Systems (Chapter 5 & 6) Flashcards
SAC Only
1
Q
what are multicellular organisms composed of?
A
Multicellular organisms are composed of cells.
2
Q
how do complex organisms survive?
A
Complex organisms, such as plants and animals, can survive because their cells are specialised, which means that they perform specific individual functions.
3
Q
how must specialised cells interact to survive?
A
However, each of these specialised cells must interact and work together with all other cells of the body to survive.
As an organism increases in size and complexity, greater cooperation and coordination of cells is required to survive, and cells begin to arrange into four different levels: cells, tissues, organs and systems.
4
Q
define cell
A
Cell the smallest functional unit of a living organism
5
Q
define tissue
A
Tissue a cluster of cells which perform a shared function
6
Q
define organ
A
Organ the organisation of tissues & cells into a distinct structure that performs a specific function
7
Q
define system
A
System a collection of organs & tissues that perform specific functions for survival
8
Q
Plant cells are organised into?
A
- Dermal tissue
- Vascular tissue
- Ground tissue
9
Q
define dermal tissue
A
Dermal tissue that lines the outside of plants
10
Q
define vascular tissue
A
Vascular tissue that is responsible for transporting water and nutrients around the plant
11
Q
define ground tissue
A
Ground tissue which describes all other tissues in a plant.
12
Q
Plant tissues are organised into many distinct organs & two different systems?
A
- root system
- shoot system
13
Q
define root system?
A
The root system contains the roots
14
Q
define shoot system?
A
The shoot system contains the leaves, stems, flowers, and fruit.
15
Q
what are the Plant Organs?
A
- Leaves
- Flowers
- Fruits
- Stems
- Roots
16
Q
function of leaves?
A
Sites of gas exchange and responsible for photosynthesis. In most species, leaves are organised to increase sunlight exposure.
17
Q
function of flowers?
A
The sexual reproductive organs of flowering plants (angiosperms). Following the fertilisation of male and female gametes which are contained in pollen, seeds develop and the ovary of a flower grows into a fruit.
18
Q
function of fruits?
A
Grown from a flower post-fertilisation. Fruits protect seeds and are often specialised to attract animals that aid with seed dispersal.
19
Q
function of stems?
A
Support the leaves, flowers, and fruits, as well as transport water and nutrients between the roots and shoots.
20
Q
function of roots?
A
Absorption and storage of water and nutrients from the soil. Roots are also responsible for anchoring the plant to the ground and providing structural support.
21
Q
Animal cells combine to form the four major animal tissue types?
A
- Muscle
- Nerve
- Connective
- Epithelial
22
Q
what are tissues further organised into?
A
Tissues are further organised into organs which make up systems such as the digestive system, respiratory system, and the immune system.
23
Q
what are the common types of animal cells?
A
Common types of animal cells include skin, muscle, blood, nerve, and fat cells.
24
Q
The four types of tissues in animals?
A
- Muscle tissue
- Nervous tissue
- Connective tissue
- Epithelial tissue
25
function of muscle tissue?
Contracts to exert a force. The three major types are skeletal, cardiac, and smooth muscle tissue.
26
function of nervous tissue?
Detects stimuli and transmits electrical signals
Composed of neurons that detect stimuli and carry electrical signals and glia that assist neuron signal transmission.
27
function of connective tissue?
Connects and supports other tissues and organ structures of the body`
28
function of epithelial tissue?
Composes the external and internal lavers of the body. These tissues assist in protection, secretion, and absorption.
29
what are the main animal systems?
- Digestive system
- Excretory system
- Endocrine system
- Skeletal system
- Muscular system
- Integumentary system
- Nervous system
- Immune system
- Respiratory system
- Blood circulatory system
- Reproductive system
30
function of digestive system?
Breaks down and processes food to be used by the body. Eliminates food waste that is not digested via egestion.
31
Organ and tissue examples of digestive system?
Stomach, liver, pancreas, small intestine, large intestine
32
function of Excretory system?
Removes waste substances from the blood via excretion. Also assists in the control of water balance in the body.
33
Organ and tissue examples of excretory system?
Kidneys, bladder, lungs
34
function of Endocrine system?
Responsible for the production and secretion of hormones which control and regulate bodily processes.
35
Organ and tissue examples of endocrine system?
Hypothalamus, pituitary gland, thyroid gland, thymus, pancreas, adrenal glands
36
function of skeletal system?
Provides an internal structure to support the body.
Works in tandem with the muscular system to enable movement of the body.
37
Organ and tissue examples of skeletal system?
Bones, joints, cartilage
38
function of muscular system?
Responsible for contractions in skeletal muscle, the heart, and other contractions throughout the body. Works in tandem with the skeletal system to enable movement of the body.
39
function of Integumentary system?
Protects internal body structures from the external environment.
40
Organ and tissue examples of muscular system?
Skeletal muscles, cardiac muscles, tendons
41
Organ and tissue examples of Integumentary system?
Skin, hair, nails, subcutaneous fat
42
function of nervous system?
Detects and processes sensory information to activate responses in the body.
43
function of Immune system?
Defends the body against infection. Contains the lymphatic system which transports lymph fluid around the body.
44
function of Respiratory system?
Responsible for removing carbon dioxide from the body and delivering oxygen to the blood via respiration.
45
function of Blood circulatory system?
Delivers oxygen and nutrients to the tissues of the body via blood.
46
function of Reproductive system?
In males, regulates the production of sperm and certain hormones.
In females, regulates the production of egg cells, certain hormones, ovulation, and nurturing offspring during development.
In both males and females, the reproductive system coordinates action for the purposes of reproduction.
47
Organ and tissue examples of Nervous system?
Brain, spinal cord, peripheral nerves
48
Organ and tissue examples of Immune system?
Bone marrow, spleen, thymus, tonsils, lymph nodes
49
Organ and tissue examples of Respiratory system?
Lungs, nasal passage, trachea
50
Organ and tissue examples of Blood circulatory system?
Heart, blood vessels (arteries, veins, and capillaries)
51
Organ and tissue examples of Reproductive system?
Testes, penis, ovaries, vagina, uterus, mammary glands
52
what are the levels of the body?
- cells
- tissues
- organs
- systems
- organisms
53
what are vascular plants?
Vascular plants contain vascular tissues, which transport water from the roots to the leaves of a plant, and glucose and nutrients throughout the plant.
54
what are the two types of vascular tissue?
The two types of vascular tissue, xylem and phloem, are responsible for moving water, minerals, and the products of photosynthesis throughout the plant.
55
Why does transport need to occur?
Materials need to be transported between the root system and the shoot system
56
what are the steps of transport in a plant?
1. Roots absorb water and dissolved minerals
from the soil
2. Water and minerals are transported upward from roots to shoots as xylem sap.
3. Transpiration, the loss of water from leaves (mostly through stomata), creates a force within leaves that pulls xylem sap upward.
4. Through stomata, leaves take in CO, and expel 02.
The CO, provides carbon for photosynthesis. Some 02 produced by photosynthesis is used in cellular respiration.
5. Sugars are produced by photosynthesis in the leaves.
6. Sugars are transported as phloem sap to roots and other parts of the plant.
7. Roots exchange gases with the air spaces of soil, taking in O2 and discharging CO, In cellular respiration, 02 supports the breakdown of sugars.
57
There are two main types of vascular tissue?
- Xylem tissue
- Phloem tissue
58
what is Xylem tissue?
tubes that transport water, and minerals (such as potassium, nitrogen & phosphorus) in one direction from the roots to the leaves of a plant
- has no end walls
59
what is Phloem tissue?
tubes that transport sugars and other nutrients around a plant in both directions.
- end walls with perforations
60
what is the arrangement of xylem and phloem called?
The arrangement of vascular tissues is different between plant species. The close arrangement of xylem and phloem tissues are called vascular bundles.
61
what are the two ways of transport in plants?
Transpiration & Translocation
62
define transpiration
Transpiration is the evaporation of water from leaves and other parts of the plant
63
how is water lost in transpiration?
Water is lost through the stomata of leaves which are pores on the leaf’s surface that regulate gas exchange.
64
process of transpiration?
1. Roots take up water from the soil
2. Water is drawn up the stem to the leaves
3. Water vapour lost from leaf pores in transpiration
65
how much water does a maple tree lose?
An average maple tree loses more than 200 L of water per hour during the summer!
66
what happens if water is not replaced in transpiration?
Unless this water is replaced by water absorbed by the roots, leaves will wilt and die
67
what vascular tissue is used during transpiration?
Xylem transports the water throughout the plant
68
how does transpiration work in depth (how does water travel up plant)?
- When water evaporates from the leaf the air pressure in the leaf becomes lower than the pressure in the roots. This creates a force that draws water up from the xylem.
- Because water likes to stick together (a characteristic called cohesion), even more water is drawn up than would be expected.
- This works the same way as when you ‘suck’ liquid up a straw – you create a lower pressure in your mouth compared to the atmospheric pressure, so water moves up the straw.
- Capillary action (adhesion of water molecules to the surface of the xylem), also helps water flow in the xylem.
69
what is translocation?
Sugar Transport
70
what vascular tissue does translocation?
Phloem carries phloem sap (food) from a sugar source to a sugar sink
71
what is a sugar source?
- an organ where sugar is being produced
- Usually leaves
72
what are sugar sinks?
- an organ that consumes or stores sugar
- Usually roots, growing stems, buds, & fruits
73
how does translocation move between sugar sources and sinks?
moves away from the sugar source to the sugar sink
74
how can translocation occur?
The movement of fluid in the phloem, a process called translocation, can occur in any direction, up or down the plant.
However, the fluid typically flows from source cells to sink cells.
75
what is the Mechanism of Translocation in Phloem?
The mechanism of phloem translocation is described in a model of phloem function called the pressure flow model. It proposes that water containing food molecules flows under pressure through the phloem.
76
Factors Affecting Transpiration Rate?
- At higher temperatures, more water evaporates from the leaves.
- In high light conditions stomata open, further increasing the amount of water lost to transpiration.
- As the humidity increases, less water can evaporate into the air and so the transpiration rate decreases.
- On windy days, this humid layer is blown away, encouraging water vapour to exit the leaf.
- When water availability is high the plant can then afford to increase the rate of transpiration & lose more water.
77
define Digestive system
the collection of specialised tissues and organs responsible for the digestion of food and absorption of nutrients
78
define Digestive tract
pathway of organs that food and liquids travel through after being swallowed, leading to digestion and elimination (also called the gastrointestinal tract or alimentary canal)
79
define Peristalsis
coordinated muscular contractions and relaxations of the digestive tract wall that move food along the system
80
define Chyme
mixture of partially digested food and digestive juices that passes from the stomach to the small intestine
81
what type of organism are we with producing food?
Unlike plants, animals are heterotrophs that have to consume other organisms or their products to obtain organic molecules.
82
what do organic molecules do?
Organic molecules provide chemical energy to the animal so they are able to live, survive and reproduce.
83
examples of organic molecules?
Organic molecules include carbohydrates, lipids, proteins, vitamins and minerals.
84
can we absorb food?
Food molecules are too large for animals to simply absorb into their bodies.
85
what is digestion?
Digestion is the breakdown of large food molecules into smaller forms that can cross plasma membranes and be used by the body.
86
importance of Carbohydrates?
Provide a source of immediate energy
87
importance of Lipids (such as fats)?
Energy storage in animals
88
importance of Proteins?
Structural components of cells, cell receptors, enzymes
89
importance of Vitamins?
While required in small amounts, many vitamins are used to make enzymes
90
importance of Minerals?
While required in small amounts, minerals are used in many structural components of organisms
91
There are two methods of food digestion?
- Physical (or mechanical) digestion
- Chemical digestion
92
what is Physical (or mechanical) digestion?
- Mechanical movement of organs and tissues causes the breakdown of food into smaller pieces
- Movements include chewing, muscle contractions and stirring of food and digestive juices by muscle movements
93
what is chemical digestion?
- Breakdown of food into smaller molecules that can be absorbed by digestive enzymes and stomach acid
- Three major types of digestive enzymes are amylases (act on carbohydrates), proteases (act on proteins) and lipases (act on lipids).
94
Steps of digestion?
1. Ingestion
2. Digestion
3. Absorption
4. Elimination/egestion
95
what is ingestion?
food is taken into the body. Teeth physically break down food into smaller pieces, enzymes in saliva chemically break down food into a soft mass that can be swallowed.
96
what is digestion?
occurs along the digestive tract, where the soft mass travels from the mouth and continues to be broken down both physically and chemically by a variety of organs.
97
what is absorption?
once food macromolecules are broken down into smaller molecules, they are absorbed across the plasma membrane of cells in the digestive tract into the bloodstream. Energy from food is now ready to be used by the body.
98
what is Elimination/egestion?
final step is the elimination of undigested food content that has travelled along the digestive tract and has not been absorbed. Undigested food is eliminated from the body as faeces.
99
what is the digestive system made up of?
In humans, the digestive system is made up of a number of organs including the stomach, liver, pancreas, and small and large intestines.
Each organ is a collection of cells forming specialised tissues.
100
order of digestion in organs and tissues?
1. Oral cavity
2. Salivary glands
3. Oesophagus
4. Stomach
5. Liver
6. Gallbladder
7. Pancreas
8. Small intestine
9. Large intestine
10. Appendix
11. Rectum
12. Anus
101
digestion in Oral cavity?
Beginning of the digestive tract where food is prepared for the stomach. Chews food and mixes it with saliva.
102
digestion in Salivary glands?
Glands that produce and release saliva into the mouth and oesophagus. Saliva which contains a starch-digesting enzyme called salivary amylase
103
digestion in Oesophagus?
Muscular tube lined with mucus that connects the mouth and stomach. Movement of the food is aided by waves of muscular contractions of the tube, known as peristalsis. Moves the bolus to the stomach.
104
digestion in Stomach?
Muscular organ that receives food from the oesophagus and temporarily stores it, where it is broken down by stomach acids, enzymes and peristaltic movements (ph 1 - 3). Mixes and churns food with gastric juice that contain acid and a protein-digesting enzyme called pepsin creating chyme.
105
digestion in Liver?
Large organ found in the abdomen that is involved in many metabolic processes including the breakdown of toxins. Site of bile production which aids in the digestion and absorption of fat.
106
digestion in Gallbladder?
Bile-storing organ that releases bile into the small intestine.
107
digestion in Small intestine?
Connects the stomach to the large intestine and is a major site of nutrient absorption during digestion. Divided into three sections: duodenum, jejunum and ileum. Digests food and absorbs nutrients into blood or lymph.
107
digestion in Pancreas?
An organ of the digestive and endocrine system that releases both digestive juices and hormones, namely insulin and glucagon which regulate blood glucose levels. Releases bicarbonate to neutralize intestinal contents; produces enzymes that digest carbohydrates, protein, and fat.
108
digestion in Large intestine?
Final area of absorption of water, vitamins and minerals along the digestive tract and the site of faeces production. Home to intestinal bacteria; passes waste material.
109
digestion in Rectum?
Final area of the large intestine that stores faeces for elimination.
109
digestion in Appendix?
Small sac of tissue that sits at the junction between the small and large intestines and is believed to play a role in immune functions.
110
digestion in Anus?
Opening at the end of the digestive tract that releases faeces.
111
what is the pharynx in digestion?
Swallows the chewed food mixed with saliva called bolus
112
are all animals digestive systems the same?
Different animal species have different food requirements and feeding behaviours.
113
what is a key determinant of an animals digestive system?
A key determinant of the structure and specialisation of an animal’s digestive system is its diet.
114
why are different animals have different digestive systems?
Herbivores, omnivores and carnivores contain different digestive systems due to their differences in diet.
115
define herbivore
Herbivore: an animal that almost exclusively feeds on plant material. (more stomachs, larger cecum, longer small intestine)
116
define omnivore
Omnivore: an animal that eats a variety of food from plants to other animals.
117
define carnivore
Carnivore: an animal that almost exclusively eats meat. (one stomach, smaller small intestine, teeth)
118
define Excretory system
the collection of organs and tissues that remove excess, waste materials from the body.
119
define Urinary tract
the series of channels in which urine is produced and excreted from the body
120
define Urea
the main nitrogenous product of protein breakdown in mammals. Excreted in urine.
121
define Urine
a fluid formed by the kidneys and stored in the bladder. One of the body’s major ways to remove excess water, solutes and waste substances from the blood
122
define kidneys
a pair of bean-shaped organs that are responsible for removing waste substances from the blood and the production of urine
123
define nephron
a functional unit of the kidney consisting of a glomerulus and tubule system through which filtrate passes and urine is produced
124
what happens during cellular processes?
During cellular processes, the human body accumulates unwanted waste materials within cells.
125
what do waste materials include?
Waste materials include: carbon dioxide from respiration, toxins and nitrogenous waste from protein breakdown.
126
what does excretory system do?
The body has a specialised system called the excretory system that removes excess and unwanted waste substances from the body and maintains the ideal concentration of water and solutes (ions).
127
what are the organs and tissues of the excretory system?
Organs and tissues that make up the excretory system include: kidneys and bladder.
128
Wastes that need to be disposed of and their sources?
ammonia - protein metabolism
urea - processing of ammonia
carbon dioxide - cellular respiration
lactic acid - anaerobic respiration
excess salts - food eaten
hydrophobic substances - food eaten
bile - liver
excess water - drinking
129
what are the parts of the excretory system?
- adrenal glands
- kidneys
- ureter
- urethra
- bladder
130
what is a major component of the excretory system?is it responsible for?
A major component of the excretory system is the urinary tract, which is responsible for filtering waste materials out of the blood and excreting these materials in urine.
131
what does the urinary tract consist of?
- Kidneys
- Ureters
- Bladder
- Urethra
132
where are the kidneys?
In humans, the kidneys are two bean-shaped organs located in the upper back on either side of the spinal column.
133
role of kidneys?
Role of the kidneys is to filter blood, reabsorb the useful substances within the filtrate and secrete the unwanted ones.
134
where does blood enter and leave in the kidney?
Unfiltered blood enters the kidney by the renal artery.
Filtered blood leaves the kidney through the renal vein.
135
what does a kidney contain?
A kidney contains millions of nephrons (functional unit of the kidney.
136
How do the kidneys filter blood?
1. Unfiltered blood enters the kidney.
2. Nephrons, located within the kidney, filter the blood. Toxins and waste are removed and collected as urine.
3. Urine drains into a central collection channel from filtration areas throughout the kidney.
4. Urine exits the kidney through the ureter which leads to the bladder.
5. Filtered "clean" blood leaves the kidney.
137
The nephron is the functional unit of the kidney and is comprised of the following components?
- Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting duct
138
what is the kidneys components?
- nephron
- cortex
- medulla
- renal pelvis
- renal artery
- renal vein
139
what does each part of the nephron help with?
Each part of the nephron helps with either filtration, reabsorption, or secretion
140
steps of the blood in a nephron?
(1) Bowman’s capsule - FILTRATION
(2) Proximal Convoluted Tubule - REABSORPTION
(3) Distal convoluted tubule - SECRETION
(4) Collecting Tubule - EXCRETION
141
what happens in filtration?
- Blood enters the kidney via the renal artery and makes its way to the nephron.
- Bowman's capsule collects blood filtrate and sends it to renal tubule for further processing in order to form urine.
- Glomerulus filters the blood plasma.
142
what is filtrate?
Filtrate is made up of water, salt, glucose, amino acids, urea, creatinine, ions etc
143
what happens in reabsorption?
After the filtrate passes the Bowman’s capsule it then moves into the proximal convoluted tubule.
- Glucose, specific ions (K+, Na+, Cl-), and amino acids are reabsorbed
- About 65% of water is reabsorbed via osmosis.
- Some urea is incidentally reabsorbed by passive transport.
NOTE: Water is also reabsorbed in the Loop of Henle.
144
what happens in secretion?
- The filtate now moves into the distal convoluted tubule (DCT).
- Here some substances like drugs, and some other toxins will leave the blood vessels and enter the nephron.
- The DCT will also secrete different ions to maintain the correct pH balance of the blood
145
what happens in excretion?
Some reabsorption of water can also occur in the collecting duct but generally the filtrate enters the collecting duct has the composition of urine.
146
what is urine?
Urine is made up of water, urea, Na+, Cl-, K+, and creatine.
147
what is the final step of the kidney?
Urine now leaves the collecting duct and enters the ureters and is sent to the bladder for storage.
Once full, the bladder is emptied. Urine passes out of the body through the urethra.
148
what is secreted in the proximal convoluted tubule?
* ammonia
* creatinine
* some toxins
* urea/uric acid
149
what is reabsorbed in the proximal convoluted tubule?
* glucose
* amino acids
* some ions
* vitamins
* urea
150
what is secreted in loop of Henle?
- ions
- urea
151
what is reabsorbed in loop of Henle?
- water
- ions
152
what is secreted in distal convoluted tubule?
K*, H, NHA,
some toxins
153
what is reabsorbed in distal convoluted tubule?
optional: water, ions
154
what is secreted in the collecting duct?
H*, NHA,
some toxins
- urea
155
what is reabsorbed in the collecting duct?
optional: water, ions
156
define Endocrine system
the collection of organs and glands in animals responsible for producing hormones that can be transported in the bloodstream to regulate distant organs/cells
157
define Signalling molecule
a molecule which can interact with and initiate a response on a target cell
158
define Hormone
signalling molecule released from endocrine glands that regulates the growth or activity of target cells
159
define Receptor
structure (usually a protein) that detects a signal or external change
160
define Target cell
a cell that will receive and respond to a specific signalling molecule
161
define gland
a group of cells that secretes chemical substances to regions of the body or discharges them into the surroundings
162
what must cells be able to do in multicellular eukaryotes?
In multicellular eukaryotes, distant cells must be able to communicate with each other in order to perform many synchronised functions within the body.
163
what happens if cells detect change?
If one cell detects a change in the environment, communication allows other cells to respond.
164
how do cells communicate?
To communicate, cells send and receive special chemicals called signalling molecules.
165
what do signalling molecules do?
Signalling molecules can instruct cells to do a variety of things, e.g. open and close protein channels, release other signalling molecules or even die.
166
what is the endocrine system responsible for?
The endocrine system is responsible for producing hormones, a major group of signalling molecules that have a variety of effects throughout the body and help to maintain a stable internal environment.
167
how do hormone molecules function?
Hormone molecules function by binding to specific receptors on target cells that are complementary to the hormones, eliciting a response in the target cell.
168
what can hormones influence?
Hormones only influence cells with specific receptors (hormonal communication is specific).
169
what happens after hormones are released?
After being produced by the glands of the endocrine system, hormones are transported to where they are needed in the body via the bloodstream in the blood circulatory system.
170
are all organs important in the endocrine system?
Each organ is responsible for producing the hormones needed to keep the body running.
171
Organs of the endocrine system?
- Hypothalamus
- Pituitary gland
- Pineal gland
- Thyroid and parathyroid glands
- Thymus
- Pancreas
- Adrenal glands
- Placenta (in pregnant females)
- Ovaries (females) and testes (male)
172
description of Hypothalamus?
A small region in the brain that helps maintain body temperature and often influences the function of the pituitary gland
173
description of Pituitary gland?
A pea-sized area in the brain that is often called the 'master gland' as it regulates many other glands, including the thyroid glands, adrenal glands, and ovaries or testes
174
description of Pineal gland?
Located in the brain, the pineal gland is involved in sleep regulation. Studies suggest that it also may be involved in influencing the pituitary gland and the regulation of bone metabolism
175
description of Thyroid and parathyroid glands?
Several small glands located in the base of the neck that are involved in controlling the growth rate, metabolic rate, and development of the body
176
description of Thymus?
Located between the lungs, produces the hormone thymosin which stimulates the development of cells of the immune system. The thymus is only active in the body until puberty
177
description of Pancreas?
An organ that sits across the back of the abdomen that is involved in the functioning of the digestive system and maintenance of blood glucose levels by releasing insulin and glucagon
178
description of Adrenal glands?
Found above the kidneys, the adrenal glands are involved in the body's stress response, metabolic regulation, blood pressure, and immune system
179
description of Placenta (in pregnant females)?
The placenta is located in the uterus. It maintains a healthy pregnancy and stimulates mammary growth
180
description of Ovaries (females) and testes (male)?
Play a major role in developing and regulating the body's reproductive system
181
hormones produced --> Target organs/cells --> Response of Pituitary gland?
Growth hormone --> Bone and muscle --> Promotion of protein synthesis and growth
182
hormones produced --> Target organs/cells --> Response of Thyroid glands?
Thyroxine --> Many cells --> Regulation of the rate of cellular metabolism
183
hormones produced --> Target organs/cells --> Response of Adrenal glands?
Adrenaline (epinephrine) --> Many cells --> Increased heart rate and blood pressure, increased respiratory rate, increased muscle contractions
184
hormones produced --> Target organs/cells --> Response of Pancreas?
Insulin --> Many cells --> Regulation of blood glucose levels
185
hormones produced --> Target organs/cells --> Response of Ovaries?
Oestrogen (estrogen) --> Female reproductive tissues --> Sexual development, breast development, regulation of the menstrual cycle
186
hormones produced --> Target organs/cells --> Response of Testes?
Testosterone --> Male reproductive tissues --> Sexual development, increased muscle, body hair growth
187
define Homeostasis
the maintenance of a relatively stable internal environment in the body despite changes in the external environment
188
define Positive feedback system
a stimulus-response process in which the response increases the stimulus
189
define Negative feedback system
a stimulus-response process in which the response counters the stimulus
190
define Receptor
a structure that detects a signal or external change, usually a protein
191
define Hormone
a signalling molecule released from endocrine glands that regulates the growth or activity of target cells
192
what do cells inhabit?
Cells inhabit the internal environment of our bodies. Within this environment, cells like to exist within a set range of parameters.
193
what happens if the parameters for cells are not met?
If these parameters are not met, then cells can’t function normally and may potentially become damaged or die.
194
Parameters that affect the functioning of cells include?
- Temperature (optimal internal body temperature is 36.5 - 37.5°C)
- Blood sugar levels (maintained between 4.0 - 7.8 mmol/L)
- Fluid balance
- pH - acidity level (optimal pH of the blood is 7.35 - 7.45)
- Ion balance
195
what is homeostasis?
Homeostasis is the maintenance of a relatively stable internal environment in the body despite changes in the external environment.
196
what process is homeostasis and what does it do?
It is a complex process that maintains the internal environment of an organism within set limits so that cells and systems can function properly.
197
how can homeostatic processes be explained?
Homeostatic processes can be explained using the stimulus-response model and feedback loops.
198
what do homeostatic processes do when there is change?
When changes occur in the internal environment, homeostatic mechanisms act to restore it to the ‘normal’ state.
199
what are the steps/components of the the stimulus-response model for homeostasis?
1. Stimulus
2. Receptor
3. Modulator or processing centre
4. Effector
5. Response
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what happens in the stimulus component?
change in the external or internal environment of an organism
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what happens in the receptor component?
stimulus is detected by a receptor in the body, which then transfers this stimulus into a chemical or electrical signal for transmission to the modulator
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what happens in the modulator or processing centre component?
evaluates the information from the receptors and compares the information received against an ideal condition the body aims to maintain. Modulator then sends signals to an effector
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what happens in the effector component?
a molecule (usually a hormone), cell or organ that responds to a signal from the modulator and produces a response
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what happens in the response component?
any change in the function of a target cell, organ or organism after stimulation from an initial stimulus
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Types of receptors in the body?
- Thermoreceptors
- Nociceptors
- Baroreceptors
- Chemoreceptors
- Photoreceptors
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what are Thermoreceptors?
detect changes in temperature
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what are Nociceptors?
detect painful stimuli
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what are Baroreceptors?
detect changes in pressure
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what are Chemoreceptors?
detect changes in chemical concentration
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what are Photoreceptors?
detect changes in light
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what is Positive feedback systems?
- Positive feedback systems occur when the response increases the initial stimulus.
- They are rare in the body and don’t form part of homeostasis.
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Positive feedback system example?
- contractions and oxytocin release during childbirth
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what are Negative feedback systems?
Negative feedback systems occur when the response counteracts the original stimulus (the response attempts to revert the system back to the state it was in before the stimulus occurred).
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why are negative feedback systems important?
Important control mechanism in almost all processes of homeostatic regulation.
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what is the process described as of negative feedback systems?
- Process in which the body senses a change in a variable and activates mechanisms to reverse the change so that internal conditions within the body are maintained within narrow limits.
- Response is opposite in direction to that of the original stimulus
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what are the stimulus-response model at a cellular level three-step process?
1. reception (by receptor)
2. transduction
3. response (be effector)
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how is the cellular level different to the homeostatic stimulus-response model?
The same processes occur as in the five-step process, although they’re grouped together a little differently.
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what is Reception?
detection of a stimulus and the transmitting of this stimulus into a mechanical, electrical or chemical signal
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what is Transduction?
transmission of a signal during cellular signalling. Series of events that occur after the reception of a signal, which results in the generation of a response
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what is Response?
the change in the function of a target cell, organ or organism
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what are the levels of blood glucose?
- Hypoglycemia (low blood sugar)
- Normal Level
- Hyperglycemia (high blood sugar)
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define Glucose
a six-carbon carbohydrate that comes from the food we eat
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define Glycogen
a polysaccharide of glucose that stores energy. Serves as the main storage of glucose in the body
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define Glycogenesis
the process of creating glycogen from glucose
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define Glycogenolysis
the process of breaking down glycogen into glucose
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define Blood glucose level
a measure of the amount of glucose present in the blood. Normal homeostatic mechanisms keep blood glucose levels between 4.0 - 7.8 mmol/L
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define Pancreas
an organ of the digestive and endocrine system that releases both digestive juices and hormones
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define Alpha cells
cells that occupy the islet of Langerhans and secrete glucagon
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define Beta cells
cells that occupy the islet of Langerhans and secrete insulin
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define Insulin
a hormone secreted by beta cells of the pancreas when blood glucose levels are elevated
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define Glucagon
a hormone secreted by the alpha cells of the pancreas when blood glucose levels are low
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what roles does glucose have?
Glucose plays a number of key roles in the human body and must be maintained within a narrow range in order for the body to function correctly.
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what role does glucose play?
Glucose plays a number of key roles in the human body and must be maintained within a narrow range in order for the body to function correctly.
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what is the main role of glucose?
Glucose is the main source of energy for all the cells in our body.
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Sources of glucose include?
- Carbohydrates in the food we eat (broken down into glucose by the digestive system)
- Glycogen stored in skeletal muscle and liver cells (long series of glucose molecules joined together)
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what can explain blood glucose levels regulation?
The stimulus-response model can be used to explain how blood glucose levels are regulated in humans via negative feedback loops.
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what is stimulus for blood glucose level?
change in blood glucose levels to above or below the normal range (above 5 mmol/L)
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what is receptor for blood glucose level?
pancreas, specifically, clusters of specialised cells called the islets of Langerhans. These islets are comprised of two types of cells (alpha cells and beta cells) that detect blood glucose levels.
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what is modulator for blood glucose level?
also islet of Langerhans. Insulin or glucagon is released depending on whether glucose levels are high or low
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what is effectors for blood glucose level?
insulin and glucagon travel through the bloodstream to alter effectors throughout the body.
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what is response for blood glucose level?
increase/decrease in blood glucose levels to within normal limits
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What happens when blood glucose levels increase?
When an islet of Langerhans detects elevated blood glucose levels, beta cells release insulin. Insulin goes on to stimulate two different effectors via two different pathways.
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what pathways do insulin stimulate for effectors?
1. Skeletal muscle and fat cells increase their uptake of glucose from the blood.
2. Liver cells are stimulated to increase conversion of glucose into glycogen.
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what do skeletal muscle cells used glucose for?
In skeletal muscle cells, glucose is used by mitochondria to create energy or converted to glycogen for storage.
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what do fat cells used glucose for?
In fat cells, glucose is converted to fatty acids for long term storage.
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what happens when cell absorb glucose?
When cells absorb glucose, the levels in the blood are lowered. Once levels are back around 5 mmol/L, insulin will stop being released by beta cells.
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Pathways used by the body to reduce elevated blood glucose levels?
stimulus - blood glucose levels above 5 mmol/L
receptor and modulator - Islets of Langerhans - beta cells secrete insulin
effector and repsonse - skeletal muscle and fat cells (increased uptake of glucose via insertion of glucose transporters into cell membrane) or/and liver cells (increased conversion of glucose to glycogen)
- blood glucose levels decreased
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What happens when blood glucose levels decrease?
- When an islet of Langerhans detects low blood glucose levels, alpha cells secrete glucagon.
- Glucagon stimulates liver cells to break down glycogen into glucose and release it into the bloodstream.
- Once glucose levels are close to around 5 mmol/L again, alpha cells stop secreting glucagon and the liver cells (effector) stop breaking down glycogen and releasing glucose into the blood.
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how does glucose get released from the liver?
Glucose gets stored as glycogen in the liver and skeletal muscle cells. When blood glucose levels fall, glycogen gets broken down back into glucose and re-enters the bloodstream.
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Pathway used by the body to increase low blood glucose levels?
stimulus - blood glucose levels below
5 mmol/L
receptor and modulator - Islets of
Langerhans - alpha cells secrete glucagon
effector - liver cells
response - breakdown of glycogen into glucose which is released into the bloodstream
- blood glucose levels increased
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blood glucose level elevated (>5mmol/L) --> cell stimulated --> hormone released --> effector --> response
Beta cells --> Insulin -->
1. Liver cells and skeletal muscle cells --> Increased production of glycogen
2. Skeletal muscle and fat cells --> Increased uptake of glucose
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blood glucose level decreased (<5mmol/L) --> cell stimulated --> hormone released --> effector --> response
Alpha cells --> Glucagon --> Liver cells and skeletal muscle cells --> Breakdown of glycogen into glucose and release into bloodstream
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define Hyperglycaemia
the state of having blood glucose levels above the normal range (>7.8 mmol/L)
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define Hypoglycaemia
the state of having blood glucose levels below the normal range (<4.0 mmol/L)
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define Type 1 diabetes
an autoimmune disease in which beta cells of the pancreas are destroyed, resulting in an inability to regulate blood glucose levels
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define Autoimmune disease
a disease in which an individual’s immune system initiates an immune response against their own cells
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define Autoantibodies
proteins created by the immune system that destroy an organism’s own tissues
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define Insulin replacement therapy
the injection of insulin to maintain blood glucose levels within normal limits
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describe Type 1 diabetes
Type 1 diabetes is an autoimmune disease in which the body’s immune system recognises beta cells in the pancreas as non-self (foreign) and attacks them using autoantibodies.
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what does type 1 diabetes cause?
- Due to this, people with type 1 diabetes produce very little or no insulin, which means their blood glucose levels are left unregulated.
- Additionally, neighbouring alpha cells are also impaired and no longer function properly.
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Type 1 Diabetes Age of onset?
usually children and young adults
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cause of Type 1 Diabetes?
Cause is uncertain (both genetic & environmental factors)
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what is insulin's function?
move glucose from our bloodstream into the body's cells to make energy
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Symptoms of Type 1 Diabetes?
- Increased urination
- Excessive thirst
- Excessive hunger
- Tiredness (lethargy)
- Weight loss
- Dry skin
- Blurred vision
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Long term consequences of uncontrolled diabetes?
- Vision loss
- Heart disease & stroke
- Prolonged wound healing
- Kidney damage
- Tingling or numbness in the feet and/or hands
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when does Hypoglycaemia occur?
Hypoglycaemia occurs when blood sugar levels drop below 4.0 mmol/L.
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People with Type 1 Diabetes can become hypoglycaemic if they?
- Inject too much insulin
- Exercise to much
- Don’t consume enough glucose
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what does Hypoglycaemia cause?
- Due to the additional impairment to alpha cells, people with Type 1 Diabetes don’t produce normal levels of glucagon, causing their blood glucose levels to continue to fall.
- Hypoglycaemia is a very dangerous condition, as without glucose, cells don’t have enough energy to function.
- This can cause the individual to feel weak and dizzy and can even result in them losing consciousness and dying if glucose levels are not corrected quickly.
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Management of Type 1 Diabetes?
Type 1 Diabetes is managed with medication, nutrition, physical activity and glucose monitoring.
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cure for Type 1 Diabetes?
There is NO cure at this time.
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what is the goal for people with Type 1 Diabetes?
The goal is to maintain blood glucose levels within their homeostatic set points.
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what is the main way to maintain blood glucose levels for people with Type 1 Diabetes?
The main way this is done is through insulin replacement therapy.
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what is Insulin replacement therapy?
Insulin replacement therapy involves diabetic patients artificially altering their insulin levels to regulate their blood glucose levels.
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Insulin replacement therapy options?
- Manual regulation of blood glucose levels
- Regulation by insulin pump
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Manual regulation of blood glucose levels?
- Patients can measure their blood glucose levels via a finger prick test.
- If blood glucose levels rise above normal, the patient injects themselves with the correct amount of artificial insulin to return levels back to normal.
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Regulation by insulin pump?
- Blood glucose levels of insulin can be managed by an insulin pump.
- A sensor is placed under the skin that constantly monitors blood glucose levels.
- When levels rise above normal, the pump automatically injects the appropriate amount of insulin to return blood glucose levels back to normal.
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define Thyroid gland
butterfly-shaped gland in the neck that produces hormones that influence metabolic rate
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define Thyrotropin-releasing hormone (TRH)
a hormone released by the hypothalamus that stimulates the anterior pituitary gland
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define Thyroid-stimulating hormone (TSH)
a hormone released by the anterior pituitary gland that stimulates the thyroid gland
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define Hyperthyroidism
overactivity of the thyroid gland, resulting in increased production and secretion of thyroid hormones
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define Graves’ disease
an autoimmune disease that causes hyperthyroidism
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define Goitre
a swelling in the neck caused by an enlarged thyroid gland
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review of thyroid gland?
The thyroid gland is a small butterfly-shaped gland located in the base of the neck and is part of the endocrine system.
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what is the thyroid glands role?
It plays a key role in a number of different processes in the body and its functioning is tightly regulated as part of maintaining homeostasis.
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what hormones does the thyroid gland secrete?
- The thyroid gland secretes two hormones: triiodothyronine (T3) and thyroxine (T4).
- These hormones have a wide range of effects throughout the body
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Effect of normal level of thyroid hormones on Basal metabolism?
Promotion of normal heat production and oxygen consumption by cells
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Effect of normal level of thyroid hormones on Nutrient metabolism?
Metabolism of glucose, lipids, and proteins
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Effect of normal level of thyroid hormones on Nervous system?
Development of the nervous system in a developing foetus, and allows for the normal functioning of the nervous system in adults
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Effect of normal level of thyroid hormones on Cardiovascular system?
Regulation of heart rate
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Effect of normal level of thyroid hormones on Respiratory system?
Regulation of respiratory rate
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Effect of normal level of thyroid hormones on Musculoskeletal system?
Development and function of muscles and bone
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Effect of normal level of thyroid hormones on Gastrointestinal system?
Aids in the regulation of muscle coordination and secretion of digestive juices
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Effect of normal level of thyroid hormones on Reproductive system?
The functioning of the reproductive system, including the thickening of the endometrium in females
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what is Hyperthyroidism caused by?
Hyperthyroidism is a condition caused by an overactive thyroid gland.
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effect of Hyperthyroidism?
Due to this, increased amounts of thyroid hormones (T3 and T4) are secreted into the body, causing a wide range of symptoms.
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how is Hyperthyroidism diagnosed?
Individuals are diagnosed via a blood test.
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causes of Hyperthyroidism?
- There are a number of different causes of hyperthyroidism.
- One of the most common causes is an autoimmune disease called Graves’ disease.
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what is the stimulus-response model depicting the regulation of the thyroid gland?
stimulus - change in a variety of factors (e.g. temperature)
receptor - hypothalamus (thyrotropin-releasing hormone (TRH))
modulator - anterior pituitary gland (thyroid-stimulating hormone (TSH))
effector - thyroid gland
response - release of T3 and T4
- negative feedback inhibition of TSH secretion
- negative feedback inhibition of TRH secretion
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Symptoms of hyperthyroidism for Basal metabolism?
Increased metabolism, heat intolerance, sweating
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Symptoms of hyperthyroidism for Nervous system?
Anxiety, irritability, difficulty sleeping
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Symptoms of hyperthyroidism for Cardiovascular system?
Increased heart rate, palpitations, increased blood pressure
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Symptoms of hyperthyroidism for Respiratory system?
Increased respiratory rate
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Symptoms of hyperthyroidism for Musculoskeletal system?
Muscle pain, weakness, and atrophy; osteoporosis
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Symptoms of hyperthyroidism for Gastrointestinal system?
Increased gastrointestinal motility, resulting in diarrhoea; vomiting
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Symptoms of hyperthyroidism for Reproductive system?
Lighter menstrual flow and increased duration of menstrual cycle
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other symtoms of hyperthyroidism and Graves' disease?
enlarged thyroid gland, known as a goitre, people with Graves' disease might also experience exophthalmos, a condition in which their eyes bulge out of their sockets.
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how many approaches to hyperthyroidism are there?
Number of different approaches to managing hyperthyroidism depending on the cause.
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what are some ways to manage hyperthyroidism?
- Some treatments aim to counteract the effects of increased hormone levels, e.g. drugs like beta-blockers to reduce heart rate.
- Other medications called antithyroid drugs, reduce the production of thyroid hormones.
- Radioactive iodine is sometimes given to people with hyperthyroidism
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what does radioactive iodine do?
- Iodine is a key ingredient in the production of thyroid hormones and absorbed only by cells in the thyroid.
- Radioactive iodine kills the cells that absorb it and reduces the amount of thyroid hormone produced and secreted.
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what is the most radical treatment for hyperthyroidism?
Most radical treatment is surgical removal of the thyroid gland.
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define Metabolism
the set of chemical reactions within cells that help maintain the body’s normal functioning including converting food and drink to energy
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define Thermoregulation
the homeostatic process of maintaining a constant internal body temperature
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define Endotherm
an animal that produces the majority of its own heat via metabolic processes
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define Ectotherm
an animal that obtains heat primarily from the environment, rather than its own metabolic heat
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define Hypothalamus
a section of the brain in mammals that controls the maintenance of the body’s internal environment
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define Cerebral cortex
the outer layer of the brain that plays a key role in a number of processes including memory, attention and perception
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how do humans gain and lose heat?
The human body can gain heat from the environment or lose heat to it. Heat will always travel from a region of higher temperature to a region of lower temperature.
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Heat transfer in the body occurs via four methods?
Heat transfer in the body occurs via four methods: conduction, convection, evaporation and radiation.
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explain Conduction
The transfer of heat through physical contact with another object
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define Convection
The transfer of heat via the movement of a liquid or a gas between areas of a different temperature
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define Evaporation
The loss of heat via the conversion of water from liquid to gas form
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define Radiation
The transfer of heat via electromagnetic waves such as light (i.e. doesn't require physical contact with another object)
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why does body temperature need to be regulated?
Body temperature of organisms needs to be tightly regulated so that their cells can function properly.
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what system is thermoregulation?
Thermoregulation occurs via a negative feedback stimulus-response system.
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what is balance of overall body temperature?
The overall body temperature of an organism is a balance of the heat being put into the system, the heat generated by the system and the heat lost by the system.
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what can species can be divided into two different groups based on where the majority of their heat energy is gained?
Endotherms (warm-blooded animals) - able to generate the majority of their heat energy internally using metabolic processes.
Ectotherms (cold-blooded animals) - produce very little metabolic energy and instead rely on environmental sources of heat to warm themselves.
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General negative feedback stimulus-response model of thermoregulation in humans?
stimulus - change in internal body and/or
environmental temperature
receptor - thermoreceptors
modulator - hypothalamus
effector - variety of cells and tissues
response - change that alters heat transfer in body
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Physiological responses for heat gain & loss features?
- These occurs automatically and are not under an individual’s conscious control (i.e. you do not have to think about starting them).
- These processes are initiated by centres in the hypothalamus of the brain.
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Behavioural responses for heat gain & loss features?
- Cerebral cortex causes changes in behaviour.
- Actions that are under an individual’s control.
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Heat loss (increase in core temperature) Physiological responses?
- Vasodilation: arterioles dilate (enlarge) so more blood enters skin capillaries and heat is lost.
- Sweating: sweat glands secrete sweat which evaporates from the skin, taking heat energy with it.
- Pilorelaxation: small muscles attached to hair follicles in the skin relax, which flattens body hair against the skin.
- Decrease in metabolic rate: signals are sent by the hypothalamus to slow metabolic processes, which reduces the amount of heat made by the body.
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Heat loss (increase in core temperature) Physiological responses?
- Vasoconstriction: arterioles get smaller to reduce the blood flow to the skin and heat is retained.
- Shivering: skeletal muscles are stimulated to cause shivering (muscle cells are stimulated to move quickly, which increases their metabolism and creates more heat energy).
- Piloerection: small muscles attached to hair follicles in the skin contract, lifting hair follicles up, causing goosebumps and trapping an insulating layer of air.
- Increase in metabolic rate: signals are sent to increase metabolic processes, which results in more heat energy being produced.
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Behaviours for gaining and conserving heat?
Vigorously exercising
Putting on another layer of clothing
Soaking in a hot bath
Having a hot drink
Rubbing your hands together
Reducing body surface area by wrapping your arms around you or curling up
Wearing a hat and gloves
Standing in front of a heater
333
Behaviours for losing heat?
Removing a layer of clothing
Having a cold shower
Resting in the shade
Using an ice pack
Removing your hat and gloves
Maximising the body surface area exposed to a cooling wind
Soaking your feet in cold water
Sitting in front of a fan
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Methods used by the body to remain COOL (effector and response)?
sweat glands - sweating
small blood vessels in the skin - dilation of arterioles
cerebral cortex - change in behaviour
arrector pili muscles - flattening of hair
cells - decrease in metabolic rate
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Methods used by the body to remain WARM (effector and response)?
skeletal muscle cells - shivering
small blood vessels in the skin - constriction of arterioles
cerebral cortex - change in behaviour
arrector pili muscles - lifting of hair
cells - increase in metabolic rate
brown fat - burning of triglycerides
