The Systems of the Body

1. The Systems of the Body

2. 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.

3. The Nervous System

4. Diencephalon • Thalamus • Hypothalamus • Telecephalon • Cerebrum • Limbic system Three sections of the brain • Forebrain • Diencephalon • Telecephalon • Hindbrain • Medulla • Pons • cerebellum • Midbrain • Pathway connecting • hindbrain and • Forebrain.

5. Four lobes of the cerebral cortex • Temporal • Hearing • Vision • Smell • Memory • Frontal • Motor activity • Higher level • intelligence • Planning • Problem solving • Emotions • Self-awareness • Parietal • Bodily sensations, • e.g., pain, heat • Body movement • Occipital • Primary visual • area of the brain

6. Diencephalon • 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.) • Thalamus • Chief relay centre for • directing sensory messages • Helps regulate awareness • Relays commands going • to the skeletal muscles • from the motor cortex.

7. Diencephalon • Thalamus • Hypothalamus • Telecephalon • Cerebrum • Limbic system Three sections of the brain • Forebrain • Diencephalon • Telecephalon • Hindbrain • Medulla • Pons • cerebellum • Midbrain • Pathway connecting • hindbrain and • Forebrain.

8. 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.

9. Hindbrain continued • Consists of: • Pons – involved in eye movement, facial expressions and eye movement • Medulla – controls breathing, heart rate, blood pressure

10. 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.

11. 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

12. Peripheral Nervous System • Autonomic nervous system • Somatic nervous system

13. 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

14. Autonomic nervous system • Controls what is generally involuntary, automatic activity • Consists of the sympathetic and parasympathetic nervous systems.

15. 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

16. 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

17. Parasympathetic nervous system • Restores equilibrium in the body • Decreases arousal, slows breathing and heart rate, lowers heart rate and blood pressure, etc.

18. Neurotransmitters • Electrochemical messengers: • Catecholamines, consisting of epinephrine and norepinephrine • Dopamine • Acetycholine • Serotonin

19. 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.

20. 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

21. 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)

22. 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.)

23. Pancreas • Located below the stomach • Regulates level of blood sugar by producing insulin which absorbs blood sugar. • Important gland in diabetes mellitus

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.

31. 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)

32. 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

33. 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.

34. 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.

35. 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)

36. 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.

37. 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.

38. 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.

39. Risk Factors for Essential Hypertension • Lack of exercise • Body weight • Salt consumption • Stress • Age • Gender • Ethnicity (blacks at higher risk) • Genetics

40. Blood • Two components • Formed elements • Plasma • Formed elements consist of three elements: • Red blood cells • Leukocytes (white blood cells) • Platelets

41. 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

42. 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.

43. 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.

44. 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.

45. 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.

46. 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.

47. Risk Factors for Atherosclerosis • Hypertension • High fat intake leading to hyperlipidemia • Smoking • Stress • Diabetes, • Lack of exercise • Genetics • Gender

48. 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

49. Immune System

50. 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.