?
a person can see close objects well
objects that are far away appear blurry
What effect does dagga have on the CNS?
Acts on receptors on neurons in brain areas that are involved in:
- memory
- cencentration
- perception
- movement
How are middle ear infections treated?
antibiotics
surgical insertion of grommets
What does connective tissue surround (in terms of nerves)?
Each nerve fibre (with its mylin)
What are three functions of the medulla oblongata?
- control breathing and heartrate
- nerves between spinal cord and brain cross over here
- impulses cross over from one side of the brain to the other
What do the nerves of the PNS do?
Carry nerve impulses to and from the CNS
i.e. carry nerve impulses from the CNS to sites of action (effectors)
Which are the ONLY arteries that are dilated by the sympathetic nervous system?
Coronary arteries
What does a middle ear infection result in?
the swelling of the lining of the middle ear
pressure on the eardrum (which can burst it)
What does the parasympathetic nervous system do?
Brings the body back to normal
What is the spinal cord enclosed and protected by?
the vertebrae
What is the pupil?
the black hole in the centre of iris
light passes through here
What are cone cells?
Cells located in the yellow spot (on the retina) which enable one to see colour vision
What do the outer layers of the brain consist of?
Grey matter
How do scientists hope to treat spinal cord injuries?
By introducing sterm cells into the damaged area.
The stem cells will then form new neurons, replacing the damaged neurons.
What are reflex arcs?
nerve pathways that bring about reflex actions
What is the most common visual defect?
Astigmatism
How are the lenses shaped when using near vision?
shorter
rounder (more biconvex)
refract (bend) light more
How many dendrites may a neuron have?
several
What increases with age? Long-sightedness or short-sightedness?
long-sightedness
What does an axon do?
Carries impulses away from the cell body
What uses rapid reactions to control the body’s response to external and internal stimuli?
The nervous system
What is a pre-synaptic vs. a post-synaptic neuron?
Pre-synaptic neuron - where nerve impulses are coming from
Post-synaptic neuron - where nerve impulses are going to
What type of nerve process do sensory nerves mostly contain?
Sensory nerves contain mostly long dendrites of sensory neurons
What important role do the utriculus and sacculus play?
position of head in speace
whether you are upside down or not
muscle control (of legs, body and neck)
What does the nervous system use in order to function?
Electical signals
What type of lens is used to correct short-sightedness?
A concave lens
What do motor neurons do?
They carry impulses from the CNS to an effector organ.
What is the ANS (Autonomic Nervous System) regulated by?
The hypothalamus
AND
The medulla oblongata
What do drugs do to people?
They alter the way nerve impulses are transmitted, mainly by affecting the secretion and activity of neurotransmitters.
This results in changes in how a person:
- feels
- thinks
- behaves
How does our body protect us from potentially harmful threats?
By responding to external stimuli in the environment
Does the sympathetic nervous system speed up or slow down peristalsis (which happens in the alimentary canal)?
Slows down peristalsis
Does the parasympathetic nervous system dilate arteries or constric arteries?
dilates arteries
What other organ has a similar function to the utriculus?
the sacculus
What is the ciliary body and ciliary muscle?
Part of the choroid layer attached to the lens by suspensory ligaments
Ciliary body, Ciliary muscle and Suspensory ligaments work together to change the shape of the lens
How can cataracts be treated?
By surgical lens replacement
Label a motor neuron and a sensory neuron
What are sensory receptors?
Receptors that detect a variety of stimuli from both the external and internal environment of the body
What do the semicircular canals do?
They are involved in maintaining balance
What do sense organs contain?
specific receptors that respond to external stimuli
Eg: light and sound
What two main functions does the ear have?
hearing
equilibrium and balance
Where are nerve impulses carried?
To and from the CNS
What is accomodation?
The ability of the lenses of the eye to change shape when viewing near or distant objects
What are rod cells?
Cells found on the retina of the eye which enables one to see black and white images
What do nerves carry?
nerve impulses
What is the part where nerves travel in and out of the spinal cord called?
Spinal nerve
What kind of infections do middle ear infections often start with?
infections that cause:
- sore throats
- colds
- other respiratory or breathing problems
What does a synapse consist of?
The gap and the membranes of the two neurons
What is long-sightedness?
a person can see far objects well
objects that are near appear blurry
How is the neurotransmitter broken down once it reaches the post-synaptic membrane?
With the help of enzymes
How does the nervous system work?
It sends impulses along nerves to activate muscles or glands
What are the semicircular canals filled with?
endolymph fluid
What gives axons a white appearance?
The fatty composition of myelin
What is an effector?
A muscle or gland that responds to the nerve impulse sent by the sensory nerves
Effectors can also be called sites of action
What does grey matter consist of (in nerves)?
Cell bodies and dendrites
What can also be enclosed in the connective wrappings of a nerve?
Blood vessels
What effects does ecstasy have on the drug user?
increased awareness
feelings of pleasure
increased energy levels
headaches
chills
eye twitching
jaw clenching
clurred vision
nausea
dehydration
hyperthermia
seizures
Define homeostasis
The maintenance of a constant internal environment in your body
What is ear wax called? What does it do?
It is called cerumen
traps dirt
prevents drying out
Can astigmatism worsen over time?
Yes. However, usually is remains stable throughout life.
What do the ciliary body and ciliary muscles do when using far vision?
What happens to the suspensory ligaments?
The ciliary body and ciliary muscles contract
suspensory ligaments become slack
What carry impulses across a synapse?
neurotransmitters
What is considered to be far or distant vision?
anything that is more than six metres from the eye
What happens when circular muscles of the iris when they contract?
The iris gets BIGGER
What does the round window do?
passes vibrations from the inner ear back to the middle ear
This prevents echoing
Is there a cure for MS?
No, but doctors can prescribe drugs to reduce the symptoms
How do other infections spread to the middle ear?
via the eustachian tube
What are the ampullae and what do they do?
Swellings at the base of the semicircular canals
contain sensory cells called cristae (concerned with balance)
Where are the nerves of the PNS located?
Outside the CNS
Where does the word binocular come from?
Latin roots:
- bini* = double
- oculus* = eye
What gives the grey matter (in nerves) its colour?
The cytoplasm of the cell bodies
The ear is located ___ within the skull
What structures do the ampullae contain?
jelly-like structures called cristae
What is a (cross section) of a spinal cord called?
A transverse section
In what age category are middle ear infections common?
in young children
Explain, in detail, how equilibrium and balance is maintained in the human body
- semicircular canals (right angles) are filled with endolymph
- each canal has a swelling called an ampulla
- ampullae contain jelly-like structures tootached to sensory hairs (called cristae)
- As the head moves, fluid in semicircular canals moves, sitmulting the cristae
- cristae send impulses via the vestibular nerve to cerebellum
- brain responds by coordinating body movements
- other sensory structures (maculae) in sacculus and utriculus provide info to brain regarding position of head relative to gravity
- eyes also assist in balance
What is the utriculus filled with?
endolymph
What involves several parts of the body and requires the body to work as a complete unit?
Response to the environment
What acts as protection for the ear?
The fact that the ear is located internally within the skull
How many dendrites do motor neurons have?
many
TRUE OR FALSE
The ANS is under the control of will
False
What are two different kinds of nerve processes?
- dendrites
- axons
What is the blind spot?
The area where the optic nerve passes through the retina
has no light-sensitive cells
What is the mechamism that we use to communicate with the environment?
Taking in the stimulus and giving a quick response
This allows us to survive
What can enable some people with brain and spinal injuries to regain some feeling and function?
ongoing and long-term physical, occupational and speech therapy
What is the most common cause of brain and spinal cord injuries?
motor vehicle accidents
What is the main function of the nervous system?
To detect and react to changes in our environment
What do sensory neurons do?
carry impulses from a receptor to the CNS
What does a burst eardrum lead to?
hearing loss
What effect does tik have on the CNS?
stimulant of the CNS and sympathetic nervous system
release of dopamine
blocks dopamine reuptake
inhibits storage of dopamine in cesicles
neurons are over-stimulated
What happens when the ciliary body and ciliary muscles contract?
The ciliary body and ciliary muscles become BIGGER
What effect does heroin have on the drug user?
Alters chemical balance in brain (causing user to want more)
Overdose results in respiratory failure
What do the inner layers of the brain consist mainly of?
White matter
What must happen in order for vision to occur?
Light rays must enter the eyes
AND
become focused on the retina
What is the cause of Alzheimers disease?
nobody knows
What are the tops and bottoms of the butterfly-shaped grey matter inside the spinal cord called?
Dorsal horn
OR
Ventral horn
What does the typmpanic membrane do?
it is a thin membrane
vibrates and transmits the sound waves to the middle ear
How long does a grommet stay in the eardrum for?
6 to 12 months
it usually falls out on its own
What are spaces in the brain filled with?
Cerebrospinal fluid
What kind of vision do humans have?
binocular vision
What does a fluid build up in the middle ear cause?
pressure and pain
How can astigmatism be corrected?
prescription glasses
contact lenses
refractive laser surgery
What is present in the pre-synaptic neuron, besides vesicles and neurotransmitters near the synaptic cleft?
mitochondria to supply energy
Does the sympathetic nervous system open or constrict air passages?
Opens air passages
What does a dendrite do?
Brings impulses into the cell body
Does the parasympathetic nervous system dilate or constrics pupils?
constrics pupils
What is the sclera?
protective layer
helps to keep rounded shape of eyeball
tough layer to which eye muscles are attached
What effect does heroin have on the CNS?
Stimulates a pleasure system as a result of the release of the neurotransmitter, dopamine:
- feeling of well-being
- lack of pain
- drowsiness
Affects medulla oblongata:
- breathing
- other reflexes
What happens to the eye in bright light?
Circular muscle contracts
Pupil becomes smaller
Does astigmatism accompancy long-sightedness or short-sightedness?
either
What type of lens is used to correct long-sightedness?
A convex lens
What, besides an inner ear, is also present in mammals?
an outer ear
What is the sacculus filled with?
endolymph
How many axons may a neuron have?
Only one
What happens when the suspensory ligaments are slack?
The lens become more convex
What are two functions of the cerebellum?
- Coordinates movement
- maintains balance
What is the “natural” shape of the eye’s lenses?
Flat
As if you are looking at an object far away
To react to stimuli in the environment, a message is sent via the ___ to an ___.
CNS
effector
What can brain injury affect?
movement
memory
speech
mental handicap
coma (in severe cases)
What does the corpus callosum do?
It connects the left and right hemispheres of the brain
What are nerves made of?
nervous tissue
(which, in turn, is made up of cells called neurons)
What do the scars (as a result of MS) result in?
The interference with the transmission of nerve impulses in the brain and spinal cord
Give some examples of things that are maintained by homeostasis in the human body
water and salt balance of body fluids
oxygen and carbon dioxide concentrations
glucose content in the blood
body temperature
What are the symptoms of MS?
They may be mild:
- numbness in the limbs
OR
They may be severe:
- paralysis
- loss of vision
Senses recieve ___ from the environment such as the sound of a friend’s voice
information
Simply put, what is a middle ear infection?
an infection in the middle ear
Is astigmatism a lifelong condition?
Yes
What are the human eyes protected by?
The bony sockets of the skull (called orbits)
What does a bundle of nerve fibres consist of?
axons and dendrites
What is the eardrum also called?
the tympanic membrane
What is the lens?
transparent
biconvex
light passes through it
bent to focus on the retina
lens changes shape in order to focus images (light) on the retina
What does the eustachian tube do?
links the middle ear to nose and throat
equalises air pressure in the middle ear with air pressure on the outside
What does a person with an advanced stage of Alzheimer’s disease need?
Help in all aspects of life
Eg:
- Bathing
- Eating
- Using the toilet
What does are two functions of the spinal cord?
pathway for nerve impulses (travelling to and from the brain and peripheral organs)
involved in reflex actions
What is the pupillary reflex controlled by?
The ANS
Why can’t the build up of fluids caused by a middle ear infection escape the middle ear?
the eustacian tube gets blocked due to inflammatin
fluids cannot drain as they normally would
What is the middle (circle) of the spinal cord called?
central canal
Is Alzheimer’s disease a normal part of ageing?
No
Do two neurons ever touch when nerve impulses pass from one neuron to another?
No, two neurons never touch
Does the sympathtic nervous system accelerate the heart rate or slow down the heart?
accelerates heart rate
What prepares the body for an emergency?
Sympathetic nervous system
What is a coordinated response?
The process of [a series of events] working in harmony [in order to respond to the environment]
What are the effects of tik on the drug user?
Short-term effects:
- increased heart rate
- increased blood pressure
- reduced appetite
- dilation of pupils
- feelings of happiness and power
- reduced fatigue
Long-term effects
- insomnia
- paranoid psychosis
- hallucinations
- violent and aggressive behaviour
- significant weight loss
- termors
What does the oval window do?
passes sound virations from the stirrup to the inner ear
What do neurons consist of?
a cell body and one or more nerve processes
Does the parasympathetic nervous system constrict or relax the bladder walll?
contracts the bladder wall
What type of nerve processes do motor nerves mostly contain?
Mostly long axons of motor neurons
What is dementia? Which disease is it associated with?
Dementia is the progressive loss of intellectual abilities
Dementia is associated with Alzheimer’s disease
Is there a cure for Alzheimer’s disease?
No. It is irreversable
How do cataracts affect vision?
By clouding the eye’s lens which scatters the incoming light
What detects a stimulus?
A sense receptor
What is a slower control process that the body uses to respond to the environment?
The endocrine system
Which 3 regions does the ear consist of?
outer ear
middle ear
inner ear
What type of structures are found in both the sacculus and utriuculus?
maculae (singular macula)
What does the cochlea do?
coiled tube
filled with endolymph
contanins organs of Corti (converts sound waves into nerve impulses)
What can hearing defects cause?
a distortion of sound
varying degrees of deafness
What is the inner ear filled with?
perilymph fluid and endolymph fluid
What is reflection of light inside the eye called?
internal reflection
What are the symptoms of Alzheimer’s disease?
- gradual memory loss
- difficulties with language
- difficulties with emotions
What is the outer ear filled with?
air
Where do impulses travel in a reflex arc?
From a receptor to an effector
What is the central canal filled with?
cerebrospinal fluid
What are three functions of the cerebrum?
- Perception of senses
- Origin of voluntry movements
- Higher mental activities (memory, thought, judgement)
What can sensory neurons also be called?
Afferent neurons
Does the sympathetic nervous system increase or decrease secretion of sweat?
Increases secretion of sweat
How are the lenses shaped with looking at far or distant vision?
Longer
flatter (less biconvex)
retracting power of lens is less
What is the advantage of binocular vision?
It gives a wider field of view
Perception of depth
Explain the sequence of events involved in the formation of an image
- light enters the eye through the cornea
- light passes through the aqueous humour
- light passes through the lend
- cornea and lens bend (refract) the light
- Inverted (upside down) image forms on yellow spot on retina
- rod and cone cells initiate nerve impulse
- Impulse travels along optic nerve to brain
What effect does ecstacy have on the CNS?
releases the neurotransmitter, serotonin
neuron damage
permanently alter emotions and memory
What effects does dagga have on the drug user?
reduced coordination
reduced blood pressure
sleepiness
relaxed feeling
disrupted attention
altered sense of time and space
hallucinations
delusions
loss of memory
disorientation
What does the endocrine system use in order to coordinate essential processes?
chemical messengers
Living things need a ___ to coordinate essential processses within the body.
control system
What does white matter consist of (in nerves)?
Axons, many of which are surrounded by a myelin sheath
What causes scars on the nervous tissue due to the breakdown of the fatty myelin sheath that covers the neurons?
Multiple sclerosis (MS)
What is the purpose of reflexes?
- enable the body to respond quickly to a stimulus
- provide safety mechanisms to protect the body from injury
What can chemical messengers also be called?
hormones
What is the choroid?
thin membrane containing many blood vessels to nourish the eye
contains dark pigment called melanin to stop reflection of light inside the eye
If you are long-sighted, is light focused in front of or behind the retina?
behind the retina
What are the suspensory ligaments?
fibres around the lens that hold the lens in place and assist with changing the shape of the lens for focusing
What is the iris?
the coloured part of the eye
has a circular opening in its centre (pupil)
muscles in iris control the size of the pupil
What is the synaptic cleft?
the gap between the pre-synaptic neuron and the post-synaptic neuron
What is the brain surrounded and protected by?
three membranes
These membranes are called MENINGES
What is the functional unit of the nervous system?
a reflex arc
What is the vestibular nerve and what does it do?
passes information from the semicircular canals, sacculus and utriculus to brain
concerns itself with balance and equilibrium
What is the brain enclosed and protected by?
The bones of the cranium
Is the ANS part of the CNS or the PNS?
The ANS is part of the PNS
Name the ear ossicles of order from outside in
hammer
anvil
stirrup
What could an effector be?
A muscle or gland
The ___ and ___ enable animals to respond to external changes and to control changes inside their bodies
nervous and endocrine systems
What are visual defects?
Conditions of the eye that negatively affect vision
What does the utriculus do?
contains maculae (with sensory cells)
concerned with position of head in space
What does the sacculus do?
contains sensory cells concerned with position of the head in space
How do our bodies respond to the environment?
In a variety of ways
Eh) turning towards your friend to listen
