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Flashcards in Module 5 Deck (62)
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Describe sensory neurones

Transmit impulses from a sensory receptor to relay neurone, motor neurone or brain.
1 dendron, cell body and 1 axon


Describe relay neurones

Transmit impulses between neurones
Many short axis and dendrons


Describe motor neurones

Transit impulses from really/sensory neurones to an effector
1 long axon and many short dendrites


What happens in the membrane of the sensory receptor in response to pressure

Pascinian corpuscle changes shape
Na+ channels open
Na+ ions enter
depolarisation (+40mV)
generator potential creates an action potential


Outline two roles of synapses in the nervous system.

transmit information between neurones
ensure one way transmission of impulses (unidirectional)


Describe how a resting potential occurs

=Na+ are actively transported out of the axon , K+ actively transported into the the axon by sodium-potassium pumps. (3 sodium for every 2 potassium)
=Na+ diffuse back into, K+ diffuse out of axon down an electrochemical gradient
=However most of the sodium channels are closed and most of the potassium channels are open, allowing potassium out.
=This creates an resting potential of -70mV, with the inside negative to the outside


What is an action potential?

A depolarisation of the cell membrane so it becomes more positive on the inside than outside, creating a nerve impulse


Describe how an action potential is created

-Energy of stimulus triggers some sodium channels to open, making the membrane more permeable to Na+ ions, Na+ diffuse into the axon down an electrochemical (inside is less negative)
-More sodium ion channels open (positive feedback)
-When potential difference reaches +40mV sodium ion channels close and potassium ion channels open (depolarisation)
-Potassium ions diffuse down an electrochemical gradient, causing the inside to become more negative (hyperpolariation) Axon turns to resting potential


What is the refractory period?

A short period of time when the axon can't be excited again


What is saltatory conduction?

Where the action potential jumps from one node to another


What is the all-or-nothing principle?

if the threshold is reached an action potential is always created


What are the 2 types of neurotransmitters?

1 ) Excitatory= result in depolarisation and an action potential if the threshold is reached (e.g.. Acetylcholine)
2 ) Inhibitory= result in hyperpolaristion, prevents action potential (e.g. GABA)


Describe the transmission of impulses across a synapse

-Action potential reaches the end of the presynaptic membrane
-Depolaristion. Calsium channels open and calcium ions diffuse into the presynaptic knob
-Neurotransmitters are release into the synaptic cleft via vesicles by exocytosis
-Sodium ion channels open and sodium ions diffuse into the post synaptic neurone.
-Action potential is created


What is spatial summation?

Where many presynaptic neurones connects to one post synaptic neurone


What is temporal summation?

Where a single presynaptic neurone releases neurotransmitter several times


What is the somatic nervous system?

This system is under conscious control (voluntary)


What is the autonomic nervous system?

This system works constantly and is under subconscious control (involuntary)


What are the 5 main areas of the brain?

Cerebrum, cerebellum, medulla oblongata, hypothalamus, pituitary gland


Describe the cerebrum

Controls voluntary actions (e.g. memory)
-Highly convoluted, which increases SA so theres greater capacity for complex activity


Describe the cerebellum

Controls unconscious actions (e.g. balance)


Describe the medulla oblongata

Used in autonomic control (e.g. heart rate)


Describe the hypothalamus

Regulatory centre for temperature and water balance
-controls complex behavioural patterns (sleeping)
-monitors composition of blood plasma
-produces hormone, endocrine gland


Describe the pituitary gland

Stores and releases hormones


What is the adrenal cortex responsible for?

Outer region- produces hormones that are vital to life (glucocorticoids, mineralocorticoids, androgens)


What is the adrenal medulla responsible for?

Inner region- produces non-essential hormones
(adrenaline, noradrenaline)


What are the functions of the pancreas?

Exocrine gland-produces and releases enzymes via a duct
Endocrine gland-produces hormones and releases them into the blood


What is glycogenolysis?

Where glycogen stored in the liver and muscles is broken down in to glucose which is released into the bloodstream (increasing BGC)


What is gluconeogenesis?

The production of glucose from a non-carbohydrate source


What is glycogenesis?

When excess glucose is converted into glycogen and stored in the liver


What is the role of insulin?

Lowers BGC by:
-Increasing rate of absorption of glucose by cells
-Increasing rate of glycogenesis
Increasing respiratory rate of cells


What is the role of glucagon?

Increases BGC by:
-Reducing the amount of glucose absorbed by liver cells
-Increasing gluconeogenesis


How is insulin secretion controlled?

-At normal BGC, potassium channels in B cells are open causing potassium to diffuse out. Inside at -70mV
-When BGC increases, glucose enters the cell by a glucose transporter
-Glucose is metabolised inside the mitochondria, producing ATP
-The ATP bind to the potassium channels causing them to close. They are ATP-sensitive potassium channels
-potential difference reduces to -30mV and depolarisation occurs
-Voltage gated calcium ions open
-Calcium ions enter the cell and cause secretory vesicles to release the insulin they contain by exocytosis.


What are ectotherms?

most animals are ectotherms and use their surrounding stores warm their bodies.
Invertebrate animals, fish, amphibians and reptiles


What are endotherms?

they rely on their metabolic processes to warm them up
mammals and birds


What is the function of the hepatic artery

brings oxygenated blood into the liver


What is the function of the hepatic portal vein

carries blood loaded with products of digestion from the intestine to the liver


What is the function of hepatocytes

secrete bile from the breakdown of the blood into canaliculi


What is the function of canaliculi

bile drains from the bile ductules which take bile to the gall bladder


What is the function of gall bladder

holds bile from the liver until its needed to digest fatty acids


What is the function of kupffer cells

act as resident macrophages in the liver, ingesting foreign particles and protecting against disease


What is the function of sinusoids

supply hepatocytes with oxygen where blood from the hepatic artery and hepatic portal vein mix


What are the functions of the liver?

Carbohydrate metabolism
Deamination of excess amino acids (the body can't store proteins/amino acids) resulting in the ornithine cycle


Describe the descending limb of the proximal convoluted tubule

upper=impermeable to water
lower=permebale to water, runs through medulla causing sodium and chloride ion concentration to increase

-Filtrate entering is isotonic to blood. As it travels down, water passes out by osmosis down a CG
-Not permeable to odium and chloride ions, no active transport


What is the fluid like at the hairpin in the loop of henle?

Very concentrated and hypertonic to the blood in the capillaries


Describe the ascending limb of the proximal convoluted tubule

lower=permeable to sodium and chloride ions and they diffuse out down a CG
upper=sodium and chloride ions are actively pumped out into the medulla tissue fluid against a CG.

-Impermeable to water, causing fluid in the limb to be dilute
-This is important so that urine is more concentrated than the blood


Describe the distal convoluted tubule

Permeability varies depending on levels of ADH
Lack salt= sodium (+chloride) ions will be pumped out
Water can also leave, concentrating the urine


Describe the collecting duct

Permeability is controlled by levels of ADH, determine how much/little is reabsorbed


What does ADH cause

Permeability of the DCT and collecting duct to increase


More ADH means? Less ADH means?

More=small amount of concentrated urine
Less=large amounts of dilute urine


What is haemodialysis?

Blood leaves patients body from an artery and flows into dialysis machine, where it flows between partially permeable dialysis membranes.


What is peritoneal dialysis?

Done inside the body Using a catheter into the abdomen, takes place across the peritoneal membranes, so that urea and excess mineral ions can pass into tissue fluid and into the dialysis fluid.


Describe primary and accessory pigments

Primary act as reaction centres
Accessory pigments transfer energy to primary pigments
Accessory absorb different wavelengths of light


How is light energy absorbed by photosystems is converted into chemical energy

Non-cyclic photophosphorylation
PS1 and PS11
Exited electrons
Electron transport chain
Thylakoid membrane
ATP produced by chemiosmosis
Electrons move from PS11 to PS1
Cyclic photophosphorylation
PS1 only


Describe the Calvin cycle

Occurs in the stroma
Carbon dioxide fixed by RuBP
Enzyme is Rubisco
Unstable 6C intermediate is produced
Breaks down into 2 molecules of GP
2 TP molecules are formed using ATP and reduced NADP
ATP and reduced NADP from the light dependent reaction
TP regenerates RubP using ATP
TP can be used to form lipids amino acids


What factors affect the rate of photosynthesis?

Light intensity=as it increases, rate of ATP and reduced NADP increases
CO2 concentration=as it increases, the rate of carbon fixation in the Calvin cycle increases, and therefore TP
Temperature= affects enzyme-controlled reaction. Rate increases until enzymes denature.


What happens during glycolysis?

-Two phosphates from ATP attach to glucose forming hexose biphosphate
-Splits into 2 triose phosphates
-Phosphates added forming 2 triose biphosphates
-Dehydrogenation occurs forming 2 pyruvate and 4 ATP (net 2 ATP)


What happens during the link reaction?

-Decarboxylation and oxidation of pyruvate.
-Reduced NAD released
-Acetyl coA formed


What happens during Krebs Cycle?

-Acetyl group combines with 4C to form citrate (6C)
-Decarboxylation and dehydrogenation occurs forming reduced NAD and CO2
-5C formed
-More decarboxylation and decarboxylation regenerating oxaloacetate


What happens at the ETC

-Hydrogen atoms are delivered by FAD and NAD and dissociate into H ions and electrons by chemiosmosis
-Diffuse through through ATP synthase, forming ATP
-Water formed, oxygen final electron acceptor


Describe lactate fermentation

-Pyruvate acts as hydrogen acceptor from NADH, catalysed by lactate dehydrogenase
-Pyruvate converted into lactate and NAD is regenerated


Describe alcohol fermentation

-Not reversible
-Pyruvate converted into ethanal by pyruvate decarboxylase
-Ethanal accepts hydrogen ions from NADH becoming ethanol


RQ value of carbohydrates, proteins and lipids?