B3 Flashcards
(303 cards)
1
Q
what is the nervous system responsible for?
A
detecting changes in your environment and responding to them by coordinating actions in the body.
2
Q
what are the steps in a nervous response
A
- Detection of a change in the environment (stimulus).
- Detection by receptor cells (sensory receptors).
- Response occurs from effectors, such as muscles or glands.
3
Q
How do muscles and glands respond to a nervous impulse?
A
Muscles respond by contracting, while glands release hormones.
4
Q
Name the part of the body that detects changes in your external environment.
A
Receptor cells.
5
Q
What are receptor cells, and where are they found?
A
Receptor cells are located in sense organs and detect different stimuli, converting them into electrical impulses.
6
Q
What happens to the electrical impulses produced by receptor cells?
A
They travel along neurons to the central nervous system (CNS).
7
Q
What is the CNS, and what does it consist of?
A
The central nervous system, consisting of the brain and spinal cord.
8
Q
How is the brain protected?
A
It is protected by the skull
9
Q
How is the spinal cord protected?
A
it is protected by the backbone (vertebral column).
10
Q
What do light receptor cells in the eyes detect?
A
Light
11
Q
What type of stimulus do chemical receptors in the nose detect?
A
chemicals
12
Q
What type of receptors does the skin have?
A
Pressure receptors.
13
Q
What do temperature receptors in the skin detect?
A
Temperature changes.
14
Q
How can blocking receptor cells affect your food taste?
A
Blocking receptor cells, can interfere with the ability to detect chemicals, altering taste.
15
Q
What are the three types of neurons?
A
- Sensory neurons.
- Relay neurons.
- Motor neurons.
16
Q
What is the role of sensory neurons?
A
They carry electrical impulses from receptor cells to the CNS.
17
Q
Where are relay neurons located, and what is their function?
A
They are found only within the CNS and transmit impulses between sensory and motor neurons.
18
Q
What is the function of motor neurons?
A
They carry electrical impulses from the CNS to effectors.
19
Q
State the difference between a neuron and a nerve.
A
Neurons are individual cells that carry electrical impulses, while nerves are bundles of hundreds or thousands of neurons.
20
Q
What is a coordinated response?
A
When the brain processes information and sends signals to different parts of the body to produce a response.
21
Q
How long does a nervous reaction typically take?
A
About 0.7 seconds.
22
Q
What can blocking receptor cells lead to?
A
t can affect how food tastes, as suggested by Table 1.
23
Q
What is an electrical impulse in the context of the nervous system?
A
Signals that are carried along neurons to communicate information
24
Q
What are neurons often bundled in?
A
Bundles of hundreds or thousands called nerves.
25
Describe the path of a coordinated response starting from a stimulus.
Stimulus → Receptor cells → Sensory neuron → Spinal cord → Brain → Spinal cord → Motor neuron → Effector → Response.
26
is sneezing a reflex action?
Yes, it is an automatic reaction to an irritation in the nose.
27
What is a reflex action?
An automatic and rapid response to a stimulus that occurs without conscious thought.
28
How does a reflex action differ from voluntary responses?
Reflex actions occur without conscious effort, whereas voluntary responses are a result of deliberate decision-making.
29
Can reflex actions be overridden?
Yes, in some circumstances, the body can override even faster reflex responses.
30
What reflex action occurs when bright light shines into your eye?
Muscles in the iris contract, making your pupil smaller to reduce the amount of light entering the eye.
31
What happens when you touch something hot?
The biceps muscle contracts, pulling your arm away from the heat.
32
What is the reflex action when an object is heading towards your eye?
Muscles in the eyelids contract, causing you to blink.
33
How does the body respond to a sudden loud noise?
Muscles in the neck contract, turning your head towards the sound.
34
What happens when blood pressure drops significantly?
The heart rate increases, and blood glucose concentration rises.
35
Why does the pupil dilate?
It allows more light into the eye, so you can see better in dim light.
36
Suggest another reflex action that is not a response to danger.
Coughing to clear the throat.
37
What steps are involved in a reflex action?
1. Stimulus is detected (e.g., touching a hot object).
2. Receptor cells sense the stimulus.
3. Sensory neurons transmit the impulse to the spinal cord.
4. The spinal cord processes the impulse and sends it via motor neurons.
5. The effector (e.g., muscle) produces a response.
38
What is the term used for the nerve pathway involved in a reflex action?
Reflex arc
39
What happens before your brain registers that your hand is hot?
Your arm muscles contract to pull your hand away, preventing damage
40
Your arm muscles contract to pull your hand away, preventing damage.
Q: What is this automatic response called?
Withdrawal reflex
41
What is measured to assess reflex reaction time?
The time it takes to catch a falling object.
42
How can you measure reflex reaction time using a ruler?
Drop a ruler and measure how far it falls before being caught; convert the distance to a reaction time.
43
What can you investigate about reflex reaction times?
Whether reflex reaction time decreases with age.
44
How should you draw a reflex arc for a given scenario?
Draw a standard flow diagram, label each part, and write sentences to make it specific to the situation.
45
What example is given for labeling a reflex arc?
Stimulus - hot saucepan;
Receptor - temperature
receptors in the skin;
Sensory neuron - transmits signal to the spinal cord;
Motor neuron - transmits signal to effector;
Effector - biceps muscle contracts; Response - hand pulls away.
46
Explain why reflex actions occur more quickly than voluntary actions.
Reflex actions bypass the brain and are processed by the spinal cord for a quicker response.
47
Draw a flow diagram to show how your body responds to stepping on a sharp stone.
Stimulus (stepping on sharp stone) → Receptor (pain receptors in the skin) → Sensory neuron → Spinal cord → Motor neuron → Effector (leg muscles) → Response (lift foot away).
48
What is the function of the cornea in the eye?
The cornea is a transparent coating on the front of the eye. It protects the eye and refracts light entering the eye
49
Describe the pupil and its function.
The pupil is the central hole in the iris that allows light to enter the eye.
50
What role does the iris play in vision?
The iris is the colored ring of muscle tissue in the eye. It alters the size of the pupil by contracting or relaxing, which helps to control the amount of light entering the eye.
51
Explain the function of the lens in the eye.
The lens is a transparent, biconvex structure that focuses light clearly onto the retina.
52
What is the function of the ciliary muscles in the eye?
The ciliary muscles are a ring of muscle tissue that helps change the shape of the lens to focus on objects at different distances.
53
What are the suspensory ligaments, and what do they do?
Suspensory ligaments are ligaments in the eye that connect the ciliary muscles to the lens, aiding in the adjustment of the lens shape for focusing.
54
Describe the optic nerve and its function.
The optic nerve is made of nervous tissue. It carries nerve impulses from the retina to the brain, where visual images are processed.
55
Where is the retina located, and what is its role in vision?
The retina is located at the back of the eye. It contains light-sensitive cells (photoreceptors) that detect light and convert it into electrical signals sent to the brain via the optic nerve.
56
How are images formed in the eye?
The cornea refracts incoming light rays, providing most of the eye’s focus. Light passes through the pupil and is refracted further by the lens, creating a sharp image on the retina. The retina’s photoreceptor cells produce a nervous impulse, which travels to the brain via the optic nerve, allowing the brain to interpret the signals as a visual image.
57
How does the eye focus on nearby and distant objects?
Nearby objects: When the ciliary muscle contracts, the lens becomes more convex (fatter), allowing the eye to focus on nearby objects.
Distant objects: When the ciliary muscle relaxes, the lens becomes less convex (thinner), enabling the eye to focus on distant objects.
58
What causes short-sightedness?
Short-sightedness is caused by a person’s lens being too strong or the eyeball being too long, making distant objects appear blurry
59
What causes long-sightedness?
Long-sightedness is caused by a person’s lens being too weak or the eyeball being too short, making nearby objects appear blurry.
60
How is short-sightedness corrected?
It is corrected with concave lenses, which bend light rays outward before they enter the eye.
61
How is long-sightedness corrected?
It is corrected with convex lenses, which bend light rays inward before they enter the eye.
62
Which type of lens would be used for someone who has difficulty focusing on a computer screen?
A convex lens, which corrects long-sightedness
63
What is colour blindness?
Colour blindness is a condition where a person has difficulty distinguishing certain colours, usually due to non-functioning cone cells in the retina.
64
What are the two types of photoreceptor cells in the retina?
Rods, which respond to light and dark, and cones, which respond to different colours (red, blue, green).
65
What is the most common form of colour blindness?
Red-green colour blindness, where people cannot distinguish between red and green.
66
Describe the case study mentioned in this section involving Phineas Gage.
Phineas Gage was a railway worker who survived an accident where an iron rod went through his skull, causing changes in his personality. This case shows how brain injury can impact behaviour and personality.
67
What is the main function of the brain?
To process information from the body and coordinate a response.
68
Why is having a single brain an advantage for neuronal communication?
A single brain allows for faster communication between neurons than if control centers were spread throughout the body.
69
Approximately how many neurons are in an adult brain?
About 86 billion neurons.
70
What is the function of the cerebrum?
It controls complex behaviours such as learning, memory, personality, and conscious thought.
71
What role does the cerebellum play in the brain?
It coordinates posture, balance, and involuntary movements.
72
What is the function of the medulla?
It controls automatic actions such as heart rate and breathing rate
73
What does the hypothalamus regulate?
Temperature and water balance in the body.
74
What is the role of the pituitary gland in the brain?
It stores and releases hormones that regulate various body functions.
75
How did scientists initially study brain function?
By observing patients who had brain damage, especially those who had suffered strokes.
76
How do electrodes help scientists investigate brain function?
Electrodes transmit electrical impulses, linking specific brain areas to body movements, allowing scientists to study brain function.
77
What is a CT scan, and how does it work?
A CT (computed tomography) scan uses X-rays to create 3D images of the brain’s structure, helping to identify damaged or diseased areas.
78
What is a disadvantage of using CT scans?
They use X-ray radiation, which increases the risk of cancer with prolonged or repeated exposure.
79
What does an MRI (magnetic resonance imaging) scan do?
MRI uses powerful magnets to create detailed images of the brain’s structure and detect abnormalities.
80
How does an fMRI (functional magnetic resonance imaging) scan differ from a regular MRI?
An fMRI produces images in real-time, showing active areas of the brain when a person is performing specific tasks, which helps link brain activity to function.
81
What are some difficulties associated with investigating brain function?
Difficulties include the need for patient consent, managing and analyzing large datasets, the involvement of multiple brain areas in functions, and ethical concerns, especially regarding animal testing.
82
Why are there ethical concerns in brain research?
Many people believe that testing on animals is unethical, raising concerns about the methods used in studying the brain.
83
Into which two main systems is the human nervous system divided?
The central nervous system (CNS) and the peripheral nervous system (PNS)
84
What does the CNS consist of? And what is the main function of the CNS
The brain and the spinal cord. To process information received from the body and coordinate responses.
85
What does the PNS consist of?
Neurons that carry information to and from the CNS to the rest of the body.
86
How can damage to the PNS affect the body?
It can lead to an inability to detect pain, numbness, or a loss of coordination.
87
What are the main types of damage that can affect the nervous system?
Damage from injury, disease, or a genetic condition.
88
What are some symptoms that could arise from nervous system damage?
Symptoms include numbness, inability to detect pain, loss of coordination, and difficulties in communication within the nervous system.
89
How can sports injuries lead to nervous system damage?
Sports injuries, such as those affecting the spine or head, can damage the nervous system, potentially causing issues with movement and coordination.
90
Why is it difficult to repair damage to the CNS?
The spinal cord and brain are often difficult to repair as damage to these areas is usually permanent due to a lack of cell regeneration and the complexity of these tissues.
91
What can happen if the CNS is damaged?
Damage to the CNS can lead to permanent disability because the spinal cord and brain cannot easily repair themselves.
92
What can damage to the CNS lead to in terms of body functions?
It can impair control of body systems, leading to loss of specific bodily functions, paralysis, or in severe cases, death.
93
Why is damage to the PNS often less severe than damage to the CNS?
PNS damage has the potential to self-repair over time, and surgery can sometimes correct or alleviate symptoms.
94
What treatments are available for PNS damage?
Treatments include surgery to repair or replace damaged nerves and physical therapy to regain lost function.
95
What are some diseases that affect the nervous system and might be worth researching further?
Diseases such as multiple sclerosis and Huntington’s disease affect the nervous system and may involve symptoms like nerve cell degeneration and brain damage
96
Explain why damage to sensory neurons could prevent pain sensation.
Damage to sensory neurons affects the transmission of signals, which means the brain may not receive signals associated with pain.
97
How could damage to motor neurons affect muscle function?
Damage to motor neurons can prevent signals from reaching muscles, leading to muscle weakness or paralysis.
98
Why does damage to the CNS often result in permanent disability, unlike damage to the PNS?
The CNS lacks the ability to regenerate cells, making it difficult to repair; in contrast, the PNS has some regenerative capability and can sometimes recover from damage.
99
What is the endocrine system?
The endocrine system is a network of glands that produce and secrete hormones into the bloodstream, which then travel to target organs to regulate body processes
100
What are hormones?
Hormones are chemical messengers produced by endocrine glands, carried in the blood to target organs where they initiate specific effects.
101
How do hormones reach their target organs?
Hormones are secreted directly into the bloodstream, allowing them to travel throughout the body and reach their specific target organs.
102
What is homeostasis, and why is it important?
Homeostasis is the maintenance of a stable internal environment within the body. It is crucial for proper functioning and survival.
103
How does the endocrine system help maintain homeostasis?
The endocrine system releases hormones that regulate various body processes, ensuring stable internal conditions are maintained.
104
What can cause acne during puberty?
An increase in testosterone levels during puberty can cause the glands to become more active, leading to acne.
105
What role does the pituitary gland play in the endocrine system?
The pituitary gland, known as the “master gland,” regulates other endocrine glands and essential functions such as growth, metabolism, and reproduction.
106
What hormone is associated with the adrenal glands, and what is its function?
The adrenal glands produce adrenaline, which prepares the body for “fight or flight” by increasing heart rate and energy availability.
107
How does the pancreas regulate blood sugar levels?
The pancreas secretes insulin, which helps control blood sugar by promoting the uptake of glucose into cells.
108
What is a target cell?
A target cell has specific receptors for a particular hormone. When the hormone binds to the receptor, it triggers a specific response.
109
What is the significance of negative feedback in hormone regulation?
Negative feedback mechanisms maintain stability by reducing hormone release when the desired effect is achieved, such as insulin lowering blood sugar levels.
110
what is negative feedback in the endocrine system
Negative feedback is a regulatory mechanism in which the levels of a hormone in the bloodstream are regulated by the hormone itself. When the level of a hormone in the bloodstream is too high, it triggers the release of a different hormone that decreases its production.
111
Where are the primary endocrine glands located?
Primary endocrine glands are located in various regions: pituitary gland (brain), thyroid (neck), adrenal glands (above kidneys), pancreas (abdomen), ovaries (female pelvis), and testes (male groin).
112
How do hormonal responses compare to nerve impulses?
Hormonal responses are slower and longer-lasting, while nerve impulses produce quick and short-lived effects
113
Describe the thyroid gland’s function.
The thyroid gland controls metabolism, influencing the speed of bodily processes like growth and energy use.
114
What are the endocrine gland functions?
Pituitary gland: Controls other glands and body functions.
Thyroid: Regulates metabolism.
Adrenal glands: Produce adrenaline for stress responses.
Pancreas: Manages blood sugar with insulin.
Ovaries: Involved in female reproduction.
Testes: Involved in male reproduction.
115
Why is it important for the body to maintain stable conditions?
Stable conditions are essential for the body’s processes to function correctly and prevent health issues caused by imbalance.
116
What is negative feedback?
Negative feedback is a process that helps maintain a stable internal environment by reversing changes away from the normal range, bringing the body back to a steady state.
117
How does negative feedback maintain homeostasis?
Negative feedback detects change from normal conditions and activates mechanisms to counteract the change, restoring the body to its set point.
118
Give examples of negative feedback in the body.
Examples include regulation of body temperature, blood glucose levels, and water balance.
119
How does the body regulate temperature through negative feedback?
If body temperature rises, mechanisms like sweating and vasodilation are activated to cool it down. If it falls, mechanisms like shivering and vasoconstriction help to warm it up.
120
What happens when thyroxine levels in the body are too high?
When thyroxine levels are too high, the pituitary gland decreases the secretion of TSH, which reduces thyroxine production by the thyroid gland.
121
What is the role of the thyroid gland?
The thyroid gland produces thyroxine, which regulates metabolism, growth, and energy use in the body.
122
How are thyroxine levels controlled in the body?
Thyroxine levels are controlled by a negative feedback loop involving the pituitary gland and TSH. When thyroxine is high, TSH production decreases, and when thyroxine is low, TSH production increases.
123
Where is adrenaline produced?
Adrenaline is produced in the adrenal glands, which are located above the kidneys
124
What is TSH, and what does it do?
TSH, or thyroid-stimulating hormone, is released by the pituitary gland to stimulate the thyroid to produce thyroxine.
125
What is adrenaline, and what role does it play in the body?
Adrenaline is a hormone produced by the adrenal glands that prepares the body for “fight or flight” by increasing heart rate, boosting energy availability, and enhancing alertness.
126
How does adrenaline affect the heart?
Adrenaline increases heart rate, allowing more blood and oxygen to reach the muscles during a stressful situation.
127
How does the body control adrenaline levels?
.Respiring more quickly to increase the rate of ATP production
. Increase in the rate of breathing to cope with extra demand for oxygen.
. Increasing heart rate.
128
Describe the “fight or flight” response.
The “fight or flight” response is an automatic reaction to stress or danger where adrenaline prepares the body for physical activity by increasing heart rate, blood pressure, and energy availability.
129
How does the regulation of thyroxine via negative feedback work?
When thyroxine levels are high, TSH secretion decreases, leading to reduced thyroxine production. When thyroxine levels are low, TSH secretion increases, prompting more thyroxine production.
130
What effect does thyroxine have on metabolism?
Thyroxine increases the metabolic rate, promoting energy consumption and heat production in the body.
131
How do adrenaline levels affect energy supplies during stress?
Adrenaline mobilizes stored energy, making glucose and fatty acids available for muscle use during a stressful situation.
132
What happens when the body’s temperature falls below normal?
The body responds by shivering (to generate heat) and vasoconstriction (to reduce heat loss), increasing the core temperature
133
Describe the importance of adrenaline in extreme sports.
In extreme sports, adrenaline provides the energy and mental focus needed to cope with physically demanding or dangerous activities, enhancing performance and survival.
134
What happens to TSH levels when thyroxine levels drop?
TSH levels increase when thyroxine levels drop, stimulating the thyroid gland to produce more thyroxine to bring levels back to normal.
135
What is the main function of negative feedback mechanisms?
The main function is to detect and correct deviations from normal conditions, helping to maintain stability in the body’s internal environment.
136
What happens to adrenaline levels once the stressful situation ends?
Once the stress is gone, adrenaline levels decrease, and the body returns to a state of relaxation and normal physiological function.
137
What is the menstrual cycle, and what triggers it in females?
The menstrual cycle is a monthly process that prepares a woman’s body for pregnancy. It starts when a girl reaches puberty, typically between the ages of 8-14, around age 12
138
What are the key components of the female reproductive system involved in the menstrual cycle?
The primary components are the ovaries, which produce eggs and hormones, and the uterus, where the lining thickens to prepare for a possible pregnancy.
139
Describe the duration and frequency of the menstrual cycle.
The menstrual cycle typically occurs every 28 days, although it can vary from 21 to 35 days in adult women
140
What is the role of the uterus lining in the menstrual cycle?
The uterus lining thickens to prepare for a fertilized egg. If pregnancy does not occur, this lining is shed, resulting in menstruation.
141
Follicle-Stimulating Hormone (FSH): And what is its function
Released by the pituitary gland, it stimulates egg growth and prompts the ovaries to release estrogen.
142
Luteinizing Hormone (LH): And its function
Also from the pituitary gland, it triggers ovulation and encourages the production of progesterone.
143
Estrogen: And its function
Produced by the ovaries, it thickens the uterine lining.
144
Progesterone: And its function
Produced after ovulation, it maintains the thickened lining. If no pregnancy occurs, levels fall, leading to menstruation.
145
What does FSH also stimulate
It also stimulates the ovaries to produce oestrogen
146
As oestrogen levels rise, what happens?
they inhibit the production of FSH. This usually prevents more than one egg mature it also stimulates the pituitary gland to reach release Lutenising hormone.
147
What happens in Menstruation (Days 1-5):
The uterus lining is shed.
148
What happens in Follicular Phase (Days 1-13):
FSH promotes egg development, and estrogen levels rise, thickening the uterus lining.
149
What happens on Ovulation (Day 14):
LH surge causes the release of a mature egg from the ovary.
150
What happens on Luteal Phase (Days 15-28):
Progesterone maintains the lining, preparing for pregnancy. If pregnancy doesn’t occur, hormone levels drop, and the cycle restarts
151
What is the role of Follicle-Stimulating Hormone (FSH) in detail?
FSH is secreted by the pituitary gland at the start of the cycle to stimulate the growth of an egg in the ovaries. FSH also causes the ovaries to release estrogen, which thickens the uterus lining.
152
Describe the function of Luteinizing Hormone (LH) in the menstrual cycle.
LH, also produced by the pituitary gland, spikes around day 14, triggering ovulation. It also stimulates the ovaries to produce progesterone, which maintains the uterus lining.
153
What does estrogen do during the menstrual cycle?
Estrogen, produced by the ovaries, thickens the uterine lining in preparation for a potential pregnancy.
154
What is the role of progesterone, and how does its level affect the menstrual cycle?
Progesterone, produced after ovulation, maintains the thickened uterine lining. If there is no pregnancy, progesterone levels drop, leading to the breakdown of the lining and the start of menstruation.
155
How do FSH and LH levels change throughout the menstrual cycle?
FSH levels are high at the start of the cycle to stimulate egg growth. LH levels peak at around day 14 to cause ovulation.
156
What happens to estrogen and progesterone if fertilization does not occur?
If fertilization does not occur, estrogen and progesterone levels fall, leading to the breakdown of the uterine lining, which is shed during menstruation.
157
How can graphs depicting hormone levels help in understanding the menstrual cycle?
These graphs show the rise and fall of hormone levels throughout the cycle, helping to illustrate the timing of key events like menstruation, ovulation, and the preparation for pregnancy.
158
What is the purpose of contraception?
Contraception is used to prevent pregnancy by stopping a sperm from fertilizing an egg. It allows individuals to control reproduction and family planning.
159
What types of hormonal contraception are available?
1. Combined Pill
2. Progesterone-only Pill
3. Contraceptive Patch
4. Contraceptive Injection
5. Contraceptive Implant
6. Intrauterine Device (IUD) - hormonal type
160
Describe the Combined Pill as a contraceptive method.
how it works: prevents ovulation thickens mucus from the cervix stopping sperm reaching an ovum
type: hormonal
notes: taken for 21 days of the menstrual cycle
161
What is the Progesterone-only Pill?
how it works: thickens mucus from the cervix stopping sperm from reaching over them. It also thins the line of the uterus preventing implantation.
Type: Hormonal
Notes: must be taken around the same time every day
162
Describe the intrauterine system and its usage.
How it works: inserted into the uterus has the same effect on the body as the progesterone only pill
Type: hormonal
Notes: remains effective for 3 to 5 years
163
What is an Intrauterine device
Type: non-hormonal
how it works : inserted into the uterus releases copper which prevents sperm surviving in the uterus and fallopian tubes
Notes: remain effective for 5 to 10 years
164
what is a diaphragm or cervical cap?
How it works: inserted into the vagina to cover the cervix prevent sperm cells from entering the uterus
Type: Non-hormonal
Notes: not effective unless used in combination with spermicide
165
What is a condom used for?
How it works: placed over the penis or inside the vagina prevents sperm entering the vagina
Type: Non-hormonal
Notes: prevents the spread of STI
166
Effectiveness of condom male and female
Condom M: 98
Condom F: 95
167
Diaphragm and cap effectiveness
92-96
168
intaurine device effectiveness
over 99
169
oestrogen and progesterone pill
over 99
170
progesterone pill effectiveness
over 99
171
intrauterine system effectiveness
over 99
172
Evaluate how male and female condoms are described as different from each other.
Male condoms are worn on the penis and create a barrier to prevent sperm from entering the vagina. They are typically made of latex and are designed to fit snugly over the penis.
Female condoms are inserted into the vagina and line the vaginal walls to create a barrier against sperm. They are generally larger and provide internal protection.
173
Describe how you would use a combined contraceptive pill to prevent pregnancy.
To use a combined contraceptive pill effectively, you need to take one pill daily for 21 days, followed by a 7-day break where you do not take any pills. During the break, you may have a withdrawal bleed, similar to a period. After the 7-day break, you start a new pack of pills. Taking the pill at the same time each day is important to maintain its effectiveness.
174
Why might some couples be unable to conceive naturally?
Reasons include blocked fallopian tubes in women, preventing sperm from reaching the egg, and low sperm count in men, which lowers the chance of fertilization.
175
What are the two main hormones used in fertility treatments, and what is their role?
FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are used to stimulate the ovaries to produce and release eggs, increasing the chances of pregnancy.
176
What is In Vitro Fertilisation (IVF)?
IVF is a process where eggs are fertilized by sperm outside the body in a lab. This treatment is used to assist couples who have difficulty conceiving naturally.
177
Describe the steps of IVF treatment
1)FSH and LH are given to stimulate the ovaries to produce several mature eggs simultaneously.
2) Mature eggs are collected from the ovaries using a fine needle inserted into the ovaries through the vaginal wall.
3) The collected eggs are mixed with sperm in a petri dish to allow fertilization to occur outside the body.
4) One or more fertilized embryos are chosen and inserted into the woman’s uterus, where they may implant and develop into a pregnancy.
178
Why are FSH and LH crucial for IVF success?
FSH stimulates egg maturation, while LH triggers ovulation. Together, they increase the number of mature eggs available for collection, improving the chances of fertilization and pregnancy.
179
What ethical issues might arise from IVF?
IVF raises concerns such as creating excess embryos that may not be used, the unnatural aspect of fertilization outside the body, and the potential for choosing specific traits, which some view as “designing” children
180
What are some of the challenges associated with IVF?
IVF can be physically demanding due to hormone treatments and procedures. It can also be emotionally stressful, with uncertain success rates and the possibility of multiple cycles.
181
What are some of the challenges associated with IVF?
IVF can be physically demanding due to hormone treatments and procedures. It can also be emotionally stressful, with uncertain success rates and the possibility of multiple cycles.
182
How does age affect IVF success rates, according to Table 1?
Under 35: 32% success rate
• 35-39: 25% success rate
• 40-42: 13% success rate
• 43-44: 5% success rate
• Over 44: 2% success rate
As age increases, the success rate decreases
183
What factors should couples consider before undergoing IVF?
Couples should consider financial costs, physical demands, emotional impact, ethical concerns, and the risks associated with multiple births.
184
Why might younger women have higher success rates with IVF?
Younger women typically produce healthier eggs, which are more likely to result in successful fertilization and implantation, leading to a higher chance of pregnancy.
185
Suggest one reason for blocked fallopian tubes as a cause of infertility.
Blocked fallopian tubes can result from infections, scarring, or previous surgeries, which prevent the egg and sperm from meeting.
186
State one cause of infertility in men and one in women.
In men: Low sperm count
In women: Blocked fallopian tubes
187
What is a tropism in plants?
A tropism is the growth movement of a plant in response to an external stimulus. If a plant grows toward the stimulus, it is called a positive tropism. If it grows away from the stimulus, it is a negative tropism.
188
What are the two main types of tropisms discussed in this text?
The two main types of tropisms are phototropism, which is a response to light, and gravitropism (also called geotropism), which is a response to gravity.
189
Define phototropism and explain its significance for plants.
Phototropism is the growth of a plant in response to light. In shoots, this response is positive phototropism, where the plant grows toward light. This allows the plant to maximize its exposure to light, which is essential for photosynthesis.
190
How does auxin affect plant growth during phototropism?
Auxin, a plant hormone, accumulates on the shaded side of a shoot when exposed to light. This concentration of auxin stimulates faster growth on the shaded side, causing the shoot to bend toward the light source.
191
Describe the process of phototropism in shoots, step by step.
1. Light causes auxin to move to the shaded side of the shoot.
2. Cells on the shaded side grow faster than those on the light-exposed side.
3. This uneven growth causes the shoot to bend towards the light.
192
What is the phototropic response in roots?
Roots are either unaffected by light or display negative phototropism, growing away from light. This helps roots grow deeper into the soil where they can access water and nutrients.
193
Define gravitropism (or geotropism) and its purpose in plants
Gravitropism, also known as geotropism, is a plant’s growth response to gravity. Roots exhibit positive gravitropism by growing towards the pull of gravity, anchoring the plant and aiding in nutrient and water absorption. Shoots exhibit negative gravitropism, growing against gravity to reach light for photosynthesis.
194
Explain how auxin affects root growth in response to gravity.
When a root grows horizontally, gravity causes auxin to collect on the lower side of the root. In roots, auxin inhibits cell elongation, so cells on the upper side grow faster than those on the lower side. This causes the root to bend downwards, demonstrating positive gravitropism.
195
How does auxin influence shoot growth in response to gravity?
In a horizontal shoot, gravity causes auxin to accumulate on the lower side. In shoots, auxin promotes cell elongation on this lower side, causing the shoot to bend upwards, away from gravity. This is an example of negative gravitropism.
196
Summarize the role of auxin in plant responses to environmental factors.
Auxin is a plant hormone that controls growth by promoting or inhibiting cell elongation depending on the plant part. It moves within the plant in response to light and gravity, allowing plants to adapt their growth direction for optimal survival conditions, such as reaching light or anchoring in soil.
197
Why is light important for the shoots of plants?
Light is essential for photosynthesis, the process by which plants convert light energy into chemical energy (glucose) to fuel growth and reproduction. Positive phototropism helps shoots grow towards light sources to maximize photosynthesis.
198
Describe an experiment to investigate gravitropism in roots
Place seedlings on damp cotton wool in a Petri dish. Lay the Petri dish on its side so that the roots are horizontal. After several days, observe that the roots bend downwards, demonstrating positive gravitropism in response to gravity.
199
What observations would confirm positive gravitropism in the root experiment?
Observing that the roots have bent downward over time, even though the seedlings were placed horizontally, would confirm that they are responding to gravity by growing in the direction of its pull.
200
What would happen if the tip of a plant shoot is cut off, and why?
If the tip of a plant shoot is removed, the plant cannot grow towards light because auxin, which is primarily produced in the shoot tip, is no longer available to promote growth toward light.
201
Explain the effect of gravity on auxin distribution in roots and shoots.
Gravity causes auxin to accumulate on the lower side of both roots and shoots. In roots, this auxin accumulation inhibits cell elongation on the lower side, causing downward growth. In shoots, auxin stimulates growth on the lower side, resulting in upward growth.
202
What are the practical steps in the investigation box titled “Investigation: Gravitropism in Roots”?
1. Place seedlings on damp cotton wool in a Petri dish.
2. Position the Petri dish on its side so that the roots grow horizontally.
3. Check the direction of root growth after a few days to see if they bend downward.
203
What is the role of controlled conditions in the gravitropism investigation?
Controlled conditions, such as consistent light and temperature, are essential to ensure that only gravity influences the direction of root growth. Other variables could alter the results, so they must remain stable.
204
Why is gravitropism in roots crucial for plant survival?
Positive gravitropism in roots enables them to grow downwards into the soil, where they can better anchor the plant and access essential water and nutrients for growth and development.
205
How does phototropism benefit the overall growth of the plant?
Phototropism allows shoots to grow towards light, enhancing the plant’s ability to photosynthesize. This process produces food for the plant, supporting its growth, reproduction, and overall health
206
How does auxin concentration differ in roots and shoots when exposed to gravity or light?
In roots, high auxin concentration inhibits growth on the lower side, causing bending towards gravity. In shoots, high auxin concentration stimulates growth on the shaded or lower side, causing bending towards light or away from gravity.
207
What are some commercial uses of plant hormones?
Plant hormones are widely used in agriculture and horticulture to control plant growth, ripening, and rooting. Common uses include killing weeds, promoting rooting, ripening fruit, and controlling dormancy.
208
How are plant hormones used for killing weeds?
Selective weedkillers contain auxins that target broad-leaved plants, such as weeds, but leave narrow-leaved plants like grasses and cereals unaffected. This helps increase crop yield by eliminating weeds without harming desired crops.
209
Explain the use of plant hormones in promoting rooting in cuttings.
Rooting powders contain auxins that stimulate root growth in cuttings. When applied to cuttings, these powders encourage the development of roots, making it easier to propagate new plants from existing ones. This technique is widely used in horticulture and agriculture.
210
Describe how plant hormones are used for ripening fruit.
Ethene, a plant hormone, is used to control the ripening of fruits. By exposing unripe fruit to ethene during storage or transport, ripening can be delayed or accelerated, allowing fruit to be fresh and ripe when it reaches consumers
211
What role do plant hormones play in controlling dormancy?
Gibberellins are used to break dormancy (when a plant is alive but not growing) in seeds and buds, enabling them to germinate out of season. This can speed up germination for farmers, allowing them to grow crops more flexibly and improve yield.
212
What does a plant use hormones for in its natural growth processes?
Plant hormones help regulate growth, coordinate responses to environmental changes, and manage key processes such as germination, flowering, and ripening. They allow plants to respond effectively to their environment.
213
What is ethene and how does it affect plants?
Ethene is a gaseous plant hormone that controls cell division and fruit ripening. It promotes the conversion of starches into sugars, making fruit softer and sweeter. Ethene can also cause leaves to drop from plants as part of seasonal changes.
214
How are gibberellins used commercially, and what are their effects?
Gibberellins are plant hormones that stimulate stem elongation, seed germination, and flowering. Commercially, they are used to control dormancy, allowing out-of-season germination, and to induce flowering in certain plants.
215
What is the significance of auxins in plant growth and commercial use?
Auxins are hormones that regulate cell elongation and growth direction in response to light and gravity. Commercially, they are used in rooting powders to promote root development in cuttings and in selective weedkillers to target unwanted broad-leaved weeds.
216
Describe the use of ethene in fruit ripening within the commercial food industry.
In the food industry, ethene gas is used to control the ripening process of fruits during storage and transport. Unripe fruits are picked and ripened by exposure to ethene gas, ensuring that they reach consumers at peak ripeness and quality.
217
What advantages do selective weedkillers provide in agriculture?
Selective weedkillers, which contain auxins, target broad-leaved plants (weeds) without affecting narrow-leaved crops like wheat or grass. This selective action helps maintain crop health and increases yield by reducing competition for nutrients and sunlight.
218
How does controlling dormancy with plant hormones benefit farmers?
By using gibberellins to break dormancy, farmers can trigger seeds to germinate or buds to sprout even outside their natural season, allowing for more flexible and efficient crop production cycles.
219
How do rooting powders contribute to plant propagation? (the breeding of specimens of a plant or animal by natural processes from the parent stock)
Rooting powders, containing auxins, help cuttings develop roots more quickly. This speeds up the process of plant propagation, making it easier for horticulturists and gardeners to produce new plants from cuttings.
220
Explain the seasonal effect of ethene on plants.
Ethene contributes to leaf drop in autumn by promoting the breakdown of cell walls in the base of the leaf stalk, causing the leaf to detach. This process helps plants conserve resources in preparation for winter.
221
What are the three primary plant hormones mentioned in this text, and what are their general functions?
Auxins: Regulate growth direction and cell elongation.
• Gibberellins: Stimulate germination, flowering, and stem elongation.
• Ethene: Controls fruit ripening and leaf drop.
222
What is homeostasis?
Homeostasis is the process by which the body maintains its internal conditions, such as temperature, at stable levels despite external changes.
223
Why does the body need to regulate its internal temperature?
The body must regulate its internal temperature to ensure that enzymes function efficiently, as small temperature changes can hinder enzyme activity.
224
What can happen if the body is exposed to extreme cold?
Exposure to extreme cold can lower core body temperature, slowing down enzyme reactions, respiration, and potentially leading to hypothermia if the temperature drops below 35°C.
225
What risks do extreme high temperatures pose to the body?
High temperatures can cause heatstroke, and if the body temperature rises above 42°C, enzymes may denature, halting essential bodily functions.
226
What happens when the metabolic rate slows due to a drop in body temperature?
If the body temperature drops, the metabolic rate slows because enzyme activity is reduced, affecting the rate of biochemical reactions.
227
What brain system is responsible for regulating body temperature?
The thermoregulatory center in the brain is responsible for monitoring and controlling body temperature.
228
How does the thermoregulatory center detect changes in temperature?
It receives signals from receptors in the skin (monitoring external temperature) and internal receptors (monitoring the temperature of the blood).
229
How is body temperature controlled?
The thermoregulatory centre is responsible for regulating body temperature.
230
How does the body respond when a temperature change is detected
The brain sends signals to effectors, such as muscles and sweat glands, to either generate or release heat, thus returning body temperature to normal.
231
What happens when the body overheats?
The brain triggers cooling mechanisms such as lowering body hairs, producing sweat, and widening blood vessels near the skin surface (vasodilation) to increase heat loss.
232
What is vasodilation?
Vasodilation is the widening of blood vessels near the surface of the skin, which increases blood flow and heat loss through radiation.
233
What happens when the body is too cold?
The body initiates warming mechanisms, such as raising body hairs, stopping sweat production, narrowing blood vessels near the skin (vasoconstriction), and shivering.
234
What is vasoconstriction?
Vasoconstriction is the narrowing of blood vessels near the surface of the skin, reducing blood flow and heat loss.
235
What is the purpose of shivering?
Shivering generates heat by causing muscles to contract and relax quickly, increasing the rate of cellular respiration and transferring energy to warm the body
236
What is the difference between vasodilation and vasoconstriction?
Vasodilation: Blood vessels widen to increase heat loss.
Vasoconstriction: Blood vessels narrow to decrease heat loss.
237
Why is it important to control blood sugar levels in the body?
Controlling blood sugar levels is crucial because glucose is needed for energy production. If blood sugar remains high for long periods, it can damage the body, while low blood sugar can prevent cells from functioning properly, especially during physical activities that require more energy.
238
How can blood sugar levels be naturally decreased
Exercise: During physical activity, the body’s demand for glucose increases, which can help lower blood sugar levels as muscles use more glucose for energy.
Time between meals: When the body is not receiving new glucose from food, it relies on stored glucose, leading to a natural decrease in blood sugar levels over time.
239
What is insulin, and what role does it play in regulating blood sugar?
Insulin is a hormone released by the pancreas when blood sugar levels are high. It helps lower blood sugar by facilitating the conversion of glucose into glycogen in the liver, which is then stored for future energy use.
240
How does the liver store energy, and what triggers this process?
The liver stores energy in the form of glycogen, a storage form of glucose. When insulin is released in response to high blood sugar levels, it triggers the liver to convert excess glucose into glycogen for storage.
241
What happens if the blood glucose concentration falls too low?
When blood sugar is too low, the pancreas releases glucagon, a hormone that stimulates the liver to convert stored glycogen back into glucose, which is then released into the bloodstream to raise blood sugar levels.
242
Describe the process by which glucagon raises blood sugar level
Glucagon signals the liver to break down glycogen into glucose, which is then released into the blood, helping to maintain a constant blood sugar level, especially during fasting or between meals.
243
What is diabetes, and what causes it?
Diabetes is a medical condition where blood sugar levels remain consistently high because the body either cannot produce insulin or cannot effectively use the insulin it produces.
244
What characterizes Type 1 diabetes?
In Type 1 diabetes, the body does not produce insulin because the immune system destroys the pancreatic cells that produce it. This condition usually starts in childhood and requires lifelong insulin therapy to manage blood sugar levels.
245
What characterizes Type 2 diabetes?
In Type 2 diabetes, the body does not produce enough insulin, or the body’s cells do not respond to insulin (insulin resistance). It is often associated with lifestyle factors such as diet and physical activity, and typically develops in adulthood.
246
What are the key differences between Type 1 and Type 2 diabetes?
Type 1 diabetes involves no insulin production due to autoimmune destruction of pancreatic cells, typically beginning in childhood.
Type 2 diabetes involves insulin resistance or inadequate insulin production, often linked to lifestyle factors, and usually develops later in life.
247
How does the pancreas help maintain a constant blood glucose level using insulin and glucagon?
Insulin is released when blood sugar is high, promoting the storage of glucose as glycogen in the liver.
Glucagon is released when blood sugar is low, prompting the liver to convert glycogen back into glucose to increase blood sugar levels.
248
When is insulin typically at its highest concentration throughout the day?
Insulin levels peak after meals, as the body releases more insulin to help reduce the elevated blood sugar levels that occur due to food intake.
249
Why do blood sugar and insulin levels remain low overnight?
Blood sugar and insulin levels remain low overnight because the body is fasting, and there is no new glucose intake from food. During this time, the liver releases glucose to maintain stable blood sugar levels.
250
Which meal, based on Figure 4, likely had the highest sugar content?
Dinner appears to have the highest blood sugar peak in Figure 4, indicating that this meal contained more sugar compared to breakfast or lunch.
251
Explain the importance of keeping blood sugar levels constant.
Maintaining a constant blood sugar level is essential to avoid complications. High blood sugar can damage organs and tissues over time, while low blood sugar can impair cell function and energy production, especially during physical activity.
252
Why might a diabetic footballer need more insulin than a sedentary diabetic office worker?
A diabetic footballer may require more insulin because physical activity increases the demand for glucose in the muscles, leading to higher glucose uptake. More insulin may be needed to regulate this increased glucose consumption.
253
What are some factors that can increase the risk of developing Type 2 diabetes?
Risk factors for Type 2 diabetes include genetic predisposition, poor diet, lack of physical activity, being overweight, and other lifestyle-related facto
254
What is the significance of using insulin injections in diabetes management?
Insulin injections are crucial for people with diabetes, particularly Type 1, as they replace the insulin that the body cannot produce. This helps regulate blood sugar levels and prevents complications associated with high blood sugar.
255
What lifestyle changes can help manage Type 2 diabetes?
Managing Type 2 diabetes often involves lifestyle changes such as a balanced diet, regular exercise, maintaining a healthy weight, and sometimes using medication to improve insulin sensitivity or production.
256
Why is maintaining water balance important in the body?
It is important to regulate water levels in the blood to keep plasma concentration constant. If too much water is present, it can cause cells to swell and burst (lysis). If too little water or too much solute is present, water will diffuse out of cells, causing them to shrink.
257
What are two ways water enters and leaves the body?
Water enters: through consuming food and drink.
Water leaves: through sweating, urine, and exhalation as water vapor.
258
What is urine?
Urine is a solution composed of water, urea, salts, and other waste substances. Urea is a toxic by-product formed from the breakdown of proteins, which the body removes via the kidneys.
259
How do the kidneys regulate water balance and remove waste?
The kidneys filter urea out of the blood and produce urine, which is then stored in the bladder. The urine is produced through the processes of filtration and selective reabsorption, where useful substances are reabsorbed back into the bloodstream, while excess and waste products are excreted.
260
How is urine produced?
Filtration: Small molecules such as water, glucose, salts, and urea pass into the kidney tubules, while large molecules like blood cells remain in the blood.
Selective reabsorption: The kidneys reabsorb useful substances like glucose and some water back into the blood, leaving a mixture of urea, excess salts, and excess water to form urine.
261
How can urine composition change, and why?
Urine composition changes based on water intake and loss. For example, on a hot day, more water is lost through sweat, resulting in the production of concentrated urine. Conversely, drinking large amounts of water results in diluted urine, as excess water is expelled by the kidneys.
262
How can you tell if you have not drunk enough water?
you are dehydrated, your urine will be more concentrated, appearing dark yellow
263
Why might urine made by a healthy kidney not contain any blood cells?
Blood cells are too large to pass through the kidney filtration system, so they remain in the bloodstream rather than entering the urine.
264
Why do the kidneys perform selective reabsorption?
Selective reabsorption ensures that useful substances, such as glucose and certain amounts of water, are returned to the bloodstream, while waste products are expelled in the urine
265
Why does urine become more concentrated after exercise?
During exercise, the body loses water through sweat. To conserve water, the kidneys produce less urine, and it becomes more concentrated to maintain hydration levels.
266
What can cause a person to need artificial kidneys, such as dialysis?
a person’s kidneys do not function properly due to damage from disease or injury, waste products and water cannot be efficiently removed from the blood, making dialysis necessary to filter these substances artificially.
267
What is the journey of urine from the kidney to being expelled from the body?
Urine is produced in the kidneys, flows down through the ureters into the bladder for storage, and is then expelled from the body through the urethra.
268
Describe the difference between concentrated and dilute urine.
Concentrated urine: Darker in color, produced when the body needs to conserve water (e.g., hot weather).
Dilute urine: Lighter in color, produced when there is excess water in the body (e.g., after drinking a lot of fluids).
269
Explain why urine being made by a healthy kidney does not contain any blood cells
Healthy kidneys do not contain blood cells in urine because their filtration mechanism selectively prevents large molecules, like red blood cells, from passing through the glomerular barrier, which is designed to retain blood cells while allowing smaller waste products and water to be excreted.
270
Why does urine become more concentrated after exercise?
Increased Antidiuretic Hormone (ADH): Exercise stimulates the release of ADH, which enhances water reabsorption in the kidneys, leading to more concentrated urine.
Dehydration: Fluid loss through sweat during exercise can result in dehydration, prompting the kidneys to conserve water and produce more concentrated urine.
271
What is the function of the kidneys in maintaining internal environments?
The kidneys remove waste products from the blood, help regulate the amount of water in the body, and balance salt and water levels through reabsorption
272
What are the three observable sections of the kidney?
Capsule – outer membrane of the kidney, helps maintain its shape.
Cortex – outer part where the top of nephrons are located.
Medulla – inner region containing loops of Henle.
273
What is the nephron, and where is it located?
the nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. The top of the nephron is in the cortex, and the loop of Henle is in the medulla
274
How is urine produced and what does it contain?
Urine is produced in microscopic tubules called nephrons. It contains waste products and excess water filtered from the blood.
275
How is urine produced and what does it contain?
Urine is produced in microscopic tubules called nephrons. It contains waste products and excess water filtered from the blood.
276
Describe the path blood takes through the nephron.
Blood enters the kidney through the renal artery at high pressure. It passes into the glomerulus, where small molecules are filtered out into the Bowman’s capsule, and then moves through the nephron where reabsorption occurs.
277
What is the role of selective reabsorption in the nephron?
Selective reabsorption in the nephron reabsorbs all of the glucose, as well as some water and salts the body needs. This process reduces the volume of urine produced.
278
How does the body control the amount of urine produced?
The body controls urine production using a negative feedback loop. The hypothalamus detects water levels in the blood and adjusts the release of ADH (anti-diuretic hormone) from the pituitary gland, which influences water reabsorption in the kidneys.
279
What happens when ADH levels increase?
Increased ADH makes the walls of the collecting ducts in the kidneys more permeable to water, resulting in more water being reabsorbed into the blood and producing a small volume of concentrated urine.
280
What happens when ADH levels decrease?
When ADH levels decrease, less water is reabsorbed from the nephron into the blood, leading to a larger volume of dilute urine.
281
What is the significance of the hypothalamus in controlling urine production?
The hypothalamus detects the water potential in the blood and signals the pituitary gland to release ADH, helping to regulate the concentration of urine.
282
Explain why ADH production is described as a negative feedback system
ADH production is controlled by a negative feedback system because it adjusts the amount of ADH released based on blood water levels, restoring balance and preventing excessive loss or retention of water.
283
Describe the structure and function of the Bowman’s capsule
The Bowman’s capsule surrounds the glomerulus and collects filtrate (small molecules like water, ions, and urea) from the blood, which then passes through the nephron.
284
What is the loop of Henle and its function in the kidney?
The loop of Henle is part of the nephron in the medulla that reabsorbs water and salts from the filtrate, helping to concentrate urine
285
What role does the collecting duct play in the kidney?
The collecting duct transports waste solution to the bladder, where urine is stored before being excreted from the body.
286
What factors determine the volume of urine produced?
The volume of urine is determined by water potential in the blood and ADH levels. High ADH leads to concentrated urine; low ADH results in dilute urine.
287
explain why ADH production is described as a negative feedback system
ADH production is described as a negative feedback system because it adjusts urine concentration based on blood water levels to maintain balance. When blood water is low, more ADH is released to conserve water; when blood water is high, less ADH is released to eliminate excess water.
288
Why might over-consuming water be harmful?
Over-consuming water can lead to water intoxication, where excess water causes cells to swell due to osmosis, potentially resulting in dangerous health effects.
289
How much water does the body need daily?
On average, an adult needs around two liters of water per day, although this amount can increase depending on temperature, physical activity, and other factors.
290
why does a construction worker need more water than an office worker
A construction worker requires more water due to increased physical activity and sweating, which leads to higher water loss compared to someone with a sedentary job
291
What are the body’s responses to a lack of water?
The body responds to water loss by triggering thirst, decreasing urine production, and conserving water through the kidneys. Dehydration, marked by symptoms like dark urine, headaches, dizziness, and fatigue, occurs if water intake remains low.
292
What are the symptoms of dehydration?
Symptoms of dehydration include dark, concentrated urine, headaches, dizziness, fatigue, and a lack of energy.
293
What can happen if dehydration becomes severe?
Severe dehydration can lead to permanent damage to the kidneys and liver, and in extreme cases, it can be fatal.
294
How does the body respond to consuming too much water?
Drinking too much water lowers the water potential of blood, causing water to move into cells by osmosis, potentially leading to swelling, confusion, seizures, and in severe cases, brain swelling and death.
295
Explain why a lack of salt can cause blood cells to burst.
Without enough salt, the water potential outside blood cells becomes higher, causing water to enter the cells by osmosis, which can make them swell and eventually burst
296
What are the three types of sports drinks, and what do they contain?
Hypertonic – High levels of glucose and salts.
Hypotonic – Low levels of glucose and salts.
Isotonic – Glucose and salt concentrations equal to those in blood plasma
297
Are sports drinks scientifically proven to improve athletic performance?
While sports drinks are marketed to enhance athletic performance, scientific evidence is limited, and not all scientists agree with these claims
298
Which type of sports drink would be ideal for rapid rehydration in athletes?
An athlete would typically choose an isotonic drink, as it matches blood plasma’s glucose and salt concentrations, helping with quick and efficient rehydration
299
Explain why an increase in salt intake triggers the thirst response.
A rise in salt concentration lowers water potential in the blood, signaling the brain to trigger thirst, prompting increased fluid intake to balance concentration levels.
300
What is a diuretic drug, and how does it affect the body’s water balance?
A diuretic drug stimulates the production of ADH, causing increased urine output, which can lead to dehydration if water loss is not adequately replenished.
301
State and explain one advantage of consuming a sports drink rather than drinking water.
Sports drinks contain glucose and salts that help replenish lost energy and electrolytes, providing faster recovery compared to water alone.
302
Explain why an increase in salt intake triggers the thirst response
Increased salt in the bloodstream lowers water potential, stimulating thirst as a mechanism to dilute salt levels by increasing water intake.
303
Ecstasy is a recreational drug that stimulates ADH production. Explain why this may be fatal to a user who consumes a large volume of water.
Excess ADH due to Ecstasy prevents water excretion, leading to water retention and lowering blood water potential. If a large amount of water is consumed, this can cause cells to swell, leading to symptoms like confusion, seizures, and potentially fatal brain swelling.
