Integration of body systems

Question 1

What secretes melatonin

Answer 1

The pineal gland

Question 2

What function does the cerebellum serve

Answer 2

Balance and skeletal muscle contractions

Question 3

Describe function of a sensory neurone

Answer 3

Sensory neurons carry nerve impulses from receptors (that detect stimuli) to the central nervous system (CNS).

Question 4

What is a phototropism and how is auxin involved

Answer 4

Phototropism is a plant’s growth towards light. Auxin accumulates on the shaded side of a shoot, promoting cell elongation and bending the shoot towards the light source.

Question 5

Explain how feedback mechanisms are involved in the regulation of heart rate and ventilation rate in humans

Answer 5

Heart rate control:
Baroreceptors (blood pressure) and chemoreceptors (blood pH, O2, CO2) send signals to the medulla oblongata in the brain. The medulla sends nerve impulses to adjust heart rate and stroke volume to maintain homeostasis.
Ventilation control:
Chemoreceptors in the brainstem detect changes in blood pH due to CO2 levels. Signals are sent to the diaphragm and intercostal muscles, adjusting breathing rate and depth to regulate blood pH.

Question 6

Discuss the roles of auxin and cytokinin in regulating plant growth

Answer 6

Auxin: Promotes cell elongation, involved in phototropism and gravitropism. Produced in shoot tips and transported downwards.
Cytokinin: Promotes cell division and differentiation. Produced in root tips and transported upwards.
Interaction: Auxin and cytokinin work antagonistically to regulate apical dominance (auxin promotes, cytokinin inhibits). They act synergistically to stimulate cell division and differentiation in specific ratios. Their balance influences root and shoot development.

Question 7

Using an example, describe the pathway of a reflex arc

Answer 7

Receptor: Pain receptors in the skin detect the stimulus (e.g., touching a hot object).
Sensory Neuron: Transmits the impulse from the receptor to the spinal cord.
Interneuron: Relays the impulse within the spinal cord’s grey matter.
Motor Neuron: Carries the impulse from the spinal cord to the effector.
Effector: A muscle (e.g., biceps) contracts, causing withdrawal of the hand from the painful stimulus.

Question 8

What is the role of slow-acting neurotransmitters in learning

Answer 8

Slow-acting neurotransmitters modulate fast synaptic transmission; can persist for days. They help establish memory, and memory is important for learning. When there is greater synaptic transmission there is enhanced learning (learning occurs because we have new or reinforced connections)

Question 9

Explain the effect of increasing CO2 content of air on the volume expired

Answer 9

• Increase in CO2 in blood
• Change in blood pH and CO2 concentration detected by chemoreceptors
• In the brainstem
• Impulses sent to diaphragm
• The rate and depth of ventilation increases

Question 10

What would happen if CO2 were to be raised above 7% in inspired air

Answer 10

The Ve would increase until reaching a maximum.
The blood pH would drop until reaching a fatal point below 6.8

Question 11

Identify another feedback control system that will be affected by changes in the CO2 content of inspired air. How would they respond

Answer 11

The heart rate would increase by higher CO2 because of a greater need to pump CO2 out and O2 in and around the body.

Question 12

What is the function of
1. Cerebral hemisphere
2. Cerebellum
3. Medulla oblongata
4. Vertebrae
5. Spinal cord

Answer 12

1. Cerebral hemisphere: Learning, memory, voluntary muscle control
2. Cerebellum: Control of muscular coordination of skeletal muscle contractions, balance
3. Medulla oblongata: Homeostatic functions, swallowing
4. Vertebrae: Support and protection of spinal cord
5. Spinal cord: Unconscious control, reflex actions, conveying impulses to and from the brain.

Question 13

How does auxin promote growth in plants

Answer 13

It releases hydrogen ions into the wall of the plant, which loosen the cross-links between cellulose molecules, allowing turgor pressure to stretch the wall and elongate the cell.

Question 14

Outline how concentration gradients of auxin are established in a shoot apex.

Answer 14

Using auxin efflux pumps that are embedded in the plasma membrane of shoot apex cells, the auxin concentration is reduced in the cell and increased in the adjacent cell

Question 15

Explain the role of auxin gradients

Answer 15

Causes more growth on one side of the stem than another, causing it to bend. It is a phototropism response to brighter light on one side, when the shoot bends towards that side.

Question 16

Describe the roles of white matter and gray matter in the nervous system

Answer 16

White matter transmits the electrical impulses quickly due to myelinated nerves, connecting different CNS regions. Gray matter processes information locally because it contains neurone cell bodies and synapses thus is involved in the processing and transmitting of physiological processes.

Question 17

How do the palisade mesophyll and the spongy mesophyll interdependently contribute to photosynthesis?

Answer 17

The palisade mesophyll is densely packed and full of chloroplasts, which maximize its capturing of light energy. The spongy mesophyll supplies CO2 for the Calvin cycle and provides a space and surface area for gases to move (CO2, O2, water vapour)

Question 18

What is the importance of feedback mechanisms in regulating body systems

Answer 18

They maintain homeostasis. They ensure effective communication between nerves and hormones, coordinating bodily functions.

Negative feedback: counteracts changes to stabilize conditions. i.e. regulation of body temperature.

Positive feedback: amplifies responses for specific processes. i.e. oxytocin in child birth.

Question 19

What are some effects of hormonal signals on bodily reactions?

Answer 19

• Homeostais
• Metabolism
• Development and growth
• Reproduction

Slower but longer-lasting responses

Question 20

What does a loss of myelin cause

Answer 20

It slows down the electrical signals, leading to impaired movements and sensations due to the disruption of signal transmissions.

Question 21

What role does the light-dependent reaction play in photosynthesis, and how does it relate to the functions of the palisade mesophyll?

Answer 21

The light-dependent reaction converts solar energy into chemical energy (ATP and NADPH) using chloroplasts found in the palisade region.

Question 22

What is cortisol

Answer 22

A steroid hormone produced by the adrenal glands, playing a vital role in various bodily functions, including regulating metabolism, immune response, and stress response. It helps control blood sugar levels, reduce inflammation, and assist with memory formulation.

Cortisol levels peak in the morning and decline throughout the evening, in line with the body’s circadian rhythm.

Question 23

What is Cushing’s syndrome

Answer 23

Cushing’s syndrome is a condition characterized by excessive levels of cortisol in the body, often due to an adrenal adenoma (benign tumor) or other causes such as pituitary tumors or prolonged use of corticosteroid medications. Symptoms may include weight gain, high blood pressure, diabetes, and changes in skin appearance. The condition can lead to serious health complications if left untreated, making early diagnosis and management crucial.

Question 24

How might a hormonal dysfunction affect the nervous system’s ability to regulate mood and cognitive function?

Answer 24

As cortisol can impair neurotransmitter function and neuroplasticity, it will lead to mood disorders and cognitive deficits, like poor memory and high stress levels.

Question 25

How do nerves and hormones work together to regulate blood glucose levels in this patient?

Answer 25

Nerves detect when changes in blood glucose levels, signalling the pancreas to release insulin when blood glucose is high. Hormones, particularly insulin, then facilitate the uptake of glucose by cells, helping to lower blood sugar levels

Question 26

What role does the hypothalamus play in integrating the nervous and endocrine systems in response to stress?

Answer 26

The hypothalamus signals for the pituitary gland to release hormones like epinephrine or cortisol during responses to strong emotional stimuli.

Question 27

How does the nervous system contribute to intense training sessions?

Answer 27

It will respond to signals for increased hormone activity like epinephrine, which increases heart and muscle activity in the ‘fight or flight’ response and breaks down glycogen to enhance energy availability, as well as the signals from baroreceptors and chemoreceptors which will signal for increase of heart and ventilation rate.

Question 28

What role does glucagon play in feedback mechanisms related to blood sugar?

Answer 28

It raises blood sugar levels when they are low