What happens to venous return to the heart, compared to when Robin is at rest? Explain why this happens

Science (Melb)
Semester 2 DE, 2020
BIOL125 – 4C HUMAN BIOLOGY 1 – Melbourne

Lecturer: Genevieve Morris

Examination Duration: 24 hours
Weighting: 40%

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Exam Conditions: Open Book
Materials Permitted In The Exam Venue:

N/A – Hosting a LEO Quiz, LEO Assignment or Take-Home Exam

Materials To Be Supplied To Students: None

Instructions To Students: This exam contains 24 questions worth a total of 65 marks. The number of marks each question is worth are clearly indicated.

Type your answers into this Word template in a different colour to the questions.
Save your file, in a Word or PDF format only, with your name and student number in the title.
Upload your completed exam to the Turnitin link in the Examination tab on LEO.

Question 1

Mark has been away on holiday, and his friends Shruti and Shokoofeh took turns looking after his dog, named Jezebel. Jezebel is a female with yellow fur, and shortly after Mark returns from his holiday, it becomes obvious his dog is pregnant. She gives birth to three puppies, all of which have yellow fur.

Mark is very upset, and blames Shruti, because Shruti owns a male dog with yellow fur (named Goldie). Shokoofeh owns a male dog (named Blackie), but because he has black fur, Mark doesn’t think he can be the father.

Assume that the gene for colour of fur is located on autosomal chromosomes and ‘black’ fur colour is dominant, and ‘yellow’ fur colour is recessive. Assume there are no new mutations. Assume the genetics of dog fur colour work the same way as human hair colour. (4 marks total)

What is Jezebel and Goldie’s phenotype and possible genotype(s)?
(1 mark)

What is Blackie’s phenotype and possible genotype(s)? (1 mark)

What are the puppies’ phenotypes and possible genotype(s)? (1 mark)

Based only on the fur colour of the two possible fathers, is it certain that Goldie is the father? Explain your answer. (1 mark)

Question 2
Describe one similarity and one difference between steroid and protein hormones. (2 marks)

Question 3
Distinguish between the function of simple columnar epithelium and simple squamous epithelium, providing a brief example of the function of each.
(1 mark)

Question 4

Distinguish between facilitated diffusion, and secondary active transport. For each, provide an example of a molecule or ion that uses this mechanism to cross the cell membrane. In your answer, explain what characteristics of the particle being transported determines which method is used, including its relative concentration on both sides of the membrane. (3 marks)

Question 5
Describe the functional differences between red and yellow bone marrow, and where they are generally located.
Which type of bone marrow is able to convert into the other, and under what circumstances? (3 marks)

Question 6
Distinguish between any TWO (2) different structural categories of joints. In your answer, provide a specific example of each, and relate the category of this joint to its function in the body. (3 marks)

Question 7
John (25 years old) and his mother Jane (60 years old) are in a car accident.
(4 marks total)

Both John and Jane break several ribs, and also suffer abdominal trauma, requiring surgery to their intestines.
Describe one likely difference in their recovery, for each of BONE and SMOOTH MUSCLE (in the intestinal wall), based on their age. (3 marks)

John also suffers damage to his spinal cord during the accident. Compare the likely recovery of his SPINAL CORD compared to the SMOOTH MUSCLE of his intestinal wall, and long term consequences. (1 mark)

Question 8
Figure 1 below shows the changes in pressure through time in the aorta (red line), left atrium (yellow line) and left ventricle (blue line), through two cardiac cycles. Assume the heart is functioning normally.
(0.5 marks per cell; 3 marks total)
There are 4 points in time indicated on the figure: A, B, C and D

Adapted from: adh30 revised work by DanielChangMD who revised original work of DestinyQx; Redrawn as SVG by xavax – Wikimedia Commons: Wiggers Diagram.svg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50317988
Figure 1: changes in pressure in the heart and aorta
Chose the correct answer from column 3 to indicate the time (or times) the events described in column 1 occur, and write this answer in the relevant row in column 2. An example is provided for you (in bold). Please note that ‘this never happens’ is provided as an option. Options may be needed more than once; not all options will be needed.

Column 1
Event Column 2
Place your answer here Column 3
Choose from these answers
Mitral (Left AV) valve closes A A
Pressure in the atrium drops below pressure in the ventricle B
Pressure in the ventricle drops below pressure in the aorta C
All valves are Open D
All valves are Closed between A and B only
Blood starts to flow from atrium to ventricle between C and D only
Blood starts to flow from ventricle to aorta between A and B, AND between C and D
this never happens

Question 9
This question is about the cardiovascular system. Choose the most appropriate answer from column 3, that best fits the characteristic described in column 1. No option will be needed more than once; some options will not be needed.

An example is completed for you (in bold) (0.5 marks each cell; 3 marks total)

Column 1
Cardiovascular system characteristic Column 2
Place your answer here (only the letter is needed) Column 3
Choose from these answers
Red Blood Cells (erythrocytes) J A: location where gas exchange occurs
Primary means of O2 transport B: triggered by damaged blood vessels
Erythropoiesis C: bound to haemoglobin
Extrinsic pathway D: location where blood is at the lowest pressure
Arteries E: triggered by damage to the kidneys
Albumins F: manufacture of white blood cells (leukocytes)
Capillaries G: dissolved in blood
H: triggered by a rise in blood pressure
I: act in immune response against infection
J: most common blood cell
K: location where blood is at the highest pressure
L: triggered by a drop in blood pressure
M: have a role in fluid balance between vascular system and extracellular fluid

Question 10
This question is about respiratory system functions and structure. Chose the most appropriate answer from column 3, that best fits the functional or structural characteristic described in column 1. No option will be needed more than once; some options will not be needed.

An example is completed for you (in bold)
(0.5 marks each cell; 4 marks total)

Column 1
Functional or structural characteristic Column 2
Place your answer here (only the letter is needed) Column 3
Choose from these answers
Manufactures surfactant K A: Goblet cells
Only involved in active breathing B: Alveolar macrophages
Location where first respiratory surface is encountered by air entering the lungs C: Respiratory bronchioles
Allows flexibility for food to comfortably pass down the oesophagus D: Microvilli
Engulf microorganisms and debris E: Type I alveolar cells
Pleura F: Trachea
Very large surface area G: C-shaped cartilage
Move trapped dust to the back of the throat to be swallowed H: mucociliary escalator
Small airways that can dilate or constrict I: internal intercostals
J: external intercostals
K: Type II alveolar cells/pneumocytes
L: bronchioles
M: reduce friction during respiration

Question 11
With reference to the exchange of Carbon Dioxide (CO2), explain the difference between internal and external respiration. Include in your answer:
(3 marks)
The location each process occurs
The relevant partial pressures of CO2, and the direction CO2 is moving at each location

Question 12
At what point or points (if any) during the inspiration/expiration cycle is the pressure in the alveoli the same as atmospheric pressure?
Explain your answer by describing the relative changes in pressure that occur in the lungs during the normal inspiration/expiration cycle (assume quiet breathing).
In your answer, you will need to outline:
Which muscles are contracting/relaxing
Relevant changes in volume
Relevant changes in pressure
Direction of air flow
(4 marks)

Question 13
Provide TWO reasons why the resting membrane potential is more positive outside the neuronal cell than inside the cell. Justify your answer for each reason.
(2 marks)

Case Study

The following questions all concern Robin Hood, a healthy young man of 25.

Question 14
Robin is exerting himself, running away from the Sheriff of Nottingham’s men. This question is about cardiovascular changes with exercise.
(4 marks total)

As Robin runs, the temperature inside his leg muscles starts to rise. What effect does this have on local autoregulatory control of blood flow to the leg muscles? (1 mark)

What happens to venous return to the heart, compared to when Robin is at rest? Explain why this happens. (1 mark)

What effect does this change to venous return have on cardiac output? Explain your answer (1 mark)

Robin is a fit young person. How do you expect his heart rate while exercising to compare to that of someone who is not fit and healthy, and why? (1 mark)

Question 15
Robin Hood is hiding under a pile of leaves. He is worried that if he takes slow, deep breaths, the pile of leaves will move up and down and the Sherriff’s men will notice him. Therefore, he takes rapid, shallow breaths.

With reference to dead space volume, will these two methods of breathing result in the same supply of oxygen to his alveoli? Explain why or why not.
(2 marks)

Question 16
Robin Hood is on the run again, and trips and falls into a lake. He manages to drag himself out, but not before breathing in a large quantity of water. This water reaches and fills some of his alveoli. He coughs up all the water, but this has diluted the surfactant within his lungs.

If his alveoli contain less surfactant than they should, what impact, if any, will this have on his breathing, and why? (1 mark)

Question 17
Robin has run a long way, and is now in a snowy field. He collapses from exhaustion into the cold snow, and sees a Saint Bernard dog approach him with a small barrel of whisky around its neck. Robin knows from experience that alcohol makes him flushed, and that it increases peripheral vasodilation, which makes him feel warmer. With respect to alcohol increasing blood flow to his skin, should he drink the alcohol? Why or why not?
(2 marks)

Question 18
When collapsing in the snow, discuss how the pain sensation from the extreme cold will be processed in Robin’s body in term of receptor, fibres, pathway and cortical area involved (mentioning its location).
(3 marks)

Question 19
Robin has survived the lake and the snow and is now hiding in a small but deep cave. Robin is lying down resting, consuming O2 and producing CO2.

There is a bear in the cave, and Robin holds his breath to avoid the bear hearing him breath.

Could Robin die from holding his breath for too long?

With reference to the usual way that breathing is controlled, explain why or why not.
(2 marks)

Question 20
After his rest in the cave, Robin is now running away from the cave, and his leg muscles contract.
Organise the events noted below leading to the contraction of Robin’s leg muscles.
Some steps have been pre-filled for you (in bold in the table). All events will only be needed once. (0.5 mark for each correct answer, 3 marks in total)

Events to choose from:
Action potential reaches the neuromuscular junction
Opening of the calcium channel of the sarcoplasmic reticulum
Troponin binds to Calcium leading to Tropomyosin complex moving, so actin binding sites can bind to myosin
Ach binds to Nicotinic receptor letting Na+ enter the muscle cell
Influx of calcium ions into the cytoplasm
Acetylcholine is released in synaptic cleft
Depolarisation is transmitted along the sarcolemma
Myosin binds actin
Muscle contracts
Sarcomere decreases length

Sequence of events Column 2: description/event
2 Acetylcholine is released in synaptic cleft
6 Influx of calcium ions in the cytoplasm
8 Myosin binds with actin
10 Muscles contract

Robin has escaped from the cave, and is now hiding in a hollow tree. The Sherriff of Nottingham has lit a fire to try to smoke Robin out. The fire is leading to high levels of a poisonous gas in the hollow tree. This gas has two effects:

It binds to haemoglobin (Hb) more strongly than O2 does
It shifts the O2/haemoglobin dissociation curve to the left

Questions 21 and 22 below are based on this information.

Question 21
Explain what effect the gas binding more strongly to Hb (than O2 binds to Hb) will have on O2 delivery to the tissues. Assume the gas binds at the same location as O2 usually does. (1 mark)

Question 22
An example of the O2/Hb dissociation curve is provided below (Figure 2). The central blue line represents ‘normal blood’, and the typical affinity of Hb for O2. Referring to this figure will help you answer the following questions. (4 marks total)

adapted from Tortora et al.
Figure 2: O2/Hb dissociation curve
The poisonous gas shifts this curve to the left (purple line in the figure above).

What impact will this have on O2 delivery to the tissues? Explain your answer
(1.5 marks)

In a healthy body, sometimes the O2/Hb curve shifts to the left (the purple line in the figure above). Give one example of a change to blood chemistry that may shift the curve to the left in a healthy body. Explain what impact this has on O2 delivery to the tissues, and explain why this assists in maintaining homeostasis. (2.5 marks)

Question 23
Robin has escaped from the hollow tree, and has found refuge with a friend. He has had a large meal and is now sleeping safely, hidden in his friend’s attic.

Name and describe the activity level of each of the TWO divisions of the autonomic nervous system in Robin’s body while sleeping safely. (2 marks)

Question 24
Robin Hood had escaped the lake, the snowy field, the cave and the hollow tree, and has lived a long full life in hiding. He is now 85 years old, and has suffered gradual changes to his rib cage. There has been calcification and reduced motility of the rib articulations. He finds himself short of breath, when trying to perform actions that previously caused him no difficulty.

What influence do these changes (to his rib cage) have on his respiratory function, and why is this making him short of breath? In your answer, discuss a change to one lung volume or capacity.

(2 marks)


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