Year 10 Biology Flashcards
Define Homeostasis
the maintaining of a constant internal environment
Define Negative Feedback
the correction for any deviation from a set or normal condition
Name the basic examples of homeostasis
temperature regulation, basic kidney function and blood glucose regulation
How is body temperature regulated?
Sweating, shivering, vasodilation, vasoconstriction.
What is vasodilation?
During vasodilation the blood vessels widen, which decreases blood pressure and cools you down when your blood moves more toward your skin and heat is lost by radiation.
What is vasoconstriction?
During vasoconstriction the blood vessels are more narrow, which increases blood pressure, warming your body as your blood moves more toward your core and you lose very little heat via radiation.
What happens when you sweat?
Sweat makes your skin feel cooler when it’s wet. And when it evaporates it removes some heat from your body.
What happens when you shiver?
Skeletal muscles begin to shake in small movements, creating warmth by expending energy.
Which gland maintains homeostasis and how?
The hypothalamus is the control center and it determines what the body does in response to different environments to maintain homeostasis. It does this by sending messages through nerve impulses to effectors.
What is the correct range for body temperature?
36.1 to 37.2 degrees
What is an effector?
A muscle or a gland
What does BMR stand for?
Base metabolic rate
What role does BMR play in temperature regulation?
When your too hot your BMR decreases meaning less heat is produced. When your too cold there is an increase in your BMR, producing more heat
What temperature does hypothermia start
35 degrees and below
What temperature does hyperthermia start
Above 40 degrees
What are the key functions of the kidney?
Maintain water and salt balance and excrete urea.
What is ultra-filtration?
The filtering of glucose, amino acids, water, urea and salt out of the blood stream into the Bowman’s capsule which is part of the nephron.
What is reabsorbtion
The re-absorption of glucose, amino acids, 80% of the water and 75% of the salt back into the blood stream through the proximal tubule which is also part of the nephron.
What is ADH?
Anti-diuretic hormone
What does Anti-diuretic hormone do?
Reduces urine production
Where is ADH produced?
The pituitary gland
When the body has excess water levels what happens in relation to ADH production?
Less ADH is produced in order to return the body to a normal water balance
When the body has depleted water levels what happens in relation to ADH production?
More ADH is produced in order to return the body to a normal water balance
What is the normal blood glucose level ?
90mg of glucose per 100mL of blood
Where do we get glucose from?
The carbohydrates in our food
What happens when blood glucose levels are above 90mg per 100mL
The pancreas releases insulin into the blood stream
What does insulin do?
It increases glucose uptake by the liver, which in turn reduces blood glucose level
What does the glucose do inside the cell?
Turns into glycogen
What happens when blood glucose levels are below 90mg per 100mL
The pancreas releases a hormone called glucagon
What does glucagon do?
Makes the liver turn some of its stored glycogen into glucose
Define hypoglycaemia
Deficiency of glucose in the blood
Define diabetes
The bodies incapability to produce or act upon instruction given by insulin, resulting in elevated blood glucose levels
What happens when the body comes into contact with a hot/cold stimuli
Temperature receptors send a signal to spinal cord which sends a signal back to a muscle to contract, all whilst the temperature receptors send a message of pain/cold/heat to the brai
What can an effector be?
Muscle or gland
What do muscles and glands do?
Contract and secrete
What are the two types of neurons?
Sensory and motor
Where is the cell body on a motor neuron?
End of neuron 0———-
Where is the cell body on a sensory neuron?
Middle of cell >—-0—-<
What are the parts of a sensory neuron?
Receptors, axon, cell body and nucleus, schwan cells and axon terminals
What are the parts of a motor neuron?
Dendrites, cell body and nucleus, axon, myelin sheath and axon terminals
What does a sensory neuron do?
Transmits impulses from receptors to the CNS
What does a motor neuron do?
Transmits impulses from CNS to effectors
What is the importance of a reflex action?
Prevents injury and enables you to rapidly jerk away your hand from something hot or sharp etc
Describe a reflex arc
If you stand on something sharp, nerve impulses travel from the pain receptors in your foot to the spinal cord via the sensory neuron. The impulses then travel directly to the leg muscles via the motor neuron, causing the leg muscle to contract.
What does the medulla do?
Controls automatic actions such as heartbeat, breathing and blood pressure
What does the cerebral cortex do?
Gives sensation of feeling from eyes, ears, tongue, nose and skin. Controls muscle movement along with memory and thinking
What does the cerebellum do?
Coordinates muscles and balance for walking, running, cycling etc
What are the 6 major glands
Thyroid, adrenal, pituitary, pancreas, testes and ovaries
What is the hormone produced by the thyroid
Thyroxine
What is the hormone produced by the Adrenal gland
Adrenaline
What is the hormone produced by the pituitary gland
ADH
What is the hormone produced by the pancreas
Insulin and glucagon
What is the hormone produced by the testes
Testosterone
What is the hormone produced by the ovaries
Oestrogen and progesterone
What does thyroxine do?
Regulates growth and metabolism
What does adrenaline do?
increase levels of activity
What does ADH do?
Regulates water balance
What does insilin do?
Reduce blood glucose levels
What does Glucagon do?
Increase blood glucose levels
Where is DNA located?
Cell nucleus
Which letters pair with “A”
T and U
Which letter pair with “G”
C
What is the structure of DNA?
Double helix
What is the function of DNA?
To code for protein production
What are the 2 phases of protein synthesis ?
- DNA is copied into mRNA
2. mRNA is converted into protein
What can gene mutation cause?
Altered proteins or no proteins at all
Define evolution
A change in the genetic composition of a population over time
In order, what are the parts of a nephron
Bowman’s capsule, proximal tubule, loop of Henle, distal tubule, collecting duct
Define phenotype
The word of trait
Define genotype
The letters used to represent a trait
Define homozygous
Having same alleles e.g AA
Define heterozygous
Having different alleles e.g. Aa
