Human and Animal Physiology Flashcards
State the definition of nutrition
Nutrition is the process by which an organism acquires the matter and energy it requires from the environment.
List the types of nutrition
- Heterotrophic nutrition - animals obtain matter and energy from other organisms.
- saprotrophic nutrition - feeding on the
dead matter
- parasitic nutrition - feeding on the host’s
tissues.
- holozoic nutrition- the ingestion of liquid
and solid material from the bodies of other
organisms. - Autotrophic nutrition- the green plants synthesize their organic molecules from the inorganic substances through photosynthesis.
State the five steps of nutrition
- Ingestion- food is taken into the mouth for processing in the gut.
- Digestion - we include mechanical digestion (action of teeth and muscular walls of the gut) and chemical digestion (by the enzymes).
- Absorption - the process of the digested products being absorbed into the bloodstream.
- Assimilation - products of digestion absorbed in the blood stream are then transported to body tissues.
- Egestion - removal of the undigested food, bacteria as the feces from the body.
What is the role of digestion in the nutrition?
Digestion helps in the processing and breaking down the large molecules into smaller ones that can’t enter the blood system.
What is the mechanical digestion?
Mechanical digestion includes the action of chewing food by teeth, to break the ingested food into smaller pieces that are more readily digested by the chemical digestion.
Explain the peristalsis movement
Peristalsis can be defined as the involuntary muscle movement of food through the gastrointestinal tract. Therefore, it helps to move the food to the stomach where it can go through chemical digestion.
Chemical digestion
Chemical digestion is the breakdown of the large molecules into small molecules through the enzyme activity and hydrolysis. It breaks down complex molecules such as fats, proteins, and carbohydrates.
State the human digestive enzymes
- Amylase - it is the carbohydrate macromolecule. Example: salivary amylase (mouth).
- Protease - protein macromolecule. Example trypsin (duodenum).
- Lipase - lipid macromolecule. Example: Pancreatic lipase (pancreas).
How the digestion looks like in the carbohydrates?
Food reaches the mouth and salivary amylase breaks down the disaccharides and starch. Then it is broken down in the pancreas by the pancreatic amylase. In small intestine the disaccharides are broken down into lactose, maltose, and sucrose.
Explain the digestion of lipids
They are ingested as large masses and digested within the duodenum by the pancreatic lipase. This enzyme breaks down the large molecules into smaller droplets. It increases the surface area of fat which increases the rate of lipid digestion.
How the digestion of proteins looks like?
Digestion in proteins occurs as the endopeptidases break down the peptide bonds of the proteins (large proteins - small proteins). Exopeptidases remove the amino acids that will be needed for absorption.
What are the structures specialized for the digestion and absorption of food (10)?
- Mouth
- Trachea
- Oesophagus
- Liver
- Gall bladder and bile duct
- Stomach
- Pancreas
- Small intestine (duodenum, jejunum, ileum)
- Large intestine (colon, rectum)
- Anus
What happens in the mouth?
- chewing (mechanical digestion)
- salivary amylase begins the chemical
digestion of starch
What happens in the oesophagus?
- peristalsis pushes the food into the
stomach
What happens in the stomach?
- gastric pits release the gastric acid and
enzymes - the hydrochloric acid lowers the pH and
kills the bacteria - pepsin enzyme starts protein digestion
and stretches receptors in the muscular
wall to trigger the release of enzymes
Digestion in the small intestine
Duodenum: chyme enters the duodenum and the liver is emptied into it. Bile from the liver and gall bladder neutralizes the acid. Pancreatic amylase and lipase digest carbohydrates and fats. Trypsin digests polypeptides to amino acids.
Ileum: lower half of the small intestine absorbs nutrients into the blood via the villi.
Digestion in the large intestine
Water and mineral salts are reclaimed and returned to the blood. It leaves the feces which is stored in the rectum.
What happens in the anus?
The undigested food, dead cells, and other water is forced out of the anus and released out of the human body.
Define the function of lumen
It stores the food when it reaches the stomach space.
What are the components of the gastric juice?
- hydrochloric acid
- protease enzymes - break down the proteins into short chains of amino acids
- goblet cells - secrete mucus
- Mucus - prevents the destruction of stomach wall (autolysis)
The function of villi
It increases the surface area for absorption and have a rich blood supply.
How absorption works in the small intestine?
It is the uptake into the body of the useful products of digestion. It is efficient because intestine has a huge surface area, due to large number of villi.
What is the structure of the ileum?
- Villi - contains epithelial cells joined with tight junctions and microvilli which increase the surface area.
- Mucosa - secretes mucus
- Submucosa - contains secretory cells
- Muscles - generate peristalsis
How the absorption of the glucose works?
Absorption through the epithelium and this transport is called a sodium-glucose symporter. The protein binds to glucose and Na+. This mechanism is optimizing the glucose absorption. Coupling with the NA+ permits getting glucose out of the lumen. Then glucose is absorbed to the bloodstream by facilitated diffusion.
Explain assimilation
Uptake of nutrients into cells and tissues from the bloodstream (after absorption). Absorbed nutrients are transported from intestine and then they are moved to the liver. The enzymes also pass into the capillary network and then to the liver. New proteins in the liver are made.
Function of the liver
It secretes biles and helps in maintaining homeostasis by removing or adding nutrients to the blood. Regulates the quantity of nutrients circulating in the blood. It also converts excess glucose to glycogen and then stores it.
What are the exocrine glands?
They release their sections into ducts. We include the:
- goblet cells in the small intestine
- pyloric glands in the stomach
- salivary glands in the mouth
What are some of the contents of saliva (4)?
- amylase for starch digestion
- lipase for digestion of fats
- water for moistening
- antibacterial compounds
Where is the gastric juice produced and what it contains?
In parietal cells in the stomach wall. It contains the HCL, mucus and enzymes such as pepsin.
What pancreatic juice contains?
- pancreatic lipase
- pancreatic amylase
- trypsin
What are inactive precursors?
If pepsin and trypsin were secreted as active enzymes they would cause damage to exocrine glands (autodigestion). They are instead secreted as inactive precursors, that become activated under the right conditions so they do not cause any damage.
Explain the enterokinase
Enzyme produced by cells of the duodenum. It helps the food from the stomach to enter the intestine.
How the proton pump inhibitors work?
- drugs that irreversibly bind to the proton pumps and prevent the H+ secretion
- they raise the pH in the stomach to prevent the discomfort caused by gastric juice.
Normal proton pumps
- secrete H+ ions which combine with Cl- ions to form hydrochloric acid
- lower the pH in the stomach (kills the bacteria)
How the gastric juice secretion is controlled (exam question)?
- Reflex response to visual and smell stimulus leads to release of the gastric juice.
- As the food arrives in the stomach, it triggers the release of gastrin in the stomach walls. This hormone stimulates the production of gastric juices.
- Chyme passes from the stomach to the duodenum. Duodenum releases the CCK and secretin hormones. CCK stimulates the release of digestive enzymes from the pancreases and of the bile from gallbladder. Secretin stimulates the pancreas to neutralize the chyme.
- However, if the chyme is rich in fats, the high levels of secretin and CCK act on stomach to inhibit peristalsis and secretion of gastric juices, which slows down the digestion process.
State the definition of chyme
An acidic mixture of partially digested food
Pre-ingestion meaning
The sight and smell of food triggers an immediate response by which gastric juice is secreted by the stomach.
How the pre-ingestion works and how it leads to digestion?
Smell and sight receptors send signals to brain, which triggers the secretion of gastric juice. Stomach releases gastrin, which promotes the production of the stomach acids. Whereas, the pancreas releases secretin and CCK. It stimulates the secretion of the pancreatic juice and bile.
What is the cholera toxin?
Cholera is the infection that increases the adenylate cyclase activity which increases the cAMP action. It leads to release of excess concentrations of water and therefore that causes the diarrhea.
What are the epithelial cells?
They are adapted to maximize absorption of digested food molecules in the ileum.
Function of microvilli
Maximize the surface area for absorption
Function of tight junction
Prevent the movement of molecules between the neighboring cells.
Function of mitochondria in digestion
Provides the ATP for the active transport of digested food molecules.
How the processing of food works in the large intestine?
The colon reabsorbs water. The undigested material contains the fiber called the cellulose fiber. This fiber helps to move food along the alimentary canal. Then the undigested food is released from the anus.
How blood vessels carry the blood?
The blood is carried through the body via the blood vessels. The artery carries blood away from the heart, where it branches into arterioles which branch into capillaries. Capillaries combine with other vessels to form venules. They carry blood into the vein, which returns the blood to the heart.
Pulmonary circuit
In this circuit arteries carry blood low in the oxygen to the lungs for gas exchange. Pulmonary veins return freshly oxygenated blood from the lungs to the heart, which is pumped into the systematic circulation.
Systemic circuit
Organs are supplied with blood by the artery branching from the main aorta. The artery branches into arterioles and the smallest arterioles supply the capillary network. Capillaries drain to venules and venules join to form veins. The veins join the vena cava carrying blood back to the right side of the heart.
Explain the blood supply in the liver
The liver has the double supply of the blood. It receives the oxygenated blood via the hepatic artery, which sustains the liver cells. It also receives the nutrient-rich blood from the gut via the portal vein. Oxygenated blood is transported from the liver via the hepatic vein which is transported to the lungs.
Liver structure
- vena cava
- right lobe of the liver
- right hepatic duct
- bile duct
- gallbladder
- hepatic portal vein
What is the portal triad in the liver?
The structure that contains bile duct, hepatic artery and hepatic vein.
- hepatic artery - oxygen blood
- hepatic portal vein - nutrient rich blood
Explain the sinusoids
Small, wide blood vessels found in the liver. They have the surrounding basement membrane which is incomplete and endothelial layer that contains large gaps.
Function of Kupffer cells
Break down erythrocytes
Role of the liver in the regulation of nutrient levels in the blood
- the liver stabilizes blood glucose levels
- if they drop, the hepatocytes break down the glycogen and release glucose into the bloodstream
- they also synthesize glucose from other compounds -> glucogenesis
- if the blood climb - hepatocytes remove glucose from the bloodstream
- then liver stores it and synthesizes lipids
Explain the concept of the bile
Bile is the structure that is produced by hepatocytes. It is carried in the large ducts to the gallbladder, where it is stored.
Explain the function of the bile
- Its acids break down fat globules and those fats are emulsified into small droplets.
- It is important for the transport and absorption of fat-soluble vitamins.
Explain how the red blood cells are broken down
Red blood cells are destroyed by Kupffer cells through the process called phagocytosis. Hemoglobin is converted into a yellow pigment called bilirubin. The protein is broken down to amino acids. Bilirubin is transported to bile and the released in the intestine. It is converted by a bacteria to a yellow pigment. This pigment is normal to feces.
State the definition of jaundice
Jaundice is the yellowish pigment that appears on the skin, which is caused by hyperbilirubinemia. It is the excess of the bilirubin in the blood and therefore body fluids are also yellow.
What are the major causes of jaundice?
- heavy drinking
- infections
- some medicines
What are the advantages of blood circulation?
- oxygenated blood reaches the body tissues
- high-pressure delivery of oxygenated blood to all regions
What is the branching sequence in the double circulation ?
aorta - artery - arterioles - capillaries - venules - veins - vena cava
What are the components of the blood and its functions ?
- water - solvent
- ions (sodium, chloride, potassium) - osmotic balance and membrane permeability.
- plasma proteins - clotting, defense
- substances transported by blood (nutrients, waste products)
- white blood cells (monocytes, neutrophils, lymphocytes) - defense, immunity
- platelets - blood clotting process
- red blood cells - transport of carbon dioxide and oxygen.
- phagocytes - ingesting bacteria
Define hemoglobin
It is the protein in red blood cells that consists of the globin and four heme groups.
Types of the vessels in the circulation system
- Arteries - carry blood away from the heart
- Veins- carry blood to the heart
- Capillaries - networks that link arteries and veins.
What are arteries?
The structures that convey blood at high pressure from the heart to the tissues of the body and lungs. It consists of the:
- narrow lumen - maintains high pressure
- thick wall - contains collagen
- arterial wall - contains muscles
Define capillaries
they exchange the materials between the cells in the tissues and blood travelling at low pressure.
What are 3 types of capillaries?
- continuous - they contain endothelial cells joined together by tight junctions to limit the permability of large molecules.
- fenestrated - they contain pores
- sinusoidal - they have open spaces and are permeable to large molecules
Define valves
Those are structures that are in veins and they ensure that blood flows in one direction, towards the heart.
Define heart
Muscular organ that has four chambers. Two upper chambers are called atria and they move the blood into the heart. Whereas, the two lower chambers are ventricles that pump blood out of the heart.
The heart consists of…
- Vena cava
- Right pulmonary artery
- Right atrium
- Tricuspid valve
- Right ventricle
- Left ventricle
- Bicuspid valve
- Semilunar valves
- Left atrium
- Left pulmonary artery
- Aorta
Explain the coronary circulation
Coronary arteries deliver oxygenated blood to the heart muscles. Cardiac veins remove the deoxygenated blood from the heart.
Myocardium
Circulation of the blood vessels of the heart muscle
Distinguish the cardiac cycle
When the heart contracts the blood is pumped out of the heart - systole. However, when the heart relaxes, the heart is filled with blood - diastole.
What is the difference between the AV valves and semilunar valves?
AV valves open when the blood enters the heart and then the pressure increases. Semilunar valves open when the blood leaves the heart so the pressure decreases.
Sympathetic nerve
It releases the adrenaline that increases the heart rate. This increases the blood pressure, metabolic activity, and breathing rate.
Parasympathetic nerve
It releases the acetylcholine which decreases the heart rate.
Define atherosclerosis
Sickness that damages the artery wall and the cholesterol builds up there. The wall loses its elasticity and leads to the blood clotting that blocks the artery. Therefore the coronary muscle dies as there is a lack of blood and oxygen incoming.
State the definition of the gaseous exchange
It is the process that takes place by diffusion and the molecules move along the concentration gradient.
Define diffusion
Passive movement of the molecules from the region of high concentration gradient a a region of low concentration gradient.
Factors affecting diffusion
- size of surface area
- concentration gradient
- length of the diffusion path
Explain the ventilation system
The pumping mechanism that moves the air into and out of the lungs, maintaining the concentration gradient for diffusion. Breathing increases the concentration gradient of oxygen between the alveoli in the lungs and blood.
What is thorax?
Area where lungs are located. The surfaces there are lined up by the plural membrane which secretes pleural fluid.
Function of pleural fluid
It protects the lungs from the friction during breathing movements.
The movement of air in the body
Air reaches the trachea and then passes through oesophagus. Then trachea divides into bronchi that divide into bronchioli and the air ends up in the air sacs (alveoli).
What happens with O2 and CO2 in the lungs cycle?
- o2 levels stay high in the lungs and diffuse into blood
- co2 levels stay low in the lungs and diffuse out of the blood
The lungs consist of…
- trachea
- superior right lobe
- middle lobe
- inferior right lobe
- bronchi
- lobar bronchus
- segmental bronchus
- superior left lobe
- middle left lobe
- inferior left lobe
What is the alveolar structure?
bronchiole, alveolar duct, alveoli, alveolar sac
What system wraps up around the alveoli clusters?
capillary system
State the function of pneumocytes
They carry the gas exchange
State the function of pneumocytes type II
Prevent the water from causing the sides of alveoli to adhere when air is exhaled from lungs. Also it provides the area from which CO2 can evaporate into air.
How alveoli minimize the diffusion distances
They have thin layers
What is the function of capillary networks in the alveoli?
They increase the capacity for gas exchange and contain fluids that help gases to be better diffused into the bloodstream.
Inspiration
When the pressure in the chest is less than atmospheric pressure, air will move into the lungs.
Expiration
When the pressure in the chest is higher than atmospheric pressure, air will move out of the lungs.
Emphysema
Lung condition where walls of alveoli lose their elasticity due to low surface area for the gas exchange. Cause: smoking.
How can gas exchange be efficient?
- High concentration gradients must be maintained in the alveoli
- Breathing increases the concentration of oxygen between the alveoli and the blood so it diffuses into blood
- Breathing out removes the CO2 and the concentration increases between the blood and alveoli.
What is the function of hemoglobin in the lungs?
hemoglobin binds to O2 in the lungs and unloads it somewhere else in the body.
What happens during asthma attack?
During astma attack the smooth muscle walls of the bronchi contract, blocking air flow into the lungs.
Why plasma proteins are pH buffers?
the pH of blood is required to stay within a very narrow tolerance range. Its range is maintained by plasma proteins. They contribute to increase in alkalinity.
What is the myoglobin?
It is used to store oxygen in the muscle tissues. it increases the efficiency of the respiration in the muscle tissues.
Why fetal hemoglobin is important?
It helps to take up oxygen at lower pressures.
State the definition of hormones
Chemical substances that are secreted from the cells of the endocrine glands. They circulate in the bloodstream (briefly).
Where hormones are broken down?
in the liver and the breakdown products are excreted in the kidneys.
Define endocrine system
Control system of ductless glands that secrete hormones.
Explain two types of hormone secretion
- Regulatory secretion - hormones are secreted in the secretory granules and released into bursts. It helps to secrete large amount of hormones over short period of time.
- Constitutive secretion - the cell does not secrete hormones, but secretes them from secretory vehicles.
Peptide hormones
short polypeptide chains that are hydrophilic and go through the regulatory secretion. we include the insulin and ADH.
Steroid hormones
lipids derived from cholesterol. they are lipophilic and go through the constitutive secretion. examples include oestrogens, testosterone
Amine hormones
they are derived from amino acids and they are hydrophilic. they undergo the regulatory secretion. examples include epinephrine
hydrophilic
cannot cross the membrane
lipophilic
can cross the membrane
How do steroid hormones activate the genes?
- They enter the target cells though the plasma membrane because they are lipophilic.
- The hormone-receptor complex is being created and it enters the nucleus.
- This complex binds to a specific DNA region.
- Steroid affects the gene expression Those hormones act as the transcriptional regulators.
How do polypeptide/amine hormones activate enzymes?
- Those hormones bind to the plasma membrane
- It activates the second messenger within the cell
- They act indirectly to change the cellular activity
Remember: the cannot enter the target cells!
Function of the amine hormones
- activation of enzymes
- secretion of specific molecules
- altering transcription
what are the main endocrine glands in the human body?
- hypothalamus (posterior pituitary gland and anterior pituitary gland)
- pineal gland
- thyroid glands
- parathyroid glands
- adrenal glands (adrenal cortex and adrenal medulla)
- islets of langerhans
- ovaries (female)
- testes (male)
Hormones produced by hypothalamus
Produces and secretes releasing hormones. It produces hormones such as ADH and oxytocin which are stored and released by the posterior pituitary gland.
What hormones posterior pituitary gland releases?
- oxytocin - uterine contractions and milk ejection
- ADH - released when we are dehydrated (stops peeing)
What hormones are released by the anterior pituitary gland
Releases hormones such as:
- thyroid stimulating hormone (thyroid gland): calcitonin and T3, T4 hormones.
- adrenocortico stimulating hormone (adrenal glands): cortex-cortisol and aldosterone, medulla- noradrelanine, norepinephrine.
- growth hormone: growth stimulation, protein synthesis.
- prolactin: increases milk production
- gonadotropins: ovaries- estrogens and progresterone, testes-androgens.
Pineal gland hormones
Secretes melatonin
Thyroid gland
secretes calcitonin and T3, T4 hormones (thyroxin hormones)
Parathyroid gland hormones
Secretes parathyroid hormones that oppose the calcitonin.
Adrenal cortex hormones
secretes cortisol and aldosterone
Adrenal medulla
secretes epinephrine and norepinephrine
Islets of Langerhans hormones
- alpha cells: secrete glucagon
- beta cells: secrete insulin
Ovaries hormones
secretes estrogens
Testes hormones
androgens
What is the antidiuretic hormone (ADH)?
It is the hormone that regulates the kidney processes. It helps to maintain the normal blood osmolarity.
State the roles of oxitocin
- in females oxitocin controls the milk secretion from mammary glands
- stimulates the ejection of milk
Posterior pituitary lobe
It releases hormones produced by neurosecretory cells of the hypothalamus. These hormones are released through the nerve cells to the posterior pituitary gland and then the hormones are released through the blood vessels to other endocrine glands.
Anterior pituitary lobe
Hypothalamus synthesises hormones that are released to the anterior pituitary gland through the portal vessel. The endocrine cells in this lobe stimulate the release of the hormones to other endocrine glands through the blood vessels.
How the hormonal regulation of growth works?
The growth hormone is secreted by the anterior pituitary gland and stimulates growth. The liver responds to the action of this hormone and releases insulin-like growth factors. It contributes to increase in the muscle mass.
What if GH is absent?
The skeleton of mature animal stop growing.
What if the hypersecretion of the GH occurs?
It leads to gigantism and the person is unusually tall but maintains the normal body proportions.
Explain the release of melatonin
When the photons of light stimulate the retinas of the eyes, nerve impulse is sent to a region of the hypothalamus called the suprachiasmatic nucleus (SNC). Then the signal is carried to pineal gland, where the production of melatonin is inhibited. The blood levels of melatonin fall, and as light levels decline the melatonin production increases which boosts blood levels.
The function of calcitonin
lowering the calcium levels
The function of thyroxine
They are essential for normal human growth and development. Thyroid hormones increase the metabolic rate and also help to control body temperature. They also help to regulate the synthesis of proteins.
What is the function of cortisol?
regulating the immune system
What is the function of aldosterone?
increasing the reabsorption of salt
Function of melatonin
regulates the biological rhythms
Function of epinephrine and norepinephrine
raising blood glucose levels and increasing the metabolic activities
Function of insulin
lowering the blood glucose levels
Function of the glucagon
raising blood glucose levels
Function of estrogens
development and maintenance of female secondary sex characteristics
What is the function of androgens?
support the sperm formation and promote development of male secondary sex characteristics
How does the ADH influence the water uptake in the kidney’s collecting ducts?
The binding of the ADH to receptor molecules leads to an increase in the number of aquaporin proteins inserted in the membranes of collecting duct cells. The channels recapture more water and that reduces the urine volume.
How temperature affects the thyroxine release?
- hotter temperature causes the hypothalamus to inhibit thyroxin release, which decreases the metabolic rate of the body to reduce heat production.
- colder temperatures cause the hypothalamus to stimulate the thyroxin release which increases the metabolic rate to generate more heat.
State the definition of hypothyroidism
Condition that occurs when there is thyroid hormone deficiency. Results in low metabolic activities and affects the physical development. Typical symptom can be the feeling like sleeping all the time.
State the definition of hyperthyroidism
Condition that occurs due to an excessive production of the thyroid hormone. The fluid accumulates behind the eyes - typical symptom.
What happens when there is an iodine deficiency?
the body cannot synthesize proper amounts of the thyroid hormone caused by low iodine in the diet.