Topic 5 Homeostasis And Responnse Flashcards
1
Q
What is homeostasis?
A
Regulation of internal conditions to maintain optimum conditions for function in response to internal and external changes
2
Q
What are 3 examples of things in the body that are controlled?
A
Body temperature
Blood glucose concentration
Water levels
3
Q
What 2 responses may automatic control systems involve?
A
Nervous
Chemical
4
Q
What are the 3 components that make up all automatic control systems?
A
Cells called receptors
Coordination centres
Effectors
5
Q
What do receptors do?
A
Detect stimuli (changes in environment)
6
Q
What are 3 examples of coordination centres?
A
Brain
Spinal cord
Pancreas
7
Q
What do coordination centres do?
A
Receives and processes info from receptors
8
Q
What are 2 types of effectors?
A
Muscles
Glands
9
Q
What do effectors do?
A
Produce response which restore optimum levels
10
Q
What does the nervous system enable humans to do?
A
React to surroundings and coordinate behaviour
11
Q
How do muscles respond to a nervous impulse?
A
Contract
12
Q
How do glands respond to a nervous impulse?
A
Secrete hormones
13
Q
What does the central nervous system consist of?
A
Brain and spinal cord
14
Q
In mammals, what is the central nervous system connected to the body by?
A
Sensory neurones and motor neurones
15
Q
What are sensory neurones?
A
Carry info as electrical impulses from receptors to CNS
16
Q
What are motor neurones?
A
Carry electrical impulses from CNS to effectors
17
Q
What are the 7 components that make up the nervous system?
A
Stimulus
Receptor
Sensory neurone
CNS
Motor neurone
Effector
Response
18
Q
What is a synapse?
A
Connection between 2 neurones
19
Q
What are reflexes?
A
Rapid, automatic responses that don’t involve conscious part of brain
20
Q
Why are reflexes important?
A
Reduce chance of injury
21
Q
What is a reflex arc?
A
Passage of info in reflex (from receptor to effector)
22
Q
How are nerve signals transferred between neurones?
A
By chemicals which diffuse across gap, set off new electrical signal in next neurone
23
Q
What does the brain control?
A
Complex behaviour
24
Q
What is the brain made up of?
A
Billions of interconnected neurones
25
What are **3 regions** of the **brain**?
**Cerebral cortex**
**Medulla**
**Cerebellum**
26
Where is the **cerebral cortex** in the **brain**?
**Outer front**
27
What are **4 things** the **cerebral cortex** is **responsible for**?
**Consciousness**
**Intelligence**
**Memory**
**language**
28
Where is the **cerebellum** in the brain?
**Back, bottom**
29
What is the **cerebellum responsible for**?
**Muscle coordination**
30
Where is the **medulla** in the brain?
**Long bit at bottom**
31
What is the **medulla responsible for**?
**Unconscious activities (breathing and heartbeat)**
32
What are **3 different methods used by scientists to study the brain**?
**Study patients with brain damage**
**Electrically stimulating brain**
**MRI scan**
33
What can **studying patients with brain damage tell scientists**?
If **small part of brain is damaged, effect on patient** can tell you what **damaged part of brain does**
34
What can **electrically stimulating the brain tell scientists**?
By **observing what stimulating different parts of brain does, get an idea of what other parts do**
35
What can **MRI scans tell scientists**?
**Produce detailed picture of brains structures**, find out what **parts of brain are active** when people are doing an **activity**
36
What has **knowledge of how the brain works led to**?
**Development of treatments for disorders of nervous system**
37
Why is **investigating and treating brain disorders very difficult**?
**Complex and delicate**, can **cause physical damage or increased problems with brain function**
38
What are the **9 parts of the eye**?
Sclera
Iris
Cornea
Pupil
Lens
Ciliary muscle
Optic nerve
Retina
Suspensory ligaments
39
What is the **eye**?
**Sense organ containing receptors sensitive to light intensity and colour**
40
What is the **sclera**?
**Tough, supporting wall of eye**
41
What is the **cornea**?
**Transparent outer layer at front of eye**
42
What does the **cornea do**?
**Refracts (bends) light into eye**
43
Why does the **iris contain muscles**?
**Control diameter of pupil, how much light enters eye**
44
What does the **lens do**?
**Focuses light onto retina**
45
What does the **retina contain**?
**Receptor cells sensitive to light intensity and colour**
46
What **2 things** is the **shape of the lens controlled by**?
**Ciliary muscles**
**Sensory ligaments**
47
What does the **optic nerve do**?
**Carries impulses from receptors on retina to brain**
48
What is **accommodation**?
**Process of changing shape of lens to focus on near or distant objects**
49
What are the **4 steps to focus on a near object**?
**1. Ciliary muscles contract**
**2. Suspensory ligaments loosen**
**3. Fat lens**
**4. Refracts light rays strongly**
50
What are the **4 steps to focus on distant objects**?
**1. Ciliary muscles relax**
**2. Suspensory ligaments pull tight**
**3. Thin lens**
**4. Slightly refracts light rays**
51
What happens when **light receptors in the eye detect very bright light**?
**Reflex triggered, makes pupil smaller**
52
What are the **3 steps** for the **eye** to **adapt to bright light**?
**1. Circular muscles in iris contract**
**2. Radical muscles relax**
**3. Reduces amount light that enters eye**
53
What are the **3 steps** for the **eye** to **adapt to dim light**?
**1. Circular muscles relax**
**2. Radical muscles contract**
**3. Pupil wider**
54
What is the **scientific term for short sightedness**?
**Myopia**
55
What is the **scientific term for long sightedness**?
**Hyperopia**
56
What are **long sighted people unable to do**?
**Focus on near objects**
57
When does **longsightedness occur**?
**Lens wrong shape, doesn’t refract (bend) light enough** or **eyeball too short**
58
Where are **images of near objects brought into focus in longsightedness**?
**Behind retina**
59
What can you use to **correct long sightedness**?
**Convex lenses**
60
What do **convex lenses do**?
**Refracts light rays so focus on retina**
61
What are **short sighted people unable to do**?
**Focus on distant objects**
62
When does **short sightedness occur**?
**Lens wrong shape, refracts light too much** or **eyeball too long**
63
Where are **images of distant objects brought into focus in shortsightedness**?
**In front of retina**
64
What can you **use to correct short sightedness**?
**Concave lenses (curve inwards)**
65
What are **3 treatments for vision defects**?
**Contact lenses**
**Laser eye surgery**
**Replacement lens surgery**
66
What are **3 advantages of contact lenses**?
**Lightweight**
**Invisible**
**Convenient for sports**
67
What are the **2 types of contact lenses**?
**Hard**
**Soft**
68
What is an **advantage and disadvantage of soft contact lenses**?
**Comfortable, higher risk eye infection**
69
What can **laser eye surgery be used for**?
**Change shape of cornea, make it less/more powerful**
70
What is **replacement lens surgery**?
**Natural lens of eye removed, artificial lens (clear plastic) inserted**
71
Why does **replacing a lens carry higher risks than laser eye surgery**?
**Involves work inside eye, possible damage to retina**
72
What is **body temperature monitored and controlled by**?
**Thermoregulatory centre in brain**
73
What does the **thermoregulatory centre contain**?
**Receptors sensitive to temperature of blood**
74
What does the **thermoregulatory centre receive nervous impulses from**?
**Temperature receptors in skin**
75
What do both **vasodilation** and **sweating cause**?
**Transfer of energy** from **skin** to **environment**
76
What **2 things happen** when the **body temperature is too high**?
- **Sweat** produced from **sweat glands**, **evaporates** from skin
- **vasodilation, blood vessels dilate** so more **blood flows close to surface of skin**
77
What is **vasodilation**?
**Blood vessels dilate**
78
What is **vasoconstriction**?
**Blood vessels constrict**
79
What **4 things happen** if the **body temperature is too low**?
**Hairs stand up- trap insulating layer of air**
**No sweat**
**Vasoconstriction, Blood vessels constrict** to **close off skins blood supply**
**Skeletal muscles contract (shiver)**
80
Why does **shivering warm up the body**?
**Muscle contraction** needs **respiration** which **transfers energy**
81
What **makes up the endocrine system**?
**Glands**
82
What are **hormones (2 things)**?
**Chemical messengers released directly into blood**, carried to **target organ** where it **produces effect**
83
What are **3 differences between nerves and hormones**?
**Hormones = slower action, longer lasting, act in general way**
84
What are **6 glands** in the **human endocrine system**?
Pituitary gland
Pancreas
Thyroid
adrenal gland
Ovary
Testes
85
Where is the **adrenal gland located**?
**Above pancreas**
86
Why does the **thyroid produce** and what does this **regulate**?
**Thyroxine, rate of metabolism, heart rate** and **temperature**
87
What does the **adrenal gland produce** and what is this **used for**?
**Adrenaline, prepare body for fight or flight**
88
What does the **pituitary gland do**?
**Secretes several hormones into blood** in **response to body conditions**
89
Why is the **pituitary gland called the ‘master gland’**?
**Hormones** it secretes **act on other glands**, **stimulate other hormones** to be **released** to bring about **effects**
90
What is **excess glucose stored as**?
**Glycogen**
91
Where is **excess glucose stored as glycogen**?
**Liver and muscles**
92
What happens if the **blood glucose concentration is too high**?
Pancreas secretes **insulin**, causes **glucose move from blood** into **liver** and **muscle cells**
93
What happens if the **blood glucose concentration is too low**?
Pancreas secretes **glucagon, glycogen converted into glucose released into blood by liver**
94
What are the **2 hormones** used to **control blood glucose concentration**?
**Insulin**
**Glucagon**
95
Why are **injections of insulin at mealtimes an effective treatment of type 1 diabetes**?
Ensures **glucose removed from blood quickly** once **food is digested, stops level getting too high**
96
What are **2 things as well as insulin therapy, people with type 1diabetes need to think about**?
**Limit intake of simple carbohydrates (cause blood glucose rise rapidly)**
**Regular exercise (helps remove excess glucose from blood)**
97
What is **type 2 diabetes**?
**Body cells no longer respond to insulin produced by pancreas**
98
How do the **kidneys produce urine**?
**Filter waste products out of blood** as **blood passes through kidneys (filtration)**
**Useful substances** like **glucose, some ions and water absorbed back into blood (selective reabsorption)**
99
What are **3 substances** that are **removed from the body in urine**?
Urea
Ions
Water
100
Why is the **amount of water we lose balanced by the amount we consume** and the **amount removed by the kidneys in urine**?
**No control over water loss** from **skin in sweat** or from **lungs in exhalation**
101
What **happens** if the **ion or water content of the body is wrong**?
**Upset balance** between **ions and water, too much of too little water drawn into cells by osmosis**
102
Why must the **right balance of ions in the body be maintained by the kidneys**?
**Some ions lost in sweat, not regulated**
103
What **happens to excess amino acids** that **can’t be stored by the body**?
**Deaminated** in **liver** to form **ammonia**
104
What **happens to ammonia** due to its **toxicity**?
Converted to **urea** in **liver** for **safe excretion**
105
Which **hormone controls the concentration of urine**?
**ADH (anti-diuretic hormone)**
106
What **happens** when the **blood is too concentrated**?
**ADH** released into **blood** by **pituitary gland**
**More water reabsorbed** from **kidney tubules**
107
What **happens** when the **water content is too high**?
**Pituitary gland** releases **less ADH**
**Less water reabsorbed** from **kidney tubules**
108
What is the **whole process of water content regulation controlled by**?
**Negative feedback**
109
What are **2 methods** of **treating kidney failure**?
**dialysis**
**Kidney transplant**
110
How are **useful dissolved ions** and **glucose not lost from the blood** during **dialysis**?
**Dialysis fluid** has **same concentration** of **dissolved ions** and **glucose** as **healthy blood**
111
How do **dialysis machines work**?
**Blood flows** between **partially permeable membranes** surrounded by **dialysis fluid, waste products (urea), excess ions** and **water diffuse out** into **dialysis fluid**
112
How **often do patients have to have dialysis sessions** and for **how long**?
**3 times a week, 3-4 hours**
113
What are **3 disadvantages of kidney dialysis**?
Risk of **Blood clots/infections**
**Expensive**
**Time consuming**
114
What is an **advantage of kidney dialysis**?
**Patient with kidney failure can wait until donor organ found**
115
What are **2 disadvantages of kidney transplants**?
**Long waiting list**
**Donor kidney can be rejected by immune system**
116
What is an **advantage of kidney transplants**?
**Cheaper (long run) than dialysis**
117
What are the **4 stages** of the **menstrual cycle**?
**Day 1) menstruation, uterus lining breaks down**
**Day 4-14) uterus lining builds up**
**Day 14) egg develops** and **released from ovary- ovulation**
**Day 14-28) wall maintained**, if **no fertilised egg cycle begins again**
118
Where are **oestrogen and progesterone produced**?
**Ovaries**
119
Where are **LH and FSH produced**?
**Pituitary gland**
120
What **2 things** does **FSH do**?
Causes **egg mature** in **follicle** of **ovary**
**Stimulates production of oestrogen**
121
What does **LH do**?
**Stimulates release of egg on day 14 (ovulation)**
122
What **3 things** does **oestrogen do**?
Causes **uterus lining to grow**
**Stimulates** release of **LH**
**inhibits** release of **FSH**
123
What happens when the **levels of progesterone fall**?
**Lining breaks down**
124
What **2 things** does **progesterone do**?
**Maintains uterus lining**
**Inhibits** release of **LH** and **FSH**
125
Why is **progesterone used in hormonal contraceptives**?
**Stimulates production of thick mucus, prevents sperm reaching egg**
126
How can **oestrogen be used to prevent the release of an egg**?
**Taken every day** to keep **level permanently high, inhibits FSH** so **egg development and production stops**
127
What are the **2 types of oral contraceptive pill**?
**Combined pill (progesterone and oestrogen)**
**Progesterone only pill**
128
What is an **advantage** of the **combined oral contraceptive pill**?
**Over 99% effective preventing pregnancy**
129
What are **2 disadvantages** of the **combined pill**?
**Side effects (headaches/nausea)**
**Doesn’t protect from STIs**
130
What are **4 methods of contraceptives** that **use hormones** other than the **pill**?
**Skin patch**
**Implant**
**Injection**
**IUD (copper or plastic)**
131
What are the **2 types of IUD**?
**Plastic- release progesterone**
**Copper- prevent implantation of fertilised egg**
132
What do the **injection, skin patch and implant all do**?
**Slow release progesterone, inhibit maturation and release of eggs, for weeks-years**
133
What are **2 barrier methods of contraception**?
**Condoms**
**Diaphragm (covers cervix)**
134
What does the **diaphragm have to be used with**?
**Spermicide**
135
What are **2 hormones** are given to women in a **’fertility drug’** to **stimulate ovulation**?
**FSH and LH**
136
What are **2 cons of hormones to increase fertility**?
**Doesn’t always work**
Too many eggs stimulated- **unexpected multiple pregnancies** (eg twins)
137
What are **3 cons** of **IVF**?
**Multiple births** (higher risk of miscarriage/still birth)
**Low success rate**
**Emotionally and physically stressful**
138
How does **adrenaline prepare you for ‘fight or flight’**?
**Increases heart rate- boosts delivery of oxygen and glucose** to **brain and muscles**
139
What does **thyroxine play an important role in**?
**Growth and development (stimulating protein synthesis)**
140
What is **thyroxine released in response to**?
**TSH (thyroid stimulating hormone)** released from **pituitary gland**
141
What are **thyroxine levels controlled by**?
**Negative feedback**
142
What is the **term** for a **plants response to light**?
**Phototropism**
143
What is the **term** for a **plants response to gravity**?
**Gravitropism/geotropism**
144
What does **auxin control**?
**Growth near tips of shoots and roots**
145
What **happens** if the **tip of a shoot is removed**?
**No auxin available, shoot may stop growing**
146
What are **3 commercial uses of auxins**?
**Killing weeds**
**Rooting powders**
**Promoting growth in tissue culture**
147
How can **auxin** be used to **kill weeds**?
**Kill broad leaved weeds not crops or grass (narrow leaves)**
148
What are **3 commercial uses of gibberellins**?
**End seed dormancy**
**Promote flowering**
**Increase fruit size**
149
How can **gibberellins** be used to **end seed dormancy**?
Make **seeds germinate at times of year they wouldn’t normally**
150
What is **ethene (2 points)**?
**Gas produced by aging part of plant**
**Stimulates enzymes that cause fruit to ripen**
