Transcript Ch 35 - Cloudfront.net

Ch 35
The Nervous System
Organization of the Body
• The levels of organization in
a multicellular organism
include
– Tissues – groups of
similar cells that perform
a single function
– Organ – a group of
tissues that work
together to perform a
complex function
– Organ System – group
of organs that perform
closely related functions
Body Tissues
• Four major types of tissues
include
– Epithelial – lines body
cavities and covers body
surfaces
– Connective – provides
support for the body and
connects its parts
– Muscle – contracts to allow
movement
– Nerve Tissue – transmits
impulses to coordinate
body system
Maintaining Homeostasis
• Homeostasis –
maintaining a controlled,
stable environment
• Negative Feedback – a
stimulus produces a
response that opposes
the original stimulus
• Positive Feedback – a
stimulus produces a
response that enhances
the original stimulus
The Nervous System
• Controls and coordinates
functions throughout the
body and responds to
internal and external stimuli.
• Cells that transmit the
impulses are called
neurons.
• Sensory Neurons – carry
information to the brain and
spinal cord.
• Motor Neurons – carry
information away from the
brain and spinal cord.
• Interneurons – relay
messages between sensory
and motor neurons.
Parts of a Neuron
• Cell Body – main part;
contains nucleus and
cytoplasm; most metabolic
activity occurs here
• Dendrites – short, branched
extensions that carry impulses
toward the cell body
• Axon – long extension that
carries impulses away from the
cell body
• Myelin Sheath – fatty layer
that covers many axons;
insulates the neuron and
speeds up the rate of
impulses.
• Nodes of Ranvier – gaps in
the myelin sheath; impulses
jump from node to node
Nerve Impulses: Resting Potential
• At rest, a neuron has a
high concentration of K+
ions inside the cell.
• A rest, a neuron has a
high concentration of Na+
ions outside the cell.
• Negatively charged
proteins and Cl- ions are
found inside the cell.
• Resting Potential: the
inside is negative with
respect to the outside.
Nerve Impulses: Action Potential
• A stimulus will cause the
membrane to change its
permeability.
• The membrane becomes
very permeable to Na+ and
Na+ rushes in.
• The membrane then
becomes permeable to K+
and K+ rushes out.
• The cell becomes less
negative on the inside.
• This is the “action
potential”.
• The impulse is selfpropagating (causing the
next point along the
membrane to be activated).
The Threshold of a Stimulus
• Impulse strength is always
the same.
• The minimum level of a
stimulus required to activate
a neuron is the threshold.
• Any stimulus stronger than
threshold will produce an
impulse.
• Any stimulus weaker than
threshold will produce no
impulse.
• A nerve impulse will
produce an impulse or it will
not produce an impulse
(All-or-none principal).
Synapses
• A synapse is the place
where an axon meets
dendrites, a muscle cell,
or a gland cell.
• The end of a neuron
(axon tip) releases
chemical messengers
called
neurotransmitters.
• Neurotransmitters cause
an impulse to travel to the
next cell.
Divisions of the Nervous System
• Central Nervous
System (CNS) – brain
and spinal cord
• Peripheral Nervous
System (PNS) – cranial
and spinal nerves.
– Autonomic Nervous
System (ANS) –
regulates involuntary
activities
The Brain
• Cerebrum – largest part
– Two hemispheres
– Site of intelligence,
learning, and judgment
– Folds and grooves on
surface increase surface
area
– Divided into lobes
• Frontal
• Parietal
• Temporal
• Occipital
Cerebellum and Thalamus
• Cerebellum
– Coordinates and
balances actions of
the muscles
• Thalamus
– Receives messages
from all sensory
receptors and relays
the information to the
proper region of the
cerebrum.
Hypothalamus, Medulla, Pons
• Hypothalamus
– Control center fro
recognition and analysis
of hunger thirst, fatigue,
anger, body temperature
• Medulla Oblongata
– Contains vital reflex
centers (swallowing,
breathing, heart rate)
• Pons
– Contains important
respiratory centers that
affect normal breathing
reflex
Spinal Cord & Reflex Arc
• Link between brain and
rest of body
• Reflex – quick, automatic
response to a stimulus
• Allows body to respond to
danger immediately; does
not require brain!
• Reflex Arc:
–
–
–
–
–
Receptor
Sensory Neuron
Interneuron
Motor Neuron
Affector (muscle, gland)
Peripheral Nervous System
• Made up of cranial
nerves and spinal
nerves
• Sensory Division –
carries info from
sense organs to
CNS
• Motor Division –
carries info from
CNS to muscles
and glands
Autonomic Nervous System
• Division of PNS
• Two subdivisions
– Sympathetic Division
– speeds up body
process; “fight-orflight” response
– Parasympathetic
Division – slows down
body processes
Ch 36
Skeletal, Muscular, and
Integumentary Systems
Functions of the Skeletal System
•
•
•
•
Protect vital organs
Store minerals
Makes blood
Aids movement
(provides site for
muscle attachment)
• Framework for body
Bone Structure
• Periosteum – tough layer of
surrounding connective
tissue
• Osteocytes – bone cells
• Haversian Canals – provide
means for blood vessels to
get to bone cells
• Bone Marrow – soft tissue
– Yellow Marrow (fatty)
– Red Marrow (makes
blood cells)
• Cartilage – reduces friction
between bones at a joint
• Compact bone
• Spongy bone
Bone Development
• Embryonic skeleton
starts off as bone
• Eventually, it is
replaced by bone
tissue
• Process called
ossification
• Ossification
completed between
ages of 18 – 25.
Human Fetus 6 Weeks
Bones of the Skeleton
• Axial Division
– Skull, Ribs, Sternum,
Vertebrae
• Appendicular Division
– Shoulders, Arms, Hips,
Legs
• Use Diagram to Learn
Bones
Joints
• Place where two bones
meet
• Immovable Joints – “fixed”
joints; allow no movement;
held by sutures or tightly
with connective tissue
• Slightly Movable Joints –
slight movement
• Freely Movable Joints
– Ball-and-Socket
– Pivot
– Hinge Joints
Miscellaneous (Bones)
•
•
•
•
Ligaments – hold bones together at a joint
Osteoporosis – weakening of bones
Arthritis – inflammation of a joint
Strain – damaged ligaments
Types of Muscle Tissue
• Skeletal Muscle
– Has striped appearance
– Voluntary
– Found attached to bones
• Cardiac Muscle
– Has striped appearance
– Involuntary
– Found only in heart
• Smooth Muscle
– Has no striped appearance
– Involuntary
– Found in walls of hollow
organs
Muscle Structure
• Myosin filaments
– Thick proteins
• Actin filaments
– Thin proteins
• Muscles contract because myosin pulls on actin.
• Requires ATP
Muscle Contraction
• Neuromuscular Junction – where neuron and
muscle cell meets
• Acetylcholine – neurotransmitter released by
neurons that triggers muscle contraction
• Muscles can only pull on bones; not push!
Muscle Names
• Tendons – connect
muscles to bone
• Use diagram to learn
muscles
–
–
–
–
–
–
–
–
–
–
Biceps brachii
Triceps brachii
Rectus femoris
Biceps femoris
Rectus abdominis
Pectoralis
Trapezius
Gastrocnemius
Gluteus Maximus
Deltoideus
The Skin
• Integumentary System
includes skin, hair, nails,
sweat glands, etc.
• Functions
– Barrier against
infection and injury
– Regulate body
temperature
– Remove waste
– Protect against UV
radiation
– Makes Vitamin D
Layers of the Skin
• Epidermis
– Outer layer
– Outermost cells are dead
and keratinized
– Keratin is a protein that
makes cells flat and water
resistant
– Inner cells are living,
contain pigment called
melanin
– Does not contain nerve
cells or blood cells.
Layers of the Skin
• Dermis
– Inner layer
– Lies beneath
epidermis
– Contains blood
vessels, nerves,
glands, hairs
– Two types of glands
• Sebaceous Glands –
oil glands
• Sweat glands
Hair and Nails
• Hair covers almost
every body surface
• Protects body and
insulates
• Hairs grow from the
root
• Nails grow from nail
root
• Fingernails grow about
4X faster than toenails.
Ch 37
Circulatory and Respiratory
Systems
Functions of the Circulatory System
• Circulates gases like
oxygen and carbon
dioxide
• Circulates heat
• Circulates water
• Circulates nutrients,
hormones, wastes
• Blood is always red!
Blood Composition
• Plasma (55%) –
yellowish
– Mostly water
– Contains dissolved
nutrients, gases,
wastes, etc.
• Corpuscles (45%)
– Erythrocytes – red
cells; carry oxygen;
hemoglobin
– Leukocytes – white
cells; immunity
– Thrombocytes –
platelets; coagulation
Blood Transfusion Compatibility
Type Antigens
Antibody
Can
Give
To
Can
Receive
From
A
Type A
Anti-b
A, AB
A, O
B
Type B
Anti-a
B, AB
B, O
AB
Type A and
Type B
None
AB
All
Types
O
None
Both Anti-a
All
and Anti-b Types
O
Transfusions with Rh Factor
examples
Type Antigens
Antibody
Can
Give
To
Can
Receive
From
A+
Type A & Rh
Anti-b
A+, AB+
A+, O+,A-,
O-
B-
Type B
Anti-a, Anti-Rh
B+, AB+,
B-, AB-
B-, O-
AB+
Type A, Type B,
and Type Rh
None
Type AB+
All Types
O-
None, Anti-Rh
Both Anti-a and
Anti-b
All Types
O-
Blood Vessels
• Arteries
– Smaller diameter than
veins
– Higher BP than veins
– Carry blood away from
heart
• Veins
– Larger diameter than
arteries
– Lower BP than arteries
– Carry blood toward heart
• Capillaries
– One cell thick
– Only site for diffusion
Circulation of Blood
• See p. 944
The Heart Beat
• There are two masses of
nerve/muscle tissue in the
heart that control the heart
beat.
• Both are located in the right
atrium.
• The SA Node (sinoatrial
Node) – natural pacemaker;
initiates beat
• The AV Node
(Atrioventricular Node) –
causes ventricles to
contract
• Heart rate varies with
activity
Blood Pressure
• Like any pump, the heart
produces pressure.
• When the heart contracts, it
produces a wave of fluid
pressure in the arteries.
• Blood pressure decreases
when the heart relaxes.
• Device called
sphygmomanometer
measures BP.
• The first number is the
systolic pressure (pressure
when ventricles contract)
• The second number is the
diastolic pressure (pressure
when ventricles relax)
• Normal reading 110 –
120/80 mmHg
Diseases of the Circulatory System
• Atherosclerosis – fatty
deposits called plaque
build up on the inner
walls of arteries
• High Blood Pressure –
Also called hypertension;
increases risk of heart
attack or stroke
• Heart Attack – blood flow
to heart muscle blocked;
heart muscle dies;
symptoms include
shortness of breath,
nausea, chest pain
The Respiratory System
• The basic function is
to bring about the
exchange of oxygen
and carbon dioxide
between the blood,
air, and tissues.
• The respiratory
system consists of the
nose, pharynx, larynx,
trachea, bronchi, and
lungs.
Parts of the Respiratory System
• Nose
– Hairs
– Smell receptors
– Mucus glands
• Pharynx
• Trachea
– Epiglottis
– Cartilage supports
• Bronchi, Bronchioles
• Alveoli
Gas Exchange & Breathing
• Gas exchange occurs
only via the alveoli.
• Inhalation
– Diaphragm
– Ribs & Sternum
– Volume vs Pressure
• Exhalation
– Diaphragm
– Ribs & Sternum
– Volume vs Pressure
Control of Breathing
• Rate of breathing
controlled by medulla
oblongata.
• Average breathing
rate at rest 12 – 15
breaths per minute.
• Affected by
– Amount of CO2 in
blood
– Emotions
– Exercise
Tobacco & The Respiratory System
• Nicotine is a stimulant
that increases heart rate
and blood pressure.
• Carbon Monoxide is a
poisonous gas that blocks
the transport of oxygen
by hemoglobin in the
blood. It decreases the
blood’s ability to supply
oxygen to its tissues.
• Tar has been shown to
cause cancer.
• Nicotine and CO paralyze
the cilia of the airways.
• Smoking causes the
lining of the airway to
swell, reducing air flow.
• Emphysema is the loss of
elasticity in the tissues of
the lungs.