Grade 12: Homeostatis: Unit 6 : FULL UNIT REVIEW Flashcards
What is homeostasis? What does it maintain?
A constant physiological adjustment of the body in response to external environment changes
Although the world varies around us over time, our bodies maintain a stable internal environment!
37° C, 0.1% blood glucose and a blood pH of 7.35!
What happens when you exercise?
1- body temperature increases
2- O2 levels are used up
3- increased cellular metabolism
4- evaporation of sweat to cool off
5- heat rate increases to increase blood flow (to get O2 levels back up)
6- pancreas signals breaking down of bio molecules to get energy needed to exercise
Homeostatic control system
1 - receptors or sensors — organs that detect changes or sense when conditions are not within the normal range
2 - control centre or integrator — organs which process information or receives from the receptor and sends signals to another part of the body
- Effector — coordinating centre sends signals to an organ / tissue which will normalize original organ
Coordination of Body Functions
The activity of various specialized parts of an animal are coordinated but the two major systems of internal communication
The nervous system — involved with high- speed messages
The endocrine system — involved in the production, release and movement of chemical messengers
Chemical signs?
Hormones = produced by the endocrine system convey information between organs of the body
Pheromones = chemical signals used to communicate between different individuals
Neurotransmitters = chemical signals between cells on a localized scale (over short distances; between neurons)
Feedback systems (negative)
Buildup of the end product of the system shuts the system off
The response counteracts further change in the same direction
Negative feedback process
—> decreases an action
—> stops when return to normal
—> most homeostatic control mechanisms are negative feedback
Feedback systems (positive)
A change in some variable that triggers mechanisms that amplify the change
Positive feedback steps
—> increase an action
—> must be turned off by outside event
—> decrease an action
—> could run away = death
What is thermoregulation?
The process in which animals maintain an internal temperature within a tolerable range
It is critical to survival because biochemical and physiological processes are sensitive to changes in temperature
—> enzymatic reactions
—> properties of membranes
One of two ways to maintain BT?
Poikilothermy: body temperatures is not controlled but varies with ambient temperature, as in invertebrates and most fishes. Poikilotherms do not necessarily have widely fluctuating body temperatures
Homeothermy: maintenance of constant body temperature that is usually high! Here consistency matters over heat!
Modes of heat exchange? —> explain
Radiation
Evaporation
Convention
Conduction
Balancing heat loss and gain
1- insulation
2- circulatory adaptations
3- cooling by evaporative heat loss
4- adjusting metabolic heat production
Insulation
feathers, hair or fat layers
Reduces the flow of heat between an animal and its environment
Lowers energy cost of staying warm
Most land animals and birds react to cold by raising fur or feathers
—> traps a thicker layer of fur
—> increasing its insulating power
Goosebumps?
Raise hair on body
Inherited by ancestors
We rely on a layer of fat underneath the skin
Circulatory adaptations
We can alter the amount of blood (hence heat) flowing between the body core and skin
Vasodilation
Muscles in superficial blood vessels relax
Increases the diameter of vessels = more blood
Increases heat transfer, releasing heat energy to surroundings
Vasoconstriction
Muscles in superficial blood vessels contract
Smaller diameter of blood vessels = less blood
Reduces heat transfer: preventing heat loss
Keeps blood (and heat) in interior of body where it’s needed
Evaporative heat loss
When environmental temperatures are above body temperature animals
Sweat, pant, bathe, spread saliva over body surfaces
Heat is carried away with water molecules as they change into a gas
Adjusting metabolic heat production
Shivering and moving —> heat production is increased by muscle activity
Non shivering thermogenesis (NGT) certain hormones can cause mitochondria to increase their metabolic activity and produce heat instead of ATP
What is the insulating material for mammals
The integumentary system (hair,skin,nails)
What regulates our temperature
Hypothalamus: contains a group of nerve cells that function as a thermostat
What is the endocrine system? What do the glands do?
Endocrine glands secrete hormones into the bloodstream
What are hormones
Chemical messages release in one part of the body, travel through bloodstream and affect the activities of target cells in other parts of the body
Example of nervous x endocrine system
Endocrine system is much slower than the nervous system, but they work together
Nervous system: reaction to a hot stove
Endocrine: growth rate as a teenager
Endocrine hormones
We have over 200 hormones or hormone like chemicals within the body
They can
Regulate growth and development
Change metabolism
Blood sugar
Blood pressure
Immune response
Gigantism
When too much growth hormones (GH) are released in early childhood
Pituitary dwarfism
Too few growth hormones produced
Regulation of hormones
The hypothalamus receives signals from various sensors in the body and releases “releasing hormones” these stimulates the pituitary gland
Tropic hormones
Hormones that stimulate endocrine glands to release other hormones are called tropic hormones. Most released from hypothalamus and pituitary glands are tropic hormones
2 types of hormones
Steroid hormones: fat soluble molecules made from cholesterol : cortisol
Protein hormones: water soluble, molecules derived from amino acids or chains of amino acids
Steroid hormones
Lipids and hydrophobic, meaning they can easily interact with cell membranes that consist of phospholipids
Therefore when a steroid hormone travels through the blood and encounters a cell, it does not stop at an cell membrane to get in. It simply can shoot through!
Protein hormones
A hydrophilic hormone cannot get into a cell, it can only bind to a receptor located on the outside of its target cells membrane
But the hormone is brining a message from your body to that target cell
Because the hormone tells the target cell that it needs to carry our some function for the body it is refereed to as the first messenger
Second messenger?
Within a target cell and must continue to carry the message of the hormone within the cell to get the job done
—> known as cAMP
What is osmosis
Osmosis is the selective passageway of solvent molecules through a porous membrane, from a diluted solution to a more concentrated one
What is osmosis pressure
The amount of pressure required to stop osmosis
Osmosis Types
Isoosmotic (Isotonic): Solutions have
an equal concentration of solute and so
equal osmotic pressure.
Hyperosmotic (Hypertonic): Solution
with higher concentration of solute.
Hypoosmotic (Hypotonic): Solution
with lower concentration of solute.
Osmoregulation
The maintenance of osmotic pressure in the fluids of an organism, by the control of water
In unicellular organisms, waste can move directly out of a cell
Excess water is regulated by contractile vacuums which pump out excess water
In multi-cellular organisms, excess cells and structures are required to help in the removal of waste
Why is the removal of waste products important? List some main parts of the body and their functions in this.
Lungs -> CO2
Large Intestine -> toxic wastes
Liver -> transforms toxins such as alcohol or heavy metals into soluble materials
Transforms products of protein metabolism into metabolites
Kidneys -> Remove waste, regulate Blood pH and maintain Water Balance
What is Deamination
the breaking up of amino acids. Produces ammonia (NH3) which is toxic
and must be further processed
What is Urea?
is a combination of 2 molecules of
highly insoluble, toxic ammonia (NH3) mixed
with 1 molecule of CO2 which is a soluble
compound
What is Uric Acid?
waste product formed from the
breakdown of nucleic acids
What does the liver do in excretion?
responsible for removing/breaking
down waste in the blood which is then sent to
the kidneys to be filtered into the bladder
Why does urine differ in color?
The amount of water present within the urine
What does clear urine indicate
Good hydration, Overhydration, Mild Dehydration
Pale Yellow Urine?
Good Hydration, Mild Dehydration
Bright Yellow
Mild or Moderate Dehydration + Vitamin Supplements
Orange - Amber
Moderate or Severely Dehydrated
Tea-colored
Severe Dehydration
What is Excretion?
Process of separating wastes from
body fluids, and then eliminating the waste.
What does the Excretory System Do? What are its Functions? Main Organs?
regulates volume and
composition of body fluids.
excreting metabolic waste,
maintenance of water-salt balance (kidneys
regulate salts in blood and also blood pressure)
Maintenance of acid-base balance (kidneys
keep blood pH at 7.4), secretion of hormones.
Main organs: kidney, bladder, ureters, sphincter
and urethra
Urinary System In
SUMMARY
Kidneys produce
urine
2. Ureters transport
urine
3. Urinary bladder
stores urine
4. Urethra passes urine
outside
What happens if one kidney is damaged or removed?
We have two, but if one is removed or
damaged, the other can increase in
size and take on workload.
What is the kidney’s principle function?
Filtering blood and removing metabolic waste
What are the kidney’s secondary function
Control water balance & pH
Regulate blood levels of sodium, potassium,
bicarbonate, calcium ions
Secretes erythropoietin to stimulate red
blood cell production
Activate vitamin D production in skin
Renal Artery vs Renal Vein Function?
Renal artery: from aorta to
kidneys
Renal Vein: returns ‘clean’
blood to body
Renal Cortex vs Renal Medulla
Renal Cortex: outer layer of
the kidney
Renal Medulla: inner layer of
the kidney, contains cone
shaped tissue masses
Renal Pelvis, Nephron
Renal Pelvis: central
space/cavity continuous with
ureter (which transports urine
to bladder)
Nephron: tiny filters
Nephron, how many per kidney? What is it referred to as?
THE NEPHRON – FUNCTIONAL
UNIT OF THE KIDNEY (10 to the power of 6 PER
KIDNEY)
What is Glomerulus Filtration
1) Glomerular filtration:
Glomerulus filters
water and solutes (not
proteins) from blood
plasma into the
nephron, specifically the
Bowman’s capsule.
The filtrate is exactly
like plasma, just no
blood cells or proteins
Tubular Reabsorption?
Filtrate passes through proximal
tubule and is reabsorbed. Actively
reabsorbs: nutrients (glucose,
amino acids), ions (Na, K).
Passively reabsorbs: water,
negative ions. Actively Secretes:
hydrogen ions
Loop of Henle?
Descending Loop of Henle:
enters salty environment (medulla)
permeable to water and slightly to
ions. Water diffuses to capillaries.
Concentration of sodium ions hits
maximum concentration at bottom
of loop.
In the Ascending loop of Henle,
no longer water permeable,
instead ions diffuse into nearby
blood vessels.
Tubular
Secretion
In Distal Tubule: also
part of tubule
reabsorption absorbs
water and sodium ions
based on the body’s
needs.
K+, H+ are secreted into
the distal tubule in order to
maintain pH. Other
substances like medicine
are also secreted into
the distal. All of this is regulated by hormones
Urine Output
Permeability of distal tubule and collecting
duct is controlled by ADH (antidiuretic
hormone)
ADH increases permeability which allows
more water to be removed from filtrate
and conserve water in body
When body needs to eliminate excess
water, ADH is inhibited
Drugs and caffeine block release of ADH
which increases volume of urine
Kidney and Blood Pressure
Kidneys can adjust blood pressure by adjusting
blood volume.
Low Blood Pressure: detected by juxtaglomerular
apparatus which releases the enzyme renin which
causes angiotensin to be released.
Angiotensin:
1) Constricts blood vessels
2) Activates aldosterone
Aldosterone: acts on nephrons to increase Na+
causing the osmotic gradient to increase. This
means more water moves out of nephrons.
Homeostasis accomplished.
PH BALANCE
Our pH is constantly around 7.4 thanks
to our kidney
Our bodies have a buffer system , any
excess H+ ions buffered by bicarbonate
ions in blood which form a less acidic
carbonic acid.
Kidneys help restore the buffer by
reversing the reaction. Nephrons
recombine bicarbonate ions and restore
them to the blood.
