animal responses

Question 1

What is the mammalian nervous system organised into and what do they consist of?

Answer 1

CNS: Brain and Spinal Cord
PNS: Neurones which connect the CNS to the rest of the body. [Sensory and Motor neurones]

Question 2

What does the PNS divide into, and what are each of these systems responsible for?

Answer 2

Somatic nervous system: Conscious control of movements such as voluntary movement of a muscle
Autonomic nervous system: Involuntary movements , for example the beating of the heart under unconscious control

Question 3

What is the difference between the parasympathetic and sympathetic nervous system

Answer 3

Sympathetic: Fight or flight, for example increased heart rate
Parasympathetic: Rest or digest, for example returning digestion to normal

Question 4

Why are many autonomic functions also controlled by the somatic nervous system?

Answer 4

People may consciously choose to control involuntary actions such as holding their breathe under water.

Question 5

What is the CNS and what is the advantage of having a CNS?

Answer 5

Processes all the information received by receptor cells about the environment and then produces a coordinated response.

The advantage of having a CNS is that communications between neurones will be faster since it is not distributed all around the body.

Question 6

What are the main components of the brain?

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Label a diagram of the brain and compare to a textbook diagram

Answer 6

Cerebrum, Cerebellum, Medulla oblongata, Hypothalamus , Pituitary gland

Question 7

What is the cerebrum, its adaptions and its functions?

Answer 7

Able to receive sensory information, interpret with previous help knowledge and send impulses along motor neurones to effectors to produce a response.

High convoluted/folded to have a high capacity for complex activity

Most sophisticated process occur in the frontal and prefrontal lobe such as decision making.

Hemispherically lateralised

Question 8

How do the sensory and motor areas in the cerebrum process information?

Answer 8

Sensory: Receives information from receptors in sensory organs. The size of sensory area is dependent on relative number of receptor cells on the sensory area. The information is then passed to association areas.

Motor: Impulses will arrive in motor areas to be send to effectors, the size of motor area is relative to the amount of motor endings in it, The main region which controls movement is the motor cortex .

Question 9

What is the function of the Cerebellum? What happens if the Cerebellum is damaged?

Answer 9

Concerned with muscular movement, posture and balance and receives information from balance organs.

Damage will lead to jerky and uncoordinated movements.

Question 10

What is the function of the Medulla Oblongata?

Answer 10

Contains the regulatory centres of the autonomic nervous system and controls functions such as ventilation and heart rate. ( Unconscious actions )

Question 11

What is the function of the hypothalamus?

Answer 11

The main controlling region for the autonomic systems containing the parasympathetic and sympathetic NS. Involved in homeostasis such as the control of blood glucose.

Question 12

What is the function of the pituitary gland and what are the differences between the two types of glands it contains?

Answer 12

Acts as the master gland and controls most the glands in the body, contains the anterior and posterior gland.

Anterior: Produces hormones
Posterior: Stores and releases hormones produced by the hypothalamus

Question 13

What is a reflex action?

Answer 13

When the body is in danger and will respond to a situation without conscious thought.

Question 14

What occurs in a reflex arc in simple terms?

Answer 14

Receptor neurone: Will detect a stimuli and creates an action potential to send to the sensory neurone
Sensory neurone: Will send the impulse to the spinal cord
Relay neurone: Will connect the sensory neurone to a motor neurone found in the spinal cord or brain
Motor neurone: Carries impulse to the effector to produce a response

Question 15

What occurs in a knee-jerk reflex?

Answer 15

1) The patellar tendon is stretched, this is a stimuli.
2) This stimulus initiates a reflex arc causing the extensor muscle to contract
3) At the same time a relay neurone will inhibit a motor neurone of the flexor muscle causing it to relax
4) This coordination will cause the leg to kick

Question 16

What occurs in a blinking reflex/corneal reflex?

Answer 16

1) Cornea is stimulated by being touched
2) The stimulus is triggered along a sensory neurone then passed to a relay neurone in the lower brain stem
3) Impulses are then sent through the branches of a motor neurone to initiate the motor response to close eyelids

Question 17

Why is blinking reflex tested in unconscious patients?

Answer 17

This reflex requires the functioning of the lower brain stem. If it is present then the unconscious person cannot be determined as brain dead.

Question 18

What are the three types of muscle in the body, their function and location?

Answer 18

Skeletal muscle: Bulk of the body in muscle tissue responsible for movement in the biceps and triceps
Cardiac muscle: Found only in the heart and are myogenic, can contract without a nervous stimuli
Involuntary muscle: Found in blood vessels and muscles

Question 19

Compare skeletal, cardiac and involuntary muscle?

Answer 19

Skeletal muscle: Controls voluntary movement, striated, regularly arranged, contracts in one direction, rapid and short contraction
Cardiac muscle: Specialised striated, controls involuntary movement , cells branch and interconnect resulting in simultaneous contractions, and have intermediate contractions and speed
Involuntary muscle: non-striated, controls involuntary actions, no regular arrangement, slow and long time contractions

Question 20

Describe the structure of a skeletal fibre

Answer 20

Made up of bundles of muscle fibres enclosed in sacrolemma
Muscle fibres have long nuclei as they are many individual embryonic muscle cells fusing together making it stronger
Have shared cytoplasm within muscle fibres called sacroplasm
Have lots of mitocondria to provide ATP for aerobic respiration produced by the sacroplasmic reticulum

Question 21

What is the sarcomere? What happens to the sarcomere when the muscle contracts?

Answer 21

The distance between the adjacent Z-lines. When a muscle contracts the sarcomere shortens

Question 22

When the muscle contracts, what happens to the alternating light and dark band?

Answer 22

The light band will become narrower
The Z-lines move closer together, the sarcomere will shorten
The H-Zone will become narrower
The dark band will remain the same

Question 23

What is the structure of the myosin?

Answer 23

Have globular heads with hinges that allow them to move backwards and forwards.
On the head has a binding site for actin and ATP.

Question 24

What is the structure of actin?

Answer 24

Actin filaments have binding sites for myosin heads called actin-myosin binding sites.
The binding sites are blocked by tropomyosin held by troponin
When stimulated, the tropomyosin will move and reveal the binding sites to allow the formation of cross bridges

Question 25

What happens at a neuromuscular junction [point where a skeletal and motor neurone meet?

Answer 25

1) An action potential arrives at the neuromuscular junctions
2) Calcium ion channels open which will diffuse from the synapse into a synaptic knob
3) Synaptic vesicles will fuse into the pre-synaptic membrane
4) Acetylcholine is released into the synaptic cleft by exocytosis and will diffuse across the synapse
5) Will bind to receptors on the post synpatic membrane on the sacrolemma , opening sodium ion channels resulting in depolarisation
6) Acetylcholine is broken down by acetylcholinesterase

Question 26

What happens during muscle contraction according to the sliding filament model?

Answer 26

1) Action potential will reach the sarcoplasmic reticulum which stimulates the opening of Ca2+ ion channels which will diffuse into the sarcoplasm
2) The calcium ions will bind to troponin moving the tropomyosin away from the actin-myosin binding sites
3) Actin will bind to myosin forming cross bridges
4) The myosin head will flex and pull the actin filament along with energy provided by an ADP releasing a phosphate group
5) ATP now can bind to the binding site of myosin which causes the head to detach from the actin filament

Question 27

How does creatine phosphate provide energy for generating ATP?

Answer 27

Creatine phosphate acts as a reserve supply of phosphate and combines with ADP to form ATP. This generates ATP rapidly but the store of phosphate is used up quickly,