The Systems of the Body. Neuron Cell body – source of life of the cell Dendrites – branches on...
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Transcript of The Systems of the Body. Neuron Cell body – source of life of the cell Dendrites – branches on...
The Systems of the Body
Neuron Cell body – source of life of the cell Dendrites – branches on the cell bodies that
act as receivers of messages from adjacent neurons.
Axon – projection through which messages travel.
Synaptic knobs: Tips of branches at end of axon. Sends messages to adjacent neurons.
Synapse: Fluid filled gap between neurons.
The Nervous System
Bra in S pina l cord
C entra l ne rvous sys tem(c a rries vo lu n ta ry n e rve im p u ls es to
m u s c les an d s k in ; c a rries in vo lu n ta ryim p u ls es to m u sc les an d g lan d s )
S om atic ne rvous sys tem(c on tro ls vo lu n ta ry
m ovem en t)
S ym pathe tic ne rvous sys tem(m ob ilizes th e b od y
fo r ac tion )
Parasym pathe tic ne rvouss ys tem
(m a in ta in s an dres to res eq u ilib riu m )
A utonom ic nervous sys tem(c on tro ls o rg an s th a top era te in vo lu n ta rily)
Periphera l ne rvous sys tem
NervousS ys tem
Three sections of the brain
Hindbrain•Medulla•Pons•cerebellum
Midbrain•Pathway connectinghindbrain andForebrain.
Forebrain•Diencephalon•Telecephalon
Diencephalon•Thalamus•Hypothalamus
Telecephalon•Cerebrum•Limbic system
Telencephalon
Upper and largest portion of the brain Involved in higher order intelligence,
memory, and personality Composed of two hemispheres
Left hemisphere – language processes, etc.
Right hemisphere – visual imagery, emotions, etc.
Four lobes of the cerebral cortex
Frontal•Motor activity•Higher level intelligence•Planning•Problem solving•Emotions•Self-awareness
Parietal•Bodily sensations, e.g., pain, heat•Body movement
Temporal•Hearing•Vision•Smell•Memory
Occipital•Primary visual area of the brain
Reticular Activating System and Limbic System Reticular activating system runs
from the medulla through the midbrain into the hypothalamus. Responsibility for activation of all
areas of the brain and if damaged – coma ensues
Limbic system controls emotion It has three sub-circuits
Limbic System - emotions
Amygdala and hippocampus – essential for self-preservation, includes aggression.
Cingulate gyrus, the septum, and areas of the hypothalamus – pleasure and sexual excitement.
Areas of the thalamus and hypothalamus – important to socially relevant behaviour
Diencephalon
Thalamus•Chief relay centre for directing sensory messagesHelps regulate awareness•Relays commands going to the skeletal muscles from the motor cortex.
Hypothalamus•Command for the control of autonomic functions such as heart rate, blood pressure, hunger, thirst.•Role in emotions and motivation (e.g., thoughts about fear get translated into arousal through hypothalamus.)
Three sections of the brain
Hindbrain•Medulla•Pons•cerebellum
Midbrain•Pathway connectinghindbrain andForebrain.
Forebrain•Diencephalon•Telecephalon
Diencephalon•Thalamus•Hypothalamus
Telecephalon•Cerebrum•Limbic system
Cerebellum Maintains body balance and
coordination of movement Damage to the cerebellum results
motor disorders such as ataxia. Ataxia is a condition where our
movements become jerky and uncoordinated.
Hindbrain continued Consists of:
Pons – involved in eye movement, facial expressions and eye movement
Medulla – controls breathing, heart rate, blood pressure
Midbrain
Midbrain – top of brain stem, receives visual and auditory information, also important in muscle movement.
Reticular formation – controls states of sleep, arousal, and attention.
Spinal cord Transmits messages from the brain
to the other areas of the body. Efferent – away from the brain out to the
body Produces muscle action
Afferent – from the periphery to the brain
Relays information from the sensory organs
Peripheral Nervous System
Autonomic nervous system
Somatic nervous system
Somatic nervous system Involved in both sensory and motor
functions, serving mainly the skin and skeletal muscles.
Efferent impulses: carry messages from the brain to the skeletal muscles
Afferent impulses: carry messages from the sensory organs to the brain
Autonomic nervous system Controls what is generally
involuntary, automatic activity
Consists of the sympathetic and parasympathetic nervous systems.
Sympathetic nervous system Fight of flight response
Sends out messages (neurotransmitters) to the body preparing the body for fight or flight.
Also prepares the body for strenuous activity
Fight or Flight ResponseIncrease in
Epinephrine & norepinephrine
Cortisol Heart rate & blood
pressure Levels & mobilization
of free fatty acids, cholesterol & triglycerides
Platelet adhesiveness & aggregation
Decrease in Blood flow to the
kidneys, skin and gut
Parasympathetic nervous system Restores equilibrium in the body
Decreases arousal, slows breathing and heart rate, lowers heart rate and blood pressure, etc.
Neurotransmitters Electrochemical messengers:
Catecholamines, consisting of epinephrine and norepinephrine
Dopamine Acetycholine Serotonin
The Endocrine System Set of glands Works in close association with the
autonomic nervous system Communicates via chemical
substances like hormones Examples are adrenaline, cortisol,
somatotropic hormone, gonadotropic hormone, etc.
Endocrine and autonomic systems work together Connection between the
hypothalamus in the brain and the pituitary gland (“master gland”)
The pituitary gland sends out hormones that communicates with other glands to send out hormones
Adrenal gland Located on top of each kidney Comprised of the adrenal medulla
and the adrenal cortex. Adrenal medulla secretes adrenaline
(epinephrine) and noradrenaline (norepinephrine)
Adrenal cortex secretes steroids (including mineralocorticoids and glucocorticoids, androgens, and estrogens)
Thyroid gland Located in the neck Produces hormone (thyroxin) that
regulates activity level and growth. Hypothyroidism: Insufficient thyroid
hormones (leads to low activity levels and weight gain)
Hyperthyroidism: Over-secretion of thyroid hormones (leads to hyperactivity and weight loss, insomnia, tremors, etc.)
Pancreas Located below the stomach Regulates level of blood sugar by
producing insulin which absorbs blood sugar.
Important gland in diabetes mellitus
Digestive system Enzymes: break-downs food
substances Commands from the brain stem
activates the production of saliva. Saliva contains enzymes that breakdown starches.
Esophagus pushes food to the stomach using peristalsis.
Digestive system - continued Stomach uses gastric juices and
churning to further breakdown food. Peristalsis moves food from the
stomach to the duodenum (small intestine)
Acid food mixture becomes chemically alkaline from secretions of the pancreas, gallbladder, and small intestine wall.
Digestive system - continued Additional enzymes and bile
continue the food breakdown. Absorption occurs. Large intestine (mainly colon)
continues absorption of water and passes the remaining waste to the rectum for excretion.
Disorders of the Digestive System Peptic ulcers – open sores in the
stomach or duodenum. Causes by excessive gastric juices and bacterial infection.
Hepatitis – liver becomes inflamed. Cirrhosis – liver cells die and are
replaced by scar tissue. Caused by hepatitis and heavy alcohol consumption.
Disorders of these SystemsDiabetes Type I – insulin-dependent diabetes
where person has to take exogenous insulin to make up for the lack of insulin produced by the pancreas.
Type II – non-insulin dependent diabetes where body is not sufficiently responsive to insulin
Leading cause of blindness in adults and 50% of dialysis patients (kidney failure) have diabetes.
Respiratory System Air enters the body through the
nose and mouth. It travels past the larynx and down
the trachea and bronchial tubes into the lung.
Bronchial tubes divide into small branches called bronchioles, and then tiny sacs call alveoli.
Disorders of the Respiratory System Asphyxia – too little oxygen and too
much carbon dioxide (can occur in small breathing space).
Anoxia – shortage of oxygen (occurs at very high altitudes). Person looses judgment, pass into comma.
Hyperventilation – deep rapid breaths that reduce the amount of carbon dioxide.
Disorders of the Respiratory System - continued Hay fever – seasonal allergic
reactions. Body produces histamines in response to the irritants entering the lungs.
Asthma – more severe allergic reaction. Muscles surrounding the air tubes constrict.
Viral infections (e.g., flu) Bacterial infections (e.g., strep throat)
Cardiovascular System Transport system of the body. Consists of the heart, blood, and
blood vessels Blood vessels consist of:
Arteries that carry oxygenated (red) blood from the heart to the periphery and brain.
Veins carries de-oxygenated (blue) blood back to the heart and lung
Heart Fist-sized muscle that circulates blood
to and from the lungs to the body. Four chambers – atrium (right & left)
and ventricles (right & left) Left side pumps oxygenated blood
from lungs out to periphery and brain. Right side takes deoxygenated blood
in to the lungs.
Blood pressure (BP) Pressure of blood in the arteries. As the heart contracts and pushed
blood into the arteries (systolic cardiac cycle) the BP rises.
As the heart rests between beats and no blood is pumped (diastolic cardiac cycle) BP is at its lowest.
Dynamics of Blood Pressure (BP) Cardiac output – force of contraction
of the heart muscle Heart rate – speed of contraction Blood volume – amount of blood in
the system Peripheral resistance – ease with
which blood can pass through the arteries (as resistance increases, BP increases)
Dynamics of Blood Pressure (BP)
Elasticity – is the give and take in the arterial walls. As elasticity decreases BP increases.
Viscosity – thickness of the blood. BP increases when the thickness of the blood increases.
Blood pressure (BP) is Dynamic
When arteries dilate (e.g., in heat) diastolic BP decreases.
BP increases when heart rate or cardiac output increases in response to activity, change in posture, while talking, when under stress, temperature, etc.
BP follows a circadian (daily) rhythm such that it is lowest when in deep sleep.
Hypertension Permanently high blood pressure
Systolic blood pressure >= 140 mmHg Diastolic blood pressure >= 90 mmHg
Essential (primary) – no known physical cause (90-95% of cases are of this type)
Secondary hypertension – due to specific cause, e.g., adrenal tumor.
Risk Factors for Essential Hypertension Lack of exercise Body weight Salt consumption Stress
Age Gender Ethnicity (blacks
at higher risk) Genetics
Blood Two components
Formed elements Plasma
Formed elements consist of three elements: Red blood cells Leukocytes (white blood cells) Platelets
Formed Blood – Red Blood Cells Most abundant cells Formed in bone marrow Contains hemoglobin – a protein
that attaches to oxygen and transports it to the cells and tissue
Anemia is when level of red blood cells are below normal
Leukocytes (white blood cells) Serve a protective function (e.g.,
destroys bacteria). Produced in bone marrow and
various organs of the body. Leukemia is when there is an
excessive production of white blood cells that crowd out plasma and red blood cells.
Platelets Granular fragments that can clump
together to prevent blood loss at site of cuts.
Produced by bone marrow Hemophilia is when platelets don’t
function properly to produce clotting and so if the person receives a cut could bleed excessively.
Plasma 55% of the blood is plasma Composed of 90% water and 10%
plasma protein and other organic and inorganic substances.
Other substances include hormones, enzymes, waste products, vitamins, sugars, fatty material etc.
Plasma - continued An important fatty substance is lipids. Consist of:
Cholesterol Low and high-density lipoprotein Triglycerides
High lipid content in the plasma can lead to plaque build-up on arteries and lipid deposits in arterial wall, causing hardening of the arteries.
Disorders of the Cardiovascular System – Hardening of Arteries
Atherosclerosis – deposits of cholesterol and other substances on the arterial wall, forming plaques that can block the artery.
Ateriosclerosis – calcium and other substances get deposited on the arterial wall leading to hardening of the plaques.
Risk Factors for Atherosclerosis Hypertension High fat intake leading to hyperlipidemia Smoking Stress Diabetes, Lack of exercise Genetics Gender
Stress and AtherosclerosisCoronary Artery Plaque in Monkeys
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DominantSubordinate
PlaqueArea(mm2)
Stress and AtherosclerosisCoronary Artery Plaque in Monkeys
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Consequences of Atherosclerosis
Angina pectoris – insufficient oxygen supply to the heart for its need and removal of waste products resulting in chest pain.
Myocardial infarction (heart attack) – when there is a blockage of blood supply to an area of the heart cutting off oxygen supply to the tissue in the area and resulting in tissue death
Immune System
The Immune System Antigens are any substance (e.g.,
bacterial, viral, fungi) that can trigger an immune response.
Bacterial – microorganisms in the environment. Grow rapidly and compete with our cells for nutrients.
Fungi – organisms like mould and yeast. Also, absorbs nutrients.
Viruses – proteins and nucleic acid. They take over the cell and generate their own genetic instructions.
Immune System Immune system recognizes itself
and foreign material Transplant success can by
increased by: Using close genetic tissue match. Using medications that inhibit the
immune system’s attack on the foreign material.
Immune System Allergies are immune response to
(normally) harmless substances.
Allergins are substances that trigger an allergic response (e.g., pollen, cat dander)
Organs of the Immune System Lymphatic and lymphoid organs
Deploys lymphocytes Lymphocytes
White blood cell that provides main defense against foreign material
Produced by bone marrow
Organs of the Immune System Lymphocytes
Form of white blood cells that provide main defense against foreign matter
Lymphocytes originate from bone marrow
Organs of the Immune System
Lymph Nodes Bean-shaped spongy tissue Largest are in the neck, arm-pit, abdomen,
and groan Filters to capture antigens (foreign material)
and has compartments for lymphocytes. Lymph vessels
Connects to lymph nodes and carries fluid called lymph into the blood stream
Organs of the Immune System
Spleen Upper left side of the abdomen Filters antigens that the lymph vessels
put into the bloodstream Home base for white blood cells Removes worn out red blood cells
Soldiers of the Immune System Phagocytes
Engulf and ingest antigens Two types:
Macrophages – attach to tissue and stay there
Monocytes – circulate in the blood Nonspecific immune processes
Specific Immune Processes Cell-mediated immunity Killer t-cells (CD8) – destroy foreign
tissue, cancerous cells, cells invaded by antigens
Memory t-cells – remember previous antigen in order to defend against subsequent invasions.
Specific Immune Processes
Delayed hypersensitivity t-cells – involved in delayed immune reactions. Produce lymphokines that stimulate other t-cells to grow, reproduce and attack.
Helper t-cells (CD4 cells) – get information of invasions and report to spleen and lymph nodes to stimulate lymphocytes for attack.
Suppressor t-cells – slow down or stop immune processes.
Immune System Antibodies – proteins produced in
the body in response to antigens. They combine chemically with antigens to overcome their toxic effects.
B lymphocytes – secrete antibodies that protect body against bacterial infection and viral infections.
Immune Response
Foreignmaterial
CoughSneeze
Phagocytesengulf it
Th
cells
KillerTc cellsB cells
Gamma-interferon
Interlukin-1
Why Can’t We Fight Cancer
Some cancer cells release substances that suppress the immune response.
Some antigens may be difficult for the immune system to recognize.
Less Than Optimal Defenses
Immune function changes during the lifespan, increasing in childhood and decreasing in old age.
Unhealthy lifestyles impair immune functioning Insufficient vitamin A or E decrease production of
lymphocytes and antibodies Vitamin C in important in effectiveness of
phagocytes High fat and cholesterol intake impair immune
functioning Poor sleep impairs immune functioning
Diseases of the Immune System
Autoimmunity Disorders Immune response attacks its own
tissue Arthritis Rheumatic fever Multiple sclerosis AIDS
Stress and the Immune System
Stress appears to suppress the immune response.
Killer T-cells are lower during periods of high stress.
Adrenaline and cortisol that are released during stress appear to increase suppressor T-cells, decrease helper T-cells, and decrease functioning of phagocytes and lymphocytes.
Chemicals released by our nerves suppress immune functioning in nearby cells.
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