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Biology {Coordination & Response School} 🐞 - Coggle Diagram
Biology {Coordination & Response School} 🐞
Homeostasis
the control/regulation of internal conditions in the body to a narrow range eg. body temperature, blood water levels
Thermoregulation
What happens when the body is too hot?
The thermoreceptors detects the rise in body temperature then the hypothalamus intiitaes several cooling mechanisms. Sweat glands produce sweat so the water can evaporate and release heat, hair lies flat so that no pocket of air can provide insulation and vasodilation occurs because the arterioles begin to dilate causing more blood to be carried to the surface of the skin so more heat is radiated from the body.
the ability to control internal body temperature
Body works best at optimum temperature 37ºC above that and enzymes can denature below that and metabolic reactions are too slow
What happens to the body when it is too cold?
The thermoreceptors detects the drop in body temperature and the hypothalamus initiated several heating mechanisms. The body stops producing sweat and the body begins to shiver these rapid short muscle movements require energy from respiration producing more thermal energy, hair stands up straight to make pockets of air that act as insulation and vasocontraction occurs where the arterioles contract and less blood is near the surface of the skin so less heat is radiated from the body.
Coordinated Response
stimulus
- change in external or internal environment
receptor
- cells that detect stimuli
coordination centre
- receives and processes information from the receptors eg. brain, spinal cord, pancreas, pituitary gland
effectors
- responses to restore optimum levels eg.muscle contractions, or hormonal releases
features of nervous system
- sends electrical impulses from brain through nerves and neurons in response to stimuli affecting muscles and glands incredibly fast and last for a short time.
features of endocrine system
- releases chemical substances in the form of hormones from glands through the bloodstream to specific cell tissues slower than the nervous system, but with longer lasting effects.
CNS-
the central nervous system coordinates response (brain and spinal cord)
nerve cells/neurones
- specialised cells that carry electrical impulses
sensory neurone
- carry impulses from sense cells (receptors)
relay neurone
- acts as a bridge for the electrical signal between neurones
motor neurone
- stimulated an effector (a muscle or gland) into a response
Plant Responses
plants respond to stimuli like gravity, light, and water, but slower than animals
phototropism- movement towards or away from a light source
geotropism- movement towards or away from gravity
hydrotropism- movement towards or away from water
positive tropism- going towards a stimulus negative tropism- going away from a stimulus
Stem and Roots responses
stem- positive phototropism stem grow towards light negative geotropism roots grow away from gravity
auxin
- hormone formed at the tip of the stem that controls the growth rate plant (causes cells to elongate)
root- negative phototropism roots growing away from light source and positive geotropism, hydrotropism growing towards gravity and water
If there is equal light distribution, the auxin will be equally spread out and the shoot will grow upwards.
If light source changes, auxin accumulates on the shaded side of the stem
Auxin causes the shaded side of the stem to elongate causing it to bend towards the light source.
Nerve Cell
axon
- long central fibre that conducts electrical impulses
myelin sheath
fatty substance insulated axon
dendrites
- bridges between neurones
node of ranvier
- uninsulated section of axon where the electrical impulse jumps from
synapse
- gap between two neurones
What is the importance of synapses?
ensures electrical impulses travel in one direction and ensures the signal cannot be misinterpreted
Synaptic Transmission
1) An electrical impulse arrives at the end of the presynaptic membrane
2) Vesicles move towards and fuse with the presynaptic membrane. This releases neurotransmitters into the synaptic cleft
3) The neurotransmitters diffuse across the synaptic cleft down a concentration gradient
4) Neurotransmitters attach to receptors on the postsynaptic membrane
5)This triggers an impulse which travels along the postsynaptic neurone
6) Neurotransmitters are recycled or destroyed once an impulse is sent
Why is the speed at the motor neuron faster?
More synaptic cleft means more diffusion of neurotransmitters across synapse meaning faster impulse speed.
The Human Eye
cornea
- convex transparent lens that refract light as it enters the eye
iris
controls how much light enters pupil
lens
- biconvex transparent discs that can change shape to focus light into the retina
retina
- contains light receptor cells (rods and cones)
rod cells
- detect light intensity
cone cells
detect colour
optic nerve
sensory neuron that carries electrical impulses between the eye and the brain
pupil
- hole that allows light to enter the eye
ciliary muscle
a ring of muscle that contracts and relaxes to change the shape of the lens
suspensory ligaments
- ligaments that connect ciliary muscle to lens
fovea
region of eye with highest density of cones
sclera
the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye
aqueous humour
- the watery liquid between the cornea and the lens
vitreous humour
- the jelly-like liquid filling the eyeball
choroid
- a pigmented layer of tissue lining the inside of the sclera that prevents the reflection of light rays inside the eyeball
blind spot
- the point at which the optic nerve leaves the eye, where there are no receptor cells
What happens in the eye when viewing near objects?
The ciliary muscles contract, suspensory ligaments slacken, lens becomes thicker and there is more light refracted.
What happens in the eye when viewing far objects?
The ciliary muscles relax, suspensory ligaments tighten, lens becomes thinner and there is less light refracted.
What happens in the eye when in dim light?
iris circle muscles relax, radial muscles contract, pupil dilates, more light let in eye
What happens in the eye when in bright light?
iris circle muscles contract, radial muscles relax, pupil constricts, less light enters eye
https://www.geoguessr.com/seterra/en-an/vgp/3802
conjunctiva
thin clear membrane that protects eye
Reflex Arc
stimulus-> receptor--> sensory neurone -> relay neurone located in spinal cord connecting to motor-> motor neuron -> effector
rapid and without conscious thought
Sight- eye- light by rods and cones in retina
Touch- skin- temperature, pressure pain throughout body
Hearing- ear- sound recepetors in cochlea
Taste- taste buds- detect sweet, sour, umami, salty, bitter
Smell- nose- chemicals receptors in nasal cavity detect vapours
Hormones
adrenaline
- adrenal glands, readies the body' 'fight of flight response' it increases blood flow to muscles as well as heart and breathing rate
insulin
- pancreas, lowers body glucose, causes excess glucose in the blood to be taken up by muscles, liver and be converted and stored as glycogen.
testosterone
- testes, main male sex hormone, development of secondary male sexual characteristics
ADH
- antidiuretic hormone, pituitary gland, controls water content in blood, increases the permeability of the collecting duct
oestrogen
- ovaries, main female sex hormone, development of secondary sexual characteristics in females
progesterone
- ovaries, maintains pregnancy, maintains uterus lining and cushions fertilised egg for it to develop
FSH
- ovaries, causes ovary to develop a mature egg cell, stimulates development of egg cell and release of oestrogen
LH
- ovaries, causes ovary to release the egg. stimulates ovulation (release of egg cell) and release of progesterone
Exam Question
Why do cells store glucose as glycogen?
since soluble glucose in high levels could cause the cells to lose water by osmosis which could be deadly.
