B1.2 Nerves and Hormones Flashcards
What does CNS stand for?
Central nervous system
-Brain and spine
What does PNS stand for?
Peripheral nervous system
-Linked with CNS by sensory neurons
What are receptors
Specialised cells on the surface
-Receive stimuli
What are the 3 types of neurones?
Sensory
Motor
Relay
What is the role of a sensory neurone?
Carry electrical impulses from receptors to the spinal chord
What is the role of a motor neurone?
Sending electrical impulses from the brain to muscles
In what order do the neurones go?
STORM
Sensory
Relay
Motor
Does a reflex arc involve the brain
No
What is a reflex arc?
A nerve pathway involved in a reflex action, that is simpler than the other electrical impulses.
Involves a sensory neruone and a motor neurone
What is a synapse?
A gap between two neurones
Neurotransmissions diffuse across them
How do synapses work?
An electrical impulse travels along an axon
This triggers the nerve-ending of a neurone to release neurotransmitters
These diffuse across the synapse
Bind with receptors on the next neruone
This stimulates the second neurone to transmit the electrical impulse
Repeats
What is a receptor?
A receptor is a group of specialised cells that react to a stimulus. They detect a specific change in the environment.
EG
Receptor = eye
Stimulii = light
What system involves the brain and spinal cord?
The central nervous system
What are neurones?
Neurones are nerve cells that carry information in the form of tiny electrical signals
What are the properties of a sensory neurone?
The sensory neurone SENSES the stimuli and stimulates signals that are sent to the brain and spinal cord
Which neurone transmits messages thoughout/within the central nervous system?
The relay neurone
What does the motor neurone do?
Carry signals from the central nervous system to the effectors (that carry out the action)
What is the axon of a motor neurone
The central strand
Where are the dendrites?
At the end of the motor neurone by the nucleus
What is the synapse?
The gap where two neurones meet and an electrical signal is diffused accross
How does a reflex action occur?
stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector
The actions do not interact with the brain
What is an effector?
Any part of the body that produces a response
eg -> a muscle contracting, gland releasing
What is the eye an example of?
A sense organ
Which type of neurone transmits a signal from a sense organ to the central nervous system?
Sensory neurone
What is a hormone?
A chemical substance produced by a gland and carried by the blood that alter the activity of target organs
How are hormones and nerves similar?
They can both control the body
What are the characteristics of a hormone?
Signal : chemical
transmission : nerve cells in the blood stream
Effectors : cells in particular tissues
Response : chemical change
Speed of response : slow
Duration of response : Long ( until hormone breaks down)
What hormone does the ovary produce?
Oestrogen
Where is insulin produced?
The pancreas
What controls the pituatiry gland?
The hypothalimus in the brain
Where is adrenalin produced?
The adrenal gland
What and when are the four stages of the menstrual cycle?
Stage 1 (days 1-4) the uterus sheds its lining (bleeding) Stage 2 ( days 4-14 ) the uterus lining is rebuilt, thick spongy layer Stage 3 ( day 14) An egg is released from the ovary Stage 4 (14 -28) The uterus lining remains for the egg to be fertilised, if not the cycle begins again
What major hormones are in the menstrual cycle?
- FSH (follicle stimulating hormone)
- Oestrogen
- LH ( luteinising hormone)
How is an egg released from the ovaries?
The pituitary gland causes the production of FSH which in turn causes an egg to mature
The ovaries release oestrogen which triggers the release of LH
LH (released by the pituitary gland) determines when an egg is released into the uterus
What are the four types of pathogen that cause disease?
Virus
Bacteria
Fungi
Carcinogen
What does FSH do?
Secreted by the pituitary gland
Causes an egg to mature
Stimulates release of oestrogen
Which hormone, secreted by the ovaries, is responsible for stopping the production of FSH and stimulating the release of LH?
Oestrogen
It stops the production of FSH so only one egg is produced
What is the job of the Luteinising Hormone?
Released by the pituatary gland
Triggers ovulation
What are the benefits of oral contraceptives?
- Oestrogen greatly reduces the chances of pregnancy by reducing the production of FSH
- Allows choice to have children
What were the risks of old fashioned oral contraceptives?
- Mood swings
- Weight loss or gain
- Change in blood pressure
This was due to more oestrogen being in the pills than there are today
How can fertility drugs aid the probability of pregnancy?
They contain FSH or LH which the patient is lacking in and so stimulates the production, maturing, and release of eggs
This can often lead to twins, triplets etc and also complications with birth such as a premature birth
How can IVF help the possibility of pregnancy?
If the quality of the mans sperm is affecting the chance of pregnancy, the egg can be fertilised outside of the womb.
Fertility drugs can also be used to increase the amount of eggs available for fertilisation
Why might some people disagree with IVF?
It could lead to the production of ‘designer babies’ if the parents have a choice of which child they want
eg a girl in a family of boys/boy in a family of girls
How are hormones transported around the body?
In the blood stream
What is a tropism?
A plants response to a stimulus
A positive tropism = towards
A negative tropism = away from
What are auxins?
Auxins are a family of hormones made in the tips of shoots or roots of plants
They can elongate cells and therefore respond to a stimulus by changing the shape of a plant
eg
If the sun is on the left, the auxins elongate the cells in the right side of the plant stem to cause it to bend towards the light
How can plant hormones be used commercially?
- In weed killers to kill some plants but cause others to survive
- In rooting powders to make stem cuttings grow and thrive
How do cells in roots react to the presence of auxins?
They grow less
Are shoots positively or negatively..
phototropic
gravitropic
Positively phototropic
Negatively gravitopic
Are roots positively or negatively…
phototropic
gravitopic
Negatively phototropic
Positively gravitopic
When a root bends gravitopically, does the bottom or top side grow more?
The top side grows more to bend the root downwards
