HUMAN PHYSIOLOGY Flashcards
1
Q
what does the digestive system process consist of
A
- mechanical/physical breakdown (eating
- chemical breakdown (enzymes)
2
Q
ingestion
A
food taken into mouth
3
Q
digestion
A
food broken down by chemical reactions
4
Q
absorption
A
nutrients abosrved by cells in digest system and transferred to bloody by lymphatic vessels
5
Q
transport
A
circulatory system delivers nutrients to body
6
Q
egestion
A
waste is stored and expelled
7
Q
proteins are ingested as… and digested as…
A
proteins…. amino acids
8
Q
lipids are ingested as… and digested as…
A
tryglycerides… glycerol and fatty acis
9
Q
carbohydrates are ingested as… and digested as…
A
monosaccharides/ polysaccharadies/disacharaides…monosaccharides
10
Q
nucleic acids are ingested as… and digested as…
A
DNA/RNA… nucleotides
11
Q
what are humans incapable of digesting? and why?
A
cellulose
- we dont have the cellulase enzyme to break it down
12
Q
role of enzymes
A
- act as catalysts
- lower activiation E to allow for reaction rate to increase
- body temperature (37.c) is perfect/optimum environment for enzymes in human body
- each enzyme specific to a substrate (breaks down a specific substance)
13
Q
amylase
A
- found in mouth/ small intestine (produced in pancreas and mouth)
- breaks down starch to maltose
- another enzyme hydrolyses maltose to glucose
- pH 7
14
Q
(endopeptidase) trypsin
A
- breaks down polypeptides to smaller polypeptides
- produced in pancreas + secreted into small intestine
15
Q
pepsin
A
- found in stomach
- breaks down proteins to amino acids
- pH 1-2
16
Q
lipase
A
- found in pancreas and small intestine
- breaks down fat
- pH 8
17
Q
function of the mouth
A
mechanical breakdown of food; salivary glands release amylase to chemicall digest starch to maltose + moisten food
18
Q
function of the oesophagus
A
food travels down using peristalsisis (smooth muscle contraction by the autonomic nervous system) to keep food moving down
19
Q
function of the stomach
A
food turned into chyme through acids, enzymes and churning (peristalsis)
- chemical + mechanical digestion
- pepsin breaks down proteins
- contains HCl (acidic)
20
Q
function of the liver
A
filters toxins from blood + produces bile (breaks down fats with lipase)
21
Q
function of the gall bladder
A
bile stroage (released to small intestine)
22
Q
function of the small intestine
A
absorbtion of nutrients/minerals (via diffusion via villi)
continued digestion
- pancreatic juice excreted into small intestine to break down starch to maltose using amylase
- maltase breaks down maltose into glucose
23
Q
function of the large intestine
A
- absorb + recyle water + mineral salts via diffusion
- maltase breaks down maltose to glucose
- undigested matieral excreted
24
Q
function of the rectum
A
storage of faecus
25
function of the anus
site of excretion using peristalsis
26
function of the pancreas
- produces insulin and glucagon
- glucose metabolism
- produces lipase, amylase and endopeptidase (trypsin) that become pancreatic joke
27
intestinal villus
in mucose (lining) of small intestine; surround lumen
- each villus has cells which absorb molecules through epithelieal layer
- contains capillary bed for absorbtion and transportation
- the lacteal (lymphatic system) absorbs larger monomers (fatty acids)
- villi and micrvilli increase surface area for absorbtion
28
list of substances absorbed through villus
```
water
glucose
amino acids
nucleotides
glycerol
mineral ions
fatty acids
vitamins
```
29
simple diffusion
- passive mechanism
- very small and non polar molecules (e.g. fatty acids)
- movement into cell membrane along concentration gradient
30
membrane pumps
need atp
- molecules move AGAINST concentration gradient by proteins using ATP to pump molecules
- e.g. glucose, amino acids, minerals
31
endocytosis
molecules trapped using invagination of membrane + transported by vescicles
-undigested macromolecules
32
endocytosis
molecules trapped using invagination of membrane + transported by vescicles
-undigested macromolecules
33
arteries
- carry blood away from heart to the body
- thick walls (many muscles and elastic fibres)
- high pressure (systolic peak)
- no valves
- smooth and thin lumen
- pumps by vasoconstriction
34
veins
- carry blood to heart
- have valves to prevent backflow at low pressures
- thin walls (few muscle and elastic ties)
- low pressure
- flexible when squeezed
- moderate lumen
35
capillaries
```
walls 1 cell thick
all exchanges (gas, nutriets, etc.)
no internal vales
low internal pressure
```
36
cardiac cycle
completle heart beat (systole +pause + diastole)
37
function of the right atrium
deoxygenated blood enters from vena cava and pumps it here
38
function of the left atrium
oxygenated blood enters from pulmonary beins and pump it into the left ventricle
39
function of the right ventricle
recieves deoxygenated blood and pumps it at low pressure into lungs via pulmonary artery
40
function of the left ventricle
(THICK WALLED)
| recieves oxygenated blood and pumps it at high pressure to body via aorta
41
function of the aorta
largest artery in body that carries oxygeanted blood from right ventricle to the body
42
function of the vena cava
large vein that carries deoxygenated blood into the heart
43
function of the pulmonary arteries
artery carries blood from right ventricle to lung for oxygenation
44
function of the pulmonary veins
vein carries blood from lungs to left atrium
45
function of the semilunar valves
valve at base of aorta and pulmonary artery to prevent back flow
46
function of the atrioventricular valves
valve between atrium and ventricle;
| bicuspid and tricuspid valve
47
the human heart
- cardiac muscle tissue that contracts involuntarirly
- has alot of mitchondria
- is connected by cytopaslmic bridges
- cardiac cycle
- gas exchange and circulation
48
atherosclerosis
- build up of plague in coronary arteries
| - causes blockage and derives oxygen supply= leads to occlusion(which leads to heat attack)
49
coronary heart diesease
fat blocks the artery
50
heart cancer
heart degenerates and stops functioning
51
systole
heart muscle contracts and pumps blood from chamber to arteries
52
diastole
heart mucle relaxes and allows fhambers to fill with blood from veins
53
human circulation
have double circulation; higher pressure and greater blood flow
54
control of heart rate
myogenc muscle contraction controls cardiac muscle without nervous system
- uses pacemaker cells and muscle cells in heart
55
pacemaker cells
have electrical impulses that allow for heart beat
56
muscle cells in heart
slight electrical charge across membrane (are polarized) when charged is reveresed, they contract (depolarize)
- this occursin the sinoatrial node (SAN)
57
SA node
- sinoatrial node
- signal sent out every 0.8 seconds
- in right atrium
- acts as a pacemaker for the heart by sending out an electrical signal to intiate the contraction of both atria
58
AV node
atrioventricular node
- in atrium (bottom)
- specialized muscle tissue that recieves the signal from the SA node and delays it for aprox. 0.1 seconds, and then sends out another elettical signal to the ventricles (for contraction)
59
process of heart rate control
1. wave of depolarization spreads from SAN over atria
2. atria depolarize, contract and pump blood into ventricles
3. wave reaches AVN where there is a 0.1 second delay and another electical signal is sent out which is transmitted down the bundle of his
4. wave transmitted along purkinge fibres into ventricles
5. ventricles depolarize and contract and pump blood into arteries
6. atria and ventricles depolarize and relax
7. atria fill with blood from vena cava + pulmonary bein
60
heart rate influenzes
- excersize
- stress
- chemicals (adrenaline; epinephrine)
61
how does excersize influence heart rate
- increase demand for oxygen
- increase of CO2 level toxitiyt in blood
- medulla in grain senses the carbon dioxide and sends signal down cranial nerve to cardiac never
- signal sent to SA node to adjust control of heart
62
how does stress influence heart rate
adrenal glands produce adrenaline to fire SA node more frequently
63
primary defence of immune system
SKIN
MUCOUS MEMBRANE
64
how does the skin protect the body?
Skin:
- dermis: underneat leayer (structure and strength; sweat glads, cappilaries and sensory receptors)
epidermis: dead dermal cells; barrier against pathogen (prevents interaction with living cells)
65
how does the mucous membrane protect the body?
it protects none- skin areas
- all cells produce and secrete a lining of sticky mucos which traps pathogens and prevents infection
- some mucous membranes are lined with cilia
e. g. trachea, nasal passages, urethra, vagina
66
blood clotting
damaged blood vessels on skin; give pathogens a point of entry to skin
67
clotting proteins
"prothrombin" and "fibrogins"
- blood plasma contains circulating plasma proteins and platelet cell fragments (no nucleus and short cellular life span)
68
blood clotting process
1. damaged blood cells release chemicals that stimulate platelets to group together at an area
2. platelets and damaged tissue releases a clotting factor
3. clotting factor chemicals convert prothrombin to thrombin (as active enzymes)
4. thrombin catalyzes conversion of soluble fibrogin to insolube fibrogen (fibrin)
5. fibrin creates a platelet plug; cellular debris gets trapped
6. clog created!
69
secondary defence is when..
pathogens enter the blood
70
primary immune response
first encounter with a particular pathogen
- symptoms
- takes a week to be effective
71
secondary immune response
quicker + more intense
'immunity'
- not the first encounter with pathogen
-body already knows how to handle it
72
macrophage
can change cellcular shape to surround invadin cells by phagoctyosis
- no real immunity gained
73
phagotic white blood cells (leucocytes) process
1. macrophage encounters cell and determiens whether it is a natural, 'self' cell or a 'not self' cell
2. macrophage enguls 'not self' cell
3. lyosomes digest 'not self' cell
74
plasma cells
produce antibodies, but only one type of antibody specific to pathogen
75
antibodies
y-shaped protein molecules produced in response to a specific pathogen
- has a binding site to attach to the antigens on the pathogen
- produced by lymphocyes
76
primary immune response action (lymphocytes)
1. a specific antigen is identified
2. a specific plasma cell is identified that can produce an antiody to bind to antigen
3. the specific plasma cell clones itself to increase amount
4. army of plasma cells being antibody production
5, antibodies find their antigen match
6. antibodies eliminate pathogen
7. some plasma cells remain in blood stream and provide immunity in case a second infection occurs (MEMORY CELLS)
8. Memory plasma cells respond quickly if the same antigen is encountered again (secondary immune response)
77
HIV: human immunodeficency virus
- infects the key lymphocyte cells (host cell)
- causes drop in lymphocytes and antibody production
- beomes aids when person loses immune response capability (acquired immune deficency syndrome)
78
how is HIV transmitted?
- unprotected sex
- hypodermic unclean needles
- preganacy, labour and delivery/breastfeeding
- blood transmusions
79
antibodies + viruses
- combat bacterial infections; block protein synthesisi or inhibit cell wall production
= have no effect on viruses, only target procaryotic cells with no effect on eurkaryotic cells
80
bacterial resistance
- - bacteria divide quickly; can mutate rapidly/genetic variation
- resistant bacteria rapidly repopulate colonies
- long term and overuse of antibodiotics have caused this
- new antibodies have to be produced ( by manipulating r-groups)
81
how does blood clotting occur?
- platelets release clotting factors which stimulate fibrin production
82
cornoary thrombosis
blood can clot the coronary arteries in patients with coronary heart disease
- causes blood clot, which derives heart from oxygen and nutrients
- prevents cells from creating enough ATP
- causes quivering movement in heart (filllibration)= heart can't pump properly
83
risk factors of heart attacks + coronary thrombosis
- smoking
- stress
- alcohol
- high blood cholesterol
- high blood pressure
- obesity
- diabetes
- lack of excersize
84
Penicillin
- discovered by alexander fleming
- extracted and purified by florey and chain
- they conducted tests on mice + human patients
- has a b-lactam ring
- prevents bacteria enzyme B-Lactamase from building cell wall
- bacterial cell wall weak= bursts due to osmosis
85
drugs that caused problems
thalidomide- to relieve morning sickness in women; caused birth defects in fetuses
86
why do antibiotics not effect viruses?
- they live inside a host cell
- they dont have metabolic processes (e.g. cell wall binding)
- dont have their own mean of transcription and translatation (use chemical means gained by the metabolism of the host cell)
87
Ventilation
Ventilation: Pumping fresh air of water to the gas exchange surface to replace air/water already there, essentially maintaining a concentration gradient
- maintain concentration gradients of O2 and CO2 between air in alveoli and blood flowing in adjacent capillaries
88
Cell Respiration:
Cell Respiration: the controlled release of energy in the form of ATP from organic compounds in cells
89
Gas Exchange:
Gas Exchange: the process of absorbing one gas from the environment and releasing another
90
Trachea
Trachea: the tube that carries the air to and from the lungs; has many branches bumpy structure
91
Bronchus
Bronchus: the passages that direct air from the trachea into the lungs
92
Bronchiole
Bronchiole: branches that branch out from the bronchus to bring the air into the alveoli
93
Intercoastal muscles
Intercostal muscles: muscles between the ribs which help form and move the chest wall, involved in the mechanical aspect of breathing
94
lungs
Lungs: an organ responsible for ventilation and gas exchange
95
Diaphragm
Diaphragm: muscle separating the abdominal and thoracic cavities, and also responsible for the movement of the lungs exhalation and inhalation
96
Alveoli
Alveoli: thin walled air sacs, covered in capillaries, in the lungs where gas exchange occurs
- aprox 30 million in the lung; look like crapes
- each cluster has one or more capillary beds
97
Larynx
'voice box with the vocal cords'
| - airs passes through it from the pharynx to the trachea
98
MECHANISM OF BREATHING:
Based on the inverse relationship between pressure and volume
AN INCREASE IN VOLUME= A DECREASE IN PRESSURE
Lungs are located within the thorax, and have only one opening (through the trachea)
CLOSED ENVIRONMENT and INTERNAL ENVIRONMENT must be considered
99
INSPIRATION (Breathing in)
1. Diaphragm contracts; external intercostal muscles and a set of abdominal muscles raise the ribcage,
2. therefore increasing in volume of the thoracic cavity, due to minimal pressure
3. thoraic volume volume increase= pressure inside lung cavity decreases
4. less pressure is pushing on the passive lung tissue
5. This causes the pressure inside of your lungs to decrease (creating a vacuum)
6. air comes in through open mouth/nasal passages to counter the partial vaucuum within the lungs and fill the alveoili
100
EXPIRATION (breathing out)
1. Air leaves the alveoli into the lungs
2. This causes in increase in pressure in the lungs
3. The lung tissue decreases in volume as there is more pressure exerted on it
4. Because the thoracic cavity has decreased in volume, the pressure increases, leading to there being more pressure pushing onto the passive lung tissue
5. This causes the volume of the thoracic cavity to decrease, the the external intercostal muscles, diaphragm and abdominal muscles to relax and allow for the air to be released
101
TYPE 1 PNEUMOCYTES
TYPE 1 PNEUMOCYTES
Alveolar cell very thing, with large membrane SA (well designed for diffusion)
If damaged, cells incapable of mitosis for replacement
102
TYPE 2 PNEUMOCYTES
TYPE 2 PNEUMOCYTES
Cuboidal in shape
Small SA
Produce and secrete a solution that acts as a surfactant (reduces surface tension of moist inner surface of alveoli)
Capable of mitosis of both types of alveolar cells if damaged
103
emphysema
a disease whereby the alveoli in the lungs are progressivley destroyed
- its a COPD (chronic obstructive pulmonary disease)
- chronic, slowly progressive disease that turns healthy alveoli into irregurar shaped structures with gaping holes
104
causes of emphysema
- smoking
- tobacco smoking
- marijuana smoke
- fumes from manufacturing plants
- coal dust
- ir pollution
105
consequences of emphysema
- burst/deformed alveoli= reduces surface area for gas exchange= less oxygen reaches blood
- shortness of breath
- breathing problems
- chronic bronchitus
106
lung cancer
cancerous growth in lungs; prone to spreading (metastaizing)
| - high mortality rate
107
causes of lung cancer
- cancerous growth takes over areas of healthy tissue once provided a combination of bronchioles and alveolies
- carcinogens (smoking)
108
consequences of lung cancer
- internal bleeding
- mestastizis
- lungs become defective
109
homeostasis
reguation and limits of bodies physiological variables
| blood pH, sugar, gas concentration, temperature, water balance
110
thryoxin
a hormone that increases metabolic rate + regulates body temperature
- produced by thyroid gland
111
leptin
- hormone produced by fat tissue in body
- targets hyothalmus of brain
- regulates appetite
- obese people; high leptin levels
112
melatonin
- produced in pineal gland
- regualtes circardian rythym
- more produced at nigh
- can be used to fight jetlag
113
insulin
hormone produced in pancreas to regulate glucose in blood
114
glucagon
hormone produced in pancreas that breaksdown glycogen into glucose in the liver
115
what does blood sugar control do
- osmosis regulation
| - glucose needed for respiration
116
pancreas
gland behind the stomach that secretes digestive enzymes and through the isle of langer haans, hormones into the blood
117
diabetes
metabolic diseas in which body can't produce insulin which causes high glucose levels
can lead to;
- retina damage
- kidney failure
- nerve damage
- poor wound healing
118
diabetes I
when B cells dont produce enough insulin
- in children
- controlled by injection of insulin at appropriate times
119
diabetes II
body cell receptors don't response to insulin
- in adults
- controlled by diet
- assosiated with obesity, genetic history, age and lack of excersize
120
LOW BLOOD SUGAR body response
- glucagon released by alpha cells in pancreas
-glucagon breaks down glycogen to glucose
- blood sugar elevates
- liver releases glucose into the blood
=normal levels in blood
121
high blood sugar
- insulin released by beta cells of pancreas
-stimulates glucose to form glycogen
- glycogen lowers the blood sugar
-fat cells take in glucose from blood
= normal levels in blood
122
how is sex inherited?
- XY and XX chromosomes (50 50 chance)
123
Y chromosomes genes
1. SRY; formation of testes
2. House keeping genes (puberty) and testosterone production
3. sperm production
124
what does testoerone hormone do?
- determines the development of male genitalia during embryonic development
- ensures the development of secondary sex charateristics during puberty
- ensures sperm production as well as maintains sex drive following puverty
125
testes
male gonads which contain seminiferious tubules which produce spermatazoa
126
scrotum
- external sec containing testes
| - keep them at 3C below body temp for optimum sperm production
127
penis
- organ which introduces sperm into vagina
| - contains erticle tissue that stiffens with blood
128
vas defernes
sperm duct that connects penis and testes
| -muscular tube
129
epididymis
area where sperm is recieved, becomes mature and are capaable of swimming motion via flagella
130
urethra (male)
| female
tube for semen(male only) and urine
131
seminal vesicle
- produces mucus secretion that helps sperm movement
| - small glands that produce + add seminal fluid to the semen
132
prostate gland
- a glad that produces much of the seminal fluid (carbs for sperm)
- produces alkaline solution to neutralize urine in urethra and aid sperm movement
133
ovaries
- female gonad; produce egg (ovum) which develop into follicles when mature
- produce and secrete oestrogen
- can produce progesterone
134
oviducts (fallopian tubes)
- ducts that carry the ovum to the uterus
| - fertilization occurs here
135
uterus
- muscular structure where the embryo implants + pregnancy occurs
- mucous membrane
136
endometrium
mucous membrane; well supplied with blood; where embryo implants itself
137
cervix
lower portion of uterus; has opening to vagina which allows sperm to enter for fertliization and birth canal
138
vagina
site of penis acceptance and opening into uterus
139
In vito fertilization
IVF: VITRO FERTILIZATION:
“Test-tube” babies
Some couples unable to bear children, therefore infertile ( low sperm count, impotence, females do not ovulate properly, blocked fallopian tubes)
IVF: women have hormone therapy, where she takes the FSH (follicle stimulating hormone) to produce ova, which can be harvested surgically then mixed with cultured sperm cells in a petri dish until a healthy embryo develops
140
secondary female sex characteristics
- breast
- pubic hair
- widening of hips
141
secondary male characteristics
- facial, underarm, chest and public hair
- larynx enlargement (deeping of voice)
- increased muscle
- penis enlargement
142
FSH
follicle stimulating hormon; cuaes production and maturation of egg
- produced in pituitary gland
143
LH
lutinizing hormone: stimulates the relase of the egg
| - produced by pituitary gland
144
oestrogen
- stimulates release of LH and development of endometrium
| - produced in ovaries
145
progestrone
- maintains endometrium and inhibitits FSh and LH production
| - produced by ovaries initially, but then maintained by corpus luteum
146
menstruation steps
1. FSH produced by pituitary gland which causes a follicle to mature and the ovaries to start producing estrogen
2 Rising levels of estrogen cause the lining of the uterus wall to thicken and for the pituitary gland to stop producing FSH and produce LH instead
3. LH stimulates the release of the mature egg at day 14. The remains of the follicle develop into a structure called a ‘corpus luteum’ which then secretes progesterone
4. Progesterone then maintains the lining of the uterus and inhibits production of FSH and LH.
5. When the level of progesterone falls, the lining breaks down, which allows FSH to be produced again, and for the process to restart.
147
CNS
central nervous system (brain and spinal cord); recieves, itnerprets and processes sensory information from receptors
- if a response is needed, CNS intiates a motor response carried by neuron cells (individual cells that carry electical impulses from one point to another)
148
Human nervous system
nerve impulsues;
receptpors use sensory neurons to send impulses to the CNS which interprets them and then using a motor nueron, send a response to the effector
149
sensory neurons
bring information to the CNS from the receptor
150
motor neurons
carry response information to the muscles
151
what is a nerve?
neurons grouped together
152
peripheral nerves
- sensory neurons and moto neurons
| - componses of neuurons that carry electrical impulses
153
spinal nerves
spinal cord
154
cranial nerves
12 pairs; emerge from brain stem (e.g. optic eye nerve)
155
how are nerves and the CNS connected
- spinal nerves
| - cranial nerves
156
nerve impulse
- action potential along an axons of a neuron
157
action potential
a self-propagating wave of ion movements in and out of the membrane
- reversal and restoration of the electrical potential across the plasma membrane of a cell as an electrical impulse passes it (depolarization and repolarization)
- uses sodium pottasium pump
158
resting potential
0 time during which neuron is ready, but not actually sending an action potential
- electrical potential across the plasma membrane of a cell that is not condutin an impulse
159
how is a resting potential created
created by being polarized; created by active transport of Na + to in intracellular space and K + ions to cytoplasm
-3Na + are pumped out for ever 2K + ions pumped in
= negative ions in cytoplasm of axon which creates a net positive charge on the axon membrane and a net negative charge inside the axon membrane
160
depolarization
where an impulse is sent
161
depolarization processes
- reaches minimum threshold in order to be self-propagated
- first receptor neuron; modified to being sequence of events by transducing physical stimulus
- inside of membrane; become temporarily positive as Na + ions diffuse into membrame and K+ ions diffuse out
- "depolarized membrane" intiates the next area of the axon to open up for sodium channels
- action potential propagated along axon (where synaptic terminals are located)
162
repolarization
- process by which membrane reaches resting potential again
163
repolarization process
- after an area of an axon has been opened; chanels allow Na + to diffuse in
- area can't send another action potential until ions have veen restored to resting potential; requires active transport
- after Na+ ions and K+ ions diffuse, both are actively transported back to resting potential by membrane protein pumps (seprate ions on different membrane sides)
- to reach resting potential again; Na/K pumps actively transport them in (2K in for 3Na out)
164
summary of how a nerve impulse passes along a non-myelninated neuron
1. resting potential rises above threshold level
2. voltage gated Na+ channel open
3. Na+ flows into the cell; move Na+ channel open in direction of self propagating wave
4. inside of cell develops a net positive charge compared to outside and results in depolarization
5. voltage gated K+ channels open and K+ ions flow out of the cell
6. cell develops a net negative charge and results in repolarization
7. concentration gradient restored by sodium pottasium pumps to resting potential
165
saltatory conduction
transmission of an impulse by jumping (neurons with a myelin sheath)
166
advantages of saltatory conduction
- impulse travels faster in and out of membrane (ion movement takes time; reduces areas of the membrane)
- ATP required to transmit impulses; only place needed is for sodium potassium pump to reestablish resting potential; LESS ENERGY NEEDED
167
axons with a myenliated sheath
- series of schwann cells that wrap themselves equally and create a node of ranvier
- that acts as an insulator which prevents charge leakeage
168
what are synpases
- the joint area of chemical communication between neurons
| - two neurons align so that the axon's synpatic terminals of one neuron adjoin with the dendrites of another
169
neurotransmitter
a chemical relased from the synpatic terminal buttons that sends the impulse to the second neuron (chemical messenger)
- found in terminal buttons
170
presynpatic neurone
neurone that sends the neurotransmitter
171
postsynaptic nerve
neurone that recieves the neurotransmitter
172
example of a neurotransmitter
- acetylcholine
173
what happens when an action potential reaches the area of the terminal buttons?
1. action potential results in calcium ions diffusing into the terminal buttons
2. vescicles containing the neurotransmitter fuse with the plasma membrane and release the neurotransmitter
3. the neurotransmitter diffuses across the synaptic cleft from the presynpatic neuron to the postsynaptic neurone
4. the neurotransmitter binds with a receptor protein on the postynatic neurone membrane
5. this binding results in an ion channel opening and sodium ions diffusing in through this channel
6. this initiates the action potential to being moving down the postsyynaptic neurone because it is now depolarized
7. the neurotransmitter is degraded by a specific enzyme + neurotransmitter is relased from the receptor protein
8. the ion channel closes to sodium ions
9. the neurotransmitter fragmeents diffused back to the synaptic clef to be reassmelened in the terminal buttons of the presnaptic neurone (REUPTAKE)
174
what is neuromuscular junction
when synapses occur where a motor neurone adjoins musle tissue
- this mechanism results in muscle contraction
- another place for a synapse is between a receptor neurone cell and the first sensory neurone
175
neoincotinoid
- a type of insecticide that blocks synpatic tramsmission
- binds to postynaptic receptors that normally accept the neurotransmitter acetylcholine; when acetylcholine tries to binnd, it results in an action potential not being propagated
- neuoincotonid moleucles aren't broken down by the acetylecholine enzyme and thus the receptors become blocked= leads to the paralysis and death of the inffected insect
