B3 Flashcards
What is your nervous system?
It detects changes in your external environment, processes it and responds to it accordingly
What are the 3 main stages to a nervous response?
- Change in environment
- Detecting the stimulus
- A response occurs from the effectors
What is a stimulus?
A change in the environment
What are the sensory receptors?
A group of cells that detects the stimulus
What are the effectors?
Muscles or glands
How do muscles respond to a impulse?
They contract which causes movement
How do glands respond to an impulse?
They release hormones
Where are receptors cells found?
In your sense organs
What do receptor cells do?
They change the stimulus into electrical impulses that travel along neurones to your central nervous system
What is your central nervous system (CNS) made up of?
Your brain and spinal cords - delicate nervous tissue so are protected by bones
What protects the brain?
The skull
What protects the spinal cord?
The vertebral column (backbone)
What are the receptor cells for you eyes?
Light
What is the stimulus for your eyes?
Light
What are the receptor cells for you tongue?
Taste
What is the stimulus for your tongue?
Chemical
What are the receptor cells for your skin?
Pressure and temperature
What are the stimuli for your skin?
Pressure and heat
What are the receptor cells for your nose?
Small and taste
What are the stimuli for your nose?
Chemical and chemical
What are the 3 types of neurones?
Sensory neurones
Relay neurones
Motor neurones
What do sensory neurones do?
Carry electrical impulses from receptor cells to the CNS
What do relay neurones do?
Carry electrical impulses from sensory neurones to motor neurones
What do motor neurones do?
Carry electrical impulses from the CNS to effectors
What are nerves made of?
Hundred or thousands of neurones
What are the steps involved in a nervous reaction?
- Stimulus
- Receptor cells
- Sensory neurone
- Spinal cord
- Brain
- Spinal cord
- Motor neurone
- Effector
- Response
How long does a nervous reaction usually take?
0.7 seconds
What is a coordinated response?
When you brain takes in a lot of information at the same time (all the time) and makes responses based on the information
What does a coordinated response usually end with?
A series of impulses being sent to different parts of the body to produce the required action
What a reflex action?
Faster, automatic, involuntary actions
What is different about a reflex action?
They miss out the brain so your body can react even faster
How long do reflex actions usually take?
0.2 seconds
What is an example of a reflex action?
Cutting your hand on broken glass - biceps contract to pull the arm away
What are the basic reflex actions?
Basic bodily functions:
Breathing
Heart rate
Digestion
What are the steps in a reflex action?
- Stimulus
- Receptor cells
- Sensory neurone
- Spinal cord
- Motor neurone
- Effector
- Response
What is a reflex arc?
The nerve pathway that an impulse follows
Describe a reflex arc with steps (draw the flow diagram then add the sentences to make is specific).
- Stimulus - very hot saucepan
- Receptor cells - temperature receptors in skin
- Sensory neurone
- Spinal cord
- Motor neurone
- Effector - biceps muscle contracts
- Response - hand pulled away
What is the cornea?
Transparent coating on the front of the eye
What does the cornea do?
Protects the eye, refracts light entering the eye
What is the pupil?
Central hole in the iris
What does the pupil do?
Allows light to enter the eye
What is the iris?
A colouring ring is muscle tissue
What does the iris do?
Alters pupil size by contracting or relaxing
What is the lens?
Transparent biconvex lens
What does the lens do?
Focuses light clearly onto the retina
What are the ciliary muscles?
Ring of muscle tissue
What do the ciliary muscles do?
Alters the shape of the lens
What are the suspensory ligaments?
Ligament tissue
What do the suspensory ligaments do?
Connects the ciliary body to the lens
What is the optic nerve?
Nervous tissue
What does the optic nerve do?
Carries nerve impulses to the brain
What does refracts mean?
Changes direction of
How are images formed (step by step)?
- Cornea refracts incoming light rays - provides focus on the light
- Light passes pupil
- Light refracted again by lens - creates sharp image on retina
- Photoreceptors in retina produce nervous impulse (when expose to light)
- Impulse travels down the optic nerve to brain
- Brain interprets the impulses as a visual image
What are photoreceptors?
Light sensitive cells
What happens when your ciliary muscle contracts?
Your lens becomes more convex (fatter) - to focus on nearby objects
What happens when your ciliary muscle relaxes?
You lens becomes less convex (thinner) - to focus on distant objects
How is short-sightedness caused?
A person’s lens being too strong or the eyeball is too long
How is long sightedness caused?
A person’s lens being too weak or by the eyeball being too short.
Why are images blurry when you are short sighted?
The light rays meet in front of the retina (not on it) making the image blurry
How do you correct short-sightedness?
A CONCAVE lens bends the lights rays outwards before entering the eye.
Why is the image blurry in long sightedness?
The lights rays don’t meet on the retina (wider) so the image is blurred.
How do you correct long-sightedness?
A CONVEX lens lens bends light rays inwards before they enter the eye.
What are the 2 types of photo preceptor cells in the retina?
Rods
Cones
What do rods do?
Respond to light
Allow you to see in low light level
They aren’t responsive to different colours
What do cones do?
Respond to different colours
Different cone cells respond to red, blue and green
How does colour blindness happen?
When people don’t have certain cones in their retina
What is the most common form of colour blindness?
Red-green - people can’t distinguish between red and green light
Who does red-green colour blindness mainly affect?
Males - it is genetically inherited
What are the 5 main areas of the brain?
Cerebrum
Cerebellum
Medulla
Hypothalamus
Pituitary gland
What does the cerebrum do?
Controls complex behaviour - learning, personality, memory and thought
What does the cerebellum do?
Controls involuntary movements - posture and balance
What does the medulla do?
Controls automatic actions - heart rate and breathing rate
What does the hypothalamus do?
Regulates water balance and temperature
What does the pituitary gland do?
Stores and releases hormones that may regulate body functions
What are the difficulties when investigating brain functions?
Patients must give consent for medical information to be shared
Many case studies need to be analysed to draw reliable conclusions
Several areas of the brain may be involved with a specific function
Some people believe animal testing is unethical
How can you investigate brain function?
Placing electrodes inside the brain
CT scans (x-rays)
MRI scans - powerful magnets
What does placing electrodes in a brain do?
They transmit electrical impulses which result movement in different parts of the body - can link area of brain to body region it controls
What are the systems in the mammalian nervous system?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What does the central nervous system consist of?
Brain
Spinal cord
What does the peripheral nervous system consist of?
All the neurones that connect the CNS to the rest of the body
What is nervous system damage?
Damage to any part of your PNS or CNS
What are examples of how you can get nervous system damage?
Injury - falling off a ladder
Disease - diabetes or cancer
A genetic condition - Huntington’s disease
Ingesting a toxic substance such as lead
Why is nervous system damage bad?
It prevents impulses from being passed effectively though the nervous system.
E.g - sport injury damage neurone - explain neurone function
What are some effects of nervous system damage?
Inability to detect pain
Numbness
Loss of coordination
What happens if you injure your peripheral nervous system?
It has a limited ability to regenerate but surgery is needed for major injuries
What can damage to the central nervous system lead to?
Loss of control of body conditions
Paralysis
Memory loss or processing difficulties
Why is it difficult to repair the spinal cord?
It consists of 31 pairs of nerves each containing nerve fibres, repairing 1 nerve without damaging others is extremely hard
How could you treat a brain tumour?
Radiotherapy and chemotherapy
How could you treat damaged brain tissue?
Surgery to remove it
How could you help brain function?
Deep brain stimulation - insertion of an electron
What is different about repairing the CNS to the PNS?
The PNS has limited regeneration but the CNS cannot regenerate
What are hormones?
Chemical messengers
Where are hormones made?
The endocrine glans and secreted into the blood
How are hormones transported around the body?
Blood transports the hormones in the plasma around the body
How fast are hormonal responses?
Fairly slow and long lasting (e.g puberty)
What is homeostasis?
Keeping the conditions in your body constant
What does the hypothalamus and pituitary gland do?
Produce hormones that regulate production of other hormones
What does the thyroid gland do?
Produce thyroxine
Where is adrenaline produced?
Adrenal glands
Where is insulin produced?
The pancreas
Where is oestrogen and progesterone produced?
Ovaries (females)
What produces testosterone?
The testes
How do hormones do their job?
The diffuse out the blood and bind to specific receptors for that hormone found on the membrane or cytoplasm of cells in the target organs
What are target cells?
The cells that bind to their specific hormone
What do hormones do once bound?
They stimulate the target cells to produce a response
What is the endocrine system?
The name given to all the endocrine glands and the hormones produced
What does the endocrine system do?
Controls and coordinates body processes with the nervous system
What do the endocrine system and nervous system both do?
Send messages around the body to provide information about any changes in the internal and external environment and how to respond to that.