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 Nrv u e os Ss m y te Cn l n rv u s s m e tra e o s y te (c rrie v lu ta n rv imu e to a s o n ry e e p ls s ms le a ds in c rrie in o n ry u c s n k ; a s v lu ta imu e toms le a dg n s p ls s u c s n la d ) Prip e l n rv u s s m e h ra e o s y te B in ra S in l c rd pa o S mticn rv u s s m o a e o s y te (c n lsv lu ta o tro o n ry mv mn oe e t) A to o icn rv u s s m u n m e o s y te (c n lso a sth t o tro rg n a o e tein o n rily p ra v lu ta ) Sma e n rv u s s m Pra y p th ticn rv u y p th tic e o s y te a s ma e e o s (mb e th b d o iliz s e o y fo a tio ) rcn ss m y te (min in a d a ta s n re to se u riu ) s re q ilib m Three sections of the brain Hindbrain •Medulla •Pons •cerebellum Midbrain •Pathway connecting hindbrain and Forebrain. Forebrain •Diencephalon •Telecephalon Diencephalon Telecephalon •Thalamus •Cerebrum •Hypothalamus •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 It has three sub-circuits Limbic system controls emotion 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 Hypothalamus Thalamus •Command for the •Chief relay centre for control of autonomic directing sensory messages functions such as heart Helps regulate awareness rate, blood pressure, •Relays commands going hunger, thirst. to the skeletal muscles •Role in emotions and from the motor cortex. motivation (e.g., thoughts about fear get translated into arousal through hypothalamus.) Three sections of the brain Hindbrain •Medulla •Pons •cerebellum Midbrain •Pathway connecting hindbrain and Forebrain. Forebrain •Diencephalon •Telecephalon Diencephalon Telecephalon •Thalamus •Cerebrum •Hypothalamus •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 Relays information from the sensory organs Afferent – from the periphery to the brain 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 Response Increase 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 Systems Diabetes 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 Atherosclerosis Coronary Artery Plaque in Monkeys 0 .8 0 .7 Plaque Area (mm2) 0 .6 0 .5 0 .4 0 .3 0 .2 0 .1 0 S ta b le U n sta b le D o m in a n t S u b o rd in a te Stress and Atherosclerosis Coronary Artery Plaque in Monkeys 0 .8 0 .7 Plaque Area (mm2) 0 .6 0 .5 0 .4 0 .3 0 .2 0 .1 0 T re a te d U n tre a te d D o m in a n t S u b o rd in a te 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 White blood cell that provides main defense against foreign material Produced by bone marrow Lymphocytes 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 Macrophages – attach to tissue and stay there Monocytes – circulate in the blood Two types: 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 Foreign material Cough Sneeze Phagocytes engulf it Th cells Interlukin-1 Gammainterferon B cells Killer Tc cells 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. Please answer anonymously these questions What is the main thing you learned from this lecture? What is the main question you have that wasn’t answered? The things the instructor did best …OR the best things about the lecture that were? The things the instructor did worst …OR the worst things about the lecture that were?
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