C3.1 Integration of body systems

Question 1

Comparing hormonal and nervous signalling

Answer 1

Hormone signalling: GDRCCCM
- God do repreat can’s country mice
Nervous signalling: CCCS
- can cooks clean sinks

Question 2

What is crucial to integrate systems

Answer 2

communication between the different components

Question 3

The difference between unconscious processes and conscious processes

Answer 3

Unconscious processes:
- can happen when asleep
- involunatary
- controlled by the brain and the spinal cord
- glands and smooth muscle are controlled involuntarily
- e.g.: peristalsis (though this is controlled by the enteric nervous system)

Conscious processes
- only happen when awake
- volunatry
- controlled by the cerebral hemispheres of the brain
- striated muscle is controlled voluntarily
- example: chewing food

Question 4

What acts as the integrating centre for unconscious processes?

Answer 4

• the grey matter of the spinal cord

Question 5

The pathway how unconscious actions occur

Answer 5

• neurons bring information to the grey matter of the spinal cord and from the sense organs
• interneurons pass impulses via synapses between neurons in the grey matter
• decides the appropriate action for the stimuli
• motor neurons convey signals from grey matter -> muscles and glands

sense organs/receptors -> sense neurons -> interneurons (spinal cord) -> motor neurons -> effectors (for the response)

Question 6

Why does the spinal cord coordinate unconscious processes

Answer 6

Quicker than conveying signals to the brain
- useful especially in dangerous situations

Question 7

How does the sensory neuron convey messages from the receptors to the CNS?

Answer 7

• receptor cell detect a change in the external/internal environment*
• receptor cells sends a signal to sensory neurons*
• the sensory neurons convey the impulses to the CNS via the spinal nerves or the cranial nerves (axon)

spinal or cranial depending on where the signal is coming from

• note: for sensory neurons, they have nerve endings that already act as receptors for touch and heat. so in that case, then no need for a receptor cell

Question 8

Where are the receptor cells located?

Answer 8

• in the skin and sense organs

Question 9

What do receptor cells do?

Answer 9

Detect changes in the external environment
- e.g. the rod and cone cells in the retina of the eye detect light

Question 10

From which source does the spinal cord attain sensory information?

Answer 10

• signals from other organs of the body (skin, muscles)

Question 11

From where does the brain attain sensory information?

Answer 11

• all the signals come from the sense organs on the head: the eyes, ears, nose and tongue
• sensory inputs to the brain are received by specialized areas in the cerebral hemispheres
• for example, the visual cortex receives signals from rod and cone cells

Question 12

Parts of the spinal cord

Answer 12

Two main tissues:
1.) The white matter
- transmission centre.
- contains axons
- carry impulses to and from the brain
2.) The grey matter
- contains cell bodies of neurons and many synapses
- processing centre for unconscious movements
- decides on the appropriate reaction for the stimuli

Question 13

Describe the cerebral hemisphere

Answer 13

• part of the brain that plays a major role in conscious movements
• conscious movements -> control of striated muscles
• specifically the motor cortex sends the signals

Question 14

Striated muscle where is it attached?

Answer 14

To the bone

Question 15

Wh

What is striated muscle used for?

Answer 15

• to maintain posture
• for locomotion (e.g. standing up)

Question 16

Overall, how is information conveyed from receptors to the CNS?

Question 17

How do motor neurons convey messages from the CNS to the muscles?

Answer 17

• the motor neurons receive signals from interneurons from their many dendrites
• one axon leads from the cells body of the motor neuron out of the brain and down the spinal cord
• there, synapse is formed with a second motor neuron whose axon leads to one specific muscle
• the second motor neuron’s axon leads to a specific straited muscle
• then contraction is stimulated once the nerve impulse reaches the end

summary: interneuron -> first motor neuron which has the axon leading out of the brain and down the spinal cord -> the second motor neuron receives the signal via synaptic transmission -> signal sent to the effector for response

Question 18

Define what a nerve is

Answer 18

• bundle of nerve fibres enclosed in a protective sheath

Question 19

Which nerve is the widest?

Answer 19

• ## the sciatic nerve is the widest (20 mm across)

Question 20

Optic nerve

Answer 20

contains up to 1.7 million nerve fibres

Question 21

How many fibres would small nerves contain

Answer 21

• fewer than a hundred

Question 22

How many nerves do the organs of the body have

Answer 22

• one or two nerves

Question 23

Define reflex arc

Answer 23

rapid involuntary response to a specific stimulus

Question 24

What helps to speed up reflexes?

Answer 24

• reflexes being the simplest type of coordination in the nervous system
• signals pass through the smallest number of neurons

Question 25

Outline the process of the reflex arc

Answer 25

1. Receptor cells/sensory nerve endings perceive the stimulus.
2.** Sensory neurons receive signals**. Pass them as nerve impulses to the brain or spinal cord via long axons
- The axons end at the interneuron in the grey matter of the spinal cord or brain
3. Interneurons in the grey matter process the signals and make decisions on an appropriate response
4. Motor neurons receive signals via synapses with interneurons. If action potential is achieved, the motor neuron will transmit the signal to an effector
5. Effectors carry out the response after receiving the signal

Question 26

Describe the cerebellum

Answer 26

• part of the brain
• the coordination center of the brain
• important in: balance, posture, actions that need muscle memopry and the timing of contractions
• BUT does not decide which muscle to contract

Question 27

How long is a cicardian rhythm?

Answer 27

24 hours

makes sense because it is to be in sync with the day and the night

Question 28

Describe the superchiasmatic nucleus

Answer 28

• group of cells that set the cicardian rhythm
• controls the secretion of the hormone melatonin by the pineal gland
• a nucleus in the hypothalamus

Question 29

When is melatonin secretion at its highest and its lowest?

Answer 29

• Highest: during the night
• Lowest: during the dawn

Question 30

How is melatonin decreased?

Answer 30

• by being “rapidly removed” by the liver
• so blood concentration rise and fall rapidly in response to rate of secretion

Question 31

The effects of melatonin

Answer 31

• sleepiness or drowsiness (sleep-wake cycle)
• affecting sexual maturation (puberty) by the regulation of the growth hormone
• enhances the immune response of the helper T cells to avoid inflammation (?)
• reduction in urine production
• drop in core body temperature
• decrease in blood pressure

Question 32

Explain the sleep-wake cycle effect of melatonin

Answer 32

• ^ melatonin = ^ sleepiness
• v melatonin levels = encourage waking at the end of the night

Question 33

How does the SCN know whether to inhibit or promote melatonin secretion

Answer 33

• by knowing what time of day it is -> by synchronizing with the visible light wavelengths
• a ganglion cell in the retina of the eye detects light in the wavelength of 460-480 nm and passes impulses to cells in the SCN
• signals to SCN the timing of dusk and dawn
• allows the SCN to adjust melatonin secretion so it corresponds to the day-night cycle

Question 34

Describe epinephrine

Answer 34

• epinephrine is also known as adrenaline
• aka “fight or flight”
• secreted by the adrenal glands
• prepares the body for vigorous activity

Question 35

Outline the different effects of epinephrine

Answer 35

• striated muscle fibres convert glycogen -> glucose, increasing supplies for respiration
• liver cells do the same and put it into blood transport for the muscles
• broncioles in the lungs dilate/widen -> ventilation ez’ier
• the intercostal muscles and diaphragm contract faster and more forcefully -> a larger total volume of air is breathed in and out per minute*
• sinoatrial node speeds up the heart rate
• arterioles carrying blood to muscles and liver widen/vasodilate
• arterioles carryin blood to the gut, kidneys and skin narrow (vasoconstrict) so less blood to them

• due to the cells in the brainstem that control the ventilation (in the respiratory center)

Question 36

What controls epinephrine secretion?

Answer 36

• the brain

Question 37

When does epinephrine increase

Answer 37

it increases when vigorous activity may be necessary (threat or opportunity)

Question 38

Describe the hypothalamus

Answer 38

• small region of the brain
• major role in the integration of body systems
• links the nervous sustem to the endocrine system via the pituitary gland
• has specialized areas called nuclei which control one or more specific systems
• e.g. superchiasmatic nucleus and the sleep wake syscle

Question 39

What kind of sensors do the nuclei have?

Answer 39

• blood temperature
• blood glucose concentration
• osmolarity
• concentrations of various hormones

Question 40

What do the nuclei of the hypothalamus do exactly?

Answer 40

• they direct what hormone would be secreted by the pituitary gland

Question 41

From where do some of the many nuclei receive signals?

Answer 41

• sense organs either directly or indirectly via the cerebral hemispheres
• other parts of the brain such as the medulla oblongata

Question 42

How is the hypothalamus and the pituitary gland connected

Answer 42

by a narrow stalk

Question 43

What are the two parts of the pituitary gland?

Answer 43

• anterior and posterior lobes
• but both secrete hormones into blood capillaries (hypothalamus controlled)

Question 44

What are the hormones secreted by the posterior pituitary and the anterior pituitary

Answer 44

Posterior pituitary
- antidiueretic hormone (ADH)
- oxytocin
Anterior pituitary
- luteinizing hormone (LH)
- follicle-stimulating hormone (FSH)

Question 45

Describe how the heart rate is controlled

Answer 45

• the baroreceptor in the walls of the aorta and carotid arteries monitor blood pressure
• the chemoreceptors monitor the CO2, oxygen and pH
• if something is too low or too high, they will send a signal to the cardiovascular centre to stop it (negative feedback)
• the signal will then be send to the sinoatrial node either through the vagus or the sympathetic nerve
• the heart rate either accelerates or decreases

Question 46

What happens when the heart rate is faster?

Answer 46

• lower CO2 and higher oxygen (because of gas exchange)
• higher pH levels due to lowered CO2
• higher blood pressure

• due to the cardiac output: heart rate x volume of blood being pumped out

Question 47

What is the normal range for blood pH?

Answer 47

7.35-7.45

kept within this range by negative feedback

Question 48

At which levels of blood pH is it considered life-threatening?

Answer 48

below 6.8 (acidosis)

Question 49

What are the causes for higher ventilation rate

Answer 49

• high CO2 levels/low blood pH (to get out the CO2 using gas exchange)
• low oxygen concentration

Question 50

What are the causes for an increased heart rate

Answer 50

• low blood pressure
• low oxygen concentration
• low pH levels (lots of CO2)

the similarities with the ventilation rate and the heart rate would make it seem that they are two positively correlational? like why when we are nervous, our heart starts to beat fast and we begin to breathe heavily

Question 51

Describe the control of the ventilation rate

Answer 51

• the chemoreceptors in the walls of the aorta and the carotid arteries monitor blood pH
• the chemoreceptors in the carotid walls monitor the O2 conc.
• if they detect something wrong, they will signal to the respiratory centre in the brain stem to alter the ventilation rate (negative feedback)
• the signals will then be sent to the muscles that are used in breathing to contract *
• then when these muscles contract, signals from stretch receptors indicate it to the respiratory centre
• it will then stop the signals of inhalling and exhaling

• depending on what the signalling is, it would lead to more contractions per period of time or not

Question 52

Define peristalsis

Answer 52

• wave of contraction and relaxation in the wall of the gut
• moves food from mouth to anus

Question 53

What are two layers of the gut involved in peristalsis

Answer 53

• both are smooth muscle
• longitudinal muscle (outer)
• the circular muscle (inner)

Question 54

Describe peristalsis

Answer 54

• The circular muscle behind the partially digested food in the gut contracts to avoid the food returning to the mouth
• the longitudinal muscles shorten to push the food forwards along the gut

Question 55

What controls the peristaltic muscle contractions in the gut?

Answer 55

the enteric nervous system

Question 56

Outline two gut movements that are not controlled by the enteric nervous system and are voluntary

Answer 56

• swallowing. tongue initiates it by pushing the food back of the mouth cavity and the tongue is made of striated muscle. tongue is also under control by the brain
• defecation — it is involuntary in babies but voluntary in adults or young children

Question 57

Describe defecation

Answer 57

• the removal of faeces from the rectum via the anus
• the amus contains a small ring of smooth muscle (ie. the sphincter
• ther wall of the rectum contains layers of circular and longitudinal smooth muscle
• during defecation, the anus relazes and widen and the wall of the rectum contracts