Homeostasis Flashcards
What is homeostasis?
Maintaining a constant internal environment
What are the main factors our bodies control?
Water levels
Temperature
Glucose concentration
What is a somatic (voluntary) nervous system?
It is conscious it involves the brain
What is an autonomic (involuntary) nervous system?
It is subconscious reflexes
What is a reflex?
Involuntary responses to a stimuli
What is a reflex arc?
A reflex arc is the nerve pathway that bypasses the conscious part of the brain
What is an example of a reflex?
Breathing
Dropping a hot object
Increasing your heart rate
How does a reflex work?
The receptor, skin cells, detect a stimuli (heat)
Sensory neurone sends an electrical message to the CNS (spinal cord)
Relay neurone passes the message to the motor neurone
Motor neurone passes the electrical message to the effector
The organ is stimulated to respond.
What is respiration?
Respiration is a chemical reaction that occurs continually in every cell in the body
What is the word equation for respiration?
Glucose + oxygen ——-> energy + carbon dioxide + water
What is the symbol equation for respiration?
C6 H12 O6 + 6O2 ——-> 6CO2 + 6H2O
What type of cells do not respire at the same rates of others?
Sperm cells have high levels of respiration as they have a very active job so they contain lots of mitochondria
Why do fat cells have a low level of respiration?
As it has a low active job and doesn’t contain mitochondria
What is anaerobic respiration?
Respiration without oxygen
What is the word equation for anaerobic respiration?
Glucose ——–> lactic acid + small amount of energy
What does the liver do to lactic acid?
It converts it into glucose
How does lactic acid get into the liver?
Through the blood
What is oxygen debt?
The amount of extra oxygen the body needs after exercise to react with lactic acid and remove it from cells
What is fermentation?
Anaerobic respiration in yeast cells
What can fermentation be used for?
To make alcohol and bread
What does anaerobic respiration make the blood?
Acidic
What is metabolism?
The sum of all the reactions in a cell or the body
Why is metabolism important?
Because it includes: Respiration The use of glucose and nitrate to form amino acids Conversion of glucose top carbohydrase Formation of lipid molecules
What factors effect metabolism?
Age Activity level Genetic traits Gender Proportion of muscle to fat
What is the cerebrum responsible for?
Consciousness
Intelligence
Memory
Language
What is the cerebellum responsible for?
Muscular activity (movement) and balance
Where is the cerebellum located?
In the base of the brain
What is the medulla responsible for?
All unconscious activities:
Heart rate
Breathing
Digestion
Where is the cerebrum located?
In the front of the brain
What does the iris do?
Controls the size of the pupil
What does the cornea do?
Let light into the eye and focuses it on the retina
What does the lens do?
Focuses light on the retina
What does the optic nerve do?
Sends messages received by the light receptors in the brain
What does the retina do?
Light sensitive cells are found
What do the muscles and ligaments do?
Controls the shape of the lens
What does the sclera do?
Protects the eyeball from damage
What is accommodation?
The process of changing the shape of the lens to focus on near or distant objects
How does the eye focus on a distant object?
The ciliary muscles relax
The suspensory ligaments are pulled tight
The lens pulled thin
Light rays are only slightly refracted
How does the eye focus on a near object?
The ciliary muscles contract
The suspensory ligaments loosen
The lens thickens
Light rays are refracted strongly
What happens in bright light?
Circular muscles contract, radial muscles relax
What happens in dim light?
Circular muscles relax, radial muscles contract
What eye treatments can u get?
Hard and soft contact lens
Laser surgery to change the shape of the cornea
A replacement of the lens
What is thermoregulation?
The process that allows your body to maintain its core internal temperature
What is your body’s core internal temperature?
37degrees
Why do you sweat?
Because the evaporation of it takes heat with it
Why do your hairs lie flat when your warn?
As more heat can be lost as there isn’t a layer of insulation
Why do you shiver?
As your muscles contract to release heat
Why do your hairs stand up when your cold?
Because it traps a layer of air round your body acting as insulation
What is vasodilation?
When you are too hot, blood vessels widen so blood flow is redirected so heat can escape
What is vasoconstriction?
When you are cold, blood vessels become narrow so less blood flows through so less blood reaches the surface and less heat can be lost via radiation
What happens when you are too cold?
Enzymes lack kinetic energy
What happens if your too hot?
Enzymes denature
What is the endocrine system?
It is a number of glands which secrete hormones into the bloodstream
What is the pituitary gland knows as?
The master gland because it coordinates the other glands
What does insulin do?
Lowers blood sugar levels
What does glucagon do?
Increases blood sugar levels
How does the body decrease blood sugar levels?
The pancreas releases insulin into the blood
Cells use glucose to make more energy
Excess glucose is absorbed and stored by the liver and muscle cells
It is converted into glucagon
How does the body increase blood sugar levels?
The pancreas releases glucagon into the blood
Excess glycogen stored by the liver and muscle cells are converted to glucose
Describe type one diabetes
It is childhood onset and is when they do not produce enough insulin so they have uncontrolled high blood sugar levels
How is type one diabetes controlled?
2-4 time a day of insulin injections
What is hyperglycaemic?
Blood glucose levels are too high
What is hypoglycaemic?
Blood glucose levels are too low
Describe type two diabetes?
Develops in adulthood and is when cells no longer respond to insulin, it is caused by obesity
How is type two diabetes controlled?
More exercise and fewer carbohydrates
What are the kidneys responsible for?
Controlling water and ion levels in our body
What is selective reabsorption?
The reabsorption of certain molecules back into the blood
How does a healthy kidney produce urine?
The kidney filters the blood Proteins are large so they remain in the blood Glucose is small so it is all reabsorbed Reabsorbs some ions and water Releases urea into the urine Goes to be stored in the bladder
How is urea made?
Amino acids in the liver are deaminated to form ammonia. It is toxic so it is immediately converted to urea for safe excretion
What does the hormone ADH control?
The amount of water reabsorbed by our kidneys
What is ADH secreted by?
Pituitary gland
What does ADH do?
Makes membranes of the kidney tubules ore permeable causing more water to be reabsorbed back into the blood
How is water reabsorbed by our kidneys?
Hypothalamus detects too little water
Pituitary gland secrets ADH
Walls of kidney becomes more permeable so water returns to the blood via osmosis
Less water in the urine (more concentrated)
What are the primary the characteristics you are born with?
Ovaries in females
Testes in males
Name some physical changes you go through during puberty
Males- voice breaks, Adams apple, shoulders widen
Females- hips widen, develop breasts
Name some hormonal changes you go through during puberty
Males- sperm
Females- menstruation begins, mood swings
What do the testes produce?
Testosterone
What do the ovaries produce?
Oestrogen
What is ovulation?
An egg is released every 12-16th day
What is the menstrual cycle?
The regular natural changes that occurs in the uterus and ovaries that make pregnancy possible
What happens in the menstrual cycle?
Egg matures in the ovary
Uterus lining thickens
12-16th day one egg is released
After 14 days if the egg is not fertilised the uterus lining is shed
What is the average day of ovulation?
14
What are the menstruation days?
1-7
What days does the egg mature?
8-10
What are the ovulation days?
11-18
On days 19-28 what happens?
The egg waits to be fertilised and the lining of the uterus thickens
What happens to hormone levels during the menstrual cycle?
FSH is secreted from the pituitary gland
FSH stimulates the secretion of oestrogen from the ovaries
Increased levels of oestrogen inhibits FSH and stimulates the release of LH
LH levels drop and progestogen increases
Progesterone inhibits FSH and LH
What is FSH?
Follicle stimulating hormone
Where is FSH secreted from?
Pituitary gland
What does FSH do?
Causes the egg to mature
What is LH?
Luteinising hormone
What does LH do?
Stimulates the release of the egg during ovulation
What does oestrogen and progestogen do?
Stimulate the build up and maintenance of the uterus lining
What does FSH stimulate?
Oestrogen
What does oestrogen inhibit?
FSH
What does oestrogen stimulate?
LH
What does progesterone inhibit?
FSH and LH
List hormonal contraceptives
Oral
Implant
Intrauterine devices
Skin patch
List non hormonal contraceptives
Surgical male or female sterilisation Condoms Diaphragm or cap placed over the cervix Spermicides Abstaining from intercourse
What is a positive and negative of a condom?
P- prevents the spread of STDs
N- easily break
What is a positive and negative of an intrauterine device?
P- very effective and last up to 5 years
N- Can cause period problems or infections
What is a positive and negative of the contraceptive pill?
P- very easy to use
N- has side effects
What is a positive and negative of a spermicide?
P- very available
N- Not very effective
What two hormones are used in IVF?
FSH and LH
Explain what happens in IVF
The mother is given FSH and LH to stimulate the maturation of an egg
Eggs are collected and fertilised by the father
Develop into embryos
One or two embryos are inserted into the womb
Spare embryos are frozen for the future or donated to other couples
Economic problems of IVF
Very expensive
Low success rate
Religion problems of IVF
Embryos are destroyed if not used
Playing God?
Life begins at conception?
Moral/social problems of IVF
Cause the mother distress
Multiple embryos inserted increase the chance of multiple births
What is negative feedback?
Initiating corrective mechanisms whenever the internal environment deviates from its normal or acceptable level
What is the negative feedback loop for when thyroxine is low?
Sensors in the brain detect a decrease in thyroxine levels
Pituitary gland releases thyroid stimulating hormone
TSH stimulates the thyroid gland to secrete thyroxine
Levels rise
What is the negative feedback loop for when thyroxine is high?
Sensors n the brain detect increased thyroxine levels
Pituitary gland releases less thyroid stimulating hormone
Thyroid gland secrets less thyroxine
Levels decrease
What is adrenaline an example of?
A hormone that DOES NOT involve a negative feedback mechanism
Where is adrenaline secreted from?
Adrenal gland
What does adrenaline help your body to do?
Increase heart and breathing rate
Cause pupils to dilate
Increase mental awareness
Why is temperature important?
Stops the denaturing of vital enzymes
Why are water levels important?
Cells may shrivel or burst
Why is heart rate important?
Meet respiratory needs, repay oxygen debts, breakdown toxic waste products
Why is thyroxine/metabolism important?
Growth and repair
Why is blood sugar important?
Maintain water potentials and meet respiratory needs
What is a growth hormone in a plant called?
Auxins
What do auxins do?
Coordinate responses
Control growth
What is a tropism?
A directional growth response causing movement of part of an organism
What is the three main tropisms?
Phototropism: response to light
Hydrotropism: response to water
Gravitropism: response to gravity
When a shoot grows up what type of tropisms is there?
Negative gravitropism
Positive phototropism
Negative hydrotropism
When roots grow down what type what type of tropisms is there?
Positive gravitropism
Negative phototropism
Positive hydrotropism
Where are auxins produced?
Apical meristem
What do auxins cause?
Cell elongation
How does cell elongation occur?
Auxins are evenly distributed so the shoot grow up
Auxins move to shaded area
Unequal growth causes shoot to elongate towards the sun
What happens once the light falls evenly on the shoot?
Auxins then distribute evenly again
What as the control variable in the plant hormone practical?
Number of seeds
Type of seeds
Volume of water
Temperature
What as the independent variable in the plant hormone practical?
The amount of light
What as the dependant variable in the plant hormone practical?
The growth of seedlings (height)
How to investigate the effect of light intensity on growth of seedlings
3 petri dishes with cotton wool, 10 mustard seeds and 10cm3 of water
1 petri dish at the window (in full light)
1 petri dish in a dark cupboard
1 petri dish on the desk (out of direct sunlight)
What are auxins used for?
Weed killers
Rooting powders
Promoting growth in tissue culture
What is tissue culture?
The growth of tissues or cells separate from the organism
How do weed killers work?
Spray auxins onto plant
Auxins are absorbed
Uncontrolled growth occurs
Plant dies
How do you get tissue culture?
Take a cutting from a plant with desired features Cut end is dipped in rooting powder Hormone stimulates growth of new roots Helps to grow into a new plant Helps gardeners and horticulturists
What are gibberellins used for?
End seed dormancy
Promote flowering
Increase fruit size
What is ethene used for?
In the food industry to control ripening of fruit
What are the advantages of using ethene?
Harvest fruit when it’s not ripe
Less likely damage during travel if unripe
Don’t arrive over ripe
Less waste = less money lost
What are the disadvantages of using ethene?
Temperature not controlled can affect ripening process
Different preferences to fruit ripening
Too ripe may increase waste
What are the advantages of using gibberellins?
Produce food quicker as ends seed dormancy
Increased flowering all year round
More money earned
Increase growth of seedless fruit
What are the disadvantages of gibberellins?
End dormancy too early will not develop
All year round flowering may interfere with food web/ecosystem
Possibility of increased waste
