BELLRINGER 11/30

• What is homeostasis?

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UNIT 3 PART 1: LIFE FUNCTIONS• ALL LIVING THINGS MUST MAINTAIN

HOMEOSTASIS – THE CONDITION OF A CONSTANT INTERNAL ENVIRONMENT• This means controlling many things like temperature,

pH, concentrations of molecules, etc.• All life processes together make up an organism’s

METABOLISM.• Failure to maintain homeostasis causes disease and

death.• Organisms use several life processes to maintain

homeostasis.2

1. GROWTH is the process by which organisms increase in size. It is accomplished mainly by cell division (mitosis) or an increase in cell size.

2. SYNTHESIS is the process of making or building something. It involves putting together small molecules to make larger ones. For example, dehydration synthesis.4

3. NUTRITION IS TAKING IN MATERIALS FROM THE EXTERNAL ENVIRONMENT AND CHANGING THEM INTO A FORM THAT CAN BE USED.

• Autotrophic nutrition• Organisms that are

able to make (synthesize) their food from inorganic compounds

• Photosynthesis• Green plants, algae &

some bacteria

• Heterotrophic Nutrition• Organisms that must eat

food• Digest food to obtain

nutrients• All animals, fungi, some

protists and bacteria5

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HETEROTROPHIC NUTRITION1. Ingestion (eating)2. Digestion (hydrolysis)

• Starches Sugar• Proteins Amino Acids• Lipids Fatty Acids

3. Absorption (diffusion)4. Egestion (elimination)

• Undigested (fecal) waste

• Never enters the body7

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DIGESTION• Starts with mechanical breakdown of food

into smaller pieces (chewing)• Increases the surface area of food• Followed by chemical digestion by digestive

enzymes to make food small enough so nutrients can be absorbed

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THE DIGESTIVE SYSTEM

• The function of the digestive system is nutrition. • to break down food into usable parts providing

nutrients for other processes.

Pasta (starch) + digestive enzymes (hydrolysis) Simple sugars (glucose)

Starch is too big to be absorbed into cells but glucose is small. It will diffuse through the cell membrane and cells can use it to produce energy. How? Where? What molecule is the energy molecule?

HUMAN• A Tube made up of

• Mouth• Pharynx• Esophagus• Stomach• Small intestine• Large intestine• Rectum• Anus

• Food moves through by peristalsis

• Accessory glands that secrete enzymes are

• Liver• Pancreas• Salivary glands

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THE SMALL INTESTINE

• Most chemical digestion and absorption takes place here

• Muscular like the esophagus

• Intestinal glands secrete• Amylase: digest starch• Protease: digest protein• Lipase: digest lipids

• Villi increase surface area & absorb digested food molecules.

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12/1 BELLRINGER• How long do you think the small intestine

and large intestine each are?

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VILLI • Villi are millions of small, fingerlike projections that line the small intestine

• Villi contain capillaries to absorb sugars, vitamins, minerals, and amino acids into the blood

• Villi contain lacteals to absorb fats into the lymph

• Absorption happens by diffusion. 15

4. TRANSPORT is the process by which substances move into and out of cells or are distributed within cells. This involves diffusion, osmosis, and active transport.

What are some organelles involved in transport?16

HUMAN CIRCULATION

More complex organisms need a circulatory system to transport materials to all body cells. This is the link between the cells and their environment.

Plasma is the liquid portion of the blood and transports everything except oxygen. 17

BLOOD CELLS• Red blood cells (RBCs)

have hemoglobin to carry oxygen, O2.

• White blood cells (WBCs) fight disease by attacking pathogens or making antibodies.

• Platelets are cell fragments that help in blood clotting.

• All blood cells are made in the bone marrow.

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BLOOD VESSELS

• ARTERIES are vessels that carry blood Away from the heart.

• VEINS are vessels that carry blood back to the heart.

• CAPILLARIES are the smallest vessels & carry blood from arteries to the veins 19

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ICF• All body cells are

surrounded by intercellular fluid (ICF).

• It helps to move materials between cells and capillaries.

• It is formed from parts of blood that diffuse out of capillaries – water, salts, proteins, and nutrients.

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5. RESPIRATION is the process of releasing chemical energy.

• Most organisms need to get O2 for aerobic respiration and remove CO2. This is gas exchange or breathing (NOT respiration!).

• Gas exchange between an organism and its environment takes place at the respiratory surface.

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• Gas exchange (G.E.) happens by diffusion, so it depends on the concentration of gases on each side of the respiratory surface.

• A larger respiratory surface area means more diffusion. 24

HUMAN RESPIRATORY SYSTEM

• Lungs and air tubes• Lungs fill most of chest

cavity• Separated from abdominal

cavity by diaphragm – muscle that allows breathing

• Breathing rate is controlled by the concentration of CO2 in the blood.

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ALVEOLI• Alveoli are tiny air sacs

that are in clusters at the ends of the bronchioles in the lungs.

• They are surrounded by capillaries.

• The walls of the alveoli are the respiratory surface where gas exchange takes place by Diffusion.

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6. EXCRETION is the process by which wastes and excess heat are removed.

ELIMINATION (defecation) is the removal of unabsorbed and undigested food (feces) from the digestive tract. This is different from excretion.

The human body needs to remove these wastes:• CO2 – from cellular respiration

• H2O – from cell. resp. & dehydration synthesis

• Salts – build up during metabolism

• Urea – from the breakdown of proteins27

HUMAN

• Excretory wastes pass from the body cells to the ICF to the blood by diffusion where they are removed by the excretory organs.

• The excretory organs include the:

• Lungs

• Liver

• Kidneys

• Skin 28

• The lungs function in the excretion of CO2 and water vapor, the wastes of cellular respiration. Some heat is also lost.

• The sweat glands excrete salt, water, and urea through pores in the skin.

• Evaporation of water helps to cool the body. The skin’s major role in excretion is the removal of excess heat.

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THE LIVER HAS THREE FUNCTIONS:

1. Detoxification – removes harmful substances like bacteria, drugs, and hormones from the blood, inactivates them, and returns them to the blood for excretion.

2. Makes bile – used by the small intestine to emulsify fats. It is stored in the gall bladder. It is made from old red blood cells.

3. Forms urea from the breakdown of proteins. Urea contains nitrogen (N) and is returned to the blood for excretion at the kidneys.

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URINARY SYSTEM

• Works to remove wastes from the blood and produce urine.

• The human urinary system consists of the:• Kidneys• Ureters• Urinary bladder• Urethra

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KIDNEYS• Kidneys remove urea

from the blood and maintain body fluid concentrations.

• Blood enters the kidney through the renal artery.

• Plasma filters into the kidney by diffusion.

• Sugar, amino acids, some salts, and most of the water are then reabsorbed back into the blood.

• What is left behind in the tubule is called urine, and is drained from the kidneys to the bladder.

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7. REGULATION is coordination and control of all other life functions.

When there are changes in the internal or external environment, organisms must respond. The human body has two systems of regulation that work together.

NERVOUS REGULATION

• A nervous system is a network of specialized cells called neurons, that carry electrical signals (impulses) throughout the organism.

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• A stimulus is anything that causes a receptor to start impulses.

• Receptors are specialized structures sensitive to certain changes, forces, or chemicals both in and out of the organism. They are proteins on the surface of cell membranes.

• Stimulation of a receptor sends an impulse to an effector, which is a specialized structure that responds to commands of the nervous system. These can be muscles, glands, other neurons. This is where the action is.

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THE NEURON• The basic structure in the nervous system.• It has three parts:

1. Body - contains the nucleus and organelles

2. Dendrites - short extensions from the body and receive impulses and carry them toward the cell body

3. Axon – long thin fiber that extends away from the body and carries impulses Away from the cell to another

neuron or effector

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• The axon is surrounded by Schwann cells which are surrounded by a myelin sheath with nodes between the cells. Impulses travel in jumps from node to node.

• The terminal branches at the end of the axon almost, but do not touch other cells or effectors. The gap is called a synapse, and one axon can have thousands of synapses.

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LABEL THE NEURON BELOW USING THESE TERMS:

AXON DENDRITE NODE SCHWANN CELL

AXON TERMINALS NUCLEUS CELL BODY MYELIN SHEATH

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THE SYNAPSE • A synapse is a small gap between nerve cells or effectors.

• The axon secretes a neurotransmitter to cross the synapse and start an impulse in the next cell.

• The neurotransmitter is then removed by enzymes so new signals can be sent.

• Synapses are important because:

• They ensure one-way movement of impulses

• They act as an on/off switch39

THE HUMAN NERVOUS SYSTEM

Two subsystems:• The central nervous system

(CNS) is the brain and the spinal cord. This system controls most activities. It is protected by the skull and vertebrae, meninges, and cerebrospinal fluid.

• The peripheral nervous system (PNS) is the network of nerves that take impulses between the CNS and receptors and effectors.

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REFLEXES• A reflex is an involuntary, automatic response to a stimulus – blinking, sneezing, coughing, breathing, heartbeat, peristalsis, pupil response

• The reflex arc is the pathway over which the nerve impulses travel – most have 3 neurons: a sensory neuron, an interneuron, and a motor neuron. The brain is NOT involved.

41(effector)

LABEL THE PARTS OF THE REFLEX ARC USING THESE WORDS:

SPINAL CORD MOTOR NEURON INTERNEURON

EFFECTOR SENSORY NEURON RECEPTOR

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CHEMICAL REGULATION• Animals must make constant adjustments to

maintain homeostasis. The nervous system acts quickly and sends its message to specific parts of the body.

• The endocrine system helps to maintain homeostasis by releasing chemicals into the blood. When the chemicals reach the target organ, a reaction occurs. This is slower than the nervous system, but the effects usually last longer. 43

These systems can also

work together. When you

sense danger, nerves

control muscles so you

can run away and other

nerves stimulate part of

your endocrine system

which then stimulates

your heart rate and

respiratory system to

provide increased energy. 44

ADRENALINE/EPINEPHRINE

GLANDS ARE ORGANS MADE UP OF CELLS THAT SPECIALIZE IN THE SECRETION OF SUBSTANCES NEEDED BY THE ORGANISM.

• Exocrine glands use ducts that carry their secretions to where they are used.

• Pancreas• Sweat• Mammary• Salivary• Sebaceous (oil)

• Endocrine glands release their secretions into the blood stream and affect some other part of the body.

• These secretions are called hormones, or chemical messengers.45

HORMONES

• Help to regulate metabolism, homeostasis, growth, reproduction, and other processes.

• Each hormone acts only on specific types of cells called target cells. How does a hormone recognize its target cell?

• A hormone can stimulate (start or increase) or inhibit (stop or decrease) cell activity.

• Many endocrine glands are regulated by other hormones. 46

FEEDBACK

• The chemical regulation of hormone secretions is accomplished by feedback.

• A feedback system operates as a cycle in which the last step affects the first.

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Stimulus

Receptor

Effector

Response

FeedbackControl Center

NEGATIVE FEEDBACK

• Changes in step A produce a change in B.

• The change in B then feeds back to stop A.

• Ex.: Heat from a furnace feeds back to turn off the thermostat 48

Feedback

Control Signal

NEGATIVE FEEDBACK IN YOUR BODY: REGULATION OF THYROXIN LEVEL IN THE BLOOD

• Negative feedback is used to keep some variable (thyroxin level) at a set point.

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Low thyroxin level in blood

(change) Pituitary secretes TSH

Thyroid to produce thyroxin

Normal thyroxin level

Pituitary stops secreting TSH

Thyroid stops producing thyroxin

POSITIVE FEEDBACK

• A change starts a response that intensifies the change. In your body:

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Contractions during childbirth

Pushes baby’s head against the uterus wall

Increases contractions of the uterus

PITUITARY: THE MASTER GLAND

• Located at the base of the brain

• Controls many of the other endocrine glands

• Secretes:

• Oxytocin, FSH, LH, Prolactin: Repro

• Vassopressin: Kidneys

• TSH: Thyroid

• ACTH: Adrenals

• GH: Growth hormone

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PANCREAS – ISLETS OF LANGERHANS

• Small clusters of cells located throughout the pancreas

• Secretes insulin to lower blood glucose levels and glucagon to raise levels

• Because these hormones do opposite jobs they are said to be antagonistic.

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• Insulin secretion is controlled by negative feedback.

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OVARY & TESTES

• Ovaries are located on both sides of the uterus.

• They produce estrogen and progesterone for promotion of the secondary sex characteristics and regulation of the menstrual cycle.

• Testes are located in the scrotum, outside the body.

• The testes produce testosterone for promotion of the secondary sex characteristics.

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