2i + j - Excretion + Co-ordination Flashcards
What are some examples of metabolic wastes?
- Carbon Dioxide
- Urea
- Water
Why are waste products dangerous?
- can have toxic effects
- body fluids can become more concentrated
- enzyme activity can decrease
What are the waste products in plants?
- oxygen
- carbon dioxide
- water
What are the excretory organs in humans?
- kidneys
- lungs
- skin
- liver
What do kidneys excrete?
- Water
- mineral ions
- urea
What does the skin excrete?
- water
- mineral ions
What are the functions of the urinary system?
- to filter waste products from the blood and expel it from the body as urine
- osmoregulation
What is the function of the urethra ?
carries urine from the bladder to outside the body
What is the function of the renal artery?
Delivers oxygenated blood to the kidney
What is the function of the renal vein
Delivers the deoxygenated blood from the kidney to the vena cava
What is the function of the kidneys?
- regulate the water content of the blood
- excrete toxic waste products
What are the 3 regions of the kidney?
Cortex, medulla, renal pelvis
Describe ultrafiltration
- smaller molecules in the blood are forced out of capillaries into the bowman’s capsule
- filtrate is formed
- some useful substances are reabsorbed back into the blood further down the nephron
Where is water reabsorbed at?
Loop of henlé and collecting duct
Where are salts reabsorbed at?
Loop of henlé
Where does selective reabsorption of glucose occur at?
In the Proximal convoluted tubule by active transport
How is a nephron adapted for reabsorption?
mitochondria to provide energy for active transport
What is osmoregulation?
The process of maintaining water and salt concentration in the body
What happens to a cell if there is too much water?
Cells swell and burst (lysis)
What happens to a cell if there isn’t enough water?
Cell Dehydration and death
What does ADH control ?
The water content of the blood
Where is ADH released?
Pituitary gland
What happens if water content of blood is too high?
- less ADH is released by pituitary gland
- tubules become less permeable
- less water is reabsorbed
What happens if the water content of blood is too low?
- more ADH is released by pituitary gland
- tubules become more permeable
- more water is reabsorbed
What does homeostasis control?
Water, temperature, pH
Give two examples of homeostasis in humans?
- control of body temperature and water content
What is vasodilation?
The widening of blood vessels at the skin surface to increase heat loss
What is vasodilation a response to?
Being too HOT
What happens to the arterioles during vasodilation?
Get wider
What are two examples of vasodilation?
Sweating + flattening of hairs
Describe how sweating cools the skin
By evaporation which uses up heat energy to convert liquid into vapour
What is vasoconstriction a response to?
Being too COLD
What is vasoconstriction?
The narrowing of blood vessels at the skin surface to reduce heat loss
What happens to arterioles during vasoconstriction?
Get narrower
What are two examples of vasoconstriction?
Shivering + erection of Hairs
Describe shivering
- involuntary muscle contractions require energy from respiration
- respiration releases heat to warm body
Describe erection of hairs
Trapped air between hairs stops heat loss by radiation
What happens if the water content of blood falls below a certain level?
Blood is too concentrated
What happens if water content of blood rises above a certain level?
Blood is too dilute
How is water reabsorbed in kidneys?
Filtrate passes through the tubules, where water is reabsorbed
If the water content of the blood is too high, how much water is reabsorbed?
Less water
If the water content of the blood is too low, how much water is reabsorbed?
More water
What does the hypothalamus detect ?
Water level
What is a plants response to light?
Phototropism
What is a plants response to gravity?
Geotropism
When is it a positive tropism ?
If the growth is towards the stimulus
When is it a negative tropism?
If the growth is away from the stimulus
What happens as shoots grow upwards?
positive phototropic response + negative geotropic response
What happens as roots grow downwards Into the soil?
negative phototropic response + positive geotropic response
What are auxins ?
Plant growth regulators which coordinate and control tropisms
Where are auxins produced?
In the tips of shoots and the roots
What do auxins do in the shoots?
Promote cell elongation (more growth)
What do auxins do in the roots?
Inhibit cell elongation (less growth)
If a shoot/root is placed on its side, where will auxins be?
Along the lower side due to gravity
What is the central nervous system (CNS) ?
The brain and spinal chord
How do dendrites help electrical impulses travel faster?
Neurones can connect to each-other, forming a easy communication network
What do sensory neurones do?
Carry impulses from receptors to the central nervous system
What do relay neurones do?
Connect sensory and motor neurones (found inside CNS)
What do motor neurones do?
Carry impulses from the CNS to effectors
Describe the pathway through the nervous system
Stimulus —> sensory neurones —> relay neurone —> motor neurone —> effector —> response
What is a synapse?
The small gap between neurones
How does the electrical signal pass the synaptic cleft?
It is converted to a chemical signal briefly
What two types of receptor cells does the retina of an eye contain?
Cones and Rods
What are rods sensitive to?
Light
What are cones sensitive to?
Colour
What is the function of the cornea ?
Transparent lens that refracts light
What is the function of the iris ?
Controls how much light enters the pupil
What is the function of the lens ?
Changes shape to focus light onto retina
What is the function of the retina ?
Contains receptor cells (rods + cones)
What is the function of the optic nerve ?
Sensory neurone that carries impulses between the eye and brain
What is the function of the pupil ?
Hole that allows light to enter the eye
What is the function of the ciliary muscle ?
changes the shape of the lens
What is the function of the suspensory ligaments?
Connect the ciliary muscle to the lens
What is the function of the sclera ?
Strong outer wall of eyeball which keeps the eye in shape
What is the function of the fovea ?
Region of the retina with the highest density of cones
What happens in the eye when an object is close?
- ciliary muscles CONTRACT
- suspensory ligaments LOOSEN
- lens becomes FATTER
- light is refracted MORE
What Happens in the eye when an object is far away?
- ciliary muscles RELAX
- suspensory ligaments TIGHTEN
- lens becomes THINNER
- light is refracted LESS
In dim light what happens to the pupil?
Pupil dilates (widens) to allow lots of light
In bright light what happens to the pupil?
pupil constricts (narrows) to prevent too much light entering the eye and damaging the retina
What happens to the eye muscles in dim light?
- radial muscles CONTRACT
- circular muscles RELAX
- MORE light enters eye
What happens to the eye muscles in bright light?
- radial muscles RELAX
- circular muscles CONTRACT
- LESS light enters eye
What does thyroid produce?
Thyroxine which controls metabolic rates + growth
What does the pancreas produce?
Insulin
What do adrenal glands produce?
Adrenaline
What does adrenaline do?
- prepares the body for a “flight or fight” response in danger
- increases breathing + heart rate
