5.1.5 plant and animal responses

Question 1

What is the Central nervous system and the Peripheral nervous system?

Answer 1

The CNS consists of the brain and spinal cord (relay neurones), and the PNS consists of all the neurones that connect the CNS to rest of the body (sensory and motor neurones).

Question 2

What is the Somatic nervous system?

Answer 2

The system which is under conscious control, conducts impulses from the sense organs to skeletal muscles.

Question 3

What is the Autonomic nervous system?

Answer 3

The system which is under subconscious control and is involuntary, and conducts impulses to the cardiac muscle, smooth muscle, and glands.

Question 4

What is the sympathetic motor system?

Answer 4

‘fight or flight’ response, and neurotransmitter: noradrenaline.

Question 5

What is the the parasympathetic motor system?

Answer 5

relaxing responses, and neurotransmitter: acetylcholine.

Question 6

What are the five main parts of the brain?

Answer 6

-Cerebrum
-Cerebellum
-Medulla Oblongata
-Hypothalamus
-Pituitary gland

Question 7

What is the function of the Cerebrum?

Answer 7

The Cerebrum controls voluntary actions: vision, hearing, learning, and thinking.

Question 8

What is the function of the Cerebellum?

Answer 8

The Cerebellum controls unconscious functions: posture, balance, and non-voluntary movement.
It does not initiate movement but coordinates it.

Question 9

What is the function of the Medulla Oblongata?

Answer 9

The Medulla Oblongata is used in autonomic control and controls reflex actions. It controls heart rate and breathing rate for example.

Question 10

What is the function of the Hypothalamus?

Answer 10

The Hypothalamus is the regulatory centre for temperature and water balance.
It controls complex patterns of behaviour, monitors the composition of blood plasma, and produces hormones (endocrine gland).

Question 11

What is the function of the Pituitary gland?

Answer 11

The Pituitary gland stores and releases hormones, and stimulates other glands.

Question 12

What is the Posterior and Anterior Pituitary?

Answer 12

The Posterior Pituitary (back) stores and releases hormones made by the Hypothalamus e.g. ADH.
The Anterior Pituitary (front) produces six hormones involved in reproduction and growth e.g. FSH.

Question 13

What are the four parts of the Cerebrum?

Answer 13

-Frontal lobe
-Temporal lobe
-Parietal lobe
-Occipital lobe

Question 14

What does the Frontal lobe control?

Answer 14

Behaviour, decision making, and emotion.

Question 15

What does the Temporal lobe control?

Answer 15

Auditory (languages).

Question 16

What does the Parietal lobe control?

Answer 16

Senses.

Question 17

What does the Occipital lobe control?

Answer 17

Vision, perception, motion, and colour.

Question 18

What is the standard pathway for the reflex arc?

Answer 18

-Stimuli
-Receptor
-Sensory neurone
-Relay neurone
-Motor neurone
-Effector
-Response

Question 19

What is the knee-jerk reflex?

Answer 19

The knee-jerk reflex is a spinal reflex commonly tested by doctors.
The Patellar tendon is knocked which causes stretching and stimulates stretch receptors in quadriceps, this is passed to sensory neurone and then motor neurone and to the effector.
The leg should normally straighten.
The reflex helps the body to maintain posture and balance.

Question 20

What is the blinking reflex?

Answer 20

The blinking reflex is a cranial reflex.
When the cornea detects a stimulus, it sends a signal to the brain and sent along branches to close the eyelids at the same time (consensual response).
Doctors test this reflex on unconscious people, if the reflex works it indicates the lower brain stem is functioning, if not the patient is considered brain dead.

Question 21

What are the three main types of muscle?

Answer 21

-Skeletal muscle.
-Cardiac muscle.
-Involuntary muscle.

Question 22

What is the structure of Skeletal muscle?

Answer 22

-Striated.
-Regularly arranged=>muscle contracts in one direction.
-Fibres are tubular and multinucleated.

Question 23

What is the structure of Cardiac muscle?

Answer 23

-Specialised striated.
-Cells branch and interconnect=>simultaneous contraction.
-Fibres are branched and uninucleated.

Question 24

What is the structure of Involuntary muscle?

Answer 24

-Non-striated.
-No regular arrangement=>different cells contract in different directions.
-Fibres are spindle shaped and uninucleated.

Question 25

What is the contraction speed and length of Skeletal, Cardiac, and Involuntary muscle?

Answer 25

Skeletal- rapid speed and short length. Cardiac- Intermediated speed and length. Involuntary- slow speed and relatively long length.

Question 26

What is the control of Skeletal, Cardiac, and Involuntary muscle?

Answer 26

Skeletal-conscious/voluntary. Cardiac-involuntary. Involuntary-involuntary.

Question 27

What is the gross structure of skeletal muscle?

Answer 27

-Muscle cells fused together to form bundles of parallel muscle fibres (myofibrils)=>ensures there is no point of weakness between cells. -Each bundle surrounded by endomycium: loose connective tissue with many capillaries.

Question 28

What is the structure of a muscle fibre?

Answer 28

Enclosed in sarcolemma, shared cytoplasm within a muscle fibre called sarcoplasm. Parts of the sarcolemma fold inwards (transverse tubules). Contains myofibrils which are high specialised for contraction, and Sarcoplasmic reticulum.

Question 29

What is the role of the Sarcoplasmic reticulum?

Answer 29

-storage and release of Ca2+ for muscle contraction.

Question 30

What is Actin?

Answer 30

Actin is the thinner filament.

Question 31

What is Myosin?

Answer 31

Myosin is the thicker filament.

Question 32

What are I-bands in myofibrils?

Answer 32

Areas appear light because they are the region in which Actin and Myosin do not overlap (only Actin).

Question 33

What are A-bands in myofibrils?

Answer 33

Areas appear dark because of the thick Myosin filaments, with dark edges because of the overlap of Myosin and Actin.

Question 34

What are Z-lines in myofibrils?

Answer 34

Line in the centre of each I-band, distance between adjacent z-lines is a sarcomere.

Question 35

What is the H-zone in myofibrils?

Answer 35

Lighter coloured region in the centre of each A-band (only Myosin).

Question 36

What happens during contraction when Myosin filaments pull Actin filaments towards centre of sarcomere?

Answer 36

-The I-band becomes narrower. -The Z-lines move closer together, shortening the sarcomere. -The H-zone becomes narrower.

Question 37

Which part of the brain is responsible for controlling heart rate?

Answer 37

Medulla Oblongata.

Question 38

What does the Inhibitory centre do in the Medulla Oblongata?

Answer 38

The Inhibitory centre decreases the heart rate by sending impulses through the parasympathetic nervous system, these impulses are transmitted through the vagus nerve.

Question 39

What does the Accelerating centre do in the Medulla Oblongata?

Answer 39

The Accelerating centre increases the heart rate by sending impulses through the sympathetic nervous system, these impulses are transmitted through the accelerator nerve.

Question 40

What receptors detect blood pressure and blood pH?

Answer 40

Blood pressure-Baroreceptors. Blood pH-Chemoreceptors.

Question 41

Why does exercise increase cardiac output?

Answer 41

Exercise increases breathing rate, and increases CO2 concentration in blood. This causes the pH of the blood to rise.

Question 42

How does the body respond to an increase in blood pH?

Answer 42

The increase in blood pH is detected by chemoreceptors carotid arteries. This stimulates the ventilation centre of the medulla to increase breathing rate. By releasing noradrenaline through the sympathetic nerve, this stimulates frequency of nerve impulses to acceleratory centre and increases heartrate.

Question 43

How does the body respond to an increase in blood pressure?

Answer 43

Increase in blood pressure is detected in the carotid arteries and aorta. A nerve impulse is sent in the medulla to the inhibitory centre. By releasing acetylcholine through the parasympathetic nerve, impulses sent to SA node and heart rate decreases.