Humans Flashcards
(120 cards)
1
Q
What are the two control systems in humans that work together to help us respond to stimuli?
A
the nervous system
the endocrine system (hormonal system)
2
Q
What acts as stimuli for our bodies?
A
changes in our external or internal environment
3
Q
What does the nervous and endocrine system do?
A
they coordinate a suitable response to the stimuli allowing us to coordinate and regulate body functions
4
Q
How is information sent through the nervous system?
A
information is sent through the nervous system as electrical impulses
5
Q
What do the electrical impulses that send information through the nervous system pass along?
A
the electrical impulses pass along nerve cells known as neurones
6
Q
What kind of speeds do the electrical impulses travel at?
A
very high speeds (up to 100 metres per second)
7
Q
What does the very high speeds that the electrical impulses allow?
A
the very high speeds allows rapid responses to stimuli
e.g. the withdrawal reflex that causes you to move your hand away extremely quickly when it touches a flame
8
Q
What 3 parts of the body does the nervous system coordinate?
A
-the activities of sensory receptors
-decision-making centres in the central nervous system
-effectors such as muscles and glands
9
Q
How is information sent through the endocrine (hormonal) system?
A
information is sent through the endocrine (hormonal) system as chemical substances known as hormones
10
Q
What kind of functions does the nervous system control?
A
functions that need instant (or very rapid) responses
11
Q
How are the hormones for the endocrine system carried around the body?
A
hormones are carried by the blood and can therefore circulate around the whole body
12
Q
What do the hormones in the endocrine system do?
A
the hormones transmit information from one part of the organism to another and bring about a change (they provide a signal that triggers a response)
13
Q
What kind of functions are hormones used to control in the endocrine system?
A
they are used to control functions that do not need instant responses
(slower speed of action than the nervous system)
14
Q
What are the hormones produced by for the endocrine system?
A
the hormones are produced by endocrine glands
15
Q
What are the endocrine glands that produce hormones in animals known as?
A
they are collectively known as the endocrine system
16
Q
What is a gland?
A
a gland is a group of cells that produces and release one or more substances (a process known as secretion)
17
Q
What 3 parts of the body is the nervous system made up of?
A
nerves (bundles of neurones)
brain
spinal cord
18
Q
What is the duration of effect for the endocrine (hormonal) system?
A
it is a long duration of effect until the hormone is broken down in the body
19
Q
What is the duration of effect for the nervous system?
A
it is a short duration of effect until the nerve impulse stops
20
Q
What does both the nervous and endocrine (hormonal) system require?
A
both systems require stimuli, receptor and effector
21
Q
What two nervous systems does the human nervous system consist of and what part of the body is each one?
A
central nervous system (CNS) - the brain and spinal cord
peripheral nervous system (PNS) - all of the nerves in the body
22
Q
What is a bundle of neurones known as?
A
a nerve
23
Q
What does the central nervous system act as for the body?
A
it acts as a central coordinating centre for the impulses that come in from (or are sent out to) any part of the body
24
Q
What can be summarised as the stages through the human nervous system?
A
stimulus
sensory neurone
relay neurone
motor neurone
effector
response
25
What two parts of the body can be the coordinator in the central nervous system of a human?
either the brain or the spinal cord
26
In the CNS what happens to the impulses after they travel along a sensory neurone?
the impulses are passed onto a relay neurone which links to a motor neurone, along which the impulses travel until they reach the effector
27
What is the role of the effector and what could it be?
the effector is what carries out the response and it may be a muscle or a gland
28
What does the sensory neurone look like?
skinniest out of all three and only branches out at the end
29
What does the motor neurone look like?
looks like a tree with a bar at the bottom (sometimes)
30
What does the relay neurone look like?
similar to a motor neurone but less branching out
31
What is the role of a motor neruone?
carry the impulses away from the central nervous system as it must end in a muscle or a gland
32
What order do the 3 neurones go in for the CNS?
sensory neurone
relay neurone (CNS)
motor neurone
33
What do relay neurones allow?
they allow sensory neurones and motor neurones to communicate
34
Explain the process of coordinated rapid responses in the CNS?
stimuli is detected by receptors, stimulating sensory neurons that send electrical impulses to the central nervous system (CNS) - brain and spinal cord
central nervous system relays impulse across the synapse (gaps between neurones) to relay neurons via synaptic transmission
relay neurons relays impulse to motor neurons in the effector, which will quickly carry out rapid response
35
What is the example answer for a question about CNS for touching a hot object (reflex arc) (6)?
1) stimulus (e.g. hot object) detected by temperature receptors
2) this triggers a nerve impulse in the sensory neurone
3) nerve impulse travels in sensory neurones to the spinal cord
4) sensory neurone connects by a synapse to a relay neurone, which in turn connects to a motor neurone
5) the impulse travels along the motor neurone and out of the spinal cord to the effector (the BICEPS MUSCLE in the arm)
6) the muscle contracts and the arm moves away from the hot objects
36
What is a synapse?
where the dendrites of two neurones meet (to make a connection between the neurones) a junction known as s synapse
37
Do neurones come in direct contact of each other?
NO
38
What is the very small gap ,at a synapse, between neurones known as?
synaptic cleft or synaptic gap
39
Why can't electrical impulses travel directly from one neurone to the next?
they can't because of the synaptic cleft as electricity cannot 'jump' the gap
40
What do the electrical impulses do instead as they cannot 'jump' the synaptic cleft?
the electrical impulse is briefly converted to a chemical signal that CAN cross the synaptic cleft by DIFFUSION
41
What is a neurotransmitter?
the chemical signalling molecules used to transfer the signal between neurones at a synapse
42
What happens once the chemical neurotransmitters cross the synaptic cleft and meet the neurone on the opposite side?
the chemical signal is converted back into an electrical impulse, which can then pass along the neurone
43
How is the chemical neurotransmitters converted back into electrical impulses once they reach the next neurone?
once the chemical neurotransmitters diffuse across they BIND WITH THE RECEPTORS MOLECULES on the membrane of the second neurone (known as the postsynaptic membrane)
this stimulates the second neurone to generate an electrical impulse (which then travels down the second axon)
the neurotransmitters are then destroyed to prevent continued stimulation of the second neurone
44
How are the electrical impulses converted into chemical neurotransmitters?
the electrical impulse travels along the axon of the first neurone (known as the presynaptic neurone)
this triggers the end of the presynaptic neurone to release chemicals called neurotransmitters from vesicles
these vesicles fuse with the presynaptic membrane, releasing their contents into the synaptic cleft
45
What is a reflex response also known as?
an involuntary response
46
What part of the body does a reflex response involve?
the reflex response involves the conscious part of the brain as the coordinator of the reaction
47
In terms of speed how fast are reflex responses?
they are automatic and rapid which helps minimise damage to the body and aids survival
48
Give examples of reflex responses?
pain-withdrawal
blinking
coughing
49
What is the reflex arc?
the pathway of a reflex response
(specifically, the pathway taken by electrical impulses as they travel along neurones)
50
What is the example answer of a reflex response for the pain-withdrawal reflex that occurs when someone steps on a pin (6)?
1) the pin (stimulus) is detected by a pain receptor in the skin on the person's foot
2) a sensory neurone sends electrical impulses to the spinal cord (the coordinator)
3) an electrical impulse is passed to a relay neurone in the spinal cord (part of the CNS)
4) a relay neurone synapses with a motor neurone
5) a motor neurone carries an impulse to a muscle in the leg (the effector)
6) when stimulated by the motor neurone, the muscle will contract and pull the foot up and away from the sharp object (the response)
THIS ALL OCCURS WITHIN A FRACTION OF A SECOND
51
What is the eye and does it contain receptors cells?
the eye is a highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light
52
What are the two types of receptor cells that the retina of the eye contains?
receptor cells that are sensitive to light (known as rods)
+
receptor cells that can detect colour (known as cones)
53
What is the CORNEA and what is its function?
transparent lens that refracts light as it enters the eye
54
What is the IRIS and what is its function?
controls how much light enters the pupil
55
What is the LENS and what is its function?
transparent disc that can change shape to focus light onto the retina
56
What is the RETINA and what is its function?
contains light receptor cells - rods (detect light intensity) and cones (detect colour)
57
What is the OPTIC NERVE and what is its function?
sensory neurone that carries impulses between the eye and the brain
58
What is the PUPIL and what is its function?
hole that allows light to enter the eye
59
What is the CONJUCTIVA and what is its function?
a clear membrane that covers the white of the eye and the inside of eyelids ; it lubricates the eye and provides protection from external irritants
60
What is the CILIARY MUSCLE and what is its function?
a ring of muscle that contracts and relaxes to change the shape of the lens
61
What is the SUSPENSORY LIGAMENTS and what is its function?
ligaments that connect the ciliary muscle to the lens
62
What is the SCLERA and what is its function?
the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye
63
What is the FOVEA and what is its function?
a region of the retina with the highest density of cones (colour detecting cells) where the eye sees particularly good detail
64
What is the eye's extraordinary ability of the lens of the eye to change shape, allowing for a change in focus from far to near called?
ACCOMMODATION
65
What part of the eye can change the shape of the lens?
the suspensory ligaments attached to it become tight or loose which changes the shape of the lens
66
What part of the eye causes the suspensory ligaments to become tight or loose?
the change in the suspensory ligaments are brought about by the contraction or relaxation of the ciliary muscles
67
What are the stages for the eye when focusing on an object close up?
1) the ciliary muscles CONTRACT (the ring of muscle decreases in diameter)
2) this causes the suspensory ligaments to loosen
3) this stops the suspensory ligaments from pulling on the lens, which allows the lens to become short and fatter
4) light is refracted more
68
What are the stages for the eye when focusing on an object far away?
1) the ciliary muscles RELAX (the ring of muscle increases in diameter)
2) this causes the suspensory ligaments to tighten
3) the suspensory ligaments pull on the lens, causing it to become long and thinner
4) light is refracted less
69
What is the pupil reflex?
a reflex action carried out to protect the retina from damage
70
How does each part of the eye change when focusing on a near object?
ciliary muscles - CONTRACTED
suspensory ligaments - LOOSEN
lens - SHORT AND FATTER
light refraction - MORE
71
How does each part of the eye change when focusing on a distant object?
ciliary muscles - RELAXED
suspensory ligaments - TIGHTEN
lens - LONG AND THINNER
light refraction - LESS
72
What happens to the pupil in DIM light and why does it do that?
the pupil DIALATES (widens) in dim light in order to allow as much light into the eye as possible to improve vision
73
What happens to the pupil in BRIGHT light and why does it do that?
the pupil CONSTRICTS (narrows) in bright light in order to prevent too much light from entering the eye and damaging the retina
74
What is the order of changes for the pupil reflex in DIM light?
1) photoreceptors detect change in environment (dark)
2) radial muscles of iris CONTRACT
3) circular muscles of iris RELAX
4) wide dilated pupil (MORE light enters eye)
75
What is the order of changes for the pupil reflex in BRIGHT light?
1) photoreceptors detect change in environment (bright)
2) radial muscles of iris RELAX
3) circular muscles of iris CONTRACT
4) narrow constricted pupil (LESS light enters eye)
76
How does each part of the eye change for the pupil reflex in DIM light?
radial muscles of iris - CONTRACTED
circular muscles of iris - RELAXED
pupil size - WIDE
light entering eye - MORE
77
How does each part of the eye change for the pupil reflex in BRIGHT light?
radial muscles of iris - RELAXED
circular muscles of iris - CONTRACTED
pupil size - NARROW
light entering eye - LESS
78
What is our largest sense organ?
skin
79
How does skin regulate our body temperature?
structures within the skin play an important role in regulating body temperature (an example of homeostasis)
80
What is thermoregulation?
maintenance of optimum internal body temperature for optimum enzyme activity
81
What is vasodilation?
vasodilation is a response to being too hot, the process includes the widening of blood vessels at the skin surface to increase heat loss through the surface of the skin
82
What happens during vasodilation?
1) muscles of arterioles (small vessels that connect arteries to capillaries) relax to allow MORE blood to flow through them
2) this causes the arterioles near the skin to DIALATE (get wider) and allow a greater volume of blood to flow through capillaries
3) this then loses heat to the environment via radiation
83
What is sweat secreted by?
sweat is secreted by sweat glands
84
How does sweating act as a cooling mechanism?
it cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour
85
How does the flattening of hair on the body act as cooling mechanism?
the hair erector muscles in the skin RELAX, causing hairs to lie flat
this stops them from forming an insulating layer by trapping air and allows air to circulate over the skin
this allows heat to leave by RADIATION
86
What is vasoconstriction?
vasoconstriction is a response to being too cold, the process involves the narrowing of blood vessels at the skin surface to reduce heat loss through the surface of the skin
87
Why is vasoconstriction not, strictly speaking, a 'warming' mechanism for the body?
vasoconstriction does not raise the temperature of the blood but instead reduced heat loss from the blood as it flows through the skin
88
What happens during vasoconstriction?
1) the muscles of the arteriole walls (small vessels that connect arteries to capillaries) contract to allow LESS blood to flow through them
2) this causes the arterioles near the skin to CONSTRICT (get smaller) which allows a smaller volume of blood to flower through capillaries
3) this then reduces heat loss from the blood as it flows through the skin
89
How does shivering act as a warming mechanism?
shivering is a reflex action in response to a decrease in core body temperature
muscles contract in a rapid and regular manner
the exothermic metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature
90
How does the erection of hairs on the body act as a warming mechanism?
the hair erector muscles in the skin CONTRACT, causing hairs to stand on end
this forms an insulating layer over the skin's surface by trapping air between the hairs
this stops heat from being lost by RADIATION
91
Where are the temperature receptors (thermoreceptors)?
in the skin and hypothalamus (a part of the brain)
92
What are the five hormones of great importance to humans?
adrenaline
insulin
testosterone
progesterone
oestrogen
93
What is the hormone adrenaline known as and why is it produced?
adrenaline is known as the 'fight or flight' hormone as it is produced when the body may be in danger
94
What effects can adrenaline have on the body?
- INCREASE IN HEART RATE AND BREATHING RATE to ensure glucose and oxygen can be delivered to muscle cells (and carbon dioxide can be taken away from muscle cells) at a faster rate
- DIVERTING BLOOD FLOW TOWARDS MUSCLES to ensure an increased supply of the reactants of respiration (glucose and oxygen)
- DIALATION OF THE BLOOD VESSELS INSIDE MUSCLES to ensure more blood can circulate through them (supplying more glucose and oxygen)
- BREAKING DOWN OF STORED GLYCOGEN TO GLUCOSE to ensure a higher blood glucose concentration for increased respiration in muscle cells (providing greater energy for movement)
95
Where is adrenaline produced?
adrenal gland
96
What is the hormone insulin and why is it produced?
insulin is a hormone that lower blood glucose levels to keep it within a narrow range (an example of homeostasis)
97
What can a too high a level of glucose cause?
a too high level of glucose in the blood can lead to cells of the body losing water by osmosis, which can be dangerous
98
What can a too low a level of glucose cause?
a too low level of glucose in the blood can lead to the brain receiving insufficient glucose for respiration, potentially leading to a coma or even death
99
What two organs work together to control blood glucose levels?
pancreas and liver
100
How does the pancreas carry out its role in controlling blood glucose levels?
the pancreas acts as an endocrine gland (making and secreting hormones into the bloodstream)
although it also plays a vital (but separate) role in digestion (making and secreting enzymes into the digestive system)
101
What is the process of lowering blood glucose levels?
cells in the pancreas detect the increased blood glucose levels
the pancreas produces the hormone insulin, secreting it into the blood
insulin stimulates muscles and the liver to take up glucose from the bloodstream and CONVERT IT INTO GLYCOGEN FOR STORAGE (a polymer of glucose)
this reduces the concentration of glucose in the blood back to normal levels, at which point the pancreas stops secreting insulin
102
What organ produces insulin?
pancreas
103
What is the hormone testosterone and what is its role?
testosterone is the main sex hormone in the male species and it is responsible for the development of secondary sexual characteristics in males
104
Where is testosterone produced?
testes
105
What is the hormone progesterone and what is its role?
progesterone is the hormone in a female that maintains pregnancy and it is responsible for maintaining the uterine lining to cushion the fertilised egg and allow it to develop
106
Where is progesterone produced?
ovaries
107
What is the hormone oestrogen and what is its role?
oestrogen is the main sex hormone of a female and it is responsible for the development of secondary sexual characteristics in females and regulating the menstrual cycle
108
Where is oestrogen produced?
ovaries
109
What are the four hormones that control the events that occur during the menstrual cycle?
oestrogen
progesterone
FSH (follicle-stimulating hormone)
LH (luteinising hormone)
110
What is oestrogen and progesterone both involved in?
stimulating and maintaining the uterus lining
111
What is the role of oestrogen specifically for the menstrual cycle?
- stimulates the uterus to develop a lining (to replace the lining lost during menstruation)
- post-ovulation, inhibits (stops) FSH and LH production in the pituitary gland
112
What is the role of progesterone specifically for the menstrual cycle?
- maintains and thickens lining of the uterus
- inhibits (stops) FSH and LH production
- if fertilisation doesn't occur, levels drop and menstruation occurs
113
What is the role of FSH?
FSH causes an egg to start maturing in the ovary and stimulates the ovaries to start releasing oestrogen
114
Where is FSH produced?
pituitary gland
115
What is the role of LH and why is it produced?
the pituitary gland is stimulated to release LH when oestrogen levels have reached their peak
LH causes ovulation to occur and also stimulates the ovary to produce progesterone
116
Where is LH produced?
pituitary gland
117
What is the role of ADH?
ADH controls the water content of the blood
118
What is the effect of ADH?
the release of ADH increases the permeability of the collecting ducts in the kidneys to water, increasing the reabsorption of water into the blood
119
Where is ADH produced?
pituitary gland
120
What detects whether the water content of blood is too low or too high so that ADH may or may not be released?
osmoreceptors in the brain (hypothalamus)
