5.1.5 animal responses Flashcards
1
Q
What is the nervous system?
A
The nervous system allows us to make sense of our surroundings and respond to them, as well as to co-ordinate and regulate body functions. Information is sent through the nervous system as nerve impulses (electrical signals that pass along nerve cells known as neurones).
2
Q
What is the central nervous system composed of?
A
-The brain
-The spinal chord.
3
Q
What is the peripheral nervous system?
A
The peripheral nervous system is a network of cells which allows messages to be sent from the environment to the central nervous system and from the central nervous system to the target organs.
4
Q
What is the autonomic nervous system?
A
The autonomic nervous system sends information between bodily organs and glands. The effects of the autonomic system are involuntary e.g digestion, blood vessel diameter.
5
Q
What is the somatic nervous system?
A
The somatic nervous system sends information from the sensory organs to the central nervous system and from the central nervous system to the muscles. The somatic nervous system controls conscious activities e.g running
6
Q
Name the response that is controlled by the sympathetic nervous system
A
The fight or flight response.
7
Q
Name the response that is controlled by the parasympathetic nervous system
A
Rest and digest.
7
Q
What can the peripheral nervous system be split into?
A
The autonomic nervous system
The somatic nervous system.
8
Q
What are the three type of nerves that make up the somatic nervous system.
A
-Sensory nerves
-Motor nerves
-Spinal nerves
9
Q
What are sensory nerves?
A
Sensory neurones which carry impulses from sensory organs to the CNS.
10
Q
What is the central nervous system composed of?
A
The brain
The spinal chord
11
Q
What is the peripheral nervous system composed of?
A
The autonomic nervous system
The somatic nervous system
12
Q
What are the two states that the autonomic nervous system is divided into?
A
Parasympathetic
Sympathetic
13
Q
Which gland is known as the ‘master gland’?
A
The pituitary gland.
14
Q
Why is the pituitary gland known as the master gland?
A
It instructs the other glands to release hormones into the blood stream.
15
Q
The human nervous consists of what two components?
A
-The central nervous system
-The peripheral nervous system
16
Q
What is a bundle of neurones called?
A
A nerve.
17
Q
What are motor nerves?
A
Motor neurones which carry impulses from the CNS to muscles and glands.
18
Q
What are spinal nerves?
A
Mixed nerves that consist of both sensory and motor neurones.
19
Q
Outline the divisions of the nervous system, staring with the peripheral nervous system.
A
Peripheral nervous system splits into autonomic nervous system and somatic nervous system.
Autonomic branches into parasympathetic state and sympathetic state.
Somatic consists of 3 types of nerve cells (sensory nerves, motor nerves, spinal nerves).
20
Q
How many lobes does the cerebrum consist of?
A
Five
21
Q
How is the cerebrum divided?
A
Divided into 2 hemispheres.
22
Q
How are the two hemispheres that make up the cerebrum joined?
A
Joined by a band of nerve fibres known as the corpus callosum.
23
Q
Which side of the body does the left side of the brain control?
A
The right side.
24
What is the thin layer of the cerebrum called?
The cerebral cortex or 'grey matter'.
25
How is the cerebral cortex adapted for its function?
Highly folded which increases surface area so it can contain a greater number of neurones so that more connections can be made.
26
What is the layer found underneath the cerebral cortex called?
White matter.
27
Function of cerebellum.
Controls motor co-ordination e.g balance.
28
Does the cerebellum function consciously or subconsciously?
Subconsciously.
29
Where is the medulla oblungata found?
Found at the base of the brain where it joins the spinal cord.
30
What are the three centres called that are found in the medulla oblungata?
The cardiac centre
The vasomotor centre
The respiratory centre
31
Function of cardiac centre?
Controls heart rate.
32
Function of vasomotor centre?
Controls blood pressure by controlling the contraction of smooth muscle in arteriole walls.
33
Function of respiratory centre?
Controls breathing rate.
34
Where is the hypothalamus found?
The middle of the lower part of the brain just above the pituitary gland.
35
Function of hypothalamus.
Monitors the blood as it flowing through it and in response, releases hormones itself or stimulates the pituatary gland to release certain hormones.
36
Main processes controlled by hypothalamus.
-Regulating body temperature- by monitoring blood temperature.
-Osmoregulation- by monitoring how concentrated the blood is.
-Regulating digestive activity- controls the secretion of enzymes in the gut and peristalsis.
-Controlling endocrine functions- releases chemicals that cause the pituitary gland to release certain hormones to control a variety of hormones e.g sleep, mood etc.
37
Where is the pituitary gland found?
At the bottom of brain, below the hypothalamus.
38
Function of hypothalamus.
Produces a range of hormones and some of these directly influence and regulate processes in the body but some stimulate the release of further hormones from specific, remote locations in the body e.g glands.
39
What are the two sub-sections of the pituitary gland called?
Anterior pituitary
Posterior pituitary
40
Function of anterior pituitary.
Produces and releases certain hormones.
41
Function of posterior pituitary.
Stores and releases hormones produced by the hypothalamus.
42
What is a reflex?
A reflex is where the body responds to a stimulus without making a conscious decision to respond.
43
Why are nerve impulses transmitted so quickly during reflex actions?
This is because the pathway of communication does not involve conscious parts of the brain.
Nerve impulses don’t have to travel across many synapses so information travels really fast from receptors to effectors.
44
Uses of reflex actions?
Reflex actions usually have protective purposes or survival value.
45
Give some examples of reflex actions?
-Yawning
-Saliva production
-Swallowing
-Blinking
-Pulling a part of the body away from a source of pain
-Constricting the muscles of the iris in response to bright light.
46
What is the sequence that reflex actions follow?
Stimulus
Receptor
Coordinator
Effector
Response
47
Explain how a reflex action works.
-Reflex actions in response to a change first require detection which involves a stimulus being detected by a receptor cell.
-There are different types of receptors e.g electrical activity or secreting substances
-The nerve impulses sent by the receptor cells travel to a co-ordinator in the spinal cord.
-From the co-ordinator, the impulse is conducted to the specific effector that will produce the appropriate
48
What is the 'blinking reflex'?
The blinking reflex
When the body detects something that could damage the eye, you automatically blink (quickly close your eyelid to protect your eye and then open your eyelid again).
49
Which part of the CNS is used as a co-ordinator in the blinking reflex?
The brain but not via any decision-making areas so the number of synapses is minimal.
50
Outline the blinking reflex action.
-Sensory nerve endings in the cornea are stimulated by touch
-A nerve impulse is sent along the sensory neurone to a relay neurone in the CNS.
-The impulse is passed from the relay neurone to motor neurones.
-The motor neurones send impulses to the effectors- the orbicularis oculi muscles that move your eyelids. These muscles contract causing your eyelids to close quickly and prevent your eye from being damaged.
51
Name of the muscles that move eyelids.
Orbicularis oculi
52
What is the 'knee-jerk' reflex?
The knee-jerk reflex works to quickly straighten your leg if the body detects your quadriceps is suddenly stretched. The reflex is often used by doctors to assess whether the nervous system of a patient is woking properly or not.
Doctors use a specialised hammer to hit the ligament and the leg will involuntary straighten in a small kicking motion.
53
Outline the 'knee-jerk' reflex.
-Stretch receptors in the quadriceps muscle detected that the muscle is being stretched.
-A nerve impulse is passed along the sensory neurone, which communicates directly with a motor neurone in the spinal cord.
-The motor neurone carries the nerve impulse to the effector (quadriceps muscle) causing it to contract.
54
Which neurone is not present in the knee-jerk reflex?
Relay neurone.
55
Which part of the CNS is used as a co-ordinator in the knee-jerk reflex?
The spinal cord
56
Identify the stimulus in the knee-jerk reflex.
Stretching of the quadriceps muscle caused by pressure on the ligament.
57
Identify the receptor in the knee-jerk reflex.
Stretch receptors in the quadriceps muscle.
58
Identify the effector in the knee-jerk reflex.
The quadriceps muscle
59
Identify the response in the knee-jerk reflex.
Contraction of the quadriceps muscle, causing the leg to straighten.
60
When does the fight-or-flight response occur?
When an organism is threatened.
61
Outline the fight or flight response.
1) Threatening stimuli detected.
2) The amygdala (small region of the brain in the cererbum) sends impulses to various other parts of the brain including the hypothalamus.
2) Nerve impulses from sensory neurones arrive at the hypothalamus activating the endocrine system
3) The hypothalamus stimulates the anterior pituitary to release a hormone called ACTH.
4) This causes the cortex of the adrenal gland to release steriod hormones such as cortisol.
5) The hypothalamus also activates the sympathetic nervous system which triggers the release of adrenaline from the medulla region of the adrenal gland.
62
Effects of the sympathetic nervous system in the fight-or-flight response.
-Increasing heart rate.
-The muscles around the bronchioles relax.
-Glycogen is converted into glucose
-Muscles in the arterioles supplying the skin and gut constrict and arterioles supplying the lungs, heart and skeletal muscles dilate.
-Erector pili muscles in the skin contract
63
Why do erector pilli muscles in the skin contract during the fight or flight response?
To make the organism appear bigger as hairs stand on end.
64
Why is glycogen converted into glucose during the fight or flight response?
So there is more glucose available for respiration)
65
Where is the hormone adrenaline secreted from in the fight or flight response?
Adrenal medulla.
66
Where is ACTH secreted from in the fight-or-flight response?
The pituitary gland.
67
Where is the hormone cortisol secreted from in the fight or flight response?
The cortex of the adrenal gland.
68
Give some effects of adrenaline in the fight or flight response.
-Stimulates the muscles in irises to contract, causing pupils to dilate.
-Increases diameter of bronchioles by relaxing smooth muscle so there is increased airflow to the alveoli.
-Decreases the amount of blood flowing to the gut and skin via vasoconstriction.
Increases amount of blood flowing to the brain and muscles.
-Increases heart rate and stroke volume.
Stimulates breakdown of glycogen into glucose.
-Stimulates target organs and tissues to increase sensory awareness, making the organism more alert so improving sensory awareness.
69
Is adrenaline a first or second messenger in the fight or flight response?
First
70
What are the second messengers in the fight or flight response?
-Adenylyl cylase
-cylic AMP
71
Outline the role of adrenaline as a first messenger and how this results in an enzyme cascade.
When adrenaline in secreted, it increases the concentration of blood glucose. It does this by binding to different receptors on the surface of liver cells that activate an enzyme cascade.
Adrenaline binds to specific receptors on the membrane of liver cells which causes the enzymeadenylyl cyclase to change shape and become activated.
The cascade amplifies the initial signal from adenaline ATP to the second messenger cyclic AMP.
cAMP binds to protein kinase A enzymes, activating them and these enzymes activate phosphorylase kinase enzymes by adding phosphate groups to them.
Active phosphorylase kinase enzymes activate glycogen phosphorylase enzymes which cadenalinehe break down of glycogen into glucose.
The cascade amplifies the initial signal from adenaline and results in the releasing of extra glucose by the liver.
72
Role of cortisol in fight or flight response.
Stimulates target organs and tissues to increase blood pressure, blood glucose, ensuring the tissues have sufficient glucose and oxygen needed for rapid response.
Also suppresses immune system.
73
Three types of muscle in human body?
-Skeletal muscle (striated, voluntary muscle)
-Smooth muscle (involuntary muscle).
-Cardiac muscle
74
Skeletal muscle is also known as...?
Striated muscle.
75
How is smooth muscle similar but different to skeletal muscle?
Smooth muscle contains actin and myosin filaments however it does not have any banding and striation.
76
Give an example of where smooth muscle could be found.
The walls of blood vessels.
77
Shape of cells in smooth muscle?
Elongated spindle shapes.
78
Feature of smooth muscle.
Mono-nucleated.
79
Where is cardiac muscle found?
The heart.
80
Features of cardiac muscle.
-Contracts on its own (myogenic).
-Does not tire or fatigue so can beat continuously.
-Cardiac muscle fibres form a network that spreads through the walls of the atria and ventricles.
-Cardiac muscle fibres are connected to each other via specialised connections called intercalated discs.
-There is a large number of mitochondria present in the muscle fibres
81
Why do the muscle fibres of cardiac muscle contain lots of mitochondria?
As these are needed to provide the large quantity of ATP needed for continual contraction.
82
How are cardiac muscle fibres connected to each other?
Intercalated discs.
83
What is the cell membrane of skeletal muscle fibres called?
Sarcolemma
84
What is the cytoplasm called of skeletal muscle fibres?
Sarcoplasm
85
What are T-tubules?
Deep, tube-like projections that fold in from the outer surface of the sarcolemma.
86
Function of T-tubules?
Help to spread electrical impulses throughout the sarcoplasm.
87
What does the sarcoplasm contain?
Mitochondria and myofibrills.
88
What are myofibrills?
Bundles of actin and myosin filaments which slide past each other during muscle contraction.
89
Where are myofibrils located?
The sarcoplasm.
90
What are the two types of protein filaments in myofibrils?
Myosin and actin.
91
Are myosin filaments thick or thin?
Thick.
92
Are actin filaments thin or thick?
Thin
93
Name of band that myosin makes up?
A-band
94
Name of band that actin makes up.
I-band
95
What are the short units in myofibrils called?
Sarcomeres.
96
What is the line called at the end of each sarcomere?
Z-line
97
In the middle of each sarcomere, what line is present?
M-line
98
What zone is found around the m-line? which filaments does it contain?
H-zone
Only myosin.
99
What is the theory of muscle contraction called?
Sliding filament theory.
100
Structure of myosin filaments.
-Globular head.
-Each myosin head has a binding site for actin and a binding site for ATP.
101
Structure of actin filaments.
-Globular prtein molecules
-Have binding sites for myosin heads, called actin-myosin binding sites.
-Two other proteins called tropomyosin and troponin are found between actin filaments and they help myofilaments move past each other.
102
Explain why microfilaments cannot slide past each other in a resting muscle.
In a resting muscle, the actin-myosin binding sites are blocked by tropomyosin (held in place by troponin) so myofilaments cannot slide past each other because the myosin heads cannot bind to the actin-myosin binding site on the actin filaments.
103
Two other proteins found in actin filaments.
-tropomyosin
-troponin
104
Where do actin and myosin bind together?
Actin-myosin binding sites.
105
Explain the sliding filament model.
When an action potential from a motor neurone stimulates a muscle cell, it depolarises the sarcolemma. Depolarisation spreads down the T-tubules to the sarcoplasmic reticulum.
This causes the sarcoplasmic reticulum to release stored calcium ions into the sarcoplasm by diffusion.
Calcium ions bind to troponin, causing it to change shape. This pulls the tropomyosin out of the actin-myosin binding site on the actin filament.
This exposes the binding site, which allows the myosin head to bind. (the bond formed when a myosin head binds to an actin filament is called an actin-myosin cross bridge).
ATP provides the energy needed to move the myosin head.
Calcium ions also activate the enzyme ATPase, which breaks down ATP into ADP + P to provide the energy needed for muscle contraction.
The energy released from ATP moves the myosin head, which pulls the actin filament along.
Breaking the cross-bridge
ATP also provides the energy to break the actin-myosin cross bridge so the myosin head detaches from the actin filament after it has moved.
The myosin head then reattaches to a different binding site further along the actin filament. The new actin-myosin cross bridge is formed and the cycle is repeated.
Many cross bridges form and break very rapidly, pulling the actin filament along which shortens the sarcomere, causing the muscle to contract.
106
What happens when excitation of a muscle stops?
-When the muscle stops being stimulated, calcium ions leave their binding sites on the troponin molecules and are moved by active transport back into the sarcoplasmic reticulum.
-The troponin molecules return to their original shape, pulling the attached tropomyosin molecules with them. This means that tropomyosin molecules block the actin-myosin binding sites again.
-Muscles are not contracted because no myosin heads are attached to actin filaments.
-The actin filaments slide back to their relaxed position.
107
What provides the energy for muscle contraction?
ATP and CP.
108
What is a neuromuscular junction?
A synapse between a motor neurone and a muscle cell.
109
Which neurotransmitter is involved with neuromuscular junctions?
Acetylcholine.
110
What are the receptors called on the post-synaptic membrane of a neuromuscular junction?
Nicotinic cholinergic
111
Explain how transmission across a neuromuscular junction leads to the sliding filament model being able to begin.
1) When an impulse travelling along the axon of a motor neurone arrives at the presynaptic membrane, the action potential causes calcium ions to diffuse into the neurone.
2) This stimulates vesicles containing the neurotransmitter ACh to fuse with the presynaptic membrane.
3) The ACh that is released diffuses across the neuromuscular junction and binds to receptor proteins on the sarcolemma.
4) This stimulates ion channels in the sarcolemma to open, allowing sodium ions to diffuse in.
5) This depolarises the sarcolemma, generating an action potential that passes down the T-tubules towards the centre of the muscle fibre.
6) These action potentials cause voltage-gated calcium ion channrel poteins in the membranes of the sarcoplasmic reticulum to open.
7) Calcium ions bind to troponin molecules, stimulating them to change shape.
8) This causes troponin and tropomyosin proteins to change position on the thin filaments.
9) The myosin-binding sites are exposed to the actin molecules.
10) The sliding filament model can begin.
112
How do neuromuscular junctions ensure that muscles are not continuously being stimulated?
The enzyme acetylcholinesterase is present in the synaptic cleft and breaks down the acetylcholine molecules.
