Biology Module 8 Flashcards
What is homeostasis?
The process of keeping conditions inside the organism relatively stable or constant to maintain a stable environment.
Things we do when cold
Shivering - muscles rub together to generate heat
Metabolism increases - break down more glucose which produces heat from respiration
Things we do when hot
Sweat - vasodilation (blood to surface of skin). Excess body heat is used to convert beads of sweat into vapour to evaporate off our skin.
negative/positive feedback
negative - response is opposite to the stimulus (e.g., if we are cold, we will warm up)
positive - response enhances the stimulus (e.g., oxytocin promotes contractions, contractions release oxytocin)
Why is homeostasis so important?
It is needed for an organism to function properly and efficiently (allows the enzyme’s optimal conditions to be met)
Flow chart of stimulus to response
Stimulus (environmental change)
Receptor (detects the change e.g., thermoreceptors) Messenger (chemical and electrical signals that contain information)
Effector (the gland that releases a hormone or muscle that carries out response)
Response
Types of neurones
Sensory - between receptor and messenger (detects stimulus)
Inter - mostly in brain/spinal cord (transmits information from a sensory to motor)
Motor - takes the impulse to the effector
Set Point
The level or point at which a body variable tends to stabilise (e.g., 37 degrees)
Control Centre
Hypothalamus
Types of Receptors
Thermoroceptor: temperature (skin/hyp)
Chemoroceptor: carbon dioxide, oxygen, pH (nose/taste buds/hyp)
Int/Exteroceptor: inside and outside of body
Osmoreceptor: changes in salt/water (kidney)
Mechanoreceptor: touch, pressure, vibration, sound (skin)
Body Temp High process
body temp rises
thermoreceptors detect change
hypothalamus
muscles and glands
the metabolism will slow down, vasodilate (excess blood flow to skin, heat loss through sweat)
Exposure to light process
increase in light
photoreceptor detects
sensory neuron (optic nerve)
interneuron CNS
motor neuron
iris (effector)
expand closing pupil
Flow of types of neurons
The nervous pathway consists of a sensory neuron (nerve cell) that sends the message to the interneurons on the central nervous system (CNS). Then travels to the motor neuron that transfers the message to the effector.
Goose bumps
Piloerection - done when cold
Constriction of the piloerection muscles around hair follicles (increases the insulating effects of hair)
Minimal effects in humans but in animals with thick fur, the layer of trapped air increases significantly
Metabolic changes
Regulated by pituitary and thyroid - impacts rate of metabolic reactions in mitochondria (releases heat)
Behavioural Responses to temp
seeking shade (e.g., kangaroo to get out of sunlight)
lick forearms (e.g., kangaroo applys saliva to skin to increase evaporation)
pant (e.g., dog, hot water from mouth is evaporated)
Structural Responses to temp
seasonal coats (thin coat in summer, thick coat in winter)
blubber (layer of fat, retains heat)
Physiological Responses to temp
thirst (indicator the animal is dehydrated, hormones released to make them thirsty)
metabolism (can be slowed or increased)
glucose/glycogen/glucagon
glucose - simple sugar
glycogen - glucose stored in the liver (glucose stuck together)
glucagon - hormone that releases glucose from glycogen
High blood glucose process
high blood glucose
pancreas
beta cells release insulin
peripheral tissue cells take glucose from the blood
normal blood glucose
Low blood glucose process
low blood glucose
pancrease
alpha cells release glucagon
glucose broken down in liver and released to blood
normal blood glucose
endotherms/ectotherms
endotherms - organism that maintains it owns body temp by generating heat metabolic processes (warm blooded) e.g., a dog, humans
ectotherms - organisms that regulate their body temp based on the external environment (cold blooded) e.g., lizards, snakes
What are neurons?
Neurons are nerve cells that transmit signals by electrochemical charges in their membrane.
Functional unit of the nervous system.
Structure of a neuron
Axon: Long section (usually only one of them, branch at the end leading to synaptic terminals, release neurotransmitters into the gap between the neurons)
Myelin Sheath: Fatty insulating material (keeps the electrical signal in the neuron so it is transmitted full length)
Dendrites: Small branch-like projections (connects to other cells, increases surfaces area and allows for the collection of incoming impulses)
The impulse goes from the dendrite, along the axon and to the end.
Synapse
Gap inbetween two neurons
For an impulse to cross the synapse, neurotransmitters are released by the axon terminals
Along the neuron (signal is electrical)
At the synapse (signal is chemical)
What are neurotransmitters?
Signalling molecules
e.g., serotonin (increases mood, sleep) and dopamine (reward-motivated behaviour)
Importance of synapse
Pass impulses in one direction only, passing between neurons, acts as junctions
Depressants/Stimulants
Affect the transmission of nerve impulses along the synapse
What are nerves
Bundles of nerve fibres outside the brain. Fibres are surrounded by myelin (to insulate)
What is an action potential?
Rapid and short-change in the membrane potential of an excitable cell.
Movement of information down a neuron.
The threshold is a particular value of the membrane voltage that needs to be reached for an action potential to be started.
Flow Chart of Action Potential
- Stimulus (e.g., light)
- Sensory receptor
- If ABOVE THRESHOLD, Na (sodium) channels open > (depolarisation)
- Wave of excitation spreads along neuron
- As the impulse arrives at a section of the neuron, causes more Na channels to open up
- Rapid influx of Na into the axon
- Further increases the permeability of the membrane to Na
- Inside is positive relative to outside (DEPOLARISED)
- Na channels shut and K (potassium) ions also move out
- Membrane is repolarised (hyperpolarised first)
- K channels shut, restores resting membrane potential
- Refractory period (drops down on graph)
- Ready to go again
Graph explanation
Voltage on Y, Time on X
Start of spike (Na channels open, Na enters)
Just before peak (K channels open, K begins to leave)
Peak (Na channels close)
Just after peak (K channels close)
Endocrine System
Body system composed of different endocrine glands that secrete hormones directly into the blood stream.
A NETWORK OF GLANDS THAT SECRETE HORMONES FOR REGULATION
Hypothalamus
Considered the link between the nervous system and the endocrine system.
Receives information from almost all parts of the nervous system.
Hormones
Diverse group of cell signalling molecules
Types of Hormones
Prolactin - anterior pituitary gland, targets breast cell glands for milk production
Adrenalin - medulla in the adrenal gland, targets the liver and heart to prepare body for fight or flight
ADH/anti-diuretic - pituitary gland, targets tubular cells in kidney to release less water, decreasing the amount of urine production
How does ADH work?
If you are dehydrated:
You need to wee less so more water is retained
Increase in ADH
Increase in water retention
Decrease urine
Drink too much:
Decrease ADH
Therefore diuresis occurs
Urine output increases
What hormones are involved in the regulation of water and salt levels?
ADH, aldosterone
What do plants need to regulate?
Maintain water balance, remove metabolic waste, internal concentrations of major nutrients
Hydrophytes
Live in fresh water, lots of water available.
Due to the water gradient (low in plant, high outside), water tries to move into the plant.
- lots of stomata
- large surface area
stops tissues from flooding
Xerophytes (e.g., spinifex)
Live in dry climates > not much water
- focus on conserving water
- small number of stomata/stomata hairs/depressions stomata sit in
- builds a microclimate around stomata (reduces air flow and water loss via transpiration)
Aussie Plant Adaptation
Eucalyptus - reduce water loss
- leaves stand vertically to decrease SA (avoids radiation)
- thick waxy cuticle to prevent evaporation and reflect heat
Genetic Disease
gene or chromosome abnormalities caused by point or chromosomal mutations
e.g., Trisomy 21
chromosomal abnormality - chromosomes don’t seperate properly during gamete formation.
Causes a partial or full extra chromosome on the 21st chromosome pair.
- large forehead
- wide set eyes
- short/flat bridge nose
- mental impairment
- life expectancy 60
e.g., Cystic Fibrosis
single gene disorder - caused by faulty gene that affects the movement of salts and water in and out of cells.
Severe damage to lungs, digestive system and other organs.
Environmental Disease
Interaction with environment, exposure to physical factors such as radiation.
Radiation (damages the DNA) e.g., skin cancer - melonoma
e.g., Minamata
Ingestion of large amounts of mercury - neurological disease
Nutritional Disease
Issues with diet, digestion problems, consumption of incorrect amounts of specific foods
E.g., scurvy (imbalance in nutrients)
E.g., Type 2 Diabetes (excessive)
Cancer
Abnormal cells divide uncontrollably.
Cause by:
- genetic disorders e.g., Breast Cancer (inheritance of BRAC1 gene)
- exposure to mutagenic factors e.g., melonoma (radiation)
- lifestyle habits e.g., lung cancer (smoking)
What is epidemiology?
The study and analysis of patterns, causes and effects of health and disease conditions in defined populations.
Epidemic Terms
Epidemic: Presence of disease on a large scale with many people infected. Can be -
- pandemic (spread to many countries in the world)
- endemic (always present in particular regions)
- sporadic (occurring in different places at different times)
3 Types of Epidemiological Studies
- Descriptive (frequency, part effected, location, time)
- Analytical (focus on finding a cause, control groups, factors before disease, factors that affect risk)
- Experimental (test the effectiveness of treatments)
Example of Epidemiology
Doll and Hill first began studying lung cancer
- thought it was car materials or new material tarmac
- then discovered tobacco smoking was the only significant common factor
Educational Programs and Campaigns
Paid Advertising
- television, radio, internet based advertising
- slip, slop, slap (believes its played a key role)
School-Based Health Education
- NSW PDHPE curriculum (e.g., drug use)
Screening Programs
- not an educational program but is used in conjunction with them
- Aus Gov every 2 years sends free bowel cancer screening kit (50-74 year olds)
Policy Changes
- packaging laws
Genetic Engineering
Gene Therapy
- the correction of genetic disorders by introducing a normal, functioning gene into cells
- can be used to treat Parkinson’s disease
CRISPR
- point mutations may be accurately introduced into genomes
- may be used to improve gene therapies
- alters the genome of all affected cells
Embryo Screening or Editing
- Allows selection of embryos only without genetic defects for implantation
Pinna
Outer part of eat (collects sound waves)
Ear Canal
Auditory Canal (vibrations travel along here until they reach the eardrum)
Tympanic Membrane (eardrum)
Vibrates at the same frequency as the incoming wave. Sound waves are changed into vibrations.
Ear Ossicles
Malleus (hammer) - attached to the tympanic membrane and vibrates at the same frequency as the vibrating tympanic membrane
Vibrations then pass through to the incus (avil) and stapes (stirrup). These tiny bones act as levers to magnify the vibrations.
Stapes connects to the oval window, and when pushed against it, vibrations are transmitted to the fluid in the inner ear.
Eustachian Tube
Narrow tube that connects the middle ear to the back of the nose and throat.
During swallowing it opens up, so that the pressure on either side of the Tympanic Membrane is the same.
Round Window
The lower one of the two.
Covered by a thin membrane.
One of the two openings in the middle ear at the level of the cochlear, allowing communication between middle and inner ear.
Oval Window
The upper one of the two.
Seperates the middle ear space from the inner ear.
Gets pushed in and causes the fluid to move.
Cochlea
Appearance of a snail shell.
Long tube wound around itself filled with liquid.
Fluid in the cochlea transfers the vibrations to the hairs in the organ Corti.
Semicircular Canals
Required for balance not sound.
Situated inside the cochlea. Contains millions of receptor hair cells connected to nerves. Hairs are turned to certain wave frequencies.
When waves pass over the hairs, an electrical signal is triggered.
Auditory Nerve
A bundle of nerve fibres bound together.
Sends the electrical signals to the brain to be interpreted.
Action Potenial in Ear
If the cell gets vibrated enough, the membrane will get moved. It will cause the channels to open up and sodium to go through, starting an action potential.
Not big enough vibration > failed action potential
Flow in Ear
Sound enters at the pinna as energy in the form of sound waves
When the sound waves reach the tympanic membrane, the energy is changed into vibrations.
The energy is then transferred and amplified by the ossicles.
At the oval window, the energy is transferred into vibrations in a fluid in the cochlea.
The energy is transduced into electrochemical energy by the hair cells.
Hearing Aid
Amplifies the sound (magnifies the vibrations), to better enable transmission to middle and inner ear.
The microphone gathers sound and converts it to electrical signal.
The amplifier increases the amplitude of the signal received by the microphone.
Used for damage to middle or outer ear (e.g., ruptured ear drum) and simply makes the sound louder.
Used for mild SNHL.
Limits: Also amplifies background noise so doesn’t work well in crowded spaces.
Can be painful.
Sound levels need to be adjusted.
Cochlear Implant
Designed to replace the loss or damage of the receptor hair cells along the basal membrane in the cochlea.
Uses an external speech processor and transmitter coil.
A receiver is attached to an electrode array implanted in the cochlea. The microphone of the speech processor detects sound, which is converted into a digital signal that is sent to the transmitter, then to the receiver. These implants bypass the malformed or damaged outer and middle ear, and transfer the vibrations directly to the inner ear (to hearing nerve).
Individuals who are profoundly deaf or have damaged/missing hair cells in the Corti. Used for profound SNHL and CHL
Bone Conduction Implant
Has a microphone that detects the sound and transforms it into vibrations, which are then passed via the implant to the bone above the ear.
The vibrations are detected through the bone to the cochlea, where they are processed as normal. These implants bypass the malformed or damaged outer and middle ear and transfer the vibrations directly to the inner ear.
Used for people with conductive hearing loss who can’t use other technologies because of medical conditions.
Works best with hearing loss associated with external or middle ear, or with profound hearing loss in one ear.
Types of Hearing Loss
Conductive Hearing Loss
- damaged or a blockage
- sound is not conducted properly through the eardrum to the canal, or from eardrum to middle ear.
- caused by earwax, perforated eardrum, build up of fluid, abnormal bone growth
- treated by medical interventions and technologies
Sensorineural Hearing Loss
- occurs when theres damage or malfunction of the hair cells in the cochlea
- most common in Aus
- treated by assertive technologies
Mixed Hearing Loss
- when both CHS and SNHL are present
- the SNHL may only be temporary
Auditory Neuropathy
- when there is a problem with the auditory nerve transmitting a signal from the cochlea to the brain
- can be very slight or full
- caused by lack of oxygen, jaundice at birth, neurological conditions
- treated by assertive technologies
Conjunctiva
FRONT MEMBRANE
(transparent membrane that covers the sclera)
Lubricates and nourishes eye.
Cornea
JUST BEHIND CONJUNCTIVA
(very sensitive transparent dome-shaped casement that covers the eye)
Reflects light and allows it to be focused on the retina.
Sclera
WHITE OF THE EYE
(tough outercoating of the eye)
Protects inner parts of the eye and keeps its shape.
Choroid
Layer of blood vessels in between retina and sclera.
Provides nutrients to back of eye.
Pupil
Opening made by the iris.
Allows light to pass through to the retina.
Retina
BACK OF EYE
(small lining made up of nerve cells - rods/cones)
Converts light stimuli into an electrochemical message that is sent to brain.
Iris
COLOURED PART
(opens and closes depending on how much light enters)
Controlled by the iris sphincter muscles that relax and contract depending on light intensity
Lens
BEHIND IRIS
(transparent disc)
Helps focus light on the retina. Shape is changed by ciliary muscles.
Aqueous Humour
FRONT SECTION OF EYE
Transparent fluid with a water consistency that is found between the cornea and the lens.
Keeps shape of eye, provides nourishment.
Vitreous Humour
BIG MIDDLE SECTION
Transparent fluid with jelly like consistency found between the lens and retina.
Provides support for back of eye, prevents infections.
Ciliary Body
Produces the aqueous humour, also contains ciliary muscles.
Optic Nerve
Group of nerve fibres that travel from the retina to the brain. Transmits electrical message.
Rods/Cones
They are photoreceptors (detect light and convert to electrochemical signals for the brain)
Cones - colour, detail. Requires more light than rods to be stimulated. Highly defined due to one cell for one ganglion cell.
Rods - black and white, very sensitive. Functions best in dim light, good for night vision. Many cells for one ganglion cell.
Why do we have a blindspot?
In the retina, the light passes through to the rods and cones at the back. Then once action potential has been stimulated, it goes back through the opposite way and along the optic nerve.
The blindspot is due to the optic nerve space, as theres no rods or cones there.
Fovea
Depression in back of retina.
Cones are at highest density here (no rods).
Rhodopsin
Transmembrane protein that is primary visual pigment of a rod
Visual Cortex
Where the brain interprets the image. Brain inverts image from retina.
Short-sighted
MYOPIA
- image falls too short of the retina
- can see close up but not far away
- fixed via a concave lens (diverge the light)
Long-sighted
HYPEROPIA
- image falls behind the retina
- we want the light to ben earlier therefore fixed via a convex lens (converge the light)
Ciliary Muscles
When focusing really hard, the ciliary muscles squeeze and push inwards (makes ligaments floppy)
- lens bulges out
When the muscles relax, they go outwards and pull tight.
- lens pulls back
Other eye disorders
- bulging cornea
- inflexible lens
Technologies to correct short/long sighted
Lasik: Performed with a laser programmed to remove a defined amount of tissue from the cornea.
- changes the shape of the cornea
Contact Lenses: Similar to glasses but sit directly on your eye
Cataracts
The clouding or opacification of the natural lens of the eye.
Cause of 50% blindness in developing countries.
Can be removed for a simple and cheap operation.
surgery - involves removing the cloudy lens tissue and replacing the natural lens with an implant called an intraocular lens (IOL). It is calculated for each person.
Kidney Role
Main role is to remove urea (nitrogenous waste) from the blood.
Kidney is responsible for osmoregulation.
Nephrons
Filtering units (millions in the kidney) and they are the functional units of the kidney.
STAGE 1 Kidney
Filtration
- blood moves into ball of capillaries (glomerulus)
- as the blood moves in, the vessels get smaller which increases pressure
- the waste gets squeezed out into the Bowman’s Capsule (e.g., glucose, ions, amino acids)
big things like red blood cells and proteins are too big to move into it
STAGE 2 Kidney
Reabsorption
- reabsorb the glucose back into the blood stream
- done in the proximal convoluted tubule
- being pushed along the gradient therefore lots of active transport (lots of ATP energy is used)
- a lot of water and salts also get reabsorbed
STAGE 3 Kidney
Secretion
- nephron removes substances and adds them to the filtrate
- the product of this is urine
Collecting Duct
Many nephrons empty urine into the collecting duct.
The collecting ducts join together at the kidney pelvis, which connects to the ureter.
- The urine then moves to the bladder.
- When the urinary sphincter muscle relaxes, urine passes into the urethra and out of the body
Hormones in Kidney
ADH - shuts down the flow of water outside the body.
released from pituitary gland.
Aldosterone - regulates blood volume and pressure
If there is more liquid in our blood vessels, the pressure is increased due to the fixed capacity of space. If I reabsorbed more sodium into the blood (becomes salty), it draws water to the blood vessels and causes higher pressure.
Causes of kidney failure
- diabetes 1 and 2 (increased glucose impacts the nephron)
- hypertension (high BP) (damages capillaries, allows larger molecules to leak out)
- recurrent kidney infections
- drugs and medications
- kidney stones
Blood Pressure Negative Feedback
As blood pressure goes down, we release ADH.
ADH opens up the distal tube which makes it more permeable to water.
(water is reabsorbed into blood vessels due to osmotic gradient - which will then increase the concentration of urine and retain water)
This slightly increases blood pressure.
Hemodialysis
Blood is pumped out of your body into an artificial kidney machine (dialyser) and returned to your body via tubes connected to the machine.
It is used for kidney failure - removes waste from blood and maintains solute concentration.
- Blood is pumped out full of nitrogenous waste
- The blood moves downwards through the dialyser and the dialyzing fluid moves upwards
- At every point there is an effective concentration gradient where urea moves towards the dialysing solution
- By the time blood is pumped back, barely any urea is left.
Done for 4 hours, 3 times a week, usually in hospital.
Peritoneal Dialysis
Using your body as a membrane - dialyses solution inside lining of belly which acts as a natural filter.
The urea moves into the peritoneum (membrane).
Usually done at home and is portable.
Either 4 exchanges each day for 30 mins, or at night for 7-8 hours.
Kidney Transplants
Surgical procedure to place a healthy kidney from living/deceased donor into a person whose kidney no longer functions properly.
Best treatment option, but takes a long time.
Why do some kidney transplants get rejected?
Antibodies and natural killer cells attack the kidney as the antigens on the kidney are recognised as non-self. This can leave you open to infection.
Therefore, we take anti-rejection drugs to lower the immune system so it doesnt attack the kidney.
Biological knowledge for kidney treatment
Dialysis - how nephrons work, filtration, osmosis/diffusion, concentration gradient (high to low), we want the urea to do this
Transplants - immune system, how it would attack non-self via antibodies, develop anti-rejection drugs
