Module 8: Non-Infectious Diseases Flashcards
What is homeostasis?
The process by which an organism maintains a stable internal environment, despite fluctuating external environmental conditions.
Why is homeostasis important?
-By maintaining constant conditions (temp, pH, levels of water) in the body our enzymes are ableto carry out their functions efficiently.
-Cells survive best in an isotonic solution: needs to be maintained so that cells don’t shrink of expand
-Enzymes are very important catalysts which require specific conditions to function at their best.
What is the internal environment?
The internal environment (of a cell) is the fluid surrounding a cell within a multicellular organism. It is internal to the organism, but the environment of the cell. Depending on where the type of cell, the internal environment could be blood plasma, tissue fluid or cerebrospinal fluid.
How is the general internal equilibrium maintained?
Adjusting physiological processes including body temperature, CO2 concentration, blood pH, blood glucose levels and water balance.
What is a negative feedback loop? (General detecting and counteracting of change)
Detecting change: receptors (sensory cells) within the body detect a change in a particular component of the internal environment (e.g. temperature, blood pH). This change is called a stimulus.
Counteracting the change: a response occurs that will reverse (or counteract) the change, which is brought about by the effector organs and will restore the body to its constant internal state.
Temperature and thermoregulation (increase in body temp)
→ increase in body temp, messages are sent to the front of the hypothalamus (the heat-loss control centre) which initiates the process to cool the body
→ vasodilation – blood vessels dilating, heat radiates from skin surface
→ activation of sweat glands to secrete sweat, removing heat from the body when it evaporates
Temperature and thermoregulation (decrease in body temp)
decrease in body temp, messages are sent to the back of the hypothalamus
→ vasoconstriction – blood vessels constricting, removing blood from skin surface + conserving heat
→ shivering begins + heat is produced
Glucose (rise in glucose levels)
→ rise in blood glucose levels, specialized cells in the pancreas detect the increase,
→ triggers the release of the hormone, insulin which then causes blood glucose levels to decrease
Glucose (drop in glucose levels)
→ blood glucose levels decrease, this is detected in a different group of cells in the pancreas
→ the hormone glucagon is released, and is then converted to glucose in the liver
→ blood glucose levels increase
What are receptors?
Receptors are responsible for detecting stimuli, any changes from set point, that are outside tolerance limits. They contain sensory cells and can take numerous forms depending on stimuli.
What are the different kinds of receptors?
→ Photoreceptors = detect light
→ Thermoreceptors = detect changes in temperature – heat
→ Osmoreceptors = detect changes in water levels
→ Chemoreceptors = detect concentration of certain chemicals
What is the stimulus response model?
The nervous system takes messages from receptors → the CC interprets the correct response to the information → sends messages to effectors in order to respond to the stimulus
The nervous system
The nervous system is responsible for coordinating all of the body’s activities. It acts as a control centre to coordinate activities that maintain homeostasis within the body. Neural pathways by which messages travel in the body are provided by the nervous system. It is composed of the central and peripheral nervous system.
What is the central nervous system?
CNS consists of the brain and spinal cord where it gathers information from all over the body + coordinated responses.
What is the peripheral nervous system?
PNS comprises all the nerves that lie outside of the CNS, connecting the CNS to the rest of the body. It carries messages to and from the CNS
What is a neuron?
Neurons are information messengers. They use electrical impulses and chemical signals to transmit information between different areas of the brain, and between the brain and the rest of the nervous system.
What is a cell body, dendrite and axon?
- Cell body = contains a nucleus and many other organelles
→ Dendrites = branch off the main cell body, receive messages in the form of impulses
→ Axons = long extension of the cytoplasm of the cell body – it transmits the electrical impulse down the neuron and is connected to the muscle to tell them what to do.
Sensory neuron
→ found in PNS
→ connected to sensory organs (eyes ears nose tongue skin) and detects stimuli
→ carry impulses from sensory cells in PNS to CNS
Interneuron
→ found in CNS
→ receives messages/impulses from sensory messages + sends response message to motor neurons
Motor neuron
→ found in PNS
→ receives message from CNS
→ connect to muscles, glands + organs (effectors) to carry out the response
What are hormones?
The main component of the endocrine system are hormones, which
are chemical messengers molecules secreted by endocrine glands.
How do hormones assist homeostasis?
➔ These hormones are transported by the bloodstream to cells
possessing the receptors for the particular hormone.
➔ The hormones cause these cells to change their activity in a way that
will maintain homeostasis within the body.
➔ Hormones achieve this by influencing the activity of particular
enzymes or the concentration of these enzymes in the cells, known
as target cells.
What is the endocrine system?
The endocrine system is a collection of glands that produce hormones that regulate the activity of the body such as metabolism, growth and development, tissue function, sexual function, reproduction, sleep etc. Glands can be stimulated to secrete hormones (chemical messenger molecules) by messages from the nervous system, by other hormones or by receptors
Behavioural adaptations (temperature)
-Movement (shaded areas regulate heat exposure), deliberate muscle use (contractions create heat), sunbaking (surface area for heat absorption), licking (heat evap through saliva), drinking water (fluids to maintain cells in an isotonic state)
Structural adaptations (temperature)
-Insulation: feathers, fur etc trap a later of air next to skin to reduce the transfer of heat to environment
-SAVR: more compact bodies reduce the surface area for heat exchange- retaining heat
Physiological adaptations (temperature) (vasoconstriction and dilation)
-Vasoconstriction- (narrowing), Vasodilation (widening) allows animals to regulate the SAVR of their circulatory systems to retain or expel heat when required
Physiological adaptations (temperature) (metabolic rates)
-Can be increased to increase the production of heat energy internally, deceased to cool body temperature
Physiological adaptations (temperature) (muscle contraction)
-Shivering or making small in the skeletal muscles to produce heart
Physiological adaptations (temperature) (sweating)
-As perspiration allows sweat to evaporate from the surface of the skin which has an evaporative cooling effect
Physiological adaptations (temperature) (panting)
-Allows evaporation from internal body surfaces, such as nasal passages, mouth and lungs which has a cooling effect
What is transpiration-cohesion-tension theory? (brief)
Its the mechanism by which water flows through the xylem of plants
Transpiration-cohesion-tension theory process
Transpiration- evaporation of water through the stomata of plants
Cohesion- that water molecules are attracted to one another, so they will move in a cohesive stream
Tension-Water molecules are attracted to the surfaces they touch
(by regulating the levels at which transpiration occurs- retain or release water as required
Homeostasis in plants (smaller leaves)
-Smaller leaves- reduces SAVR (reduces area available for transpiration- less water)
Homeostasis in plants (closing stomates and movement)
-Closing stomates: inhibits the ability for water to leave the plant through the leaves
-Movement- angling leaves away from the sun at different times- reduce transpiration (cool)
Homeostasis in plants (Dropping leaves in summer)
-Dropping leaves conserves water to essential parts of the plant
What causes genetic diseases?
-Gene or chromosomal abnormalities caused by point or chromosomal mutations
-Errors during gamete formation or exposure to mutagen
-Could be inherited from parents or as a result of acquired changes to pre-existing genes
Examples of genetic diseases
-Down Syndrome and cystic fibrosis
Examples of environmental disases
-Minamatta (ingestion of mercury)
-Mesothelioma (cancer as a result of asbestos exposure)
