B5 Flashcards
What are the 2 functions of the nervous system?
enables us to detect our surroundings and respond to stimuli and coordinate behaviour
what is the nervous system made up of? (4)
- brain
- receptor cells
- spinal cord
- nerve cells
what do receptors do?
detect changes in the environment
what is the function of the axon?
- nerve cell
carries impulses along the neurone
what is the function of the myelin sheath?
- nerve cell.
insulates the axon
- stops electrical impulses from leaving
What is the function of the Dendron?
- nerve cell
receives impulses from another neurone/ receptor
What is the function of the Node of Ranvier?
small parts of exposed axon that promote fast conduction of electrical impulses
What are the parts of the ‘reaction pathway’ that always stay the same? in what order?
stimulus –> receptor –> sensory neurone –> spinal chord –> relay neurone —> motor neurone –> effector —> response
which neurones carry electrical impulses from the receptor cells to the central nervous system?
sensory and motor neurone
what is a key role of the nervous system?
it enables humans to react to their surroundings and coordinate their behaviour - this is done through the reflex arc
what do coordination centres do?
receive and process information from receptors
what do effectors do?
bring about responses to stimuli
what is generated when a receptor cell detects a stimulus
an electrical impulse
what is the gap between 2 neurones called?
a synapse
Explain/ Describe
the general features of an automatic control system
- Receptor cells detect a stimulus (changes in the environment)
e.g internal change - conc of glucose in blood or external - skin temp - Receptor cell pass information to a coordination centre e.g brain, spinal chord or pancreas
- Coordination centre sends instructions to the effector ( a muscle that contracts or gland that secretes a hormone)
what is a reflex
an automated response to a stimulus
- the impulses generated do not travel to the brain so you can’t even think about it
what can automatic control systems in the human body involve?
nervous system or hormones
what do all automatic control systems involve? (5)
a stimulus, a receptor, a coordination centre, an effector and a response
what is homeostasis?
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for functions in response to internal and external changes
what conditions do we control in the body?
temperature, blood glucose levels and water
what is the function of the nervous system?
enables us to detect our surroundings and respond to stimuli and coordinate our behavoir
what is the main function of the human endocrine system?
lest us send signals throughout the body (like the nervous system)
Human endocrine system (4)
- provides information about internal and external environment
- uses hormones
- tells us blood glucose/sugar levels
- sends signals (hormones) to produce a coordinated response (e.g moving arms and legs)
what are hormones?
chemical molecules that are released directly into the blood to be carried around the body to activate responses in specific cells that are found in target organs
- a type of protein that is a chemical messenger that travels in the blood.
what do hormones do?
activate responses in specific cells by diffusing out of the blood - they bind to specific receptors on the membranes or on the cytoplasm cells in target organs
what are 5 examples of hormones?
- Adrenaline
- insulin
- Thyroxine
- Oestrogen
- testosterone
what does testesterone do?
Increases likelihood of acne → because increased levels of testerone makes skin produce more oil causing acne
where do these hormones travel?
in the blood vessel
where are these hormone produced?
in endocrine glands
what are the 6 main endocrine glands?
where are the pituitary glands found? what do they do?
In brain - releases many hormones that act on other glands to control the release of hormones
where are the thyroid glands found? what do they do?
Neck- produce thyroxine a hormone that regulates things like metabolic rate and heart rate
where are the Adrenal glands found? what do they do?
Found on top of kidneys - produce adrenaline (among other hormones) to prepare your body for stress
where are the pancreas glands found? what do they do?
Found near stomach - necessary for regulation of blood glucose levels because it produces insulin (a glucose-regulating hormone) that allows cells to take in glucose
where are the ovaries glands found? what do they do?
Produce oestrogen and progesterone (hormones that are involved in puberty and the menstrual cycle
where are the testes glands found? what do they do?
In males- produce testosterone _ this hormone controls puberty and sperm production
What are target organs
Organs or tissues that respond to a particular hormone.
What is insulin
A glucose- regulating hormone
What type of feedback is thyroxine controlled by?
Negative feedback.
how does a negative feedback system work?
- conditions in body move from normal level
- this is detected by receptors
- corrective mechanisms are activated
- which turns the conditions back to their normal level
- the corrective mechanisms are switched off
why is it dangerous for body temperature to ride far above 37 degrees celcius?
the enzymes in the cell denature so substrate can’t bind to active site and they can no longer do their job
why is it important for the body to get rid of excess water?
Body needs to get rid of excess water by osmosis out of the cell
-if it doesn’t the water content in blood will be too high ( blood to dilute). This means water moves by osmosis to surrounding cells causing them to swell
which organ monitors blood glucose levels?
pancreas
give 2 factors that can affect blood glucose levels?
eating and sleeping
what hormone is released when blood glucose levels are high?
insulin
what hormone is released when blood glucose levels are low?
Glucagon
Describe and explain how the body responds to a high blood glucose level.
When your body has a high glucose level is it detected by glucose receptors on the pancreas, which releases insulin into blood stream. This causes body cells to take up glucose and use it for respiration. It also causes the liver to to move excess glucose from the blood and joining it together to store as glycogen. Blood glucose levels return to normal and the pancreas tops secreting insulin
Describe and explain how the body responds to a low blood glucose level.
When your body has a low glucose level is it detected by glucose receptors on the pancreas, which releases glucagon into the blood stream. This cause the liver to break down glycogen into glucose and absorb it into the blood stream which causes blood glucose levels to increase again.
What is type 1 diabetes?
Which organ produces urine?
Kidney.
Why do marathon runners often drink sports drinks during the race?
To replace water that is lost in sweat
Why does the body need to lose water from the skin?
For cooling and to maintain body temperature
Which organ monitors body temperature?
Brain.
