Transcript Unit 3 part 1 PPT

BELLRINGER 11/30
• What is homeostasis?
1
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
2
homeostasis.
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 bacteria
5
6
HETEROTROPHIC
NUTRITION
1. 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 body
7
8
9
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
10
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?
• A Tube made up of
•
•
•
•
•
•
•
•
HUMAN
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
12
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.
13
12/1 BELLRINGER
• How long do you think the small intestine
and large intestine each are?
14
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.
16
What are some organelles involved in transport?
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.
HUMAN
CIRCULATION
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.
18
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
20
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.
21
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.
22
23
• 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
24
diffusion.
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 CO225in
the blood.
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.
26
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 proteins
27
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.
29
30
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.
31
URINARY SYSTEM
• Works to remove
wastes from the blood
and produce urine.
• The human urinary
system consists of the:
•
•
•
•
Kidneys
Ureters
Urinary bladder
Urethra
32
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.
33
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.
34
• 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.
35
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
36
• 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.
37
LABEL THE NEURON BELOW USING THESE TERMS:
AXON
DENDRITE NODE
AXON TERMINALS NUCLEUS
SCHWANN CELL
CELL BODY MYELIN SHEATH
38
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
39
• They act as an on/off switch
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 40
effectors.
• 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.
REFLEXES
(effector)
41
LABEL THE PARTS OF THE REFLEX ARC USING THESE WORDS:
SPINAL CORD
MOTOR NEURON INTERNEURON
EFFECTOR
SENSORY NEURON
RECEPTOR
42
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
43
longer.
These systems can also
ADRENALINE/EPINEPHRINE
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
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
46
hormones.
FEEDBACK
Stimulus
Receptor
Control Center
Effector
• The chemical regulation
of hormone secretions is
accomplished by
feedback.
Feedback
• A feedback system
operates as a cycle in
which the last step
affects the first.
47
Response
NEGATIVE FEEDBACK
• Changes in step A
produce a change in B.
Feedback
Control
Signal
• The change in B then
feeds back to stop A.
• Ex.: Heat from a furnace
feeds back to turn off
the thermostat
48
NEGATIVE FEEDBACK IN YOUR BODY: REGULATION OF
THYROXIN LEVEL IN THE BLOOD
Low thyroxin level in blood
Pituitary secretes
TSH
• Negative feedback is used to keep some variable (thyroxin level) at a set point.
Thyroid stops
producing thyroxin
(change)
Thyroid to produce
thyroxin
Pituitary stops
secreting TSH
49
Normal thyroxin level
POSITIVE FEEDBACK
Contractions during
childbirth
• A change starts a response that intensifies the change.
In your body:
Pushes
baby’s head
against the
uterus wall
Increases contractions
of the uterus
50
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
51
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.
52
• Insulin secretion is controlled by negative feedback.
53
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.
54