Topic 1: It’s My BodyPart 1: Cells and Body Systems of Human, Homeostasis

PLANT CELL

ANIMAL CELL

Organelles : Function :Nucleus: Contains the DNA and RNA

and manufactures proteins

Nucleolus: In nuclei where ribosomes are synthesized.

Nuclear Envelope: Membrane of lipids and proteins that surrounds

nucleusCentrioles: structure that appears

during mitosis(cell division)

Mitochondria: Energy producers of the cellRibosomes: Produce proteins

More Organelles

ORGANELLES FUNCTIONGolgi Bodies: Packages ProteinsChloroplasts: Involved in

photosynthesisVacuoles: Store waste,

nutrients, and water

Lysosome: Contains digestive enzymes,

mostly in animal cells

Endoplasmic Reticulum:Passageway that transports proteins from

the nucleusRough ER covered in

ribosomes, Smooth ER is not!

WHILE NOT EXACTLY ORGANELLES, THE FOLLOWING ARE IMPORTANT PARTS OF THE CELLS:

Cell membrane: Semi-permeable lining that surrounds the cell

Cell Wall: Is a stiff non-living wall that surrounds the

cell membrane made of cellulose

Cytoplasm: Jelly-like material surrounding the organelles

UNICELLULAR AND MULTICELLULAR ORGANISMS

Differences between unicellular and multicellular orgranisms.

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

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.

Each specific cell is grouped with cells similar in structure and function to form a tissue.

How is the body organized?

cells tissue

Animal tissues Plant tissues

muscle

bone

liver

skin

lung

mesophyll

phloem

xylem

Can you think of any more types of tissue?

Examples of tissue

Groups of tissues work together to form organs.

How is the body organized?

cell tissue organ

Groups of cells work together to form tissues.

Cells are thebasic units oflife.

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?

How is the body organized?

Tissues in the Human Body

Epithelial◦ Covering or lining tissue

Connective◦ Joins, stores and supports

Muscle◦ Internal and external movement

Nerve◦ Conducts electrical signals

Blood

Muscle

Nerve

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.

How is the body organised?

Being organised means that the body does not waste energy, so it is more efficient.

grow

reproduce

respond to things

excrete

respire

move digest food

body life processes

Human Organ Systems

Skeletal MuscularCirculatory ImmuneRespiratory DigestiveExcretory

ReproductiveNervous EndocrineIntegumentary

Matching systems and organs

• 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 environmentdespite changes in the surroundings is calledhomeostasis.

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:

Stimulus and Response .

Flow chart of stimulus-response

Homeostasis: Regulating the Internal EnvironmentA controlled, stable internal

environment Gains and losses must balanceControl 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.

Glucose levelEffect on pancreas Effect on liver

Effect on glucose level

too high

Hormone insulin secreted into the blood

liver converts glucose into glycogen

goes down

too low

insulin not secreted into the blood (instead another hormone glucagon is secreted)

liver does not convert glucose into glycogen

goes up

How glucose is regulated?

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/responses_to_environment/homeostasisrev6.shtml

Homeostasis – Negative FeedbackThe 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 FeedbackA 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)

Figure 26.8

Insulin

Beta cellsof pancreas stimulatedto release insulin intothe blood

Bodycellstake up moreglucose

Blood glucose leveldeclines to a set point;stimulus for insulinrelease diminishes

Liver takesup glucoseand stores it asglycogen

High bloodglucose level

STIMULUS:Rising blood glucoselevel (e.g., after eatinga carbohydrate-richmeal) Homeostasis: Normal blood glucose level

(about 90 mg/100 mL) STIMULUS:Declining bloodglucose level(e.g., afterskipping a meal)

Alphacells ofpancreas stimulatedto release glucagoninto the blood

Glucagon

Liverbreaks downglycogen and releases glucoseto the blood

Blood glucose levelrises to set point;stimulus for glucagonrelease diminishes

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/homeostasis/homeostasis.htm

Liver/Blood Sugar Regulation (extra notes- continue…)

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 - HomeostasisInsulin 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 diabetesType 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

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

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.

It’s my body (part 1) cells, organisms, body systems and maintaining balance - summary