Grade 12: Homeostatis: Unit 6 : FULL UNIT REVIEW

Question 1

What is homeostasis? What does it maintain?

Answer 1

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!

Question 2

What happens when you exercise?

Answer 2

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

Question 3

Homeostatic control system

Answer 3

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

3. Effector — coordinating centre sends signals to an organ / tissue which will normalize original organ

Question 4

Coordination of Body Functions

Answer 4

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

Question 5

Chemical signs?

Answer 5

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)

Question 6

Feedback systems (negative)

Answer 6

Buildup of the end product of the system shuts the system off
The response counteracts further change in the same direction

Question 7

Negative feedback process

Answer 7

—> decreases an action
—> stops when return to normal
—> most homeostatic control mechanisms are negative feedback

Question 8

Feedback systems (positive)

Answer 8

A change in some variable that triggers mechanisms that amplify the change

Question 9

Positive feedback steps

Answer 9

—> increase an action
—> must be turned off by outside event
—> decrease an action
—> could run away = death

Question 10

What is thermoregulation?

Answer 10

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

Question 11

One of two ways to maintain BT?

Answer 11

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!

Question 12

Modes of heat exchange? —> explain

Answer 12

Radiation
Evaporation
Convention
Conduction

Question 13

Balancing heat loss and gain

Answer 13

1- insulation
2- circulatory adaptations
3- cooling by evaporative heat loss
4- adjusting metabolic heat production

Question 14

Insulation

Answer 14

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

Question 15

Goosebumps?

Answer 15

Raise hair on body
Inherited by ancestors
We rely on a layer of fat underneath the skin

Question 16

Circulatory adaptations

Answer 16

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

Question 17

Evaporative heat loss

Answer 17

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

Question 18

Adjusting metabolic heat production

Answer 18

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

Question 19

What is the insulating material for mammals

Answer 19

The integumentary system (hair,skin,nails)

Question 20

What regulates our temperature

Answer 20

Hypothalamus: contains a group of nerve cells that function as a thermostat

Question 21

What is the endocrine system? What do the glands do?

Answer 21

Endocrine glands secrete hormones into the bloodstream

Question 22

What are hormones

Answer 22

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

Question 23

Example of nervous x endocrine system

Answer 23

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

Question 24

Endocrine hormones

Answer 24

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

Question 25

Gigantism

Answer 25

When too much growth hormones (GH) are released in early childhood

Question 26

Pituitary dwarfism

Answer 26

Too few growth hormones produced

Question 27

Regulation of hormones

Answer 27

The hypothalamus receives signals from various sensors in the body and releases “releasing hormones” these stimulates the pituitary gland

Question 28

Tropic hormones

Answer 28

Hormones that stimulate endocrine glands to release other hormones are called tropic hormones. Most released from hypothalamus and pituitary glands are tropic hormones

Question 29

2 types of hormones

Answer 29

Steroid hormones: fat soluble molecules made from cholesterol : cortisol Protein hormones: water soluble, molecules derived from amino acids or chains of amino acids

Question 30

Steroid hormones

Answer 30

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!

Question 31

Protein hormones

Answer 31

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

Question 32

Second messenger?

Answer 32

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

Question 33

What is osmosis

Answer 33

Osmosis is the selective passageway of solvent molecules through a porous membrane, from a diluted solution to a more concentrated one

Question 34

What is osmosis pressure

Answer 34

The amount of pressure required to stop osmosis

Question 35

Osmosis Types

Answer 35

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.

Question 36

Osmoregulation

Answer 36

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

Question 37

Why is the removal of waste products important? List some main parts of the body and their functions in this.

Answer 37

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

Question 38

What is Deamination

Answer 38

the breaking up of amino acids. Produces ammonia (NH3) which is toxic and must be further processed

Question 39

What is Urea?

Answer 39

is a combination of 2 molecules of highly insoluble, toxic ammonia (NH3) mixed with 1 molecule of CO2 which is a soluble compound

Question 40

What is Uric Acid?

Answer 40

waste product formed from the breakdown of nucleic acids

Question 41

What does the liver do in excretion?

Answer 41

responsible for removing/breaking down waste in the blood which is then sent to the kidneys to be filtered into the bladder

Question 42

Why does urine differ in color?

Answer 42

The amount of water present within the urine

Question 43

What does clear urine indicate

Answer 43

Good hydration, Overhydration, Mild Dehydration

Question 44

Pale Yellow Urine?

Answer 44

Good Hydration, Mild Dehydration

Question 45

Bright Yellow

Answer 45

Mild or Moderate Dehydration + Vitamin Supplements

Question 46

Orange - Amber

Answer 46

Moderate or Severely Dehydrated

Question 47

Tea-colored

Answer 47

Severe Dehydration

Question 48

What is Excretion?

Answer 48

Process of separating wastes from body fluids, and then eliminating the waste.

Question 49

What does the Excretory System Do? What are its Functions? Main Organs?

Answer 49

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

Question 50

Urinary System In SUMMARY

Answer 50

Kidneys produce urine 2. Ureters transport urine 3. Urinary bladder stores urine 4. Urethra passes urine outside

Question 51

What happens if one kidney is damaged or removed?

Answer 51

We have two, but if one is removed or damaged, the other can increase in size and take on workload.

Question 52

What is the kidney's principle function?

Answer 52

Filtering blood and removing metabolic waste

Question 53

What are the kidney's secondary function

Answer 53

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

Question 54

Renal Artery vs Renal Vein Function?

Answer 54

Renal artery: from aorta to kidneys  Renal Vein: returns ‘clean’ blood to body

Question 55

Renal Cortex vs Renal Medulla

Answer 55

Renal Cortex: outer layer of the kidney  Renal Medulla: inner layer of the kidney, contains cone shaped tissue masses

Question 56

Renal Pelvis, Nephron

Answer 56

Renal Pelvis: central space/cavity continuous with ureter (which transports urine to bladder)  Nephron: tiny filters

Question 57

Nephron, how many per kidney? What is it referred to as?

Answer 57

THE NEPHRON – FUNCTIONAL UNIT OF THE KIDNEY (10 to the power of 6 PER KIDNEY)

Question 58

What is Glomerulus Filtration

Answer 58

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

Question 58

Tubular Reabsorption?

Answer 58

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

Question 59

Loop of Henle?

Answer 59

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.

Question 60

Tubular Secretion

Answer 60

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

Question 61

Urine Output

Answer 61

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

Question 62

Kidney and Blood Pressure

Answer 62

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.

Question 63

PH BALANCE

Answer 63

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.