Response to changes in the environment Combined set

what is osmoregulation ?

maintaining the water potential by removing excess water/ retaining water

what is excertion ?

removing nitrogenous waste in form of urea in the blood

what are the 2 roles of the urinary system ?

• osmoregulation

• excretion

how do kidneys recieve blood ?

renal artery

what is the cotex & the function ?

• outer layer of nephrons

• where blood is filtered

what is the medulla and what does it contain ?

• inner layer which contains tubes carrying filtered waste to centre of kidney

• contains loop of henle & collecting duct parts of the nephron

what is the renal pelvis ?

• where all the collecting ducts come together & connect under ureter

what are the main parts of the nephron ?

• Bowman’s Capsule

• Proximal Convoluted Tubule

• Loop of Henle

• Distal Convoluted Tubule

• Collecting Duct

3 kidney processes ?

• ultrafiltration

• selective reaborption

• osmoregulation

Describe how ultrafilration occurs in the glomerulus ?

• high hydrostatic pressure

• small substances such as amino acids, glucose & urea are pass out

• through small gaps in capillary endothelium

4 steps water is reabsorbed into kidneys ?

1. ultrafiltration

2. selecteive reabsorption

3. loop of henle

4. distal convoluted tubule & collecting duct

Steps of selective reabsorption (how and what is reabsorbed) ?

glucose reabsorbed by co-transport from epithelial cells of proximal convulated tubule to blood capillaries

steps of loop of henle using Na+ ?

• Na+ actively transported out of ascending limb using ATP

• creates low water potential

• asending limp impermeable to water meaning water can only move out of decending limb by osmosis

• water enters blood capillaries by osomosis

• at hair pin of lopp, water potential lowest as Na+ diffuses out

what happens to water in distal convoluted tubule & the collecting duct ?

• water naturally moves out of distal convoluted tubule & collecting duct via osomosis

• collecting duct run paralel to loop of henle

what can impact the permeability of the collecting ducts ?

antidiuretic hormones

what is the change in water potential detected by ?

osmoreceptors in hypothalamus

what happens if water potential falls ?

1. osmoreceptors in hypothalamus detect low water potentialposterior putuitary gland receive impulse and release ADH

2. ADH secreted into blood & travels to kidneys

3. distal convoluted tubule and collecting duct becomes more permeable to water

4. urine volume creases & concentration increases

5. more water reabsorbed into blood

6. blood water potential increases

why are aquaporins important ?

intergral membrane proteins that serve as channel proteins in transport of water

How does ADH work ?

• cells lining walls of collecting duct has receptors for ADH on plasma membrane

• have vesticles with aquaporins

• when ADH binds to recpetors, it causes activation of phosphorylase

• activated phosphorylase causes vesticles containing aquaprins to move & fuse with membrane on filtrate side, making membrane of cells lining collecting duct to become more permeable to water

how are the cells in proximal convoluted tubule adapted ?

• folded membrane = larger surface area

• many membrane proteins

• many ribosomes

• many mitochondria

what does loop of henle do ?

create low water potential in medulla of kidney

what is homeostasis ?

maintanence of constant internal environment for optimal conditions in cells

why is homeostatis important ?

• maintaining stable blood glucose concentration

• water potential of blood

what does negative feedback do ?

restores systems to their original level

what is positive feedback ?

occurs when deviation from optimum causes changes that result in an even greater deviation than normal

steps of homeostasis during rise in blood temperature ?

1. thermoreceptors in skin & hypothalamus

2. heat loss centre in hypothalamus

3. vasodilation

4. normal blood temp

5. blood at right temp so turns off corrective measure

What is the distance between 2 “Z lines” called ?

sacromere

what causes the dark appearance of A band ?

has both thick myosin & thin actin myofilaments

why is I band light ?

only has thin actin myofilaments

image of muscle with bands ?

what changes occur to sacromere when muscle contracts ?

• I-band becomes narrower

• Z-lines move closer together

• H-zone becomes narrower

what is actin ?

a globular protein whose molecules are arranged into long chains that are twisted round each other to form a helical strand

what is tropomyosin ?

forms long thin threads that are wound around actin filaments

what is sarcoplasm ?

• shared cytoplasm in each muscle fibre

• contains mitochondria & endoplasmic rectilium

what is the Z line ?

junction between actin myofilaments in adjacent sacromeres

How does myosin shorten the sacromere ?

myosin heads move their tails, moving the centre of the sacromere, pulling the actin towards eachother

Steps of muscle contraction ?

1. calcium ions released from sarcoplasmic rectilium

2. calcium ion in sarcoplasm binds troponin & exposes mysoin- binding site on actin filament

3. myosin head binds to actin & ADP released

4. myosin head changes conformation, filament slide past one another

5. ATP binds to myosin causing it to release actin

6. hydrolysis of ATP provide energy for mysoin to return to normal position

7. myosin head attaches further along actin filament 7 cycle repeated

how does muscle relax ?

if calcium ions are returned to sarcoplasmic rectilium

why is ATP important in muscle fibres ?

• movement of myosin heads

• reabsorption of calcium ions into endoplasmic rectilium by active transport

what does phosphocreatine do that helps in ATP production ?

• Pi donated to ADP to make ATP

• anaerobic conditions

• acts as reserve supply of phosphates

What type of exercise and how are slow twitch muscle fibres adapted ?

• slow contractions over longer periods of exercise e.g. marathon

• large stores of myoglobin

• rich supply of blood vessels

• numerous mitochondria

What type of exercise and how are fast twitch muscle fibres adapted ?

• rapid release of energy during intense exercise e.g. sprinting

• thick & numerous myosin filaments

• high concentration of glycogen

• store of phosphocreatine

2 types of muscle fibres?

• slow twitch

• fast twitch

what does tropomysoin do ?

moves out of the way when calcium ions bind, allowing mysoin to bind to actin

2 main aspects of nervous system ?

• central nervouse system (CNS)

• peripheral nervous system (PNS)

what is in the CNS ?

• brain

• spinal cord

what is in the PNS ?

• sensory nervous system

• motor nervous system

what is in the motor neurone ?

• voluntary nervous system

• autonomic nervous system

what do sensory neurones do ?

carry nerve impulses from receptors to CNS

what do motor neurones do ?

carry nerve impulses away from the CNS to effectors

what is the voluntary nervous system ?

carries nerve impulses to body muscles under conscious control

what is the autonomic nervous system ?

carry nerve impulses to glands, smooth muscles & cardiac muscles & isnt under conscious control

main stages of simple reflex arc ?

1. stimulus

2. receptor

3. sensory neurone

4. coordinator

5. motor neurone

6. effector

7. response

What is stimulus ?

a detectable change in the internal/external environment of organism that leads to a response

what are stimulus detected by ?

receptors

what is a response produced by ?

effector

simple pathway of a stimulus ?

stimulus → receptor → coordinator → effector → response

what is taxis ?

a simple response whose direction is determined by direction of the stimulus

what is kinesis ?

a form of response in which the organism doesn’t move towards or away from the stimulus, instead it changes speed and rate of direction change

what is tropism ?

the growth of part of the plant in response to a directional stimulus

example of positive phototropism ?

plant shoot grows towards light

example of negative phototropism ?

plant root growing away from light

example of postive gravitropism ?

plant roots growing towards gravity

example of negative gravitropism ?

plant shoots growing away from gravity

How does light impact the shape of the plant (steps) Phototropic response

1. cells in tip produce IAA which is transported down shoot

2. initially transported evenly

3. light causes movement of IAA from light side to shaded side of shoot

4. greater concentration IAA builds up on shaded side of shoot than light side

5. IAA cause elongation of shoot cells on shaded side

6. cause shoot tip to bend towards light

how does gravity impact shape of flowering plants (steps of response of hoizontally growing root to gravity) ? Gravitropism response

1. cells in tip produce IAA which is transported along root

2. IAA initiallly transported to all sides of root

3. gravity influence movement of IAA

4. greater concentration of IAA builds on lower side of root than upper side

5. IAA inhibits elongation of roots cell so cells on lower side elongate less than on the upper side

6. causes root to bend downwards towards gravity

what does greater IAA concentration in shoots cause ?

increases cell elongation

what does greater IAA concentration in roots cause ?

decreased cell elongation

Why is the difference in IAA impact important to plants for phototropism ?

• shoot grows towards light

• root grows away from light

Symptoms of type I diabetes ?

• weight loss

• increased urination

• sugar in urine

• fatigue

Symptoms of type II diabetes ?

• increased thirst

• vision problems

• extreme humger

What is type I diabetes caused by ?

immune system attacks & destroys beta-cells

what causes type II diabetes ?

decreased insulin production or glycoprotein receptors on target cell unresponsive to insulin

how is type I diabetes managed ?

• insulin injections

• less carbohydrates

how is type II diabetes managed ?

• increased exercise

• diet control

why is tiredness caused by type I diabetes ?

• insulin not produced

• blood sugar levels fluctuate

• insufficient glucose

• cells in muscles & brain have decreased activity

why do people with diabetes experience extreme thirst ?

• high blood glucose level

• glucose excreted in urine

• low water protential in urine

• draws water from blood by osmosis

what 3 processes does the liver carry out to regulate blood glucose ?

1. glycogenesis

2. glycongenolysis

3. glucogennogensis

what is glycogenesis ?

makes glycogen from glucose removed from the blood

what is glycongenolysis ?

breaking down stored glycogen into glucose which can be released into the blood

what is gluconeogensis ?

synthesis of glucose from other molecules (e.g. amino acids)

What happens when blood glucose is too high ?

• rise in blood glucose

• detected by beta cells in Islet of Langerhans (in pancreas)

• insulin released

• insulin attaches to receptors on surface of target cells

- causing change in tertiary structure of transport proteins responsible for glucose →increased uptake of glucose (especially to muscle & liver) →acivates enzymes to convert glucose to glycogen (glycogenesis)

- enzymes activated that convert glucose to fatty acids →fats desposited in adipose tissue

- increased rate of respiration

what happens if blood glucose drops to low ?

• blood glucose level decreases

• detected by alpha-cells in Islet on Langerhans (in pancreas)

• glucagon released

• attaches to receptors on cell surface

-activates enzymes which convert glycogen into glucose (glycogenolysis)

-enzymes activated that convert amino acids & glycerol to glucose (glucogenesis)

name the second way glycogen can be broken down into glucose to raise blood glucose levels ?

secondary messenger

second way glycogen can be broken down into glucose to raise blood glucose levels (steps) ?

1. adrenaline fuses to receptors on cell surface membrane of liver cells (shape changes on inside of membrane)

2. activating enzyme adenyl cyclase

3. ATP to cAMP

4. cAMP changes shape of & activates protein kinase enzyme

5. catalysing conversion of glycogen into glucose

what is the advantage of the 2nd messanger model ?

has amplification effect

difference between alpha & beta cells in Islet of Langerhans ?

Apha cells

• larger

• produce glucagon

Beta cells

• Smaller

• produce insulin

what factors influence blood glucose ?

• food intake

• exercise

describe how stimulation of a pacinian corpuscle produces a generator potential ?

• stretch mediated Na+ channels in membrane

• increased pressure changes sensory neurone membrane

• Na+ channels open & Na+ diffuse in causing depolarisation

how to obtain the dry mass of lettuce leaves ?

• heat & weigh until mass is constant

Describe how inversion mutation can cause production of non-functional protein ?

• changes in DNA base sequence

• change in amino acids

• change in hydrogen bonding

• alters tertiary structure

Name the parts labelled A to D ?

A = cell body

B = axon

C = node of ranvier

D = schwann cell

Why can destruction of myelinated sheaths cause increased reflex response times ?

• no saltatory conduction

• impulses slowed

• effects relay neurones

Atropine is drug that attaches to post-synaptic receptors. Can increase heart rate, How ?

• less acetylchloine (neurotransmitter) binds to receptors

• fewer action potentials

• to SAN

what is a synapse ?

junction between 2 neurones

describe the sequence of events involved in transmission across cholingeric synapase ?

1. depolarisation of synaptic membrane

2. calcium channels open & calcium ions enter synaptic knob

3. synaptic vesticles fuse with presynaptic membrane & neurotransmitter produced

4. acetylchlone diffuses across synaptic cleft

5. acetylechlonine binds to receptors on membrance

6. sodium channels open & sodium ions diffuse in

7. enzymes hydrolyses neurotransmitter

how do drugs affect synapses ?

1. by blocking reabsorption of neurotransmitter or causing more to be released

2. by having similar structure & ‘tricks’ post synaptic membrane , neurotransmitter receptor allows the drug to bind to it

what is spatial summation ?

several pre-synaptic neurones join together into a single post-synaptic neurone

what is temporal summation ?

when a single presynaptic neurone releases neurotransmitter many times in a short period, therefore excededing threshold value for triggering an action potential

why does temporal summation help us filter out low level stimulus ?

effective at filtering out-low level stimuli as they dont cause the release of sufficient neurotransmitter