Human Physiology

Question 1

Which features of the alveoli adapt them to gaseous exchange?

Answer 1

• Single layer of cells.
• Film of moisture.
• Dense network of capillaries.

Question 2

Where do motor neurons conduct impulses from and to?

Answer 2

From the central nervous system to effectors.

Question 3

Which feature of striated muscle cells allows them to be considered as a possible exception to cell theory?

Answer 3

They contain more than one nucleus.

Question 4

Where can 70s ribosomes be found?

Answer 4

In prokaryotic cells.

Question 5

Which is the correct statement concerning HIV and AIDS?

Answer 5

All AIDS patients have HIV.

Question 6

Which of the following is correct for lipase?

Answer 6

Substrate: Triglycerides
Source: Pancreas
pH - 7

Question 7

What is the body’s response to low blood glucose levels?

Answer 7

Alpha cells in the pancreas secrete glucagon.

Question 8

What causes the atrioventricular valve to close during a heartbeat?

Answer 8

Pressure in the atria is lower than the ventricles.

Question 9

What happens to the external and internal intercostal muscles and diaphragm when inhaling?

Answer 9

External intercostal muscles: Contract
Internal intercoastal muscles: Relax
Diaphragm: Contracts

Question 10

What feature of arteries is most important in maintaining sufficiently high blood pressure?

Answer 10

Elastic fibres in the wall.

Question 11

Testosterone is a hormone that is important for male reproductive development. To which group of compounds does testosterone belong?

Answer 11

Lipids

Question 12

What is a feature of phagocytic white blood cells?

Answer 12

Form part of non-specific immunity.

Question 13

How do neonicotinoid pesticides cause paralysis and death in insects?

Answer 13

• Acetylcholine receptors are blocked.
• Cholinesterase fails to break down the pesticides.

Question 14

A female is overweight. feels cold and tired and often fails to ovulate during the menstrual cycle. Which two hormones are probably secretes at insufficient levels?

Answer 14

LH and thyroxin.

Question 15

When the left ventricle is relaxed, what is the state of the valves?

Answer 15

Atrioventricular valve: Open
Semilunar valve: Closed

Question 16

Which of the following tissues would be found in the human ileum and stomach
I Mucosa
II Smooth muscle
III Villi

Answer 16

I Mucosa
II Smooth muscle

Question 17

Where in the human heart would the pressure of the blood be highest?

Answer 17

Left ventricle

Question 18

Which of the following are known as increasing the risk of developing lung cancer?

Answer 18

I Tobacco smoke
II Radon gas
IV Asbestos dust

Question 19

Which of the following are involved in changing the rate of the heart beat?
I Medulla oblongata
II Adrenaline (epinephrine)
III Baroreceptors
IV AV node

Answer 19

I Medulla oblongata
II Adrenaline (epinephrine)
III Baroreceptors

Question 20

Florey an Chain tested penicillin on…

Answer 20

Bacterial infections in mice and humans

Question 21

Which of the following statements about pneumocytes is correct?

Answer 21

Type 1 pneumocytes: Exchange respiratory gases
Type II pneumocytes: Secrete surfactant

Question 22

Which of the following statements is a correct summary of inspiration?
A. Diaphragm and rib cage move down and flatten, decreasing lung air pressure
B. Diaphragm and rib cage move up and down, decreasing lung air pressure
C. Diaphragm flattens and rib cage moves upwards and outwards, decreasing lung air
pressure
D. Diaphragm flattens and rib cage moves upwards and outwards, increasing lung air
pressure

Answer 22

C. Diaphragm flattens and rib cage moves upwards and outwards, decreasing lung air
pressure

Question 23

The myelination of nerve fibres causes:
A. More accurate nervous transmission
B. Sensory stimulation
C. Saltatory transmission
D. The use of less neurotransmitter

Answer 23

C. Saltatory transmission

Question 24

Depolarisation of the neuron membrane is caused by
A. The sodium pump
B. The outflow of potassium ions
C. Active transport
D. The opening of sodium channels

Answer 24

The opening of sodium channels

Question 25

Which is the correct sequence of events in transmission across a chemical synapse?

Answer 25

Fusion of synaptic vesicles with the presynaptic membrane Diffusion of neurotransmitter across the synaptic cleft Neurotransmitter binds to receptors on the post synaptic membrane Sodium ions enter the post synaptic membrane

Question 26

Describe how leptin is involved in controlling the appetite.

Answer 26

Secreted by adipose/fat storage tissue Transported in blood (Target organ) is the hypothalamus Suppresses appetite/reduces food intake

Question 27

12. In vitro fertilisation usually involves hormonal treatment that regulates the menstrual cycle. Give one reason why this is necessary to maximise the possibility of successful treatment.

Answer 27

Overproduction/harvesting of large numbers of ovae/reduction in invasive treatment Regulating/controlling menstrual cycle for harvesting ovae/implanting Maximising success of zygote (reintroduced at correct point of cycle)

Question 28

13. Describe the role of the SRY gene in determining gender in humans.

Answer 28

SRY determines male gender On Y chromosome Stimulates the production of TDF Causes development of male gonads (in foetus)

Question 29

Explain how the damage to lung alveoli causes an emphysema patient to have rapid ventilation

Answer 29

Collapse / damage / thickening of alveoli walls / pneumocytes Gas exchange reduces because of a reduced surface area of alveoli O2 concentration in blood decreases / blood CO2 concentration increases / lower pH of blood Respiratory centre of the brain / homeostasis increases ventilation rate (medulla oblongata - but not required)

Question 30

Dialysis tubing can be used to model absorption in the human intestine. Outline two ways in which this model is limited as a representation of the living system.

Answer 30

Anatomic – no microvilli/absorptive epithelium/tissue layers Physiological – simple diffusion/no active transport/facilitated diffusion

Question 31

List four factors that increase the risk of heart attacks and coronary thrombosis.

Answer 31

High blood glucose levels/diabetes Smoking/nicotine intake High blood cholesterol levels Long term/chronic high blood pressure Obesity Lack of exercise Genetic predisposition

Question 32

Antibiotic resistance is an increasingly serious medical problem. Describe two measures which can be taken to limit the increase in the numbers of resistant strains of bacteria.

Answer 32

High hygiene standards; Prevents the transfer of bacteria; Minimise antibiotic prescription; Reduces exposure of bacteria to antibiotics; Completing a course of antibiotic treatment; Prevents resistant bacteria surviving to reinfect host.; Avoiding mass usage of antibiotics e.g. in animal farming; reduces exposure of bacteria to antibiotics; Research to develop new antibiotics; Provides more antibiotics which have less resistant strains of bacteria:

Question 33

Neonicotinoid pesticides bind irreversibly to cholinergic receptors. Describe how this mechanism allows them to be efficient pesticides.

Answer 33

Receptors in post-synaptic membrane Remain bound to receptor Prevent binding of transmitter (Therefore) prevent post synaptic excitation Effectors are not stimulated

Question 34

What happens during inspiration?

Answer 34

The volume inside the thorax increases and consequently the pressure decreases. The diaphragm contracts. Muscles in the abdomen wall relaxes. External intercostal muscles contracts. Internal intercostal muscles relaxes.

Question 35

What happens during expiration?

Answer 35

The volume inside the thorax decreases and consequently the pressure increases. The diaphragm relaxes. Muscles in the abdomen wall contracts. External intercostal muscles relaxes. Internal intercostal muscles contracts.

Question 36

Outline the negative and positive feedback loops at the end of the follicular stage

Answer 36

- Estrogen rises to a peak towards the end of the follicular stage. It stimulates the repair and the thickening of the endometrium and an increase in FSH receptors that makes the follicles more receptive to the hormone - FSH, boosting estrogen production. (positive feedback loop). - When it reaches high level, estrogen inhibits the secretion of FH, and stimulates LH secretion. (negative feedback loop).

Question 37

What happens to the hormone LH, at the end of the follicular phase?

Answer 37

- LH rises to a sudden sharp peak at the end of the follicular phase. - It stimulates the completion of meiosis in the oocyte and partial digestion of the follicle wall allowing it to burst open at ovulation. - LH promotes the development of the wall of the follicle after ovulation into the corpus luteum which secretes estrogen (positive feedback loop) and progesterone.

Question 38

Outline the negative feedback that occurs at the start of the luteal phase

Answer 38

- Progesterone levels rise at the start of the start of the luteal phase and then drops back to the low level by the end of this phase. - Progesterone promotes the thickening and maintenance of the endometrium. - Progesterone inhibits the secretion of FSH and LH secretion by the pituitary gland (negative feedback).

Question 39

Outline the roles of FH and LH in the menstrual cycle

Answer 39

- FSH and LH are protein hormones produced by the pituitary gland that bind to FSH and LH receptors in the membranes of follicle cells. - These pituitary hormones stimulates the growth of several ovarian follicles, each containing one egg. -Stimulates follicular growth and ovulation.

Question 40

Outline the roles if estrogen and progesterone in the menstrual cycle.

Answer 40

- Estrogen and progesterone are ovarian hormones, produced by the walls of the follicle and corpus luteum. They are absorbed by many cells in the female body, where they influence gene expression and therefore development.

Question 41

Outline the steps of in vitro fertilization

Answer 41

1. The woman takes a drug each day which stops the pituitary gland from secreting LH and FSH hormones. 2. Secretion of estrogen and progesterone therefore stops. 3. Intramuscular injections of FH and LSH are then given daily for about 10 days, to stimulate follicles to develop. 4. Superovulation occurs as more FSH is injected than usually, promoting further development of follicles. 5. Follicles become mature when being stimulated by the injection of HCG. 6. A micropipette mounted on an ultrasound scanner is passed through the uterus wall to wash out the eggs and the sperm cells in sterile conditions in a shallow dish which is then incubated in a shallow dish which is then incubated at 37 degrees, until the next day. 7.Embryos are placed in the woman's uterus when they are 48 hours old. 8. Extra progesterone tablet is placed in the vagina to ensure that the endometrium is thickened and lined.