r neurons.
5. Neurons pass electrical signals
6. A synapses is the connection between the axon of one neurons (providing information) and a
dendrite of another neurons (receiving information)
7. Each dendrite receives input from hundred of other neurons through a specialized structure –
SPINES.
The Cerebrum
The Cerebrum is the largest and “newest” part of the human brain and
is made up of the cortex. Major regions of the cortext are responsible
for the processing of our sensations, how we receive the world. The
Frontal Lobe is implicated in motor control, complex thoughts,
associations, and social thinking. The Parietal Lobe is key for all our
perceptions. The Occipital Lobe processes all visual input, the
Temporal Lobe processes both auditory (hearing) and olfactory
(smell) input.
The Homunculus is the somatotopic organization of our brain. The size of each cortical area
need to process a sensation and the degree of skill are represented in proportion. Clearly, the
enormous dexterity of hour hands are occupying a vastly larger cortical area compared
to our legs.
The Limbic System
This system is composed of the Hypothalamus, Pituitary gland, the amygdala, and the hippocampus.
These structures are necessary for basic survival functions as well as emotions (fear) and account to as
some of the most primitive part of our brain. Notably, all sensory
information is processed at least partially in our limbic system.
Therefore, the notion of objectivity is compromised. Humans are
unable to receive sensory input or stimuli from the surrounding
world without instantaneously associating emotions.
The Hippocampus
This relative small structure of the limbic system is
absolutely vital for learning and memory in all mammals.
This brain regions has a highly complex innervation patters
and takes on the shape of a “sea horse”, i.e. hippocampus.
Learning and memory formation parallels the continuous
restructuring and adding or new connections involving
SPINES. Spine morphology is very dynamic in response to
stimuli whether those are beneficial or detrimental. Many
adverse stimuli (alcohol, additive drugs) including chronic
stress have devastating consequences for spine formation and
dynamics and reflect cognitive dysfunction or even failure.
[2] STRUCTURE OF HEART:
The heart is a hollow muscle that pumps approximately 4.7-5.7 litres of blood per minute throughout the blood vessels to various parts of the body by repeated, rhythmic contractions.
It is found in all animals with a circulatory system, which includes the vertebrates.The adjective cardiac means "related to the heart" and comes from the Greek ?a?d??, kardia, for "heart".
Cardiology is the medical speciality that deals with cardiac diseases and abnormalities.
The vertebrate heart is principally composed of cardiac muscle and connective tissue.
Cardiac muscle is an involuntary striated muscle tissue specific to the heart and is responsible for the ability of the heart to pump blood.The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during an average 66 year lifespan.
It weighs approximately 250 to 300 grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz) in males.
The adult human heart has a mass of between 250 and 350 grams and is about the size of a fist.[5] It is located anterior to the vertebral column and posterior to the sternum.[6]
It is enclosed in a double-walled sac called the pericardium. The pericardium's outer wall is called the parietal pericardium and the inner one the visceral pericardium. Between them there is some pericardial fluid which functions to permit the inner and outer walls to slide easily over one another with the heart movements. Outside the parietal pericardium is a fibrous layer called the fibrous pericardium which is attached to the mediastinal fascia.[7] This sac protects the heart, anchors it to the surrounding structures, but has no effect on ventricular hemodynamics in a healthy person.[8]
The outer wall of the human heart is composed of three layers; the outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium. The middle layer is called the myocardium and is composed of contractile cardiac muscle. The inner layer is called the endocardium and is in contact with the blood that the heart pumps.[9] Also, it merges with the inner lining (endothelium) of blood vessels and covers heart valves.[10]
The human heart has four chambers, two superior atria and two inferior ventricles. The atria are the receiving chambers and the ventricles are the discharging chambers. During each cardiac cycle, the atria contract first, forcing blood that has entered them into their respective ventricles, then the ventricles contract, forcing blood out of the heart. The pathway of the blood consists of a pulmonary circuit and a systemic circuit[11] which function simultaneously. Deoxygenated blood from the body flows via the venae cavae into the right atrium, which pumps it through the tricuspid valve into the right ventricle, whose subsequent contraction forces it out through the pulmonary valve into the pulmonary arteries leading to the lungs. Meanwhile, oxygenated blood returns from the lungs through the pulmonary veins into the left atrium, which pumps it through the mitral valve into the left ventricle, whose subsequent strong contraction forces it out through the aortic valve to the aorta leading to the systemic circulation.
[3]EXCRETORY SYSTEM
HUMAN EXCRETORY SYSTEM
Excretion: The process of ridding the body of waste in order to maintain homeostasis.
Structures involved in Excretion
• Skin Æ Sweat is removed by the skin as a waste product (trying to remove heat)
• Lungs Æ Removes waste gases such as CO2
• Liver Æ Removes Nitrogenous waste (Urea)
Function:
• The excretory works to maintain proper water balance in the body and to also remove
liquid waste (urine).
Parts of the Human Excretory System
A. Kidney
B. Ureters
C. Urinary Bladder
D. Urethra
A. KIDNEY
• The kidney is a lima bean shaped structure found on both sides of the spinal column in
the lower back.
• Function of Kidneys: Maintain water balance and rid the body of
nitrogenous wastes (Urine) created by the liver.
STRUCTURE OF THE KIDNEY
The kidney has three distinct regions:
1. Renal Cortex
2. Renal Medulla
3. Renal Pelvis
1. RENAL CORTEX
• The outer region of kidney.
• Function: Filter Blood
2. RENAL MEDULLA
• This is the middle region of the kidney. Made up of collecting ducts.
o Function: Collects filtrate( filtered materials from the blood) and
carries it to the renal pelvis.
3. RENAL PELVIS
• This is the inner section of the kidney. It is a cavity in the center of a kidney
connected to the ureters.
o Function: Filtrate (now called urine) drains from the pelvis into the
ureters for removal.
Biology 2201 Unit 3 – Dynamic Equilibrium
Notes Human Excretory System Page 2 of 5
B. URETERS
• Hollow tubes connecting the renal pelvis to the Urinary bladder.
o Function: Carry urine from the kidney to the urinary bladder.
C. URINARY BLADDER
• Hollow muscular pouch located in the pelvic area of a human.
o Function: Hold urine until it is released from the body. A typical bladder is
able to hold up to about 500 mL of urine.
D. URETHRA
• Hollow tube leading from the urinary bladder to the outside of the human body.
o Function: Carry urine from the bladder to the outside of the body.
[4] RESPIRATORY SYSTEM
Respiratory System
The Respiratory System is crucial to every human being. Without it, we would cease to live outside of the womb.
Let us begin by taking a look at the structure of the respiratory system and how vital it is to life.
During inhalation or exhalation air is pulled towards or away from the lungs, by several cavities, tubes, and openings.
The organs of the respiratory system make sure that oxygen enters our bodies and carbon dioxide leaves our bodies.
The respiratory tract is the path of air from the nose to the lungs. It is divided into two sections: Upper Respiratory Tract and the Lower Respiratory Tract.
Included in the upper respiratory tract are the Nostrils, Nasal Cavities, Pharynx, Epiglottis, and the Larynx.
The lower respiratory tract consists of the Trachea, Bronchi, Bronchioles, and the Lungs.
As air moves along the respiratory tract it is warmed, moistened and filtered.
[1].Ventilation
Ventilation is the exchange of air between the external environment and the alveoli. Air moves by bulk flow from an area of high pressure to low pressure
All pressures in the respiratory system are relative to atmospheric pressure (760mmHg at sea level). Air will move in or out of the lungs depending on the pressure in the alveoli
. The body changes the pressure in the alveoli by changing the volume of the lungs. As volume increases pressure decreases and as volume decreases pressure increases.
There are two phases of ventilation; inspiration and expiration. During each phase the body changes the lung dimensions to produce a flow of air either in or out of the lungs.
[2]Inspirition
Inspiration
Inspiration is initiated by contraction of the diaphragm and in some cases the intercostals muscles when they receive nervous impulses. During normal quiet breathing, the phrenic nerves stimulate the diaphragm to contract and move downward into the abdomen. This downward movement of the diaphragm enlarges the thorax. When necessary, the intercostal muscles also increase the thorax by contacting and drawing the ribs upward and outward.
As the diaphragm contracts inferiorly and thoracic muscles pull the chest wall outwardly, the volume of the thoracic cavity increases.
The lungs are held to the thoracic wall by negative pressure in the pleural cavity, a very thin space filled with a few milliliters of lubricating pleural fluid.
The negative pressure in the pleural cavity is enough to hold the lungs open in spite of the inherent elasticity of the tissue.
Hence, as the thoracic cavity increases in volume the lungs are pulled from all sides to expand, causing a drop in the pressure (a partial vacuum)
within the lung itself (but note that this negative pressure is still not as great as the negative pressure within the pleural cavity
--otherwise the lungs would pull away from the chest wall).
Assuming the airway is open, air from the external environment then follows its pressure gradient down and expands the alveoli of the lungs, where gas exchange with the blood takes
place.
As long as pressure within the alveoli is lower than atmospheric pressure air will continue to move inwardly, but as soon as the pressure is stabilized air movement stops.
[3]Expiration
During quiet breathing, expiration is normally a passive process and does not require muscles to work (rather it is the result of the muscles relaxing).
When the lungs are stretched and expanded, stretch receptors within the alveoli send inhibitory nerve impulses to the medulla oblongata,
causing it to stop sending signals to the rib cage and diaphragm to contract.
The muscles of respiration and the lungs themselves are elastic, so when the diaphragm and intercostal muscles relax there is an elastic recoil,
which creates a positive pressure (pressure in the lungs becomes greater than atmospheric pressure), and air moves out of the lungs by flowing down its pressure gradient.
Although the respiratory system is primarily under involuntary control, and regulated by the medulla oblongata, we have some voluntary control over it also.
This is due to the higher brain function of the cerebral cortex.
[5] DIGESTIVE SYSTEM
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance.
Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.
When food enters the mouth, digestion of the food starts by the action of mastication, a form of mechanical digestion, and the wetting contact of saliva.
Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food.
After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus.
It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion.
Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach,
providing a slimy layer that acts as a shield against the damaging effects of the chemicals.
At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall.
This allows the mass of food to further mix with the digestive enzymes. After some time (typically 1-2 hours in humans), the resulting thick liquid is called chyme.
When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine,
in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine.
Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic about 5.6 ~ 6.9. Some vitamins,
such as biotin and vitamin K (K2MK7) produced by bacteria in the colon are also absorbed into the blood in the colon.
Waste material is eliminated from the rectum during defecation.
5. Neurons pass electrical signals
6. A synapses is the connection between the axon of one neurons (providing information) and a
dendrite of another neurons (receiving information)
7. Each dendrite receives input from hundred of other neurons through a specialized structure –
SPINES.
The Cerebrum
The Cerebrum is the largest and “newest” part of the human brain and
is made up of the cortex. Major regions of the cortext are responsible
for the processing of our sensations, how we receive the world. The
Frontal Lobe is implicated in motor control, complex thoughts,
associations, and social thinking. The Parietal Lobe is key for all our
perceptions. The Occipital Lobe processes all visual input, the
Temporal Lobe processes both auditory (hearing) and olfactory
(smell) input.
The Homunculus is the somatotopic organization of our brain. The size of each cortical area
need to process a sensation and the degree of skill are represented in proportion. Clearly, the
enormous dexterity of hour hands are occupying a vastly larger cortical area compared
to our legs.
The Limbic System
This system is composed of the Hypothalamus, Pituitary gland, the amygdala, and the hippocampus.
These structures are necessary for basic survival functions as well as emotions (fear) and account to as
some of the most primitive part of our brain. Notably, all sensory
information is processed at least partially in our limbic system.
Therefore, the notion of objectivity is compromised. Humans are
unable to receive sensory input or stimuli from the surrounding
world without instantaneously associating emotions.
The Hippocampus
This relative small structure of the limbic system is
absolutely vital for learning and memory in all mammals.
This brain regions has a highly complex innervation patters
and takes on the shape of a “sea horse”, i.e. hippocampus.
Learning and memory formation parallels the continuous
restructuring and adding or new connections involving
SPINES. Spine morphology is very dynamic in response to
stimuli whether those are beneficial or detrimental. Many
adverse stimuli (alcohol, additive drugs) including chronic
stress have devastating consequences for spine formation and
dynamics and reflect cognitive dysfunction or even failure.
[2] STRUCTURE OF HEART:
The heart is a hollow muscle that pumps approximately 4.7-5.7 litres of blood per minute throughout the blood vessels to various parts of the body by repeated, rhythmic contractions.
It is found in all animals with a circulatory system, which includes the vertebrates.The adjective cardiac means "related to the heart" and comes from the Greek ?a?d??, kardia, for "heart".
Cardiology is the medical speciality that deals with cardiac diseases and abnormalities.
The vertebrate heart is principally composed of cardiac muscle and connective tissue.
Cardiac muscle is an involuntary striated muscle tissue specific to the heart and is responsible for the ability of the heart to pump blood.The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during an average 66 year lifespan.
It weighs approximately 250 to 300 grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz) in males.
The adult human heart has a mass of between 250 and 350 grams and is about the size of a fist.[5] It is located anterior to the vertebral column and posterior to the sternum.[6]
It is enclosed in a double-walled sac called the pericardium. The pericardium's outer wall is called the parietal pericardium and the inner one the visceral pericardium. Between them there is some pericardial fluid which functions to permit the inner and outer walls to slide easily over one another with the heart movements. Outside the parietal pericardium is a fibrous layer called the fibrous pericardium which is attached to the mediastinal fascia.[7] This sac protects the heart, anchors it to the surrounding structures, but has no effect on ventricular hemodynamics in a healthy person.[8]
The outer wall of the human heart is composed of three layers; the outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium. The middle layer is called the myocardium and is composed of contractile cardiac muscle. The inner layer is called the endocardium and is in contact with the blood that the heart pumps.[9] Also, it merges with the inner lining (endothelium) of blood vessels and covers heart valves.[10]
The human heart has four chambers, two superior atria and two inferior ventricles. The atria are the receiving chambers and the ventricles are the discharging chambers. During each cardiac cycle, the atria contract first, forcing blood that has entered them into their respective ventricles, then the ventricles contract, forcing blood out of the heart. The pathway of the blood consists of a pulmonary circuit and a systemic circuit[11] which function simultaneously. Deoxygenated blood from the body flows via the venae cavae into the right atrium, which pumps it through the tricuspid valve into the right ventricle, whose subsequent contraction forces it out through the pulmonary valve into the pulmonary arteries leading to the lungs. Meanwhile, oxygenated blood returns from the lungs through the pulmonary veins into the left atrium, which pumps it through the mitral valve into the left ventricle, whose subsequent strong contraction forces it out through the aortic valve to the aorta leading to the systemic circulation.
[3]EXCRETORY SYSTEM
HUMAN EXCRETORY SYSTEM
Excretion: The process of ridding the body of waste in order to maintain homeostasis.
Structures involved in Excretion
• Skin Æ Sweat is removed by the skin as a waste product (trying to remove heat)
• Lungs Æ Removes waste gases such as CO2
• Liver Æ Removes Nitrogenous waste (Urea)
Function:
• The excretory works to maintain proper water balance in the body and to also remove
liquid waste (urine).
Parts of the Human Excretory System
A. Kidney
B. Ureters
C. Urinary Bladder
D. Urethra
A. KIDNEY
• The kidney is a lima bean shaped structure found on both sides of the spinal column in
the lower back.
• Function of Kidneys: Maintain water balance and rid the body of
nitrogenous wastes (Urine) created by the liver.
STRUCTURE OF THE KIDNEY
The kidney has three distinct regions:
1. Renal Cortex
2. Renal Medulla
3. Renal Pelvis
1. RENAL CORTEX
• The outer region of kidney.
• Function: Filter Blood
2. RENAL MEDULLA
• This is the middle region of the kidney. Made up of collecting ducts.
o Function: Collects filtrate( filtered materials from the blood) and
carries it to the renal pelvis.
3. RENAL PELVIS
• This is the inner section of the kidney. It is a cavity in the center of a kidney
connected to the ureters.
o Function: Filtrate (now called urine) drains from the pelvis into the
ureters for removal.
Biology 2201 Unit 3 – Dynamic Equilibrium
Notes Human Excretory System Page 2 of 5
B. URETERS
• Hollow tubes connecting the renal pelvis to the Urinary bladder.
o Function: Carry urine from the kidney to the urinary bladder.
C. URINARY BLADDER
• Hollow muscular pouch located in the pelvic area of a human.
o Function: Hold urine until it is released from the body. A typical bladder is
able to hold up to about 500 mL of urine.
D. URETHRA
• Hollow tube leading from the urinary bladder to the outside of the human body.
o Function: Carry urine from the bladder to the outside of the body.
[4] RESPIRATORY SYSTEM
Respiratory System
The Respiratory System is crucial to every human being. Without it, we would cease to live outside of the womb.
Let us begin by taking a look at the structure of the respiratory system and how vital it is to life.
During inhalation or exhalation air is pulled towards or away from the lungs, by several cavities, tubes, and openings.
The organs of the respiratory system make sure that oxygen enters our bodies and carbon dioxide leaves our bodies.
The respiratory tract is the path of air from the nose to the lungs. It is divided into two sections: Upper Respiratory Tract and the Lower Respiratory Tract.
Included in the upper respiratory tract are the Nostrils, Nasal Cavities, Pharynx, Epiglottis, and the Larynx.
The lower respiratory tract consists of the Trachea, Bronchi, Bronchioles, and the Lungs.
As air moves along the respiratory tract it is warmed, moistened and filtered.
[1].Ventilation
Ventilation is the exchange of air between the external environment and the alveoli. Air moves by bulk flow from an area of high pressure to low pressure
All pressures in the respiratory system are relative to atmospheric pressure (760mmHg at sea level). Air will move in or out of the lungs depending on the pressure in the alveoli
. The body changes the pressure in the alveoli by changing the volume of the lungs. As volume increases pressure decreases and as volume decreases pressure increases.
There are two phases of ventilation; inspiration and expiration. During each phase the body changes the lung dimensions to produce a flow of air either in or out of the lungs.
[2]Inspirition
Inspiration
Inspiration is initiated by contraction of the diaphragm and in some cases the intercostals muscles when they receive nervous impulses. During normal quiet breathing, the phrenic nerves stimulate the diaphragm to contract and move downward into the abdomen. This downward movement of the diaphragm enlarges the thorax. When necessary, the intercostal muscles also increase the thorax by contacting and drawing the ribs upward and outward.
As the diaphragm contracts inferiorly and thoracic muscles pull the chest wall outwardly, the volume of the thoracic cavity increases.
The lungs are held to the thoracic wall by negative pressure in the pleural cavity, a very thin space filled with a few milliliters of lubricating pleural fluid.
The negative pressure in the pleural cavity is enough to hold the lungs open in spite of the inherent elasticity of the tissue.
Hence, as the thoracic cavity increases in volume the lungs are pulled from all sides to expand, causing a drop in the pressure (a partial vacuum)
within the lung itself (but note that this negative pressure is still not as great as the negative pressure within the pleural cavity
--otherwise the lungs would pull away from the chest wall).
Assuming the airway is open, air from the external environment then follows its pressure gradient down and expands the alveoli of the lungs, where gas exchange with the blood takes
place.
As long as pressure within the alveoli is lower than atmospheric pressure air will continue to move inwardly, but as soon as the pressure is stabilized air movement stops.
[3]Expiration
During quiet breathing, expiration is normally a passive process and does not require muscles to work (rather it is the result of the muscles relaxing).
When the lungs are stretched and expanded, stretch receptors within the alveoli send inhibitory nerve impulses to the medulla oblongata,
causing it to stop sending signals to the rib cage and diaphragm to contract.
The muscles of respiration and the lungs themselves are elastic, so when the diaphragm and intercostal muscles relax there is an elastic recoil,
which creates a positive pressure (pressure in the lungs becomes greater than atmospheric pressure), and air moves out of the lungs by flowing down its pressure gradient.
Although the respiratory system is primarily under involuntary control, and regulated by the medulla oblongata, we have some voluntary control over it also.
This is due to the higher brain function of the cerebral cortex.
[5] DIGESTIVE SYSTEM
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance.
Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.
When food enters the mouth, digestion of the food starts by the action of mastication, a form of mechanical digestion, and the wetting contact of saliva.
Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food.
After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus.
It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion.
Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach,
providing a slimy layer that acts as a shield against the damaging effects of the chemicals.
At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall.
This allows the mass of food to further mix with the digestive enzymes. After some time (typically 1-2 hours in humans), the resulting thick liquid is called chyme.
When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine,
in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine.
Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic about 5.6 ~ 6.9. Some vitamins,
such as biotin and vitamin K (K2MK7) produced by bacteria in the colon are also absorbed into the blood in the colon.
Waste material is eliminated from the rectum during defecation.
