HOMEOSTASIS Flashcards
define tolerance range
The tolerance range is specific to species and is the range of environmental conditions that are tolerable for its survival. Too little or too much of a specific environmental condition may result in death.
define optimal range
Optimal range: is the climate conditions an organism thrives at
name different human body functions that are controlled by homeostasis and what is their normal tolerance range
temperature: 36.1-37.8 degrees Celsius
blood glucose: 3.6-6.8 mmol per L
water: daily intake must balance out the daily loss
neurons versus nerves
- Nerves are individual nerve cells which are a collection of neurons and part of our nervous system
- 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
Different types of neurons and their functions, also what are their other names
- sensory (afferent) Sensory nerves carry information from the sense organs and other body receptors to the central nervous system for processing
- motor (efferent): send information AWAY from the central nervous system to muscles or glands.
- interneurons (relay): send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system.
what are the main parts of a neuron and what do they do
- dendrites: receive signals from other cells
- axon: transfers signals to other cells and organs
- axon terminal: forms junctions with other cells
- cell body: organises and keeps the cell functional
- myelin sheath: increases the speed of the signal (a fatty layer)
- Schwann cell: produces the myelin sheath (the little cells along the axon)
- node of Ranvier: allows diffusion of ions (in between Schwann cells)
what is the CNS and what type of neurons and where are they found
Your central nervous system (CNS) is made up of your brain and your spinal cord, and is one of two parts of your nervous system
It consists of interneurons
what is the PNS and what type of neurons and where are they found
The peripheral nervous system (PNS) is the division of the nervous system containing all the nerves that lie outside of the central nervous system (CNS). The primary role of the PNS is to connect the CNS to the organs, limbs, and skin.
It consists of motor and sensory neurons
what is the endocrine system
The endocrine system is made up of glands that make hormones
what is the nervous system
The nervous system controls everything you do, including breathing, walking, thinking, and feeling. This system is made up of your brain, spinal cord, and all the nerves of your body.
compare the endocrine and the nervous system
- its speed of message
- its speed of response
- its duration of response
- its spread of response
- how the message travels through the body
- type of message
endocrine:
- its speed of message: slow
- its speed of response: slow
- its duration of response: long lasting
- its spread of response: usually widespread
- how the message travels through the body: circulatory system - bloodstream
- type of message: hormones (chemical)
nervous:
- its speed of message: fast
- its speed of response: immediate
- its duration of response: short
- its spread of response; localised
- how the message travels through the body: in the nervous system - along nerves and across synapses
- type of message: electrical impulses
what are synapses
Synapse; Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector)
what are hormones
Are chemical messengers that are produced by endocrine glands
Transported around the body via the circulatory system
what important hormones do the pituitary gland and pancreas produce and where are they located
pituitary: located in the brain and produces ADH
pancreas: located between kidneys and produces insulin and glucagon
what is Specificity
Hormones will only affect/activate their target cells.
“Lock and Key” hormone must “fit” receptor to activate it.
Receptors can be located on the cell membrane or inside the cell.
A hormone binding to the receptor activates signal transduction, a series of chemical reactions (domino effect) ending with a change, (gene expression, enzyme activity).
what are Negative feedback loops
All homeostatic mechanisms use negative feedback to maintain a constant value (called the setpoint).
Negative feedback means that whenever a change occurs in a system, this automatically causes a corrective mechanism to start, which reverses the original change and brings the system back towards the setpoint (i.e. ‘normal’).
(operates in the opposite direction of the stimulus)
what are Positive feedback loops
Negative feedback is a regulatory mechanism in which the system responds in the opposite direction to the stimulus, maintaining a relatively steady value for body variables (homeostasis).
e.g. temperature, blood glucose levels.
Positive feedback is when the response to the stimulus is in the same direction as the stimulus. e.g. the onset of contractions during childbirth.
what happens in a normal reflex arc
stimulus (heat) -> receptor (thermreceptors) -> sensory neuron -> CNS (spinal cord) -> interneuron -> CNS -> motor neuron -> effector (bicep) -> response (pulling away)
what are the different receptors
Chemicals (chemoreceptors)
Temperature (thermoreceptors)
Pressure (mechanoreceptors)
Light (photoreceptors)
what is thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries
what are the adaptations of being too hot
vasodilation: arteries dilate to release more heat
sweating
pilorelaxation: hairs flatten to stop trapping air/heat
stretching out: larger surface area
what are the adaptations of being too cold
vasoconstriction: arteries get smaller to reduce blood going to the skin
shivering
piloerection: hairs raise to capture air/heat
curling up
what are endotherms
are animals that produce their own heat.
what are ectotherms
are animals that gain heat through the environment
what are homeotherms
are animals that have a constant body temperature.
what are Poikilotherms
are animals whose body temperature adjusts depending on the environment.
Why is it so important for us to maintain our body temperature?
Human enzymes work best at 37ºC, so the body’s temperature is controlled
what is osmoregulation
Osmoregulation is the regulation of an organism’s water content.
It keeps the organism’s fluids from becoming too diluted or too concentrated
what is Osmosis
the diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration.
what If the concentration of solutes is not equal on both side
there will be net movement of water molecules into or out of the cell, depending on whether the cell’s environment is isotonic, hypotonic, or hypertonic.
what is tonicity
if the concentration of solutes ( the substance that dissolves in a solvent to produce a homogeneous mixture.) is not equal on both sides, there will be movement of water into or out od the cell, depending whether the cells environment is isotonic, hypotonic, or hypertonic
what is hypertonic
- lots of solute in the solution
- water moves out of the cells and cells shrink
what is isotonic
- equal concentration
- balanced
what is hypotonic
- less solute than in the cell
- cells take on water and burst (animal cells
what is antidiuretic
helps to control fluid balance in an animals body by reducing urination, opposing diuresis. Its effects are opposite to a diuretic
what is diuretic
promotes diuresis (increased urine production)
what is ADH
Antidiuretic hormone is released by the pituitary at the base of the brain after being made in the hypothalamus. ADH has antidiuretic action that prevents the production of dilute urine
what is the response to hypertonicity
decrease in water level and therefore solute concentration in the body is higher -> osmoreceptors in the hypothalamus (detects water concentration detects this change -> hypothalamus releases ADH and signals from thirst centre and released -> kidney tubules (process water in kidneys) become more permeable to water & thirst behaviour -> results in increased water absorption from kidney tubules, decreased urine volume and water intake
what is the response to hypotonicity
increases in water levels and therefore decrease in solute levels in the body -> osmoreceptors in the hypothalamus detect this change -> hypothalamus sends signals to stop the release of ADH -> kidney tubules become less permeable to water -> decreased water absorption and increase urine volume
what do the kidneys do
The kidneys remove urea and other toxic wastes from the blood, forming a dilute solution called urine in the process.
what are the different tubes/veins leading in and out of the kidneys
- The renal artery carries blood to the kidney
- the renal vein carries blood, now with far lower concentrations of urea and mineral ions, away from the kidney.
- The urine formed passes down the ureter to the bladder.
what is the nephron
The important part of the kidney is a folded tube called a nephron. There are a million nephrons in each kidney. There are five steps in producing urine in a nephron:
what is the loop of Henle
Loop of Henle – Formation of a Salt Bath. Most of the liquid is absorbed here - to recover water and salt from urine. it has a bigger surface area so it can absorb more water
what are some of te adaptations of water loss
structural: Fewer stomata Small leaves Needle-like foliage Thicker cuticles Thick fleshy leaves that can store water Loop of Henle longer in desert dwelling animals
physiological: Reabsorb water Produce highly concentrated urine Rely on metabolic water Osmoconformers Osmoregulators
behavioural:
Spend most time in burrows
Absorb water from atmosphere
Drink water
how are reflex arcs fast and why
they are fast because it helps keep the organisms from danger.
It is fast as it doesn’t go straight to the brain it just goes through the spinal cord so the interneurons can activate the motor neurons but the information goes to the brain later
