Human body systems Flashcards
tissue
a group of similar cells and cell products that arise from the same region of an embryo and work together to perfrom a specific structural or physiological role in an organ
histology
the study of tissues and the way they are arranged into organs
epithelial tissue
tissue composed of layers of closely spaced cells, covers organ surfaces, forms glands and serves for protection, secretion and absorption (e.g. epidermis, lining of digestive tract)
types of epithelial tissue
- flat or squamous cells
- cube-shaped or cuboidal cells
- tall and cylindrical or columnal cells
layers of epithelial tissue
- simple epithelium - single layer
- stratified epithelium - two or more layers
- pseudostratified epithelium - appears to have more than one layers, but it is one layer of different height cells
- transitional epithelium - where cells change shape in response to mechanical stretching
connective tissue
cells embedded within a network of fibers: the matrix
- material surrounding the cells within the matrix = the groud substance
(e.g. tendons, cartilage, fat, bone, blood)
types of connective tissue
- connective tissue proper - containing various fibers in a semifluid ground substance
- bone tissue
- blood
- cartilage tissue
nervous tissue
tissue containing excitable cells specialized for rapid transmission of information to other cells (e.g. brain, spinal cord, nerves)
muscular tissue
tissue composed of elongated, excitable cells specialized for contraction and movement (e.g. skeletal muscles, heart, walls of uterus, bladder, intestines)
skeletal system
composed of bones, cartilage and ligaments joined tightly to form a strong and flexible framework for the body
joint
a bone meets another bone
cartilage
forerunner of most bones in embryonic development; forms a growth zone in the bones of children and covers many joint surfaces in the mature skeleton
ligament
collagenous band that holds bones together at the joints
tendons
structurally similar to ligaments but attach muscles to bone
bone marrow
the soft bloody or fatty material enclosed in the bones
functions of the skeletal system
- support
- bones of the limbs and vertebral column support the body, the mandible and maxilla support the teeth and some viscera are supported by nearby bones
- protection
- bones enclose and protect the brain, spinal cord, lungs, heart and pelvic viscera
- movement
- bones provide attachment and leverage for the muscular system, allowing for actions such as limb movement and ventilation of the lungs
- blood formation
- red bone marrow is the major producer of blood cells
- storage
- the skeleton is the body’s main reservoir of calcium and phosphorus among other minerals
number of bones
there are 109 differently named bones of the skeleton (most paired)
→ an adult skeleton typically has 206 individual bones
axial region
forms the central supporting axis of the body and comprises 80 bones, including: skull, vertebral column, ribs and sternum
appendicular region
comprises the remaining 126 bones, those of the upper limb and pectoral girdle and of the lower limb and pelvic girdle
3 types of muscular tissue
- skeletal
- cardiac
- smooth
functions of the muscular system (5)
- movement
- stability
- control of body openings and passages
- heat generation
- glycemic control
structure of a muscle fiber
- each muscle fiber has multiple nuclei pressed against the plasma membrane
- deeper part of the cell:
- thick bundles (myofibrils) of contractile protein (myofilaments: actin and myosin)
- packed between myofibrils are numerous mitochondria, a network of sER, deposits of the high-energy glycogen and a red, oxygen-binding pigment - myoglobin
properties of cardiac muscle
cardiac muscle is limited to the heart, where its function is to pump blood
- involuntary (contracts automatically) and autorhytmic (has a self-maintained rhythm of contraction)
- cardiac muscle cells are short, rectangular and forked at the ends linked at the intercalated discs
smooth muscle
involuntary, like cardiac but it lacks striations
- smooth muscle cells have only one nucleus near the middle of the cell, are fusiform in shape
- it occurs in the walls of the blood vessels and many body-cavity organs (viscera) such as the respiratory, urinary, digestive and reproductive organs - visceral muscle
- smooth muscle contracts in response to nervous stimulation, stretch (e.g. full bladder), hormones (during labor contractions) and blood levels of CO2, )2 and pH
- smooth muscle is fully capable of mitosis (e.g. pregnant uterus)
3 basic components of the circulatory system
- circulatory fluid
- a set of interconnecting vessels
- a muscular pump, the heart
→ the heart powers circulation by using metabolic energy to elevate the circulatory fluid’s hydrostatic pressure
→ the fluid then flows through the vessels and back to the heart
circulation in mammals
- O2 from inhaled air diffuses across only two layers of cells in the lungs before reaching the blood
- the circulatory system then carries the oxygen-rich blood to all parts of the body
- as the blood passes throughout the body tissues in tiny blood vessels: O2 in the blood diffuses only a short distance before entering the fluid that directly bathes the cells
heart’s chambers
- the heart has 4 chambers that receive and eject blood
- the two smaller, superior chambers are the right and left ATRIA → thin-walled receiving chambers for blood returning to the heart by way of the great veins
- the two inferior chambers, the right and left VENTRICLES compose most of the bulk of the heart → strong pumps that eject blood into the arteries and keep it flowing around the body
heart’s valves
- 4 heart valves ensure a one-way flow and prevented backflow of blood
- one between each atrium and its ventricle and one at the exit from each ventricle to its great artery
atrioventricular valves
control the opening between each atrium and the ventricle below it
the pulmonary and aortic (semilunar) valves
lie between the ventricles and great arteries
the pulmonary valve
controls the opening from the RIGHT ventricle into the PULMONARY TRUNK
the aortic valve
controls the opening from the LEFT ventricle into the AORTA
pulmonary circuit
carries blood to the lungs for gas exchange and returns it to the heart
systemic circuit
supplies blood to all organs of the body, including the lungs and the wall of the heart itself → it pumps blood into the largest artery, the AORTA
- the dual circuits operate simultaneously
- the two ventricles contract almost in unison and pump the same volume of blood
- the total volume of the systemic circuit is much greater than that of the pulmonary circuit
blood vessels - differences
- direction of blood flow
- pressure they withstand
- corresponding histological structure of their walls
arteries
all vessels that carry blood away from the heart
veins
all vessels that carry blood back to the heart
capillaries
microscopic vessels connecting the smallest arteries to the smallest veins
respiratory functions
- gas exchange: oxygen enters blood and carbon dioxide leaves
- regulation of blood pH: altered by changing blood carbon dioxide levels
- voice production: movement of air past the vocal folds makes sounds and speech
- olfaction: smell occurs when airborne molecules are drawn into nasal cavity
- protection: against microorganisms by preventing entry and removing them
respiratory tract (upper + lower)
air passages from the nose to the lungs and gas-exchange surfaces in the lungs themselves
- upper respiratory tract
- from nose through larynx
- lower respiratory tract
- from trachea through lungs
the bronchial tree and alveoli
- a series of branching passages that carry air from trachea to gas-exchange surfaces in the lungs (alveoli)
- bronchi branch into smaller passageways leading to tubes called bronchioles and terminal bronchioles
- each lung contains 150 million alveoli, which provide a large surface area for gas exchange