Review posters 06/05/2016

Question 1

Which nerve has the parasympathetic supply to the heart?

Answer 1

Vagus

Question 2

Which neurotransmitter is released on parasympathetic stimulation and where does it act?

Answer 2

Neurotransmitter is acetyl choline. It acts on M2 muscirinic receptors.

Question 3

What does stimulation of the parasympathetic supply to the heart cause?

Answer 3

Decreased heart rate and increased AV nodal delay

Question 4

Name and describe the constant influence the parasympathetic nerves have on the heart?

Answer 4

Vagal tone- constantly over the SA and AV node. Brings intrinsic heart rate down from 100bpm to 70bpm.

Question 5

Stimulation of the sympathetic supply to the heart.

Answer 5

Causes increased HR and decreased AV nodal delay. Also increases the force of contraction

Question 6

Where do the sympathetic nerves supply?

Answer 6

Myocardium, AV node and SA node

Question 7

Where do the parasympathetic nerves supply?

Answer 7

AV and SA node.

Question 8

Name the neurotransmitter and the receptor to which it binds in the sympathetic supply to the heart

Answer 8

Nor-adrenaline

Binds to b1 adrenoceptors.

Question 9

Name the 5 stages of the cardiac cycle

Answer 9

Passive filling
Atrial contraction
Isovolumetric ventricular contraction 
Ventricular ejection
Isovolumetric ventricular relaxation.

Question 10

Describe passive filling

Answer 10

Pressure in atria and ventricles close to 0. Atrioventricular valve (mitral or tricuspid) open. Blood flows from SVC and IVC straight into ventricles. They become 80% filled.

Question 11

Describe atrial contraction

Answer 11

To get the remaining 20% of the blood from the atria to the ventricles, the atria contract. This completes the end diastolic volume.

Question 12

Describe isovolumetric ventricular contraction.

Answer 12

Ventricles begin to contract. When pressure in the ventricles rises above the pressure in the atria- the AV valves close. The aortic/pulmonary valves are also closed so the ventricles are a closed space.

Question 13

Ventricular ejection

Answer 13

When the pressure in the ventricles exceeds the pressure in the aorta- the aortic/pulmonary valve opens and the blood leaves the ventricles.
Stroke volume is ejected by each ventricle.
The blood left behind is the end systolic volume.

Question 14

Isovolumetric ventricular relaxation

Answer 14

The ventricles start to relax so the pressure in the ventricles starts to decrease. The aortic/pulmonary valve shut and the AV valves open when the pressure in the ventricles is less than the pressure in the atria.

Question 15

JVP

Answer 15

a= atrial contraction
c= tricuspid valve bulging into the ventricles when the ventricles contract
v= rise in atrial pressure during atrial filling

Question 16

Describe the general process of oxidative phosphorylation

Answer 16

Electrons are brought to the electron transport chain on NADH and FADH. Here, the electrons are released and travel down a series of complexes via a series of oxidation and reduction reactions. These reactions provide the energy to pump H+ ions against their concentration gradient across the mitochondrial membrane into the intermembranous space. The final electron acceptor in the chain is oxygen which is reduced to form water.
The H+ ions then flow back down the concentration gradient through ATP synthase, phosphorylating ADP to ATP.

Question 17

How does NADH and FADH get into the mitochondrial matrix from the cytoplasm?

Answer 17

Aspartate malate co-transporter.
Oxaloacetate and NADH combine to form Malate. Malate is then transported into the mitochondrial matrix where it breaks back down into oxaloacetate and NADH.

Question 18

Why do we need NADH and FADH in the mitochondrial matrix?

Answer 18

NADH cannot cross the lining

Also NAD+ can’t be used in oxidative phosphorylation.

Question 19

How are NADH and FADH linked to ATP?

Answer 19

Electron transfer from NADH and FADH ultimately is converted to the phosphoryl transfer of ATP

Question 20

What is a redox potential?

Answer 20

Reduced substance (X)- tendency to release electrons in comparison with hydrogen (h2)

Question 21

Describe trends in redox potentials and how they are related to E0

Answer 21

As the E0 becomes more negative- it is more likely to be oxidised- therefore acting as a reducing agent.
As the E0 becomes more positive- it is more likely to be reduced- therefore acting as a oxidising agent.

Question 22

What are the two steps to oxidative phosphorylation and what do they consist of?

Answer 22

Electron transfer- electrons from NADH and FADH ultimately transferred to O2.
Respiratory chain
Energy used to pump H+

ATP synthesis- electrochemical gradient of H+
Flow through ATP synthase energy used to phosphorylate ADP

Question 23

What are cytochromes?

Answer 23

Proteins with haem groups. Haem groups contain iron which can reversibly bind to electrons.

Question 24

Which complex does NADH release its electrons too?

Answer 24

1

Question 25

Which complex does FADH release its electrons too?

Answer 25

2

Question 26

Which complexes are cytochromes?

Answer 26

3 and 4

Question 27

Which complex does not pump H+ across the membrane?

Answer 27

2

Question 28

How does ATP synthase convert the flow of H+ to phosphorylating energy?

Answer 28

Flow of protons turns the rotor (made up of gamma, e and c subunits). This produces energy

Question 29

Uncoupling protein

Answer 29

Allows ‘short circuiting’ of the mitochondrial respiration.

Question 30

Where is uncoupling protein found?

Answer 30

Brown adipose tissue. Used in hibernating animals and newborns.

Question 31

Neural control of respiration

Answer 31

Pre-botzinger complex (in the medulla) stimulates rhythm. This causes the dorsal respiratory group of neurones to fire action potentials to the muscles of inspiration.

Question 32

What happens if the dorsal respiratory group fire too often (hyperventilation)?

Answer 32

This stimulates a second respiratory group of neurones called the ventral respiratory group- they fire action potentials which stimulate accessory muscles and cause a forced expiration.

Question 33

What role does the PONS play in respiration?

Answer 33

PONS alters signals. Pneumotaxic centre will be stimulated to stop long periods of inspiration with short expiratory gasps (apneusis). The apneustic centre does the opposite.

Question 34

How are the respiratory sensors influenced?

Answer 34

Stretch receptors (Hering Bruer reflex)
Joint receptors (movement of joints increases breathing)
Juxtapulmonary receptors (stimulated by pulmonary cappilary congestion or oedema)
Baroreceptors
Higher brain influence

Question 35

How does exercise influence respiration?

Answer 35

Increased joint movement- increases breathing
Adrenaline release
Accumulation of carbon dioxide
Increased body temp
Cerebral cortex

Question 36

Cough reflex

Answer 36

Short inhalation
Followed by closure of the trachea
Contraction of abdominal muscles
Opening of the trachea
Sharp expiration

Question 37

What is the hypoxic drive?

Answer 37

Driven by peripheral chemoreceptors. When O2 saturations in the blood get below 8kpa. Important in patients with COPD

Question 38

Hypercapnia and ventilation

Answer 38

Fast response- as carbon dioxide levels rise, ventilation increases massively

Question 39

Hypoxia and ventilation

Answer 39

O2 levels become very low before the peripheral chemoreceptors catch on- not as reactive to oxygen as it is to carbon dioxide.

Question 40

Acute effects of altitude training

Answer 40

Decreased partial pressure of oxygen means that hyperventilation and increased cardiac output occur.

Question 41

Chronic effects of altitude training

Answer 41

increased RBC
Increased mitochondria
Increased capillaries
Increased 2-3 BPG