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Biology Igcse > B9-B10 (human Reproduction + Nervous System) > Flashcards

B9-B10 (human Reproduction + Nervous System) Flashcards

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
Explain what happens to the body when it is: A) too warm B) too cold And why
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
Look at a diagram and label + explain the functions of all the parts of the skin
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
Why is too much/little glucose bad for the cells in the body?
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
How is glucose regulated?
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
Hyper/hypoglycemia: what is it, causes, and treatment
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
What is diabetes?
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
How do type 1 and type 2 diabetes lead to high blood sugar? What are the symptoms of both types ?
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
Compare asexual and sexual reproduction
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
What are the advantages and disadvantages of asexual and sexual reproduction
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
Explain haploids and diploids (and examples)
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
Label a diagram of the female reproductive system and explain the function of each part
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
Label a diagram of the male reproductive system and explain the function of each part
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
What is puberty?
When boys and girls become sexually mature Controlled by hormones Sex cells produced and released Several years to complete
38
What is the menstrual cycle?
Female body prepares for the pregnancy Makes sure uterus is in perfect conditions for implantation (28 days long)
39
Explain what happens during the menstrual cycle (including days)
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
What are the hormones related to the menstrual cycle (the 2 we learned about)
Oestrogen and progesterone
41
Explain the functions of oestrogen and progesterone
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
Describe the journey of the sperm
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
Describe how fertilisation occurs
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
What is the placenta?
Provides nutrients, oxygen, removes waste Connected to umbilical cord Secretes hormones -> maintain pregnancy Developed by embryo
45
What is the function of an amniotic sac?
Encloses the embryo and secretes amniotic fluid Protect the embryo from sudden movements
46
What is HIV?
Human immunodeficiency virus Affects CD4 (T-lymphocytes) in immune system -> virus replicates and destroys the cells
47
What are CD4 cells?
Lymphocytes (white blood cells) that protect against pathogens
48
What does it mean to be HIV positive?
Body creates antibodies to combat the virus If detected in body -> HIV positive
49
How is HIV transmitted?
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
How can HIV be prevented?
Condoms Not sharing drug injection equipment Protect cut, sores, eyes mouth from blood Antiretroviral drug during pregnancy No breastfeeding
51
What are common myths of HIV?
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
What is AIDS?
Acquired immunodeficiency syndrome (syndrome: group of health disorders that make up a disease) HIV becomes AIDS
53
At what point do you have AIDS?
HIV becomes AIDS when there is less that 200 CD4 cells/ml or less than 14% of CD4 cells
54
What are the effects of AIDS?
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
What are the 7 stages of HIV infection?
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
Label a diagram with the 7 stages of HIV infection
Good luck girlie pop
57
How is HIV/AIDS treated?
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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