Transcript Homeostasis - WordPress.com

Topic 1: It’s My Body
Part 1:
Cells and Body Systems of Human, Homeostasis
PLANT CELL
ANIMAL CELL
Organelles :
Function :
Nucleus:
Contains the DNA and RNA
and manufactures proteins
In nuclei where ribosomes are
synthesized.
Membrane of lipids and
proteins that surrounds nucleus
structure that appears during
mitosis(cell division)
Energy producers of the cell
Produce proteins
Nucleolus:
Nuclear Envelope:
Centrioles:
Mitochondria:
Ribosomes:
More Organelles
ORGANELLES FUNCTION
Golgi Bodies: Packages Proteins
Chloroplasts: Involved in photosynthesis
Vacuoles:
Store waste, nutrients, and
water
Lysosome:
Contains digestive
enzymes, mostly in animal
cells
Endoplasmic Reticulum: Passageway
that
transports proteins
from
the nucleus
Rough ER covered in ribosomes,
Smooth ER is not!
WHILE NOT EXACTLY ORGANELLES, THE
FOLLOWING ARE IMPORTANT PARTS OF THE
CELLS:
Cell membrane:
lining
the cell
 Cell Wall:

the
made of
 Cytoplasm:
Semi-permeable
that surrounds
Is a stiff non-living
wall that surrounds
cell membrane
cellulose
Jelly-like material
surrounding the
organelles
Differences between unicellular and multicellular orgranisms.
UNICELLULAR AND MULTICELLULAR
ORGANISMS
UNICELLULAR ORGANISMS
Most are microscopic
 Examples: Amoeba, Paramecia, E. Coli
 Perform the same tasks as multicellular
organisms
 They move, eat, reproduce and expel waste.

THE AMOEBA
Binary Fission (cell
division)
PARAMECIA
THE AMOEBA
Have characteristics of an animal cell
 Live in fresh and salt water environments and
decaying vegetation sites.
 Are predators – they prey on algae and bacteria
 Uses osmosis to get water and diffusion to get
oxygen and dispose of carbon dioxide.

MULTICELLULAR ORGANISMS

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

Rely on a variety of cells to perform cellular functions.
These are called “specialized cells”.
Specialized cells perform duties such as digestion or
movement.
Example: Eyes, Muscles and Tongue. (what duties do
these perform?)
Cells can be compared to small cities. Each one
performs a different job/function. They all work
together to be efficient. Just like we need specialist
doctors, cells need specialist cells.
How is the body organized?
Each specific cell is grouped with cells similar in
structure and function to form a tissue.
cells
tissue
Examples of tissue
Animal tissues
Plant tissues
muscle
mesophyll
bone
phloem
liver
skin
lung
Can you think of any more types of tissue?
xylem
How is the body organized?
Cells are the
basic units of
life.
cell
Groups of cells
work together
to form tissues.
tissue
Groups of tissues
work together to
form organs.
organ
How is the body organized?
Groups of organs form systems.
For example, the human digestive system is
made up of several organs including the
mouth, gullet, stomach and small intestine.
The different organs in a system are linked
together by tubes or vessels.
What other human body systems can you
think of?
Tissues in the Human Body

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
Epithelial
◦ Covering or lining tissue
Connective
◦ Joins, stores and supports
Muscle
◦ Internal and external movement
Nerve
◦ Conducts electrical signals
Blood
Muscle
Nerve
How is the body organised?
Why do organisms have to be so organised?
Organisation of the body allows complex organisms to carry
out many different jobs at the same time.
respond
to things
body
life processes
grow
reproduce
move
respire
digest food
excrete
Being organised means that the body does not waste energy, so it is
more efficient.
Human Organ Systems
Skeletal
Circulatory
Respiratory
Excretory
Nervous
Integumentary
Muscular
Immune
Digestive
Reproductive
Endocrine
Matching systems and organs
How the body response to the changes?
The conditions inside and outside our body
are always changing. Some of these changes
can be harmful.
The two organ systems helps body to adjust
to these changes are:
• The nervous systems uses electrical signal to
response to changes
• The hormonal system also coordinate some of
the body’s responses, using hormones. This
maintenance of a constant internal environment
despite changes in the surroundings is called
homeostasis.
Stimulus and Response .
Flow chart of stimulus-response
Homeostasis:
Regulating the Internal Environment
A controlled, stable internal environment
 Gains and losses must balance
 Control systems
◦ Receptor, control centre, effector
◦ Feedback loops
 Negative feedback
 Positive feedback

All internal organs contribute to homeostasis,
but this lab examines the contributions of the
lungs, kidneys, and liver.
Pancreatic Hormones, Insulin and Glucagon,
Regulate Metabolism
Blood glucose regulation
Glucose is needed by cells for
respiration. It is important that the
concentration of glucose in the blood is
maintained at a constant level. Insulin is a
hormone produced by the pancreas that
regulates glucose levels in the blood.
How glucose is regulated?
Effect on
Glucose level
pancreas
too high
too low
Hormone
insulin
secreted into
the blood
insulin not
secreted into
the blood
(instead
another
hormone
glucagon is
secreted)
Effect on liver
Effect on
glucose
level
liver converts
glucose into
glycogen
goes down
liver does not
convert glucose goes up
into glycogen
Glucagon

The pancreas releases another hormone,
glucagon, when the blood sugar levels
fall. This causes the cells in the liver to
turn glycogen back into glucose which can
then be released into the blood. The
blood sugar levels will then rise.

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/re
sponses_to_environment/homeostasisrev6.shtml
Homeostasis – Negative Feedback

The control of blood sugar (glucose) by insulin
is another good example of a negative feedback
mechanism. When blood sugar rises, receptors
in the body sense a change . In turn, the control
center (pancreas) secretes insulin into the
blood effectively lowering blood sugar levels.
Once blood sugar levels reach homeostasis, the
pancreas stops releasing insulin.
Homeostasis – Positive Feedback

A good example of a positive feedback
mechanism is blood clotting. Once a blood
vessel is damaged, platelets start to cling to
the injured site and release chemicals that
attract more platelets. The platelets
continue to pile up and release chemicals
until a clot is formed.

Glucose homeostasis – Putting it all together
(extra notes)
Insulin
Beta cells
of pancreas stimulated
to release insulin into
the blood
High blood
glucose level
STIMULUS:
Rising blood glucose
level (e.g., after eating
a carbohydrate-rich
meal)
Body
cells
take up more
glucose
Liver takes
up glucose
and stores it as
glycogen
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes
Figure 26.8
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Liver
breaks down
glycogen and
releases glucose
to the blood
STIMULUS:
Declining blood
glucose level
(e.g., after
skipping a meal)
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood
Glucagon
Liver/Blood Sugar Regulation (extra notes)
The body requires volumes of glucose in order to
create ATP. The amount of ATP demanded will
fluctuate, and therefore the body regulates the
availability of glucose to maximize its energy making
potential.
Two hormones are responsible for controlling the
concentration of glucose in the blood. These are
insulin and glucagon. The diagram illustrates the
principle of negative feedback control in action
involving blood/sugar levels.
http://bioserv.fiu.edu/~walterm/human_online/labs/ho
meostasis/homeostasis.htm
Liver/Blood Sugar Regulation (extra notescontinue…)
The level of glucose in the bloodstream drops
The person requires glucose in cells to meet the
demand for ATP
The body detects this with a particular receptor
designed for this function
These receptors release hormones, chemical
messages that initiate the start of the feedback
mechanism
The hormones travel to their target tissue and initiate
a corrective response
In this case, the corrective response is the secretion
of more glucose into the bloodstream
Homeostasis (extra notes)
Homeostasis means “steady state,” or internal
balance, and is a recurrent theme in understanding
how organisms function as a whole. A stable
environment, maintained within narrow limits, is
essential to all life.
Organisms constantly exchange energy and materials
with their environments. The gains and losses must
balance over some type of time interval. For example,
as glucose enters the blood after a meal, excess
glucose is transported to the liver to be converted to
glycogen. Between meals, as glucose levels drop, the
liver converts glycogen back to glucose and releases
it into the bloodstream.
Homeostasis (extra notes continue)
Homeostatic control systems have a receptor that detects
change, along with a control center that directs the response to
an effector. The body monitors internal conditions and makes
corrections through biofeedback loops. In negative feedback
loops, a change in the monitored variable triggers a response to
counteract further change in the same direction. If excess heat is
detected in the body, the brain signals the blood vessels near the
surface of the body to dilate and the sweat glands to increase
production. As body temperature nears normal, the brain reverses
the process by slowing sweat production and constricting blood
vessels.
In positive feedback loops, a change in the monitored variable
triggers further action rather than reversing the action. A common
example of a positive feedback loops occurs in blood clotting, with
each clotting reaction activating another until the bleeding is
stopped
Homeostasis (maintaining balance)
Task:
Write a letter to a relative :
 explaining how they have just been
diagnosed with diabetes.
 Describe what changes that will bring
to their lives and consequences of not
controlling the disease properly:
http:www.diabetesaustralia.com.au/
Maintaining Balance - Homeostasis
Insulin and glucagon are hormones that
work to regulate the level of sugar
(glucose) in the body to keep it within a
healthy range.
 Diabetes is a disorder of metabolism—
the way the body uses digested food for
energy. People with diabetes have high
glucose levels in their blood.

Diabetes
Type 1 diabetes and Type 11 diabetes
 Type 1 diabetes develops when pancreas
stops producing insulin.
 Type 2 diabetes develops when pancreas
can no longer produce enough insulin
It’s my body (part 1) cells, organisms, body
systems and maintaining balance - summary
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Stimulus- change in environment (internal and external.
E.g. Light is a stimulus from external environment.
Changes in glucose level is another stimulus
Receptors – specialised cells that can detect changes in
environment. E.g. Photoreceptors in the eye retina
detect light (a stimulus)
Effectors – any part of the body that produces
response. E.g. examples of effectors:
a muscle contracting to move the arm
a muscle squeezing saliva from the salivary gland
a gland releasing a hormone into the blood
It’s my body (part 1) cells, organisms, body
systems and maintaining balance - summary
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Hormones:- chemicals secreted by endocrine
glands in organs. E.g. insulin by pancreas and
thyroxin by thyroid glands.
Homeostasis:-physiological system of multi-cellular
organisms, to maintain internal stability, owing to
the coordinated response of its parts to any
situation or stimulus that would tend to disturb its
normal condition or function. E.g. Blood glucose
regulation by hormones such as insulin/glucagon.
Insulin:- a hormone that lowers the level of
glucose. Insulin is secreted by the pancreas.
Glucagon:- A hormone produced by the pancreas
that stimulates an increase in blood sugar levels,
thus opposing the action of insulin.