All chap definition Flashcards
(359 cards)
1
Q
Mitotic cell division
A
Involves the process of nuclear division called mitosis, followed by a cytoplasmic division called cytokinesis
2
Q
Meristematic tissues
A
Found in terminal buds, the vascular cambium and cork cambium
3
Q
Mitosis definition
A
the process of nuclear division which results in the formation of two genetically identical daughter nuclei
4
Q
Binary fission
A
Cell division by asexual reproduction which produces two new genetically identical organisms
5
Q
Chromosomes
A
Thread-like structure in every cell nucleus
6
Q
Chromosomal number
A
The constant number of chromosomes present in the cells of each species of an organism
7
Q
Diploid
A
2n
8
Q
Haploid
A
n
9
Q
Somatic cell in human body
A
Has 46 chromosomes
10
Q
Gamete/ Reproductive cells in human body
A
Has 23 chromosomes
11
Q
Diploid number of chromosomes
A
The presence of two sets of chromosomes in the nucleus of a cell
12
Q
Homologous chromosomes
A
The two chromosomes in each pair have the same structural features
13
Q
Member of each pair of homologous chromosomes
A
Homologue
14
Q
Cells with two sets of homologous chromosomes
A
Diploid cells
15
Q
Cells which contain only one set of chromosomes
A
Sex chromosomes
16
Q
Duplicated chromosome
A
Contains two sister chromatids
17
Q
Chromosome
A
Consists of DNA molecule and protein
18
Q
Chromatin
A
The chromosomes are not condensed and visible as thread-like structures
19
Q
Daughter chromosome
A
When two sister chromatids separate to become an independent daughter chromosome during mitosis
20
Q
Centromere
A
Narrow region in the centre of a chromosome
21
Q
Interphase
A
The stage at which cells grow larger and prepare for cell division
22
Q
Centrosomes
A
A pair of centrosomes is formed in the cytoplasm
Found in animal cells only
23
Q
Centrioles
A
Each centrosomes consists of a pair of centrioles
24
Q
Metaphase plate
A
The centromeres of all the chromosomes are lined up on the equator of the cell
25
Cell cycle
Interphase
| M phase/ Mitotic cell division
26
Interphase
G1 phase
S phase
G2 phase
27
M phase/ Mitotic cell division
Mitosis
| Cytokinesis
28
Mitosis
Prophase
Metaphase
Anaphase
Telophase
29
Cytokinesis
The cytoplasm of the cell divides through a process following mitosis
Process of cytoplasmic division
30
Cancer
A disease caused by uncontrolled mitosis due to severe disruption to the mechanism that controls the cell cycle
31
Tumour
An abnormal mass of cells
32
Cloning
The process of producing clones of genetically identical copies of a cell, tissue or an organism
33
Animal cloning
Involves the transfer of the nucleus from a somatic cell to an ovum or embryonic cell with the nucleus removed
34
Tissue culture technique
Involves the growth of cells or tissues outside the organisms in a suitable culture medium, which contains nutrients and growth hormones
35
Explants
Cut out of small pieces of plant tissues
36
Protoplasts
Naked cells without cell walls
37
Culture medium/ Growth medium
Consists of a complex mixture of glucose, amino acids, minerals and other substances required for the growth of tissues
38
Aggregrates of cells
The aggregrate of cells develop into a callus
39
Callus
An undifferentiated mass of tissue
40
Transgenic plants
Carry a foreign gene that has been introduced into their genetic constitution so that they possess new and different traits
41
Meiosis
A process of nuclear division that reduces the number of chromosomes in daughter cells to half that of the parent cell
42
Synapsis
Homologous chromosomes come together to form pairs of bivalents through synapsis
43
Bivalent
Each bivalent consists of a four-part structure
44
Tetrad
A tetrad consists of two homologous chromosomes, each of which is made up of two sister chromatids
45
Crossing-over
Non-sister chromatids exchange segments of DNA
46
Chiasmata
| sing. Chiasma
The points at which segments of chromatids cross over
47
Circulatory system
1. Delivers nutrients and oxygen to cells
2. Carries waste products away from the cells
3. Protects the body from infections
48
Blood
A type of connective tissue made up of plasma, blood cells and platelets
The medium of transport in humans and animals
49
Heart
Function as a muscular pump that circulates the blood throughout the body
50
Blood vessel
Consist of arteries, capillaries and veins that are connected to the heart to deliver blood to all body tissues
51
Haemolymph
A blood-like nutritive fluid which fills the entire body cavity and surrounds all cells
Transports water, inorganic salts and organic compounds throughout the haemocoel
52
Haemocoel
body cavity
53
Blood function
Regulates
1. pH of body fluids
2. The body temperature
3. The water content of cells
54
Protection from blood
Protect us from
1. Excessive blood loss in an injury through the mechanism of blood clotting
It helps to heal wounds
2. From diseases by helping to fight against infections
55
Blood plasma
The main transport medium in the body
56
Leucocytes
| Granular or Agranular
Colourless and have nuclei and mitochondria
Irregular in shape
Made by stem cells in the bone marrow
57
Granulocytes
Neutrophils
Eosinophils
Basophils
(Have granular cytoplasm and lobed nuclei)
58
Agranulocytes
Lymphocytes
Monocytes
(Have clear cytoplasm and their nuclei are not lobed)
59
Neutrophils
Phagocytic granulocytes that engulf and digest bacteria and dead cells
60
Eosinophils
Release enzymes to fight inflammation in allergic reactions
| Kill parasitic worms
61
Basophils
Involved in combating inflammatory and allergic reactions
| Secrete heparin to prevent blood from clotting
62
Lymphocytes
Produce the immune response against foreign substances
63
Monocytes
Engulf and digest bactera and dead cells
64
Cellular components
Consist of erythrocytes, leucocytes and platelets
65
Platelets
Fragments of large cells from the bone marrow
66
Erythrocytes
Shaped like a biconcave disc
(thinner in the centre than at the edges)
does not have a nucleus
Small
All these characteristics give an erythrocyte a large surface area to volume ratio for the rapid diffusion of oxygen across its plasma membrane
Has elastic membrane
(Enables it to squeeze easily into the tiniest blood capillaries)
67
Haemoglobin
An oxygen-carrying protein pigment that gives the erythrocyte its red colour
68
Haem group
Contains an iron atom and is the site of oxygen binding
69
Pulmonary artery
The only artery that carries deoxygenated blood from the heart to the lungs
70
Pulmonary vein
The only vein that carries oxygenated blood from the lungs to the heart
71
Arterioles
Small arteries that branch into a network of capillaries which reach into the tissues
72
Capillaries
Tiny, thin-walled blood vessels
73
Heart
Cone-shaped, muscular organ about the size of a clenched fist
74
Pumping of heart function
1. Carries vital materials required by the body
| 2. Removes waste products that the body does not need
75
Atria
| sing. Atrium
Recieve blood returning from the heart
76
Ventricles
Pump blood out of the heart
77
Valves
Allow blood to flow in one direction only
78
Cardiac muscle
Strong muscle
| Myogenic
79
Myogenic
It contracts and relaxes without the need to receive stimulation by nerve impulses
80
Pacemaker
A cluster of specialised heart muscle cells that set the rate of contraction
Generates electrical impulses which spread rapidly over the walls of both atria, causing the atria to contract rythmically
81
Primary pacemaker
Sinoatrial (SA) node
82
Sinoatrial (SA) node
It keeps the heartbeat regular
83
AV node
Atrioventricular (AV) node
84
Atrioventricular (AV) node
Sends impulses to the ventricles to contract
85
bundle of His fibres
bundle branches
Purkinje fibres
Specialised muscle fibres that send impulses to the apex of the heart and throughout the walls of the ventricles
86
Systole stage
Contraction of ventricles
87
Systolic pressure
The highest recorded pressure in an artery when the ventricles contract
88
Diastole stage
The relaxation stage of heartbeats
89
Diastolic pressure
The lowest recorded pressure during the relaxation stage of heartbeats
90
Baroreceptors/ Pressure receptors
Located in the arch of the aorta and carotid arteries
| Detect the pressure of the blood flowing through them
91
Carotid arteries
arteries in the neck that supply blood to the brain
92
Blood pressure
The pressure against the walls of the blood vessel when blood flows along a vessel
The force that pumps blood along the arteries and the capillaries
93
Open circulatory system
1. One or more hearts
2. A network of vessels
3. A large open space within the body
94
Haemocoel
A large open space within the body
Contains the soft internal organs and its filled with haemolymph
95
Ostia
| sing. ostium
The haemolymph is drawn through the pores called ostia back into the hearts when the hearts relax
96
Pumocutaneous circulation
delivers the deoxygenated blood to the organs involved in gaseous exchange, that is, the lungs and the skin
97
Systemic circulation
carries the oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through the veins
98
Blood clotting
A body mechanism to stop or minimise blood loss from damaged blood vessels
99
Blood clotting function
1. Prevent serious blood loss when a person is injured
2. Maintain blood pressure
3. Maintain the circulation of blood in a closed circulatory system
4. Prevent the entry of microorganisms and foreign substances into the body through the damaged blood vessels
100
Blood clotting mechanism
Involves a complex series of biochemical reactions in the blood to prevent excessive bleeding after an injury
101
Platelet plug
The aggregration of platelets that forms a plug
102
Prothrombin
inactive plasma protein
103
Thrombin
active plasma protein which acts as an enzyme
It catalysts the conversion of the soluble protein fibrinogen in blood plasma into the insouble fibrin
104
Fibrin
forms a mesh of fibres across the wound, sealing the wound and preventing further loss of blood
A fibrous protein which combines to form a mesh of long threads over the wound, trapping erythrocytes and sealing the wound
105
Haemophilia
Example of an impaired blood clotting mechanism
Hereditary disease
The afflicted person lacks the gene necessary for the production of certain clotting factors
106
Thrombosis
Example of an impaired blood clotting mechanism
107
Thrombosis
Example of an impaired blood clotting mechanism
108
Thrombus
The clot formation inside an unbroken blood vessel
109
Embolus
A blood clot moving in a bloodstream
110
Heart attack
Myocardial infraction
111
Interstitial fluid
Fills the spaces between the cells and constantly bathes the cells
112
Exchange of substances btw blood capillaries and body cells
1. Nutrients and oxygen diffuses from the blood through the interstitial fluid into the blood cells
2. Carbon dioxide and other waste products diffuse from the body cells through the interstitial fluid into the blood
113
Composition of interstitial fluid
1. Consists of water, dissolved nutrients, hormones, waste products, gases and small proteins from the blood
2. Leucocytes ooze through the openings in the capillary walls
3. It does not contain plasma proteins, erythrocytes and platelets because these are too large to pass through the capillary walls
114
Lymphatic system
A one-way system consisting of a network of lymph capillaries, larger lymphatic vessels and lymph nodes
115
Lymph capillaries
Blind-ended tubes located in the spaces between the cells
116
Blind-ended tubes
Closed at one end
117
Plasma proteins
Albumin, globulin, fibrinogen
118
Lymph nodes
1. Produce and store lymphocytes
| 2. Help to protect the body against infections
119
Thoracic duct
receives lymph from the left side of the head, neck and chest, the left upper limb and the entire body below the ribs
120
Right lymphatic duct
Receives lymph from the right arm, shoulder area, and the right side of the head and neck
121
Oedema
An excessive accumulation of interstitial fluid in the spaces between the cells
Caused by a blocked lymphatic vessel
122
Lacteals
Lymph capillaries that transport droplets of lipids and fat-soluble vitamins to the bloodstream
(in the villi of small intestine)
123
Composition of blood
Plasma and cellular components
124
Composition of interstitial fluid
Plasma without plasma proteins, erythrocytes and platelets
125
Composition of lymph
1. Plasma without plasma proteins, erythrocytes and platelets
2. More fatty substances
3. Large number of lymphocytes produced by the lymph nodes
126
The first line of defence
Consists of physical and chemical barriers that prevent pathogens from entering the body
Non-specific defences
(do not differentiate one pathogen from another)
127
Pathogens
disease-causing microorganisms such as bacteria, viruses and parasites
128
Examples of first line of defence
```
skin
mucous membrane
tears and saliva
hydrochloric acid
blood clotting
```
129
Skin
1. Provides a physical barrier that is impenetrable to bacteria and viruses
2. A chemical barrier as it secretes sebum that forms a protective film over the skin
130
Sebum
The acids and oils in the sebum prevent the growth of microorganisms
131
Sweat
contains lysozyme, an enzyme capable of breaking down the cell walls of certain bacteria
132
Mucous membrane
(line the trachea, respiratory passageways, digestive and urinary tracts)
Stop the entry of potentially harmful microorganisms
Secretes mucus
133
Mucus
contains lysozyme which traps and destroys bacteria
134
Tears and saliva
contain lysozyme which helps to protect the eyes and mouth from bacterial invasion
135
Hydrochloric acid
destroy most pathogens that gain entry into the body via the food and drinks consumed
136
Blood clotting mechanism in first line defence
prevents the entry of pathogens by sealing the wounds
137
The second line of defence
Face the pathogens that penetrate the first line of defence, such as those that enter through a break in the skin
Non-specific
138
Phagocytosis
Performed by phagocytic white blood cells or phagocytes
139
Macrophages
Found mainly in the interstitial fluid
140
The third line of defence
Face pathogens that manage to overcome the second line of defence
Involves immune system
specific or targeted defence
141
Immunity
The body resistance to the pathogen which causes a specific disease
142
Antigens
Substances usually proteins, that the immune system recognises as foreign or not part of the body
143
Antibodies
Proteins found on the surface of lymphocytes or proteins released by lymphocytes into the blood plasma
144
Lymphatic system
Return excess interstitial fluid to the circulatory system
| Help defend the body against invasion by pathogens
145
Lymph nodes
Contain macrophages that destroy bacteria, dead tissues and other foreign substances through phagocytosis
Contain lymphocytes that destroy antigens and foreign organisms
146
How antibodies work
1. Agglutination
2. Neutralisation
3. Opsonisation
4. Lysis
147
Agglutination
Antibodies cause the pathogens to clump together
| This clumping makes it easy for the phagocytes to capture and destroy the pathogens
148
Neutralisation
An antibody neutralises the toxins produced by the bacteria by binding to a toxin molecule
This prevents the toxin molecule from attaching to a cell and causing damage
149
Opsonisation
Antibodies that bind to antigens and act as markers so that antigens can be easily recognised and destroyed by phagocytes
150
Lysis
Lysins : Antibodies that bind to the anitgens and cause the antigens to rupture or disintegrate
151
Active immunity
The body produces its own antibodies in response to stimulation by an antigen
Naturally acquired active immunity
Artificially acquired active immunity
152
Passive immunity
The body receives antibodies from an outside source
Naturally acquired passive immunity
Artificially acquired passive immunity
153
Naturally acquired active immunity
Immunity that is obtained after a person recovers from an infection
154
Artificially acquired active immunity
Immunity that is obtained through immunisation or vaccination
155
Naturally acquired passive immunity
Immunity that is obtained from the mother either through breast milk or via placenta
156
Artificially acquired passive immunity
Immunity that is obtained through the injection of a serum which contains specific antibodies
157
Vaccine
A preparation of a weakened, dead or non-virulent forms of a pathogen that is not harmful to the person who receives it
Stimulates the body to produce antibodies capable of binding to the antigen
158
Immunisation
The process of inducing immunity by administering a vaccine
159
Examples of diseases with vaccines available
```
Hepatitis B
diphtheria
pertussis
tetanus
poliomyelitis
```
160
Examples of vaccines
Salk poliomyelitis vaccine
| Sabin vaccine
161
Booster dose
Increase the antibody production to a level that protects the person against the disease
162
Human immunodeficiency virus (HIV)
A virus that attacks the human immune system
163
acquired immunodeficiency syndrome (AIDS)
Infection caused by the HIV
164
HIV virus danger
1. Reproduces inside T-lymphocytes and destroys them in the process
2. inhibits phagocytosis carried out by macrophages
165
Diseases linked to the cardiovascular system
```
Coronary thrombosis
Atherosclerosis
Arteriosclerosis
Hypertension
Angina (Chest pain)
Heart attack
Stroke
```
166
Atherosclerosis
The early stage of arteriosclerosis
167
Arteriosclerosis
Formation and deposition of plaques on the inner walls of arteries
The hard plaques clog the lumen of blood vessels and narrow the lumen and also
cause the hardening of arteries and decreased elasticity of the arteries
168
Xylem
transports water and dissoved mineral salts absorbed by the roots up the stems and to the leaves
In woody plants, provides mechanical support to the plant
169
Phloem
Transport organic substances from the leaves down to the storage organs and from the storage organs
such as the roots up to the growing regions such as the buds
170
Stem
Has an epidermal layer that helps maintain the shape of the stem
171
Cortex layer
Made up of
collenchyma cells which provide support and flexibility to the stem
and parenchyma cells which store food
172
Pith
1. Used for food storage in young plants
| 2. absent in hollow plants, making them hollow
173
Vascular bundles
Arranged in a ring around the pith
In each vascular bundle, xylem is found towards the inside of the stem with the phloem on the outside
174
Cambium
lies between the xylem and the phloem
175
Root hairs
Increase the surface area for water absorption
176
Epidermis in roots
Does not have any waxy cuticles
| absorbs water and dissolved mineral ions from the soil
177
Cortex
The region between the epidermis and the vascular cylinder
178
Endodermis
a single layer of cells located immediately after the cortex
179
Pericycle
Located next to the endodermis
| Consists of sclerenchyma tissue which provides mechanical support for the roots
180
Vascular cylinder
consists of vascular tissue and the pericycle
181
Cells in xylem
xylem vessel
tracheids
fibres
parenchyma
182
parenchyma
stores food substances
183
fibres
provide support to the xylem
184
xylem vessels and tracheids
water-conducting cells
185
Lignin
make walls of xylem vessels and tracheids strong and hardy so that they do not collapse under the tension of transpiration pull
Prevents the entry of food substances
186
Pits
Small openings of xylem vessels and tracheids
| Allow water and mineral salts to pass sideways between the cells
187
Cells inside Phloem tissue
sieve tubes
companion cells
parenchyma
fibres
188
Bark ringing
removal of a ring of the bark
189
sieve tubes
A cylindrical column comprising long cells arranged end to end
Living cell
190
sieve plates
To allow substances to pass from one cell to another
191
Companion cell
A normal cell with a nucleus and a large number of mitochondria, indicating that it has active metabolism
192
Phloem sap
A very concentrated solution of dissolved organic solutes such as sugars, amino acids and other metabolites in phloem
193
Translocation
The transport of dissolved organic solutes in the phloem
194
Importance of translocation
1. Survival of a plant depend on the transport of organic substances from the leaves to the storage organs (roots) to the growth regions (buds)
2. Enables sucrose, the product of photosynthesis, to be stored or converted into other sugars when it reaches its destination
195
Transpiration
The loss of water vapour through evaporation from the surface of plants
196
Transpiration stream
The continuous stream of flowing water from the roots to leaves
197
Assistance for movement of water from roots to leaves
Root pressure
capillary action
transpiration pull
198
Casparian strips
line the sides of the endodermal cells
impermeable to water
(movement through the cell walls is blocked)
199
Gradient of water concentration
| exists across the cortex
Creates a pushing force that results in the inflow of water into the xylem
200
Root pressure
results in an upward push of water and mineral ions into the xylem of the stem
201
Capillarity / capillary action
the result of the cohesive and adhesive forces which enable water to enter and move along the very narrow columns
202
Cohesive forces
The water molecules adhere to one another
203
Adhesive forces
The water molecules adhere to the walls of the xylem vessels
204
Sensitivity
Ability to detect changes and respond to them accordingly
205
Stimuli
The changes which cause response
206
Coordination
Ensures that the activities of an organism function efficiently
207
Components of nervous system
sensory receptors
integrating centre
effectors
208
Afferent pathway
allow the transmission of nerve impulses from the sensory receptors through the afferent neurones to the integrating centre
209
Efferent pathway
Transmits nerve impulses from the integrating centre through the efferent nerves to the effectors
210
Central nervous system (CNS)
brain
| spinal cord
211
Peripheral nervous system (PNS)
all the nerve tissues outside the CNS
| consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves
212
Sensory receptors
detect stimuli from both internal and external environments and initiate nerve impulses that carry information to the CNS
213
Human brain consist of
```
cerebrum
cerebellum
medulla oblongata
pituitary gland
thalamus
hypothalamus
```
214
Hypothalamus
1. Homeostatic regulation
| 2. Controls the release of several hormones from pituitary gland
215
Cerebrum
Centre which receives sensory input and carries out integrative functions before initiating appropriate motor response
216
Cerebral cortex
| outer region of cerebrum
a structure with many folds which increases surface area
| Controls all voluntary muscle movements and for many mental abilities
217
Thalamus
1. sorts the incoming and outgoing information in the cerebral cortex
2. integrates the information from sensory receptors
218
Cerebellum
Coordinate body movements
219
Pituitary gland
Secrete hormones that control the secretion of hormones from all other glands
220
Medulla oblongata
Controls involuntary actions and regulates the internal body processes
Reflex centre
221
Cerebrospinal fluid
Acts as a shock absorber and provides spinal cord with nutrients
222
Grey matter
Consist mainly of cell bodies of neurones
223
White matter
Comprises myelin-coated axons of neurones
224
Spinal cord function
1. Process sensory information and send out responses via efferent neurones
2. Contains neurones that convey signals from and to the brain
3. Controls reflex action
225
Dorsal root
Contains the axons of the afferent neurones which conduct nerve impulses from the sensory receptors to the spinal cord
226
Spinal nerve
Contains afferent and efferent neurones
227
Ventral root
Contains axons of efferent neurones which conduct nerve impulses away from the spinal cord to the effectors
228
Neurones
Afferent neurones
Efferent neurones
Interneurones
229
Afferent neurones
| Sensory
Send nerve impulses from receptor cells to the brain and spinal cord
230
Efferent neurones
| Motor
Send nerve impulses from brain or spinal cord to the effectors (muscles or endocrine glands)
231
Interneurones
Transmit nerve impulses btw afferent and efferent neurones
232
Dendrites
fibres that receive information or signals from other neurones or from the external environment and conduct them towards the cell body
233
Axon
conducts the nerve impulses away from the cell body
234
Synaptic terminals
Swellings at the branched ends of the axons
| Transmits signals to muscle cells, gland cells or dendrites of other neurone
235
Cell body
Integrates signals and coordinate metabolic activites
236
Myelin sheath
protects and insulates the axons
| helps to speed up the transmission of the nerve impulses
237
synaptic cleft
separates the synaptic terminal from the dendrite of a receiving neurone
238
synapse
a site where two neurones, or a neurone and an effector cell communicate
1. control and integrate nerve impulses transmitted by stimulated receptors
2. Facilitate the transmission of nerve impulses in one direction
239
neurotransmitters
```
stored in small synaptic vesicles
acetylcholine
noradrenaline
serotonin
dopamine
```
240
Mitochondria
generate energy for the transmission of nerve impulses across the synapse
241
Reflex actions
rapid, automatic or involuntary responses to stimuli
242
Reflex arc
The pathway by which nerve impulses travel from the receptor to the effector in a reflex action
243
Knee-jerk reflex/
| patellar reflex
uses afferent and efferent neurones only
244
division of autonomic nervous system
sympathetic division
| parasympathetic division
245
Parkinson's disease
Progressive disorder of the CNS that affects victims around the age of 60 years onwards
due to reduced levels of dopamine
246
Alzheimer's disease
A neurological disorder which affects victims around 60 yr old, causes loss of reasoning and the ability to care for oneself
247
Hormones
chemical messengers produced by the endocrine gland
248
Endocrine glands
Ductless glands that secrete hormones directly into the interstitial fluid and subsequently into the bloodstream
249
Hormones by Anterior piuitary gland
TSH
FSH
LH
GH
250
Hormones by Posterior pituitary gland
ADH
| Oxytoxin
251
Thyroid stimulating hormone (TSH)
| @thyroid gland
Stimulates the thyroid gland to release thyroxine
252
Follice-stimulating hormone (FSH)
| @Gonad
Stimulates the development of the follicles in the ovaries in females
Stimulates spermatogenesis in males
253
```
Luteinising hormone (LH)
@gonad
```
Stimulates ovulation
development of corpus luteum
secretion of oestrogen and progesterone
stimulate testosterone
254
```
Antidiuretic hormone (ADH)
@kidney
```
Stimulates water reabsorption by the renal tubules in the kidneys
255
Throxine
by thyroid gland
| Regulates growth and development
256
Aldosterone
By Adrenal cortex
| Increases the reabsorption of mineral salts in the kidneys
257
Adrenal medulla
secrete adrenaline and noradrenaline
258
Pancreas
secrete insulin and glucagon
259
Ovaries
secrete oestrogen and progesterone
260
testes
secrete androgen
261
hypoglycaemia
over secretion of insulin
| abnormally low level of glucose in blood
262
diabetes mellitus
under secretion of insulin
| chronic condition associated with abnormally high levels of glucose in blood
263
goitre
over secretion of thryoxine
iodine deficiency
(thyroid gland cannot secrete enough thryoxine)
264
Cretinism
under secretion of thyroxine in child
265
Myxedema
under secretion of thyroxine in adult
266
Gigantism
over secretion of GH in child
267
Acromegaly
over secretion of GH in adult
268
Dwarfism
under secretion of GH
269
Oversecretion of ADH
High retention of water in the body
| 尿很浓
270
Diabetes insipidus
under secretion of ADH
271
Kidney
1. Helps to regulate water and salt balance
2. Regulate osmotic pressure
3. Excrete waste products
4. Regulate blood pH
272
Renal artery
supplies oxygenated blood and nutrients to the kidney
273
Renal vein
carries filtered blood away from the kidney
274
Bowman's capsule
made up of two layers of cells that surround glomerulus
275
capsular space
the space between the two layers of cells
276
podocytes
the cells that make up the inner wall of the Bowman's capsule
277
nephron consist of
glomerulus
Bowman's capsule
renal tubule
278
renal tubule made up of
proximal convoluted tubule
loop of Henle
distal convoluted tubule
279
ultrafiltration
the high hydrostatic pressure in the glomerulus forces fluid through the filtration membrane into the capsular space
280
glomerular filtrate
the fluid that enters into the capsular space
281
haemodialysis
process of filtering blood by using an artificial means that replaces the functions of a failed kidney
282
artificial kidney
machine which contains a dialyser
283
pancreas
the gland that is responsible for maintaining the blood sugar level within normal range
284
stimulant
increase the activity of the CNS
285
depressants
often slow down the activity of CNS
286
hallucinogens
causes a user to see, hear and perceive things that do not exist
287
narcotics
induce feelings of ecstacy, block pain signals and slow down normal brain functions
288
positive phototropism
growth of shoots towards sunlight
289
negative phototropism
growth of shoots away from sunlight
290
coleoptile
shoot of glass seedling enclosed in a sheath
291
auxins
produced in the apical meristems at the tips of the shoots
increase the rate of cell division
promote cell elongation
phototropism:
the growth of a plant towards light is caused by unequal distribution of auxins in the shoot
geotropism:
auxins control the responses of both roots and shoots to light and gravity
292
Parthenocarpy
used to produce seeless fruits
293
ethylene/ethane/ethene
plant hormone which is synthesised during the ripening of fruits
stimulate the production of cellulase
promotes the breakdown of complex carbohydrates into simple sugar
294
Reproduction necessary
to ensure:
1. the continuation of the species
2. the passing down of an individual's genes to future generations
295
sexual reproduction
the production of offspring through the fusion of haploid gametes to form a diploid zygote
296
asexual reproduction
the reproductive process in which new individuals are produced without the formation of gametes
297
zygote
fertilised egg
298
Formation of gametes
ensures:
1. the diploid chromosomal number is maintained from one generation to the next
2. genetic variations in the offspring to give them better survival chances in an ever changing environment
3. the continuity of a species
299
testes
| /male gonad
produce both the male gametes (sperms) and male sex hormones
300
scrotum
holds the testes and is located outside the main body
301
seminiferous tubules
joined together to form a tightly coiled tube called the epididymis
302
vas deferens/ sperm duct
stores the sperms
303
acrosome
contains hydrolytic enzymes that help to digest the protective layers surrounding an ovum, enabling the sperm to penetrate and fertilize it
304
mitochondria
provide the energy needed for the movement of tail
305
spermatogenesis
spermatozoa formation
| take place in the density coiled seminiferous tubules
306
ovaries / femala gonads
produce female gametes (ova) and secrete female sex hormones
hormones:
oestrogen, progesterone
307
fallopian tubes
have finger-like projections called frimbriae which surround the ovaries
combined action of the frimbriae and the beating of cilia that line the oviducts help to move the ovum along
308
uterus
a thick-walled, muscular organ that holds the developing embryo and foetus
309
Oogenesis
the formation of oocytes
310
Ovulation
the release of the secondary oocyte from the ovary
311
Menstrual cycle
the cyclic changes that occur in the endometrium of the uterus to prepare it for a fertilised ovum and its subsequent development
312
FSH
| LH
The hormones that control the changes in the ovaries
313
Oestrogen
| Progesterone
Controlthe changes in the uterus
314
FSH place of secretion
the anterior lobe of the pituitary gland
315
LH place of secretion
the anterior lobe of the pituitary gland
316
Oestrogen place of secretion
Follicle cells of the ovary
317
Progesterone place of secretion
Corpus luteum
318
FSH function
Stimulates the development of follicles in the ovary
319
LH function
stimulates ovulation
stimulates the development of corpus luteum
promotes the secretion of progesterone
320
Oestrogen function
Stimulates further the growth of the follicle
Promotes the repair of the endometrium
From about the 2th day of the menstrual cycle, it has a positive feedback action on the secretion of the FSH and LH
321
Progesterone function
Stimulates the endometrium to become thick, folded and highly vascular for the implantation of an embryo
Inhibits the secretion of FSH and LH to prevent the development of the Graafian follicles and ovulation
322
highly vascular
enriched with blood vessel
323
Menstruation
The breakdown of the lining of the uterine wall and the discharge of blood, epithelial tissues and mucus through the vagina
324
premenstrual syndrome (PMS)
cyclical disorder of severe physical, mental and emotional distress
325
Menopause
occurs between the ages of 45 and 55 years when ovaries are less stimulated by FSH and LH
This inhibits the development of the follicles and ovulation, leading to a lower secretion of progesterone and oestrogen
326
decrease in bone density
a low level of oestrogen
327
zygote
the product of fertilisation
328
fertilisation membrane
Barrier formed on the surface of the oocyte once a sperm has successfully penetrated the plasma membrane of the secondary oocyte
329
pregnancy
the period when an ovum is fertilised, menstrual cycle stops and a nine-month gestation period starts
330
implantation
the blastocyst attaches itself to the endometrium seven days after fertilisation
331
foetus
fertilised egg from the third month of development until birth
332
embryo
fertilised egg during the first eight weeks of its development
333
amniotic fluid
protects the foetus by absorbing shocks and cushioning it from any physical damage
334
blastocyst
A fluid-filled sphere consisting of an outer layer of cells and a group of cells inside the sphere
335
Trophoblast
outer layer of cells
336
Inner cell mass
clusterof cells within the sphere
337
Identical twins
Formed when the ball of cells from a fertilised ovum splits into two embryos
only one sperm and one ovum are involved in the process of fertilisation
338
Fraternal twins
Formed when two ova are released at the same time, one from each ovary.
Each ovum is then fertilised by a sperm
339
Siamese twins
Identical twins which did not separate completely during embryonic development
340
Placenta
1. The site of exchange of nutrients, respiratory gases and wastes between the foetus and its mother
2. Acts as an endocrine gland that secretes oestrogen and progesterone
341
Umbilical cord
Connect foetus and placenta
| A tube with one umbilical vein and two umbilical arteries
342
Umbilical arteries
Carry blood rich in carbon dioxide and nitrogenous waste products from the foetus to the placenta
343
Umbilical vein
Carries blood rich in oxygen and nutrients from the placenta to the foetus
344
Thin membrane of the chorionic villi
Separates the blood capillaries of the foetus (foetal capillaries) from the maternal blood
345
Rhythm method
A married couple avoid engaging in copulation during the woman's fertile period
346
Contraception
Practice of preventing pregnancy
347
Condom
A thin rubber sheath that is fitted over the erect penis before copulation
348
Withdrawal method
The penis is withdrawn from the vagina before the release of semen or ejaculation
349
Vasectomy
sperm ducts are tied and cut in a surgical operation
350
diaphragm
a dome-shaped rubber cap with a springy outer ring to ensure a close fit
351
female condom /femidom
a thin sheath which lines the vagina
352
IUD
Intrauterine device
A plastic-coated copper coil that is fitted into the uterus by a doctor and can be left in the uterus for approximately two years
353
Spermicide
Chemical cream, gel or foam that is applied to the vaginal walls before copulation
used tgt with a diaphragm
354
contraceptive pills
pills with a combination of ostrogen and progesterone
| synthetic progesterone
355
Contraceptive implant
A capsule inserted just below the skin of the upper arm
356
Tubal ligation
Both the Fallopian tubes are cut and tied in an operation
357
Depo-Provera injection
An injection of synthetic progesterone given every three months
358
Common causes of infertility
```
blocked Fallopian tubes
failure of an embryo to implant itself on the endometrium
the inability to produce ova
blocked sperm ducts
low sperm count
```
359
STD
Sexually transmitted diseases
| diseases that are spread through sexual contact
