14. Coordination And Response Flashcards
what is a nerve impulse
an electrical signal that passes along nerve cells
what is the difference between the central nervous system and the peripheral nervous system
the central nervous system is the brain and the spinal cord, the peripheral nervous system is every other part of the nervous system
what is voluntary action
an action completed with conscious thought and under our own will
what is involuntary action
an action completed without conscious thought
name the neurons shown below
sensory neurone
name the neurons shown below
relay neurone
name the neurons shown below
motor neurone
Describe the reflex arc
stimuli detected by a receptor
impulses passed along sensory neurons to relay neurons in the CNS
impulses passed along the motor neurons to effector
effectors brings about the response
what is a reflex action
a rapid response to a stimulus by an effector
what is a synapse
a junction between two neurones
label this diagram of a synapse
how is an impulse transmitted between two neurones
the impulse reaches the end of one neurone
vesicles release neurotransmitter into the synaptic gap
the neurotransmitter diffuses across the gap and binds to receptors in the membrane of the next neurone
a new impulse is triggered in the next neurone
what is the purpose of synapses
to ensure that impulses travel in one direction only
give 3 examples of drugs that affect synapses
alcohol
heroin
nicotine
what are sense organs
groups of cells that detect changes in the environment
identify the structures of the eye labelled in the diagram below
What is the cornea and what is its function
the transparent layer in front of the eye that protects the eye from damgae
what is the iris and what is its function
the colored ring around the pupil that controls its diameter
what is the pupil and what is its function
the pupil is the hole in the middle of the iris that lets light into the eye
what is the optic nerve and what is its function
the nerve coming out the back of the eye that sends signals to the brain
what is the function of the lens
the lens focuses the light rays onto the retina
state the response of the eye to bright light
the pupil decreases in diameter to let less light in
explain the response of the eye to bright light
the circular muscle contracts and the relaxes muscle relaxes, making the pupil smaller
state the response of he eye to a lack of light
the pupil increases in diameter to let more light in
explain the response of the eye to lack of light
the radial muscle contracts and the circular muscle relaxes, making the pupil larger
explain how the eye focuses on distant objects
- the ciliary muscles loosen and the suspensory ligaments relax
- the lens become thinner
- light is refracted less
explain how the eye focuses on near objects
- the ciliary muscles contract and the suspensory ligaments loosen
- the lens becomes thicker
- light is refracted more
describe the distribution of rods and cones in the human eye
mostly more rods than cones in the eye however in the fovea there are more cones than rods
what is the fovea
an area on the retina with lots of photosensitive cells so it has the highest visual acuity
what is the function of rods
they function in low light intensities
what is the function of cones
there are 3 different types of cone cells that all help to detect color (red, green, blue)
identify the fovea on the diagram below
what is a hormone
a chemical secreted by a gland into the blood that brings about an affect on one or more target organs
where are the adrenal glands located
behind the kidneys
what hormone do the adrenal glands secrete
adrenaline
where is the pancreas located
behind the stomach
what hormones does the pancreas secrete
insulin
what hormone do the tests secrete
testosterone
what hormone do the ovaries secrete
oestrogen
when is adrenaline secreted
during ‘flight or fight’ situations
give 3 effects of adrenaline
- widens pupil
- increases heart rate
- increases breathing rate
give 3 examples when adrenaline secretion increases
- during scary situations
- during stressful situations
- during exciting situations
how does adrenaline cause an increase in heart rate
- travels in the blood to the heart
- binds to receptors on the heart cells
- binding causes a cascade that increases the heart rate
how does adrenaline cause an increase in blood glucose concentration
- it travels in the blood to the liver
- it binds to receptors on the liver cells and causes a cascade which causes glycogen to be broken down into glucose which enter the blood
give 2 differences between the nervous system and the hormonal system
what does estrogen do
estrogen causes the uterus lining to thicken
what does testosterone do
- main male sex hormone
- involved in growth of testes and penis
- triggers many changes in males during puberty
what does insulin do in the body
insulin decreases blood glucose concentration
define homeostasis
maintaining a constant internal environment within a set limits despite external change
what mechanism is used to achieve homeostasis
a negative feedback mechanism
what does insulin do in the body
insulin decreases blood glucose concentration
what does glucagon do in the body
glucagon increases blood glucose concentration by increasing the conversion go glycogen to glucose in the liver
give 3 symptoms of type 1 diabetes
- feeling very thirsty
- feeling very tired
- blurred vision
give 3 methods for treating type 1 diabetes
- insulin injections
- diet monitoring
- pancreas transplant
identify the structures of the skin labelled below
Give 2 processes involving the skin that cool the body down
sweating - cools the body by evaporation
vasodilation -allows blood to flow closer to the surface of the skin where it can cool
give 3 processes that work to keep the body warm
- vasoconstriction
- shivering
- erection of hairs on the skin
describe the process of vasodilation
- the body detects a rise in temperature
- blood vessels supplying the capillaries at the skin surface dilate
- more blood flows closer to the skin where it can cool
describe the process of vasoconstriction
- the body detects a drop in temperature
- blood vessels supplying the capillaries at the skin surface constrict
- less blood flows closer to the skin surface so less heat is lost to the surroundings
what is phototropism and which part of a plant is positively phototropic
phototropism is the growth of a plant towards a light source
the shoots are positively phototropic
what is geotropism and which part of a plant is positively geotropic
geotropism is the growth of a plant towards the pull of gravity.
the roots are positively geotropic
what are geotropism and phototropism examples of
they are examples of chemical control in plants
explain how auxin controls shoot growth
- auxin is made in the shoot tips of the plant and spreads. through the plant
- it is unequally distributed in response to light and/or gravity
- it stimulates cell elongation and the growth of the shoot on the side with most auxin
why is the chemical 2, 4-D popular in synthetic weedkillers
- the 2, 4-D is very effective in entering the plant but it cannot leave the plant and so it builds up and kills the plant
- it is very specific to weeds and broad leaved plants rather than grasses and other similar vegetation
