Plant and Animal Responses

Question 1

what is the function of the autonomic nervous system?

Answer 1

controls involuntary responses, for example glands, smooth&cardiac muscles in blood vessels

Question 2

What is the autonomic nervous system divided into?

Answer 2

sympathetic and parasympathetic

Question 3

what are some functions and effects of the parasympathetic system?

Answer 3

conserves energy, rest and digest, decreases heart rate, constricts pupils, increases digestive activity

Question 4

what are some functions and effects of the sympathetic system?

Answer 4

increases activity and is most active at times of stress, fight or flight, increases heart rate, dilates pupils and reduces digestive activity

Question 5

what neurons do the sympathetic system use?

Answer 5

short preganglionic and long postganglionic

Question 6

what neurons do the parasympathetic system use?

Answer 6

long preganglionic and short postganglionic

Question 7

what system uses the neurotransmitter noradrenaline?

Answer 7

sympathetic system

Question 8

what system uses the neurotransmitter actylcholine?

Answer 8

parasympathetic system

Question 9

what does the hypothalamus control?

Answer 9

body temperature and osmoregulation

Question 10

what does the posterior pituitary do?

Answer 10

linked to the hypothalamus by neurosecretory cells which pass down from the hypothalamus and are released into the blood

Question 11

what does the anterior pituitary do?

Answer 11

produces its own hormones that are released into the blood in response to releasing factors

Question 12

what are releasing factors?

Answer 12

hormones that need to be transported a short distance from the hypothalamus to the pituitary

Question 13

what does the cerebrum control?

Answer 13

conscious thought, conscious actions, emotional responses, intelligence, reasoning, judgement, decision making and factual memory

Question 14

what is the cerebellum important for?

Answer 14

coordination, posture, balance

Question 15

what does the medulla oblongata control?

Answer 15

breathing and heart rate

Question 16

what systems does the medulla oblongata contain?

Answer 16

cardiac centre (heart), vasomotor centre (circulation and blood pressure), respiratory centre (rate and depth of breathing)

Question 17

what is a reflex action?

Answer 17

a response that doesn’t involve any processing by the brain

Question 18

what do most reflex pathways consist of?

Answer 18

sensory> relay> motor

Question 19

what is the reflex pathway of

the corneal reflex?

Answer 19

sensory nerve endings in the cornea are stimulated by touch, a nerve impulse is sent along the sensory neuron to a relay neuron which is then passed to motor neurons. They send the impulses to the effectors - facial muscles which causes blinking

Question 20

how can we prevent blinking?

Answer 20

the cerebral cortex sends inhibitory signals to the motor centre in the pons, the myelinated neurons transmit action potentials that prevent the reflex from occurring

Question 21

how does the knee-jerk reflex work?

Answer 21

stretch receptors in the quadriceps muscle detect that the muscle is being stretched, a nerve impulse travels along a sensory neuron which communicates directly with a motor neuron (no relay), this carries the impulse to the effector causing it to contract

Question 22

What is a physiological change during the fight or flight response? and what is its survival value?

Answer 22

pupils dilate - allows more light to enter eyes
heart rate and blood pressure increase - delivers more oxygen and glucose to muscles
errector pili muscles contract - sign of aggression
blood glucose levels increase - supplies energy for muscular contraction

Question 23

What is the process of the fight/ flight response?

Answer 23

1. inputs feed into the sensory centres in the cerebrum
2. the cerebrum passes signals to the association centres
3. if a threat is recognised, the cerebrum stimulates the hypothalamus
4. the hypothalamus increases activity in the sympathetic nervous system and stimulates the release of hormones from the anterior pituitary

Question 24

why is the endocrine system used in fight or flight?

Answer 24

because a prolonged response might be needed

Question 25

what is the mechanism of adrenaline action?

Answer 25

1. adrenaline binds to the adrenaline receptorsm, this receptor is associated with a G protein on the inner surface of the plasma membrane, which is stimulated to activate the enzyme adenyl cyclase 2. Adenyl cyclase converts ATP to cyclic AMP (cAMP), which is the second messenger inside the cell 3. cAMP causes an effect inside the cell by activating enzyme action. The precise effect depends upon the cell that the adrenaline has bound to

Question 26

corticotropin-releasing hormone causes the release of what hormone?

Answer 26

adrenocorticotropic hormone (ACTH)

Question 27

Thyrotropin- releasing hormone (TRH) causes the release of what hormone?

Answer 27

thyroid-stimulating hormone (TSH)

Question 28

what are the roles of the circulatory system?

Answer 28

transport of oxgen and nutrients to tissues, removal of waste products, transport of urea from the liver to the kidneys, distribute heat around the body

Question 29

how can the heart action be modified?

Answer 29

raising or lowering the heart rate, altering the force of contractions, altering the stroke volume

Question 30

what does it mean that the heart is myogenic?

Answer 30

can initiate its own beat at regular intervals

Question 31

what does the SAN do?

Answer 31

initiates a wave of excitation to override the myogenic action of the cardiac muscle

Question 32

what is the typical frequency of excitation?

Answer 32

60-80 per minute

Question 33

Action potentials sent down the accelerans nerve have what effect?

Answer 33

cause the release of the neurotransmitter noradrenaline which increases heart rate

Question 34

Action potentials sent down the vagus nerve have what effect?

Answer 34

cause the release of the neurotransmitter acetylcholine which reduces heart rate

Question 35

what do stretch receptors do?

Answer 35

detect movement of the limbs, these send impulses informing that more oxygen might be needed (increase heart rate)

Question 36

what do chemoreceptors do?

Answer 36

monitor pH of the blood, when we exercise, the muscles produce more carbon dioxide - some of this reacts with water to produce carbonic acid, this reduces pH and makes transport of oxygen more difficult, this change is detected by chemoreceptors which send action potentials to the CV centre (increase heart rate)

Question 37

what are characteristics of smooth muscle?

Answer 37

contracts slowly and regularly, controlled by the autonomic system and is found in the walls of tubular structures (blood vessels)

Question 38

what are characteristics of cardiac muscle?

Answer 38

cells are joined by intercalated discs, contracts and relaxes continuously

Question 39

what are characteristics of skeletal muscle?

Answer 39

arranged in antagonistic pairs, contracts quickly and powerfully

Question 40

what is the neuromuscular junction?

Answer 40

the gap between the nervous system and the muscle, it is similar to a synapse

Question 41

what is the process of stimulation of contraction?

Answer 41

1. Action potentials arriving at the end of the axon open calcium ion channels in the membrane. Calcium ions flood into the end of the axon 2. Vesicles of acetylcholine move towards and fuse with the end membrane 3. Acetylcholine molecules diffuse across gap and fuse with receptors in the sarcolemma 4. opens sodium ion channels, allowing sodium ions to enter the muscle fibre, causing depolarisation of the sarcolemma 5. wave of depolarisation spreads along the sarcolemma and down transverse tubules into the muscle fibre

Question 42

what is a motor unit?

Answer 42

when all muscle fibres contract together, providing a stronger contraction

Question 43

what is the structure of a myofibril?

Answer 43

thin filaments are aligned to make the light band (actin) and thick filaments make up the dark band (myosin)

Question 44

What is the composition of a thin filament in a myofibril?

Answer 44

- two chains of actin twisted together - molecule of tropomyosin wrapped round this - troponin molecules attached to tropomyosin

Question 45

what does troponin bind to?

Answer 45

one binds to actin, one to tropomyosin and the third to calcium (when it’s available)

Question 46

What is the composition of a thick filament in a myofibril?

Answer 46

consists of a bundle of myosin molecules, each has two protruding heads which can bind to actin

Question 47

what is the sliding filament hypothesis?

Answer 47

The sliding action is caused by the myosin heads, when the muscle is stimulated, the tropomyosin is moved aside, exposing the binding sites on the actin. The myosin heads attach to the actin and move, causing the actin to slide past the myosin

Question 48

how is a contraction controlled in the myofibril?

Answer 48

1. When the muscle is stimulated, the action potential passes along the sarcolemma and down the transverse tubules (t-tubules) into the muscle fibre 2. The action potential is carried to the sarcoplasmic reticulum, which stores calcium ions and causes the release of calcium ions into the sarcoplasm 3. The calcium ions bind to the troponin, which alters the shape pulling the tropomyosin aside. This exposes binding sites on the actin 4. Myosin heads bind to the actin, forming cross-bridges between the filaments 5. The myosin heads move, pulling the actin filament past the myosin filament 6. The myosin heads detach from the actin and can bind again further up the actin filament

Question 49

what is the role of ATP during muscle contraction?

Answer 49

1. The myosin head attaches to the actin filament, forming a cross bridge 2. The myosin head moves (tilts backwards), causing the thin filament to slide past the myosin filament. This is the power stroke. During the power stroke ADP and Pi are released from the myosin head 3. After the power stroke, a new ATP molecule attaches to the myosin head, breaking the cross bridge 4. The myosin head then returns to its original position (forward) as the ATP is hydrolysed, releasing energy to make this movement occur. The myosin head can now make a new cross bridge further along the actin filament

Question 50

what are the three ways that the supply of ATP is maintained?

Answer 50

aerobic respiration, anaerobi respiration and creatine phosphate

Question 51

how does creatine phosphate maintain the supply of ATP?

Answer 51

creatine Phosphate in the sarcoplasm acts as a reserve store of phosphate groups - the phosphate can be transferred from the creatine phosphate to ADP molecules - creating ATP quickly