B5 - Homeostasis and Response Flashcards
What is homeostasis?
Maintaining a stable internal environment in response to changes in both internal and external conditions.
Homeostasis is crucial for the proper functioning of cells, including enzyme action.
Why is homeostasis important for cells?
Cells need the right conditions to function properly.
This includes the right conditions for enzyme action.
What are the three main components of automatic control systems in the body?
Receptors, coordination centres, and effectors.
Coordination centres include the brain, spinal cord, and pancreas.
What mechanism do automatic control systems use to maintain stability?
Negative feedback.
Negative feedback counteracts changes in levels of substances like water or glucose.
What is the first step in the negative feedback process?
Receptor detects a stimulus.
This can occur when a level is too high or too low.
What happens after the receptor detects a stimulus?
The coordination centre receives and processes the information, then organizes a response.
This is crucial for the body’s automatic response to changes.
What is the role of the effector in the feedback mechanism?
Produces a response that counteracts the change and restores the optimum level.
The effector continues to respond as long as it is stimulated by the coordination centre.
True or False: Negative feedback can sometimes cause the level to change too much away from the ideal.
True.
This occurs if the effector continues to produce responses without regulation.
Fill in the blank: Homeostasis involves the regulation of the conditions inside your body to maintain a _______.
stable internal environment.
What types of communication systems are involved in the automatic control systems?
Nervous and hormonal communication systems.
What is the purpose of receptors in the homeostasis process?
To detect stimulus changes in the environment.
What is the primary function of the nervous system?
To respond to stimuli and coordinate behavior
Organisms need to respond to changes in their environment to survive.
What does the Central Nervous System (CNS) consist of in vertebrates?
The brain and spinal cord
In mammals, the CNS is connected to the body by sensory and motor neurones.
What are sensory neurones?
Neurones that carry information from receptors to the CNS as electrical impulses
They play a crucial role in detecting stimuli.
What are motor neurones?
Neurones that carry electrical impulses from the CNS to effectors
They facilitate responses to stimuli.
What are receptors?
Cells that detect stimuli
They can form part of larger, complex organs.
Give examples of different types of receptors.
- Taste receptors on the tongue
- Sound receptors in the ears
- Light receptor cells in the retina
Receptors are specialized for different stimuli.
What are effectors?
Muscles and glands that respond to nervous impulses
They bring about changes in response to stimuli.
How do muscles respond to nervous impulses?
Muscles contract
This is a direct response to stimuli detected by receptors.
How do glands respond to nervous impulses?
They secrete hormones
This response is different from that of muscles.
What role does the CNS play in coordinating responses?
It receives information from receptors and decides on a response
The response is then carried out by effectors.
Fill in the blank: The CNS is a ________ centre that coordinates responses.
[coordination]
What happens when a bird spots a cat while eating seeds?
Receptors in the bird’s eye are stimulated, sensory neurones carry information to the CNS, which decides on a response
The response involves muscles contracting to fly away.
True or False: Effectors only include muscles.
False
Effectors also include glands.
What are hormones?
Chemical messengers sent in the blood
Hormones control functions in organs and cells that require constant adjustment.
What is the role of endocrine glands?
They produce and secrete hormones
Endocrine glands make up the endocrine system.
How long do hormones tend to act?
Relatively long-lasting effects
What is the pituitary gland often called?
‘Master gland’
It regulates other glands by producing hormones that direct them.
What hormone does the thyroid gland produce?
Thyroxine
Thyroxine is involved in regulating metabolism, heart rate, and temperature.
What do ovaries produce?
Oestrogen
Oestrogen is involved in the menstrual cycle.
What is the function of adrenaline produced by the adrenal gland?
Prepares the body for ‘fight or flight’ response
What hormone do testes produce?
Testosterone
Testosterone controls puberty and sperm production in males.
What hormone does the pancreas produce?
Insulin
Insulin regulates blood glucose levels.
True or False: Nerves act slower than hormones.
False
Fill in the blank: Hormones act in a more _______ way.
General
Fill in the blank: Hormones have a _______ action.
Slower
What is a key difference between nervous responses and hormonal responses?
Nervous responses are very fast, hormonal responses are slower.
What happens when a response is needed very quickly?
It’s probably a nervous response.
What indicates a hormonal response?
When the effect lasts for a long time
Hormones act on a very _______ area.
Precise
What does the term ‘fight or flight’ refer to?
A physiological response to perceived threat
What are the two hormones involved in controlling blood glucose levels?
Insulin and glucagon
These hormones are produced by the pancreas and play crucial roles in regulating blood sugar levels.
What happens to glucose in the blood after eating carbohydrate-rich foods?
Glucose enters the blood from the gut
This increase in blood glucose levels triggers the pancreas to release insulin.
What role does vigorous exercise play in blood glucose levels?
Removes much more glucose from the blood
Exercise enhances glucose uptake by muscle cells, lowering blood sugar levels.
Where can excess glucose be stored in the body?
As glycogen in the liver and muscles
Glycogen serves as a reserve of energy that can be converted back to glucose when needed.
What is the purpose of the negative feedback cycle in blood glucose regulation?
To keep blood glucose levels steady
The pancreas monitors glucose levels and releases insulin or glucagon accordingly.
What happens when blood glucose levels are too high?
Insulin is added
Insulin facilitates the uptake of glucose into cells and promotes glycogen formation.
What happens when blood glucose levels are too low?
Glucagon is added
Glucagon stimulates the liver to convert glycogen back to glucose and release it into the blood.
What is Type 1 diabetes?
A condition where the pancreas produces little or no insulin
This can lead to dangerously high blood glucose levels requiring insulin therapy.
How do people with Type 1 diabetes manage their condition?
Through insulin therapy and dietary management
Insulin is usually injected multiple times a day, especially at mealtimes.
What dietary considerations should people with Type 1 diabetes keep in mind?
Limit intake of simple carbohydrates and engage in regular exercise
This helps manage blood glucose levels effectively.
What characterizes Type 2 diabetes?
Insulin resistance in the body’s cells
Individuals with Type 2 diabetes still produce insulin but their cells do not respond effectively.
What is a major risk factor for developing Type 2 diabetes?
Obesity
Being overweight increases the likelihood of developing insulin resistance.
How can Type 2 diabetes be controlled?
By adopting a carbohydrate-controlled diet and regular exercise
Lifestyle changes can significantly improve blood sugar management.
What is the monthly release of an egg from a woman’s ovaries called?
The menstrual cycle
What hormones are released at puberty that promote sexual characteristics?
Sex hormones
What is the main reproductive hormone in men?
Testosterone
Where is testosterone produced?
In the testes
What is the main reproductive hormone in women?
Oestrogen
Where is oestrogen produced?
In the ovaries
How many stages are in the menstrual cycle?
Four stages
What happens during Stage 1 of the menstrual cycle?
Menstruation starts and the lining of the uterus breaks down
What occurs from Day 4 to Day 14 of the menstrual cycle?
The lining of the uterus builds up
What is ovulation, and when does it occur?
The release of an egg from the ovary at Day 14
What happens if no fertilized egg lands on the uterus wall by Day 28?
The spongy lining starts to break down
What are the four hormones that control the menstrual cycle?
- FSH (Follicle-Stimulating Hormone)
- Oestrogen
- Progesterone
- LH (Luteinising Hormone)
What is the function of FSH?
Causes an egg to mature in a follicle and stimulates the ovaries to produce oestrogen
What does oestrogen do during the menstrual cycle?
Causes the lining of the uterus to grow and stimulates the release of LH
What is the role of progesterone in the menstrual cycle?
Maintains the lining of the uterus during the second half of the cycle
What happens when the level of progesterone falls?
The lining of the uterus breaks down
What is the role of LH in the menstrual cycle?
Stimulates the release of an egg at Day 14 (ovulation)
What is the primary purpose of contraception?
To prevent pregnancy by stopping sperm from reaching the ovulated egg.
How can estrogen be used in contraception?
Estrogen can prevent the release of an egg by keeping its levels permanently high, inhibiting the production of FSH.
What is the effect of progesterone on fertility?
Progesterone reduces fertility by stimulating the production of thick mucus that blocks sperm.
What is the combined oral contraceptive pill?
An oral contraceptive containing both estrogen and progesterone.
How effective is the combined oral contraceptive pill at preventing pregnancy?
Over 99% effective.
What are some side effects of the combined oral contraceptive pill?
Headaches and nausea.
Does the combined oral contraceptive pill protect against sexually transmitted diseases?
No.
What is the difference between the combined pill and the progesterone-only pill?
The progesterone-only pill has fewer side effects and is just as effective.
What is the contraceptive patch?
A patch containing estrogen and progesterone that lasts one week.
How long does the contraceptive implant last?
Up to three years.
What is the function of the contraceptive injection?
Contains progesterone and lasts for 2 to 3 months.
What does an intrauterine device (IUD) do?
Kills sperm and prevents implantation of a fertilized egg.
What are the two main types of IUDs?
- Plastic IUDs that release progesterone
- Copper IUDs that prevent sperm survival in the uterus.
What role do condoms play in contraception?
They prevent sperm from entering the vagina during intercourse.
What is a diaphragm in terms of contraception?
A shallow plastic cup that fits over the cervix to form a barrier.
What is spermicide and how effective is it?
A substance that disables or kills sperm, with an effectiveness of about 70-80%.
What is a permanent method of contraception?
Surgical procedures to prevent pregnancy, though there is a small chance of tubes rejoining.
What are natural methods of contraception?
Avoiding intercourse during a woman’s most fertile days.
What is the only sure way to prevent sperm from meeting an egg?
Abstinence.
What hormone is often too low in some infertile women, preventing egg maturation?
FSH (follicle-stimulating hormone)
Low levels of FSH can result in no eggs being released, making pregnancy impossible.
What two hormones can be administered to stimulate ovulation in women?
FSH and LH
These hormones are used in fertility drugs to help women ovulate.
What is a potential downside of using fertility drugs that stimulate ovulation?
Multiple pregnancies
Stimulating too many eggs can lead to unexpected multiple births, such as twins or triplets.
What procedure is commonly used when medication fails to help a woman conceive?
IVF (in vitro fertilization)
IVF involves fertilizing eggs in a lab and then transferring embryos to the uterus.
What is the purpose of Intra-Cytoplasmic Sperm Injection (ICSI) in IVF?
To inject sperm directly into an egg
ICSI is particularly useful for men with very low sperm counts.
What happens to fertilized eggs during the IVF process?
They are grown into embryos in a laboratory incubator
This step occurs before transferring embryos to the woman’s uterus.
What is the average success rate of IVF in the UK?
26%
This low success rate can make the IVF process emotionally and physically stressful.
What are some physical side effects women may experience from fertility treatments?
Abdominal pain, vomiting, dehydration
Some women have strong reactions to the hormones used in fertility treatments.
What technological advancements have improved IVF techniques?
Specialized micro-tools and time-lapse imaging
These advancements help in manipulating eggs and sperm and monitoring embryo growth.
What ethical concerns are associated with IVF?
Destruction of unused embryos and selection of characteristics
Some people believe it is unethical to destroy embryos or select traits like gender.
Fill in the blank: IVF involves collecting eggs from the woman’s ovaries and fertilizing them in a _______.
lab
This process is a critical part of in vitro fertilization.
True or False: Fertility treatments guarantee pregnancy.
False
There are no guarantees, and many couples face multiple failures in IVF.
What is adrenaline?
A hormone released by the adrenal glands in response to stress or scary situations.
What triggers the release of adrenaline?
Stressful or scary situations detected by the brain.
What is the primary function of adrenaline in the body?
Prepares the body for ‘fight or flight’ by increasing oxygen and glucose supply to cells.
What effect does adrenaline have on heart rate?
Increases heart rate.
What is negative feedback in hormone regulation?
A mechanism that maintains hormone levels by triggering responses to return to normal levels.
What role does thyroxine play in the body?
Regulates the basal metabolic rate and stimulates protein synthesis for growth and development.
Where is thyroxine produced?
In the thyroid gland, which is located in the neck.
What substances are required for the synthesis of thyroxine?
Iodine and amino acids.
What hormone stimulates the release of thyroxine?
Thyroid stimulating hormone (TSH).
How does the negative feedback system regulate thyroxine levels?
High thyroxine levels inhibit TSH secretion, reducing thyroxine release until levels normalize.
Fill in the blank: When the level of thyroxine in the blood is higher than normal, the secretion of _______ from the pituitary gland is inhibited.
TSH
True or False: Adrenaline is released by the pituitary gland.
False
What is the basal metabolic rate?
The speed at which chemical reactions in the body occur while at rest.
What is the connection between two neurones called?
Synapse
How is the nerve signal transferred across a synapse?
By chemicals which diffuse across the gap
What do the chemicals released at a synapse do?
They set off a new electrical signal in the next neurone
What are reflexes?
Rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain
How do reflexes help prevent injury?
They reduce the chances of being injured
What happens to your pupils when a bright light is shone in your eyes?
They automatically get smaller
What hormone is released when you get a shock?
Adrenaline
What is the passage of information in a reflex called?
Reflex arc
Where do the neurones in reflex arcs go through?
The spinal cord or through an unconscious part of the brain
What type of neurone sends impulses to a relay neurone in the CNS?
Sensory neurone
What triggers the release of chemicals at the synapse between the sensory and relay neurone?
Impulses reaching the synapse
What happens when impulses reach the muscle in a reflex action?
The muscle contracts
True or False: Reflex actions require conscious thought.
False
Fill in the blank: The neurones connecting sensory neurones to motor neurones are called ______.
Relay neurones
What is the role of the motor neurone in a reflex arc?
To carry impulses to the effector
What is usually the effector in a reflex action?
A muscle
Why are reflex responses quicker than normal responses?
Because they don’t require conscious thought
