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biology igcse > B9-B10 (human Reproduction + Nervous System) > Flashcards

B9-B10 (human Reproduction + Nervous System) Flashcards

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1
Q

What is stimulus?

A

Changed in the environment

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2
Q

What does the nervous system do?

A

Detects and respond to changes in the environment (stimulus)

Avoid danger
Detect food
Learn from experience

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3
Q

What are receptors?

A

Receptors pick up stimuli
More receptors-> more sensitive

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4
Q

What are the sense organs?

A

Tongue, eyes, nose, ears, skin

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5
Q

What are the organs in CNS and what does the CNS do?

A

Brain and spinal cord

Processes and coordinates sensory data + sends out motor commands

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6
Q

What are the parts of the PNS and what does the PNS do?

A

Peripheral nerves (nerve-> bundle of neurons)

Takes information from the organs to the CNS + from CNS to effectors

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7
Q

Explain the pathway of electric impulses through the nervous system

A

Receptor (stimulus) -> sensory neurons -> brain -> motor neurons -> effectors (response)

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8
Q

What are reflexes?

A

Automatic and rapid response to stimuli
Often protect from danger and doesn’t reach the brain until after the reaction has happened

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9
Q

Describe the path of an electric impulse through the nervous system for a reflex

A

Stimulus -> receptors -> sensory nerves -> relay neurons (spinal cord) (info is relayed not processed because reflexes need to be quick) -> motor nerves -> effectors

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10
Q

What are the differences and similaires between voluntary and involuntary movement?

A

Voluntary:
Slow
Conscious thought
Passes via the brain
Majority of movement

Involuntary (reflex):
Quick
Relay neurons in spinal cord
Protect the body

Both:
Both use sensory and motor neurons
Both use receptors and effectors
Involves electrical impulses

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11
Q

Using a diagram name and describe the functions of each part of the eye

A

Lens
Magnifying glass (20% of the magnifying)
Focus on further and closer things
Focuses light in the retina

Ciliary muscles
Squeezes lens -> thicker and thinner

Pupil
Hole in the center of the eye
Light enters the eye

Cornea
Protects the eye
Magnifying glass (80% of the magnifying)
Usually clear and first place light enters

Iris
Controls the amount of light entering the eye
Ring of muscle around the pupil
Muscles in the iris:
Circular and radial -> antagonistic muscles
Bright light/pupil contract -> circular contract, radial relax
Dim light/pupil dilate -> circular relax, radial contract

Suspensory ligaments
Suspense the lens
Connects to ciliary muscle

Blind spot
All receptors in the retina connect to this point (means no receptors here -> cannot see -> brain fills in image)

Optic nerve
Sensory neurons that carry impulses to brain
Retina -> brain

Sclera
White outer layer
Maintain shape and protect

Retina
Layered brain tissue
Photoreceptors
Rod -> peripheral, motion, dim light
Cone -> middle, color (red, blue, green), details (bright light)

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12
Q

What does accommodation require to happen?

A

Lens must change shape to focus light differently based on if you are looking at a closer or further object

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13
Q

Create a diagram showing how light enters the eye when looking at an:
A) close object
B) distant object

A

Close:
Thicker lens
Light enter is wider
Relaxed suspensory ligament
Contracted muscle
More refraction

Distant:
Thinner lens
Light enter is thinner
Tight suspensory ligament
Relaxed muscles
Less refraction

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14
Q

Draw a diagram and explain what causes:
A) short sightedness
B) long sightedness
And how it can be corrected

A

Fixed by glasses by focusing the focal point so it lands on the retina

Short sightedness:
Light focuses too early (before retina)
Causes:
Long eyeballs
Thick lens
Fix:
Concave/diverging lense
Spreads light rays

Long sightedness:
Light focuses to late (after retina)
Causes:
Short eyeball
Thin lens
Fix:
Convex/converging lense
Brings light to a focus

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15
Q

What are hormones?

A

Produced by glands
Chemical messengers released into the bloodstream
Alters activity of target organs (later destroyed but liver)

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16
Q

What does adrenaline do and how is it made?

A

Responds to danger -> fight or flight
Adrenal gland (on top of the kidneys) -> affects multiple organs

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17
Q

Describe the hormone response pathway

A

Adrenal gland releases adrenaline -> adrenaline is transported in the bloodstream -> receptors detect adrenaline -> effectors respond to adrenaline

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18
Q

What are some examples of effectors ?

A

Heart, stomach, eye (iris), muscles, blood vessels, brain

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19
Q

What are the effects of Adrenaline and why do they happen?

A

Increased blood glucose
More respiration -> more energy

Increased blood pressure
Blood travels faster -> more oxygen, glucose, adrenaline, take away waste

Expanding air passages of lungs
Allows more oxygen to enter and more CO2 to leave -> more respiration

Enlarged pupil
More light enters through the pupil -> see better

Redistributes blood to muscle and vital organs
Helps them work efficiently

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20
Q

Compare hormone and nerve responses

A

Hormone response:
Chemical signal
Relatively slow
Released by glands
Travels in the bloodstream
Effector -> generally organs

Nerve response:
Electrical signal
Relatively fast
Triggered by receptors
Travel along neurons
Effectors -> generally muscles

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21
Q

What is negative feedback?

A

Change occurs in the opposite direction to bring conditions back to normal

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22
Q

What is homeostasis?

A

Mechanism to maintain a constant and stable and internal environment (37°C)

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23
Q

How is temperature controlled in the body?

A

Monitored and controlled by temperature receptors in the skin and brain
Receptors -> detect changing temps in the blood (body cold -> blood cold -> brain cold)

24
Q

What is the thermoregulatory center of the brain?

A

Hypothalamus
Impulses from brain trigger reaction

25
Q

Explain what happens to the body when it is:
A) too warm
B) too cold
And why

A

Too warm (heat stroke):
Vasodilation
-> blood vessels increase in size
-> more heat radiates from the body
Sweating
-> heat energy is transferred to the sweat and evaporates
Hairs flatten
All to increase heat loss

Too cold (hypothermia):
Vasoconstriction
-> blood vessels decrease in size
-> reduces amount of heat lost
Shivering
-> more respiration
Less sweat
Hair stand up
-> insulating layer
All so reduce heat loss

26
Q

Look at a diagram and label + explain the functions of all the parts of the skin

A

Melanocyte:
Cell in the epidermis that produces melanin (protection from the sun)

Sweat/suboriferous glands:
Tube shaped glands
produce sweat on the skin
Epidermis

Sebaceous glands:
Sack shaped gland
Releases oily liquid to lubricate and soften skin
Dermis next to hair follicle

Hair shaft:
Part of hair above skin

Hair erector muscle:
Muscles that connects hair follicle to skin
Contract -> goosebumps

Hair follicle:
Tube shaped sheath
Surrounds hair under the skin
Nourishes hair and growing point
Dermis+epidermis

Blood vessel:
Carries blood

Epidermis:
Outer layer of skin

Dermis/cutis:
Layer under epidermis

Subcutaneous tissue:
Fatty tissue
Under dermis

27
Q

Why is too much/little glucose bad for the cells in the body?

A

Too much:
Excess glucose makes blood plasma+tissue fluid around the cells too concentrated
Damages the cells-> too much water diffuses out -> osmosis

Too little:
Low glucose makes cells swell but and burst
A result of too much water diffusing in to have the same water concentration as its surrounding -> lysis

28
Q

How is glucose regulated?

A

Glucose levels and concentrations are regulated by the pancreas using 2 different hormones

INSULIN:
Released by pancreas when blood sugar is high
Stimulates liver to convert glucose -> glycogen (groups of glucose, stored in liver and muscles)

GLUCAGON:
Released when blood sugar is low
Stimulates liver to convert glycogen -> glucose

Blood glucose high -> cells in pancreas detect change -> pancreas secretes insulin -> glucose stored as glycogen -> blood glucose decreases -> blood glucose too low -> cells in pancreas detect change -> pancreas secretes glucagon -> glycogen converted to glucose -> blood glucose increases -> back to start

29
Q

Hyper/hypoglycemia: what is it, causes, and treatment

A

Hypoglycemia:
Blood sugar drops below normal range
result of: extreme exercise, missed meals, too much insulin
Treatment: glucose IV drip or food

Hyperglycemia:
Blood sugar because higher than a normal range
Result of: too many carbs, lack of exercise, too little insulin
Treatment: injection insulin

30
Q

What is diabetes?

A

A disorder that causes blood sugar levels to be above a normal range and go into dangerous levels
-> a result of pancreas not producing enough insulin

31
Q

How do type 1 and type 2 diabetes lead to high blood sugar? What are the symptoms of both types ?

A

Type 1:
Immune system attacks and destroys insulin producing cells in pancreas
An immune disorder

Type 2:
Pancreas doesn’t produce enough insulin or the body has developed an insulin resistance

Symptoms:
1-> extreme weight loss
2-> infections, numbness at hands and feet, gum problems
1+2-> thirst, hunger, fatigue, increased urination

32
Q

Compare asexual and sexual reproduction

A

Asexual:
Produces genetically identical organisms
Mitosis (exact copies)
One parent
Quick (no variation and susceptible to disease)

Sexual:
Produces genetically different organisms
Meiosis (makes genetically different organisms) (gamete and zygote)
Mitosis (growth after fertilisation)
Gender: female -> XX and male -> XY
Slow (but there is variation)

33
Q

What are the advantages and disadvantages of asexual and sexual reproduction

A

Asexual:
Advantages:
Identical organisms (quick and adapted to the environment)
Only one parent
Disadvantages:
Environment can change
If a specific species they interact with goes extinct->could also go extinct
Susceptible to disease

Sexual:
Advantages:
Variation of offspring
Disadvantages:
2 parents -> takes time

34
Q

Explain haploids and diploids (and examples)

A

Haploid:
One copy of each chromosome
Ex: gametes (egg and sperms)

Diploid:
2 set of each chromosome
Ex: 2 gametes fuse to form a zygote

35
Q

Label a diagram of the female reproductive system and explain the function of each part

A

Oviduct/fallopian tube:
Carries ovum from ovary to uterus
Where the egg becomes fertilized

Ovary:
Produces ova (egg/gametes)
After puberty -> ovum released around every 28 days

Cervix:
Ring of muscle at opening of uterus and top of vagina

Uterus/womb:
If egg fertilises it is implanted onto the walls of the uterus and becomes a fetus

Vagina:
Receives the penis during sex
Sperm is deposited

36
Q

Label a diagram of the male reproductive system and explain the function of each part

A

Seminal vesicle:
Creates ingredients for semen

Ureter:
Connects kidneys to urinary bladder

Bladder:
Hold urine until it can be excreted

Prostate gland:
Secretes fluid for sperm to swim in -> forms semen

Penis:
Transfers semen to vagina during sex

Urethra:
Carries urine and semen out of the body

Scrotum:
A sac of skin which holds the testes

Testes/testis:
Produces sperm

Epididymus:
Stores sperm

Sperm duct:
Carries sperm to outside the body

37
Q

What is puberty?

A

When boys and girls become sexually mature
Controlled by hormones
Sex cells produced and released
Several years to complete

38
Q

What is the menstrual cycle?

A

Female body prepares for the pregnancy
Makes sure uterus is in perfect conditions for implantation (28 days long)

39
Q

Explain what happens during the menstrual cycle (including days)

A

Day 1-5:
Menstruation
Interns lining is shed

Day 6-13:
Uterus lining is built up
Egg matures in the uterus

Day 14:
Uterus lining at its thickest (prime)
Egg released from ovary (ovulation)

Day 15-28:
If fertilisation:
Egg implants onto lining
Uterus lining is maintained
No fertilisation:
No implantation and egg dies
Uterus lining starts to break down

40
Q

What are the hormones related to the menstrual cycle (the 2 we learned about)

A

Oestrogen and progesterone

41
Q

Explain the functions of oestrogen and progesterone

A

Oestrogen:
Rises from day one and peaks on day 14 (just before egg is released)
Uterus lining start thickening
Egg begins to mature

Progesterone:
Low day 1-14
Rises once ovulation had occurred
Increasing levels-> lining thickens (maintains lining while implantation can occur)
Decreasing levels-> lining shed (menstruation)

Both will increase if fertilisation occurs

42
Q

Describe the journey of the sperm

A

Released into vagina
Cervix
Uterus
Swims up oviduct (why it has tail)

Takes around 10h
Millions are made -> strongest survive
Quickly made -> many are deformed

43
Q

Describe how fertilisation occurs

A

Sperm reaches egg -> pushes through cell membrane (tail lost)
Enzymes in sperm break through the cell membrane
Goes in -> wall forms -> other sperm cannot enter
Travels to uterus -> implantation (around 3 day process)

Nucleus of sperm and egg fuse -> zygote
-> 23 pairs of chromosomes (2 sets)

Zygotes divides into 2 cells with identical sets of chromosomes and continue to form embryo
-> mitosis

44
Q

What is the placenta?

A

Provides nutrients, oxygen, removes waste
Connected to umbilical cord
Secretes hormones -> maintain pregnancy
Developed by embryo

45
Q

What is the function of an amniotic sac?

A

Encloses the embryo and secretes amniotic fluid
Protect the embryo from sudden movements

46
Q

What is HIV?

A

Human immunodeficiency virus
Affects CD4 (T-lymphocytes) in immune system
-> virus replicates and destroys the cells

47
Q

What are CD4 cells?

A

Lymphocytes (white blood cells) that protect against pathogens

48
Q

What does it mean to be HIV positive?

A

Body creates antibodies to combat the virus
If detected in body -> HIV positive

49
Q

How is HIV transmitted?

A

Can be transmitted from anyone with HIV and depends on viral load (HIV particles/ml)

Blood (sharing needles, blood transfusion (highly unlikely)
Vaginal fluid/semen (sexual intercourse)
Breast milk (baby drinking)
Birth (mother gives birth while infected)

50
Q

How can HIV be prevented?

A

Condoms
Not sharing drug injection equipment
Protect cut, sores, eyes mouth from blood
Antiretroviral drug during pregnancy
No breastfeeding

51
Q

What are common myths of HIV?

A

Bug bites (no bodily fluids injected)
Kissing/spitting/mouth to mouth contact (saliva and tears contains enzymes that destroy)
Contact with healthy skin
Sharing cutlery, bath, towel, swimming pool

52
Q

What is AIDS?

A

Acquired immunodeficiency syndrome (syndrome: group of health disorders that make up a disease)
HIV becomes AIDS

53
Q

At what point do you have AIDS?

A

HIV becomes AIDS when there is less that 200 CD4 cells/ml or less than 14% of CD4 cells

54
Q

What are the effects of AIDS?

A

Leaves patient susceptible to secondary infections
Ex: PCP -> pneumonia
KS -> Kaposis sarcoma -> cancer
CMV -> cytomegalovirus -> virus that infects eye
Candida -> fungal infection

Effects CD4 cells -> slowly wears down immune system and makes it harder to combat pathogens

55
Q

What are the 7 stages of HIV infection?

A

Binding:
HIV virus binds to surface of CD4 cells

Fusion:
Virus fuses with CD4 membrane and injects genetic material (RNA)

Reverse transcription:
Enzymes from virus RNA -> DNA

Integration:
Virus DNA inserts into CD4 cells DNA

Replication:
Produces virus particles along with its own proteins

Assembly:
Virus particles combine to create HIV virus

Budding:
HIV virus burst from membrane into blood stream
Infects other CD4 cells
Host cell is destroyed

56
Q

Label a diagram with the 7 stages of HIV infection

A

Good luck girlie pop

57
Q

How is HIV/AIDS treated?

A

Aim of treatment:
Reduce the viral load to undetectable levels
-> too low to detect or damage the immune system

Antiretroviral drugs (ARV)
-> stops virus from replicating and allows immune system to repair itself
-> combination of drugs
-> miss one dose -> failure of treatment
-> side effects: nausea, diarrhea, skin/body reactions, sleep difficulties

biology igcse (11 decks)

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