Science_T3_2022

a solution is

a mixture where a solute is solute is dissolves in a solvent

a solute is, a solvent is :

solute = substance being dissolves
solvent = liquid that does the dissolving

a diluted solution is

a solution with very few solute particles, can dissolve a lot more solute

a concentrated solution is

a solution with lots of solute particles, can dissolve a little more solute

a saturated solution is

a solution with the maximum amount of solute, can't dissolve any more

a hypotonic solution is ...

there is a higher concentration of water outside the cell vs in it, so the cell intakes water and swells

an isotonic solution is...

there is an equal concentration of water both in and out of the cell. the cell doesn't change.

a hypertonic solution is...

there is a high concentration of water in the cell, but a low concentration of water outside the cell. the cell's water is sucked out of it by the outside, it shrinks.

water entering a cell is called

osmosis. photo is an example of a hypotonic solution.

water leaving a cell is called

osmosis. photo is an example of a hypertonic solution

diffusion is

the movement of solute particles (nutrients or waste) moving down its concentration gradient

what is a concentration gradient

the difference in concentration inside and outside of a cell

diffusion works better in which type of organisms:

unicellular organisms

how does diffusion work in multicellular organisms?

it uses organ systems to move nutrients around the body.

why is diffusion inadequate for multicellular organims?

the low surface area to volume ratio. the surface area is where the particles diffuse, so the larger it is, the more particles can be exchanged.
humans are so big, and we have like zero surface area.

define homeostasis

the process of maintaining a stable internal environment via constant adjustments

name some examples of homeostasis in humans

production of insulin after eating certain foods, sweating to regulate heat

how does homeostasis work in humans?

all of the cells, tissues, organs and systems working together. they communicate via the nervous and endocrine systems, which monitor functioning.

flowering plants rely on what kind of response for homeostasis

a coordinated response, involving everything working together

humans rely on what kind of response for homeostasis

an automatic response

why is the endocrine system important for homeostasis?

it secretes HORMONES that regular bodily activities

the respiratory system maintains homeostasis by

a high concentration of carbon dioxide (rather than oxygen) in the blood triggers faster breathing -> lungs exhale frequently -> removes CO2.

the excretory system maintains homeostasis by

low water level in blood -> kidneys retain more water -> they produce more concentrated urine -> less water is lost

the endocrine system maintains homeostasis by

high concentration of sugar in blood -> pancreas (endocrine organ) produces the hormone insulin -> helps cells absorb sugar out of blood

the regulation is done by WHAT KIND of loop?

a negative feedback loop

what is in a negative feedback loop?

stimulus ->
receptor (sense change) ->
signal (command from brain) ->
response (ie skin makes sweat) ->
does the response work? if not, negative feedback again back to receptor etc etc.

how many kinds of receptors are there?

four. thermo (heat - on skin), mechano (pressure/touch/sound - skin and inner ear), photo (light - retina of eye), and chemo (chemicals - tongue/nose).

what does our internal environment consist of?

body temperature, ion concentrations, water content, blood glucose levels

why is it so important for us to maintain homeostasis?

humans are delicate. we need to be in a narrow range of, say, temps to survive.

in the stimulus response model, what is the control center?

stimulus->receptor->control center->effector-> response

the control center is usually the BRAIN

an example of an effector?

stimulus->receptor->control center->effector-> response

a classic one is MUSCLES. they move to a safer place, control blood pressure, or shiver to warm you up.

in a negative feedback loop, ie homeostasis, the body's response acts (AGAINST/FOR) the stimulus

AGAINST

in a positive feedback loop, ie childbirth, the body's response acts (AGAINST/FOR) the stimulus

FOR
the response AMPLIFIES the stimulus, ie childbirth or blood clotting.

positive feedback loop example; childbirth

brain releases oxytocin->
uterus contracts->
baby moves through birth canal->
stretch receptors activate ->
et cetera.

what are the parts of the nervous system

central nervous system, peripheral nervous system, and neurons

the central nervous system is made up of

the brain and the spinal cord

what the the three sections of the brain

the cerebellum (balance and movement), the MEDULLA OBLONGATA (heartbeat, body temp, breathing rate), and cereBRUM (thinking, intelligence, memory, etc.)

what is the peripheral nervous system made up of

the sensory and motor neurons that connect to the central nervous system--including all the nerves and neurons that AREN'T part of the brain or spinal cord.

what are the three main types of neurons (nerve cells)?

sensory neurons, motor neurons, and relay neurons

what do sensory neurons do?

carry information FROM the receptor to the CNS (central nervous system)

what do motor neurons do?

carry information FROM the CNS to the EFFECTOR

what do relay/connector neurons do?

COORDINATE the response within the CNS

what does a neuron do?

carry information from the nervous system as ELECTROCHEMICAL IMPULSES.

what are the six parts of the brain?

thalamus, brain stem, cerebellum, medulla, hypothalamus, cerebrum

what does the cerebrum do?

it controls all our conscious activities. it's the largest part of the brain.

what does the hypothalamus do?

it maintains a constant heart rate, body temperature, and sleep pattern. it also helps the pituitary gland.

what does the medulla do?

it controls automatic functions, i.e. respiration, digestive systems, sleep, and arousal, and it also processes sensory information, i.e. movement and vision. it's located at the bottom of the brain stem.

what does the cerebellum do?

maintains movement, balance, and coordination

what is the brain stem made up of?

it's made up of three parts--the MEDULLA, PONS, AND MIDBRAIN. it's the lower part of the brain.

what does the thalamus do?

process and carry sensory information, i.e. ears, nose, eyes, skin, and it sends these messages to the cortex

what is a stroke?

damage to the brain from interruption of its blood supply

what is a brain tumour?

a cancerous (or non-cancerous) mass or growth of abnormal cells in the brain.

the endocrine system uses hormones to...

regulate growth and regular functioning, and maintain a stable internal environment

the endocrine system is made up of different WHATs that secrete hormones

glands

what are the 9 glands of the endocrine system?

the pituitary gland, hypothalamus, pineal gland, thyroid gland, parathyroid gland, adrenal glands, pancreas, thymus, and the ovary/testis (depending on gender)

how to hormones know where to go to get to their target organ?

they have different three dimensional shapes, which bind to a target organ like a LOCK AND KEY. only the hormone whose EXACT shape matches the receptor can bind to it.

what does the pineal gland do?

it releases the hormone MELATONIN, which controls sleep patterns

what does the pituitary gland do?

it releases hormones to:
1. stimulate OTHER glands to release hormones i.e. thyroid, ovaries, testes.
2. control growth and development
3. regulate balance in childbirth + breast milk

what does the thymus gland do?

release THYMOSIN, which stimulates WHITE BLOOD CELL production to fight infection.

what does the pancreas do?

release INSULIN and GLUCAGON, which regulate blood glucose levels.

what do the ovaries do?

release oestrogen and progesterone. basically girl puberty.

what do the testes do?

release testosterone. basically boy puberty.

what do the adrenal glands do?

they release hormones i.e. ADRENALINE which increase heart rate and blood pressure. also increases amount of muscle energy.

what does the thyroid gland do?

release THYROXINE, which regulates CELL GROWTH and activity.

what do the parathyroid glands do?

release PARATHORMONE, which regulates blood calcium lvl -> BONE DEVELOPMENT

what does the hypothalamus do?

it links with the nervous system. controls REFLEX ACTIONS (breathing, heartbeat).
other hormones that control; body temp, hunger, thirst, sex drive, emotions.
CONTROLS THE PITUITARY GLAND.

what does the uterus do

hold a fetus if a woman is pregnant

what do the ovaries do

produce the female's ova (eggs)

what does the vagina do

leads from the vaginal opening to the uterus

what do the fallopian tubes do

connect the ovaries to the uterus

what is the cervix

a ring of muscle at the opening of the uterus, after the vagina ends

what does the prostate gland do

secrete PROSTATE FLUIS which nourishes sperm and lubricates sperm ducts

what does the testes do

produce sperm

what does the scrotum do

regulate the temperature of sperm by holding it outside the body

what do the sperm ducts do

transport sperm to the urethra

what does the urethra do

carry either semen or urine out of the body

what does the penis do

deliver sperm into the vagina during sexual intercourse

what does IVF stand for

in-vitro fertilisation -- 'in glass' fertilisation

how does the egg stage of IVF go?

the woman has hormone injects to stimulate egg ripening in her ovaries. a hormone (LH) triggers ovulation, and the eggs are harvested with a needle.

how does the rest of IVF go?

the father produces a semen sample. it's then combined with the eggs, and monitored until an embryo develops, which will then be placed in the woman's uterus!

who was the first IVF/test tube baby?

Louise Brown, 1978.

what are some reasons a couple might not be able to have kids?

1. not enough sperm or ova
2. woman might have blockages in reproductive system
3. pregnancy cannot be maintained

organisms that can't be seen with the naked eye are called

microbes

microbes live;

everywhere. on you. on your mum.

are all microbes harmful?

no.

how many kg of your bodyweight do microbes make up?

2kg

what causes infectious disease?

pathogens

is bacteria unicellular or multicellular?

unicellular - but they don't have a nucleus!

are viruses living or non-living?

non-living - though this is controversial. it's made up of genetic material covered with a layer of protein/fact.

what are some examples of non-infectious diseases?

genetic disease, i.e. haemophilia (blood not clotting), nutritional i.e. anorexia, physiological malfunction i.e. diabetes, or environmental, i.e. skin cancer

what is the first line of defense made up of?

barriers to prevent infection - i.e. skin, tears/saliva/mucus, stomach acid, urine, and the cilia (hairs that line airways/nose hair ig)

what can barriers be classified as? hint: 2 categories

physical barriers and chemical barriers

mucus can be found in

the nose, lungs, and intestines

what are some physical barriers in the first line of defense?

skin, cilia, and urine flow

what are some chemical barriers in the first line of defense?

stomach acid, tears, saliva, and mucus

what is the only specific line of defense?

the third line of defense! the first and second are both non-specific.

what are some common parts of the second line of defense?

a fever, inflammation, or phagocytes/pus

a type of white blood cell that destroys pathogens?

phagocyte (dead phagocytes = pus)

increased core temperature that slows or kills pathogens

fever

the second line of defense is only necessary when;

the pathogen has ALREADY entered the body