HSC biology module 8

homeostasis

the process of maintaining a constant internal environment by detecting change in stimulus, responding, and using negative feedback loops.

negative feedback

movement away from an ideal state triggers a mechanism to counteract further change and returns the state to normal a change in a variable triggers mechanisms that reverse that change

nervous system

fast-acting network of nerve cells that transmit impulses between parts of the body and brain in response to internal and external changes

stimulus

a change in the environment (either external or internal) that is detected by a receptor

response

a change in the organism resulting from the detection of a stimulus

receptor

a sensor that responds to a change in the environment

thermoregulation

maintaining the temperature of the body at a near constant level

Effector

any part of the body that produces a response to a stimulus. Eg. a muscle contracting to move the arm. a muscle squeezing saliva from the salivary gland. a gland releasing a hormone into the blood.

Neuron

a specialized cell transmitting nerve impulses; a nerve cell.

Endotherms

are organisms uses internal mechanisms to maintain their core body temperature within a narrow range, despite fluctuations in external environment.
These animals have internal mechanisms allow the generation or production of internal heat energy to regulate their core body temperature. Hence, the term 'warm-blooded' animals.

Ectotherms

are organisms that do not have internal mechanisms
These animals DO NOT have internal mechanisms to generate heat and so they must relate on heat from the external environment to regulate their core body temperature. Hence, the term 'cold-blooded' animals.

Structural Adaptations

a physical feature of an organism's body having a specific function that contributes to the survival of the organism

Mountain Pygmy Possum Structural Adaptations

It has short legs,
- round body
- small ears to minimise heat loss.
This is because it will minimise the surface area in which the blood in blood vessel under the skin is exposed to the cold temperature of the environment which will result in heat being carried away convection

Red Kangaroo Structural Adaptations

They have a lot of blood vessels under their forearm and paws. This encourages heat loss via convection to keep their core body temperature within a narrow range, despite the hot ambient surroundings.

Physiological Adaptations

changes in an organism's metabolic processes

Mountain Pygmy Possum Physiological Adaptations

During long winters, the possum can enter a state of torpor whereby rate of metabolic activities and core body temperature are reduced to conserve energy. When it is in this state, it is able to tolerate surrounding temperatures of 2 degrees celsius.
- It can also curl into a ball to minimise the surface contact in which it is exposed to the its surroundings in cold conditions.

Red Kangaroo Physiological Adaptations

The muscle glands can also be activated via thermoregulation in kangaroos to generate heat energy in response to cold temperature stimulus detected by thermo receptors on skin and in hypothalamus.
- Panting is performed by Kangaroo whereby heat energy is loss through ventilation. The process of panting allows water on the tongue and mouth surface to be evaporated as the blood under these surfaces are able to be transferred to the cooler water via conduction.

Behavioural Adaptations

The ways that behaviour is modified for survival

Mountain Pygmy Possum Behavioural Adaptations

- The possums are nocturnal. That is, they sleep during the day and are active during the night to escape the high temperatures of the body to avoid overheating.
- During the day, they can seek shade in holes within rocks or gaps under rocks.

Red Kangaroo Behavioural Adaptations

- Similar to the mountain pygmy possum, the red kangaroos are also nocturnal.
- They also seek shade to avoid overheating during the day.

Internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways

- Nervous system - neural
- endocrine systems - hormonal

nervous system in maintaining homeostasis

Hypothalamus is the control centre for regulating many internal activities
- Directs effectors to carry out responses through sending messages via neural path ways or chemical messages.
- Conditions that need to be regulated are body temps
- Hypothalamus is the link between ns and endocrine system

Hypothalamus is responsible for

hormone secretions and which helps regulate the internal factors

endocrine system - chemical

Main component are hormones which are chemical messenger secreted by endocrine glands
- Hormones are transported through the blood stream with possess the receptor cells for that specific hormone.
- Hormones help to change activity in cells to maintain homeostasis

Hormones role in internal coordination to achaieve homeostasis

Aldosterone

Aldosterone

Hormone that stimulates the kidney to retain sodium ions and water

How aldosterone works

-Produced and secreted by the adrenal glands
- receptors receive a drop in blood pressure a message will be sent to secrete the enzyme renin
- renin will then catalyse a reaction to cause the adrenal lands to secrete aldosterone

Nervous system pathway

1. stimulas (heat)
2. receptor converts info into electrical signal
3. transmitted frim receptor to sensory
4. CNS coordinates and sends response
5. passes along motor neurons to relevant effector (muscle) to bring response.

Synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

Mechanisms to maintain water balance in plants

1. reduce internal temperature
2. reduce the exposure of transporting place structure to sunlight
3. Regulating the opening and closing of the stomata
4. water storage

Reducing internal temperature - plants

- leaves covered in waxy material ensures epidermal cells are waterproof, preventing loss of water
- white hairs reflect sunlight which will also reduce the temperature o the surface leaf

reduce the exposure of transporting place structure to sunlight

- Orientation of leaves so that stomata is not exposed to direct sunlight
-Reduction of leaf size
Reduced flower or no petals can reduce the amount of water needed and reduce evaporation

Regulating the opening and closing of the stomata

- Minimise water loss through stomata opening during cooler parts of the day e.g. morning.

Water storage

some succulents have adaptions such as fleshy stems or leaves that swell up and retain moisture.

action potential

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

resting potential/ depolarization

- Maintained by active transport
- resting at 70mv
- there is more sodium ions on the outside of the cells, there is more potassium ions inside the cell

resting potential/ depolarization activation

activated by a stimulas make membrane potential more positive.
- sodium volted gates open and sodium ions diffuse across causing depolarization
- Potassium channels open but slower causing depolarization to occur more.

action potential/ repolization

This is restoration of electrical potenial across a plasma membrane.
- approaches max depolarization the volted sodium gates close
- potassium channels are open and continue to diffuse
- increase in . potassium last longer then required.
- Potential become lower than resting value
- after potassium gates close sodium and potassium re-establish resting potential

- genetic diseases

Sickle Cell Anemia
Hypercholesterolemia
Tay-Sachs Disease
Cystic Fibrosis
Hemophilia A
Huntington's Disease

diseases caused by environmental exposure

Melanoma of the skin

environmental exposure cause

Caused by prolonged exposure to UV rays as they penetrate the epidermis of the skin

environmental exposure effect

Causes freckle like spots on skin however they are cancer

Environmental exposure incidence

in 2017 13941 cases and has been increasing

Environmental exposure mortality

Mortality rate will increase with age
increase number of deaths over 1800 in 2017, 1968 has 300

nutritional diseases

Scurvy

nutritional diseases symptoms

- Sore or bleeding gums
- Fragile capillaries
Bruising
- Poor wound healing
- Failure of bone to grow or heal properly

nutritional diseases host response

- Vitamin C is essential for healthy growth and development and crucial in various aspects of the immune system, particularly immune cell function
- Vitamin C ensures that the body is able to aid in wound healing, scar formation, repairing cartilage, bone, and teeth, and the ability to absorb iron

nutritional diseases treatment

If insufficient vitamin C is consumed in the daily daily, vitamin C tablets can be used as substitute.

nutritional diseases incidence/ prevalence

prevalent in developing countries where access to vitamin C rich foods is not always accessible, as well as areas struggling with malnutrition. There have been outbreaks of scurvy in refugee camps, with Globalisation, Migration and Health: Challenges and Opportunities (2016) reporting a prevalence of 5 to 45%.

nutritional diseases mortality

The mortality rate of scurvy has since decreased and is considered to be an easily treatable disease. Within 24 hours, patients can expect to see improvement in fatigue, lethargy and pain. Bruising, bleeding and weakness start to resolve within 1 to 2 weeks. Long-term effects are not always likely, except in the case of severe dental damage.

cancer

Lung cancer is the uncontrolled growth of abnormal cells in one or both lungs, usually in the cells lining air passages.

cancer cause

Smoking
Passive smoking (secondhand smoke)
Familial predisposition
Exposure to asbestos fibers
Exposure to radon gas
Exposure to diesel exhaust

cancer host response

ow antigenicity and heterogeneous phenotype lung cancer evades host immune defense. The cytotoxic anticancer effect is suppressed by a complex mechanism in tumor microenvironment. The population of regulatory T cells (Tregs) plays a crucial role in this inhibition of immune response.

Cancer treatment

Surgery
Chemotherapy
Radiation
Or a combination of these

Cancer Incidence

- higher incidence in men rather than women
- As awareness was created incidence has begun to decrease

Cancer mortality

30 deaths per 100,000 persons with lung cancer

cancer Prevalence

13,092 diagnosed, 9,173 deaths

What is epidemiology?

study of the cause, distribution and frequency of a disease in specific population in order to establish measures to prevent the disease

Types if epidemiology

1. Descriptive
2. Analytical
3. Intervention

Descriptive epidemiology

The aspect of epidemiology concerned with organizing and summarizing health-related data according to time, place, and person

analytic epidemiology

a form of epidemiology that investigates causes and associations between factors or events and health.
- Morbidity and mortality
- Starts to develop a hypothesis

experimental epidemiology

begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people
- used to test the effectiveness of a new drug

prevention of a non-infectious disease

educational programs and campaigns
genetic engineering

Function of the kidney

1. removal of urea which is the break down amino acids into ammonia
2. Osmoregulation - the control of water balance

What is the kidney

It is the bodies filtration system. Blood is filtered out at the glomerulus, collected by the bowmans casual and then reabsorbed into the capillaries in the loop of henele. Waste products are not reabsorbed.

Ultrafiltration

a high pressure filtration through a semi-permeable membrane in which colloidal particles are retained, while the small sized solutes and the solvent are forced to move across the membrane by hydrostatic pressure forces.

Selective reabsorption

The absorption of certain selected molecules back into the blood from the fluid in the nephron tubule. This is typically glucose and amino acids.

Loop of Henle

the part of a kidney tubule that forms a long loop in the medulla of the kidney, from which water and salts are resorbed into the blood.

There is an descending loop which is permeable to water and a descending loop which ic permeable to na+

If you are controlling your water balance you are

controlling your blood pressure which means you are controlling your blood volume and maintaining homeostasis

Osmoregulation

regulation of solute concentrations and water balance by a cell or organism using ADH.

Kidney disease - causes

- Obesity
- Kindey stone + tumor
-

dialysis (hemodialysis)

an artificial method of filtration to remove excess waste materials and water from the body/an artificial method of filtration to remove excess waste materials and water directly from the blood

Steps of hemodialysis

1. a fistula needs to be created, this connects an artery to a vein in the arm.

2. Blood from the vein in pumped through a semipermeable membrane that allows wast molecules to pass through

3. The tube passes through dialysis fluid which creates a concentration gradient

4. filtered blood is returned to the body through he artery.

hearing loss

decreased ability to perceive sounds compared to what the individual or examiner would regard as normal

Sensorineural Causes of hearing loss

Caused by damage to the delicate structures of the inner ear and/or its associated nerves

. It can be caused by:

• exposure to loud noise.
• age.
• damage to the haie cells in the organ int he corti.

Conductive hearing loss

Caused by mechanical disruption to the middle ear.
It can be caused by:
• middle-ear infection.
• perforated eardrum.
• damage to the middle ear bones.
• a benign growth in the middle ear.

Technology to assist with hearing loss:

Cochlear implants
Bone conduction implants
Hearing aids

What is a cochlear implant?

Cochlear implants compensate for damaged or non-working parts of the inner ear.
Enable people to detect very soft speech and environmental soundsCochlear implants are electronic devices that are used to give hearing to those who are profoundly deaf. There are two parts. The outer part contains a microphone, while the inner part (the implant) includes an electrode that feeds into the cochlea and directly stimulates the hearing nerves.

how to cochlea implants work

Microphone in the ear picks up the sound and sends them to a microprocessor which converts them into electrical signals. These are sent to a transmitter, then a receiver implanted beneath the skin of the skill. Signals are send to the cocchlea where they stimulate auditory nerve endings

Bone conduction implants

Bone conduction implants are used to improve hearing for those who have conductive hearing loss. They transmit vibrations through bone to the inner ear, bypassing the defective outer and middle ear.

how do bone conduction implants work

The processer picks up sound signals and turns them into vibrations that are sent through the bone to the implant which in turn directly vibrates the hone and the vibrations in the inner ear.

hearing aids

Traditional hearing aids come in many different shapes and sizes and are fitted to a patient by an audiologist depending on the type and severity of the patient's hearing loss. Typically, hearing aids help a person to hear by making sounds louder as they enter the outer ear.

How do hearing aids work

Using a microphone to convert sound energy to electrical energy, an amplifier amplifies electrical energy, earphone converts amplified electrical energy back into sound energy of greater intensity.

Functions of the eye

1. receives light stimuli
2. turns stimuli into nerve impulses
3. optic nerves transmits nerve impulses to the brain
4. brain decodes and interprets nerve impulses into images

Short sightedness

Short sightedness (myopia) is caused when light is focussed at a point that falls short of the retina.

long sightedness

Long sightedness (hyperopia) is caused when light is focussed at a point beyond the retina. These vision problems can result from a defect in either the lens or the shape of the eye, or both.

Astigmatism

An astigmatism is a common eye disorder that results from a cornea which is not spherical. As a result, light is not focussed on the retina the same all planes

Cataracts

A cataract is a defect in the eye, characterised by opacity (or translucency) of the lens

Glaucoma

Glaucoma is a common eye disease caused by a build up of pressure in the eye, which damages the optic nerve and the blood vessels that carry blood to the retina. In turn this is usually caused by a blockage in the drainage channel that drains fluid from the aqueous humour.

Detached retina

A detached retina occurs when the retina begins to separate from the sclera which contains the blood vessels that provide necessary oxygen and nutrients. The first sign of retinal detachment is often 'floaters', sudden flashes of light or shadows in the field of vision

Macular degeneration

Macular degeneration is an eye disease in which the retina begins to degrade, which results in a loss of sharpness in vision.

Technology to assist with eye sight

Spectacles
contact lenses
Laser eye surgery

Corrective lenses Spectacles and contact lenses

correct the vision of people with hyperopia, myopia and/or astigmatism, by refracting the light entering the eye in a way that is complementary to the defect in the eye

laser vision correction

In laser vision correction, a small circular flap is created in the cornea using a precise metal blade or a laser that creates series of tiny closely positioned bubbles in the cornea. The flap is then folded back to reveal a layer of the cornea called the stroma. A laser is then used to vaporise material in the corneal stroma, in order to reshape the cornea, to correct for the refractive error in the eye. Finally the flap is replaced and the eye allowed to heal.

incidence rate

number of people contracting a disease during a time period

prevelance rate

the total number of cases suffering from a disorder

mortality rate

the number of deaths per thousand