Anatomy and Physio

The cardiovascular system is responsible for the circulation of blood throughout the body, and it consists of the heart and blood vessels. The heart is a muscular organ that pumps blood to all parts of the body. During the cardiac cycle, the heart chambers contract and relax in a coordinated manner to ensure efficient blood flow.

The contraction of the heart chambers is initiated by an electrical impulse generated by the sinoatrial (SA) node, which is located in the right atrium of the heart. This impulse spreads through the atria, causing them to contract. The impulse then travels to the atrioventricular (AV) node, which is located between the atria and the ventricles.

From the AV node, the impulse is transmitted through the bundle of His and then to the Purkinje fibers, which are specialized cardiac muscle fibers that conduct the electrical impulse rapidly and efficiently to the ventricles. The Purkinje fibers stimulate the ventricles to contract, which results in the ejection of blood from the heart.

Option A is incorrect because the AV node is responsible for delaying the electrical impulse before it reaches the ventricles to ensure that the atria have fully contracted first. Option B is incorrect because the SA node is responsible for initiating the electrical impulse, but it does not directly cause the contraction of the heart chambers. Option C is incorrect because the bundle of His is responsible for conducting the electrical impulse from the AV node to the Purkinje fibers, but it does not directly cause the contraction of the heart chambers.

Respiratory system

Function

  • facilitate exchange of oxygen and carbon dioxide

  • Conductive zones bring inhaled air to the respiratory zone, where gas exchange occurs.

  • External respiration is air exchange between lungs and blood, while internal respiration is between blood and tissue

  • Secondary functions: pH regulation of blood, thermoregulation, odor sense, and speech production

  • mucus in the nasal passage contain lysozymes, which break down particulate matter, and Immunoglobulin A is used to as antibodies to neutralize pathogens

  • Mast cells within respiratory tract release inflammatory chemicals to increase blood flow

  • Macrophages protect the lungs by engulfing small cells and particulates

Anatomy

  • Consists of nasal passages, pharynx, larynx, trachea, bronchial tubes, lungs, and diaphragm.

  • Alveoli are sacs in which gas exchange takes place

  • Right lung has 3 lobes, while left has 2 lobes

  • Trachea forks into right and left lung at the hilum

  • each primary bronchus separates into secondary, tertiary, and bronchioles.

  • Terminal bronchioles divide into respiratory bronchioles, which are known by their presence of alveoli, which lead to alveolar ducts, terminating in alveolar sacs

  • alveolar sacs are clusters of alveoli in the bronchi, which is where gas exchange occurs

  • Walls of alveolus are made of a single layer of cuboidal epithelial cells, that secrete surfactant to maintain alveoli integrity

  • walls are perforated with pores, and outer surface is covered in capillaries for oxygen transport

Breathing mechanics

  • Boyles law: pressure and volume of gas have an inverse relationship

Cardiovascular System

Main Functions

  • Gas exchange

  • Delivery of nutrients and hormones

  • waste removal

Anatomy

arteries are blood vessels that carry blood away from the heart

veins are blood vessels that carry blood back to the heart

exchange of material between blood and cells occur in capillaries, smallest blood vessels

Functions

  • like oxygen, CO2 can dissolve in the blood or bind to hemoglobin

  • urea produced is filtered by the kidneys

Anatomy of Heart

  • 3 layers (outer to inner):

  • Epicardium: protects and lubricates heart wit serous fluid

  • Myocardium: Muscular, and contracts to pump blood

  • Endocardium: lines chambers and valves

  • Superior chambers are atria, which are receiving chambers; right atrium receives blood from vena cava, while left atrium receives blood from the pulmonary veins

  • inferior chambers are discharging chambers, right ventricle pumps blood in pulmonary trunk, while left ventricle pumps blood in the aorta

  • tricuspid valve (right atrioventricular valve)prevents backflow into the atrium, when the ventricle contracts

  • The pulmonary semilunar valve prevents return of blood to right ventricle

  • Bicuspid valve (left AV valve) prevents blood from entering left atrium when ventricle contracts

  • Aortic semilunar valve stops backflow of blood into left ventricle as it leaves the aorta

Endothelial cells

  • Endothelium is the thin inner lining of blood vessels and all circulatory system; single layer of squamous endothelial cells held together by tight and adherens junctions

  • Their smoothness allows for less friction between the blood and vessel walls,

  • aids in vasoconstriction via release of endothelin peptides, causing smooth muscle to contract

  • release chemicals that inhibit blood coagulation, but also, if endothelium is damaged, will release coagulants

Systolic and Diastolic Pressure

  • Systolic pressure: maximum pressure during systole (or when the ventricles contract to force blood into the aorta ad pulmonary tract)

  • Diastolic pressure: when blood vessels return to normal size after elastic walls are stretched (diastole: ventricles relax and blood pressure is at its lowest point)

Electrical Conduction system

  • composed of Sinoatrial and atrioventricular nodes

  • Sinoatrial generate electrical impulse that contracts the atrium, which reaches the AV node, and slows down.

  • Travels through the Bundle of His and the bundle branches, then to perkinje fibers (carry electrical impulse that stimulates ventricles to depolarize and contract)

Composition of Blood

Plasma Chemicals, blood cells

  • 55% is plasma

  • 45% is red and white blood cells and platelets

  • Plasma is a combo of water, plasma proteins, carbs, amino acids, fats

  • most cells are red blood cells

  • Hematocrit is the % of red blood cells by volume

  • White blood cells and platelets comprise less than 1%

  • WBC (leukocytes) are only blood cells with nuclei, and can move in and out of blood

Leukocytes

  • Lymphocytes: special type of immune cell, b cells and t cells

  • monocytes: well-defined nucleus; immune response to pathogens; produced in the bone marrow

  • granulocytes: granules in cytoplasm; released in response to certain infections and allergens; are basophils, eosinophils, neutrophils, and mast cells

Blood types

  • A has A antigens, and anti-B antibodies

  • B has B antigens, and anti-A antibodies

  • AB has A and B antigens, and produce no antibodies

  • O has neither A or B antigens, and produce both anti-A and B antibodies

  • Rhesus group is either positive or negative and is an antigenic substance

Digestive system

  • Mucin is a protein that lubricates food down

  • Esophagus functions to lubricate and transfer food; has 4 layers: mucosa, submucosa, muscularis externa, and adventitia.

  • upper and lower esophageal sphincters control the passage of food.

stomach

  • cardiac region is where food is emptied into stomach

  • fundus is most superior,

  • body is the largest and most central region

  • stomach curves into a funnel region called the pylorus

  • series of ridges called rugae allow the stomach to expand

  • when the food is pummeled, it turns it into chyme

  • pyloric sphincter regulates chyme into the small intestines

  • mucosa has gastric glands which has 4 types of cells: mucous cells, parietal cells, chief cells, and endocrine cells

  • Endocrine (g-cells) release gastrin and not gastric juices

  • parietal cells release intrinsic factor to absorb B12, and HCl

  • acidic environment necessary for chief cells to secrete pepsinogen, breaks proteins into smaller peptides, and lipase

  • mucous cells release bicarbonate mucous to protect stomach from acidity and enzymes

liver

  • accessory organ that produces bile, aids in nutrient metabolism, and detoxification

  • only bile salts aid in digestion, through emulsifying fats into smaller pieces, called micelles, and aids in vitamins A, D, E, and K absorption

  • Bile is stored in gallbladder which when activated by cholecystokinin, contracts it to put bile in common bile duct. That duct joins at pancreatic duct, and bile spills into the duodenum, but can also flow directly from liver to duodenum

  • liver can turn ammonia to urea and excrete it, and breaks down drugs and alcohol

Pancreas

  • functions as exocrine and endocrine (via endocrine gland producing insulin, glucagon, and somatostatin in blood)

  • extends from duodenum to the spleen and is below stomach

  • pancreatic amylase digests starch, and pancreatic lipase digests fats; protease is released, but in inactivated form until it reaches small intestine

Small intestine

  • extends from pyloric sphincter to ileocecal valve

  • three sections: duodenum, jejunum, and ileum

  • duodenum is shortest but widest, receives chyme from stomach and neutralizing digestive juices from pancreas. Most chemical digestion occurs here, but not nutrient absorption besides iron

  • Jejunum is main site for absorption and is characterized by dense microvilli

  • ileum is longest; aggregates of lymph cells called peyer’s patches are found here. Main function is to absorb B12, bile salts, and unabsorbed nutrients

Large intestine

  • begins at ileocecal valve and ends at anus

  • wider but shorter than small intestine

  • starts at the cecum (receives chyme from small intestine), which is also the site for the appendix

  • Colon is middle portion and can be divided into, ascending colon (right side of body), transverse colon (extends from abdominal cavity), descending colon (left side of body), and sigmoid colon.

  • sigmoid colon lies in pelvic cavity, and reaches the rectum

  • haustra are pouches that are formed by smooth muscle contraction within the muscularis layer

  • specializes in absorption of vitamin K, biotin, sodium ions, chloride ions, and water

Reproductive system

Male

  • testes: primary male reproductive organ, that produces sperm and testosterone

  • Epididymis: coiled tube where sperm mature and are stored

  • Vas Deferens: tube that carries mature sperm from epididymis to ejaculatory duct

  • Seminal vesicles, prostate gland, and bulbourethral glands: produce seminal fluid, which combines with sperm to produce semen

  • Spermatogenesis: process of sperm cell production, taking place within the seminiferous tubules of testes

  • Hormonal regulation: testosterone is crucial for male secondary sexual characteristics and sperm production. its production is regulated by the hypothalamus and pituitary gland

Female

  • Ovaries: produce eggs (ova) and hormones like estrogen and progesterone for reproduction

  • Fallopian Tubes: tubes connecting the ovaries to uterus, where fertilization occurs

  • Uterus: muscular organ where a fertilized egg implants and develops

  • Cervix: lower part of the uterus that opens to the vagina

  • Menstrual Cycle: roughly 28-day cycle involving the thickening of the uterine lining, ovulation (release of an ovum), and either pregnancy or menstruation. regulated by hormones like estrogen, luteinizing hormone, and follicle-stimulating hormone.

  • Oogenesis: the process of egg cell production

  • Fertilization and implantation: if an ovum is fertilized in fallopian tubes, it moves to uterus, and implants in uterine walls

  • Fertilization implantation: hypothalamus ad pituitary gland in brain regulate hormones affecting the ovaries, which regulates the menstrual cycle and pregnancy

  • Ovarian phase:

    • Follicular phase: FSH stimulates the maturation of the follicle, which then secretes estrogen, which regenerates the uterine lining, that was shed during menstruation.

    • Ovulation: release of a secondary oocyte from the ovary, is induced by a surge of LH

    • Luteal phase: begins with the formation of the corpus luteum from the remnants of the follicle, which secretes progesterone and estrogen, which inhibits FSH and LH.

    • progesterone also maintains the thickness of the endometrium

  • Uterine cycle:

    • proliferative phase: regeneration of the uterine lining

    • secretory phase: endometrium becomes increasingly vascular and nutrients are secreted to prepare for implantation.

    • Menstruation: without implantation, the endometrium is shed

Endocrine system

  • hormones are released and enter the interstitial fluid before diffusing into nearby capillaries.

  • hypothalamus is the link between the nervous system and the endocrine system

  • hypothalamus communicates with the pituitary by secreting “release hormones“ (RH) and “inhibiting hormone“ (IH).

Urinary system

  • main components are kidneys, uterus, bladder, and urethra

  • Kidneys: filter blood, regulate fluid volume, and produce urine

  • uterus: transports urine from kidneys to bladder

  • bladder: stores urine until expelled

  • urethra: carries out urination

  • each kidney is covered in 3 layers of connective tissue: renal fascia, adipose capsule, and renal capsule (outermost to innermost)

  • renal cortex surround the entire kidneys, which has nephrons, filtration units, that connect to medulla, tubules

  • hilum is the concave portion where the blood vessels and nerves enter and leave

  • renal capsule has the Bowman’s capsule that wraps partially around a cluster of capillaries called the glomerulus

  • blood enters through the renal artery, which branches off into smaller vessels until it reaches the glomerulus, which is where it gets filtered

  • the renal cortex is the site for ultrafiltration: nonspecific filtration of blood under high pressure; granular in appearance due to high amounts of nephrons

  • Medulla: