L1b - Tissues & Systems (2) Flashcards
Define ‘gland’.
A single or a group of epithelial cells adapted for secretion.
What are the two major types of glands? Describe their characteristics.
- Exocrine Glands (secrete materials directly into ducts or onto the apical epithelial surface; composed of glandular epithelia and secrete mucus, sweat, oil, earwax and digestive enzymes)
- Endocrine Glands (“ductless glands” that secrete materials through the basal surface which diffuses through the basement membrane, connective tissue and into the bloodstream)
Describe the structural features of exocrine glands.
- Unicellular glands
- Goblet cells
- No ducts involved
- Multicellular glands
- Most glands are of this type
- Usually involves ducts
- Duct system can be classified according to shape
Describe the structural features of endocrine glands.
- Ductless, basal secretion
- Secretion diffuses into bloodstream
- Acts at a distant location (hormone)
State the main exocrine gland shapes.
- Simple Tubular Structure
- Compound Tubular Structure
- Simple Alveolar Structure
- Compound Alveolar Structure
(Simple: duct portion does not branch)
(Compound: duct portion branches)
Describe the different types of exocrine gland secretion.
- Holocrine Secretion (Cell accumulates substance for secretion, dies and discharges its content; oil in sebaceous glands)
- Merocrine Secretion (Secretion occurs by exocytosis; sweat glands)
- Apocrine Secretion (Small pieces of cell containing secretion breaks off and cell repairs itself; mammary gland milk lipid droplets)
What are the 2 major control systems of the body?
- Nervous System
- Endocrine System
How does the endocrine system aid communication?
1) Endocrine glands throughout the body secrete hormones - target cells have hormone receptors
2) Hormone binds and initiates or inactivates selective metabolic activities within these cells
List the endocrine organs.
- Pituitary gland
- Thyroid gland
- Pineal gland
- Parathyroid gland
- Adrenal glands
What are endocrine cells found within?
- Hypothalamus
- Skin
- Thymus
- Liver
- Stomach
- Pancreas
- Small intestine
- Gonads (testes and ovaries)
What are endocrine organs?
Single organs that are entirely endocrine in function.
What are endocrine cells?
Present in clusters in organs which have a different primary function.
Describe different endocrine function.
- Maintaining homeostasis of blood composition and volume
- Controlling reproductive activities
- Regulating development, growth and metabolism
- Controlling digestive processes
Name the releasing hormones of the hypothalamus.
- TRH
- PRH
- GnRH
- CRH
- GHRH
Name the inhibitory hormones of the hypothalamus.
- PIH
- GIH
Describe the involvement of the thyroid in the endocrine system.
Thyroid-stimulating hormone (TSH) stimulates thyroid gland to release thyroid hormone.
Describe the involvement of the mammary gland in the endocrine system.
Prolactin (PRL) acts on mammary glands to stimulate milk production.
Describe the involvement of the gonads in the endocrine system.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) act on gonads (testes and ovaries) to stimulate development of gametes (sperm and oocyte).
Describe the involvement of the body tissues in the endocrine system.
Growth hormone (GH) acts on all body tissues, especially cartilage, bone, muscle, and adipose connective tissue to stimulate growth.
Describe the involvement of the adrenal gland in the endocrine system.
Adrenocorticotropic hormone (ACTH) acts on the adrenal cortex you cause release of corticosteroids.
Where is the thyroid located?
- Anterior to trachea
- Inferior to thyroid cartilage of larynx
What is the shape of the thyroid?
Butterfly
What does the thyroid produce and release?
Thyroid hormone
What does the thyroid hormone do?
Increased metabolic rate and results in:
- Increased protein synthesis (especially in neurons)
- Increased glucose uptake
- Increased breathing, heart rate and force of contraction
- Increased glycogenolysis, gluconeogenesis and lipolysis
- Decreased glycogenesis and lipogenesis
What are the 3 ways in which endocrine secretion can be triggered?
- Hormonal release
- Humoral agents in the blood (e.g. nutrients, sugars, chemicals)
- Direct neural input
What occurs in hyperthyroidism?
- Upregulates all metabolism
- Tend to be heat intolerant (body temperature is already quite high)
- May lose weight
What type of organs are adrenal glands?
Retroperitoneal organs
Where are adrenal glands located?
At the superior pole of the kidneys
Describe the different parts of the adrenal gland.
Adrenal Medulla (inner core) - Releases epinephrine and norepinephrine in response to sympathetic stimulation
Adrenal Cortex (outer layers) - Releases corticosteroids (e.g. aldosterone which controls fluid/electrolyte balance, cortisol, corticosterone and androgens)
Where is the pancreas located?
- Posterior to the stomach
- Between the duodenum and the spleen
What are the functions of the pancreas?
- Exocrine (digestive enzymes) function
- Endocrine function
Describe the role of the pancreatic islets.
- Alpha cells produce glucagon
- Beta cells produce insulin
What does the cardiovascular system comprise?
- Heart
- Blood vessels
What is the role of blood in the cardiovascular system?
- Transportation
- Regulation
- Protection
- Homeostasis
Describe the manner in which blood is circulated.
- Systemic Circulation (arteries away from heart)
- Pulmonary Circulation (veins towards heart)
Describe the location of the heart.
- Located in the mediastinum
- Enclosed in the pericardium
How many chambers are there in the heart? Name them.
- 4 Chambers
- Left Atrium
- Left Ventricle
- Right Atrium
- Right Ventricle
What is the role of valves in the heart?
To ensure one-way passage of blood
What is the electrical activity of the heart controlled by?
Nerve fibres / bundles
Describe the different blood vessels found in the heart.
- Arteries
- Veins
- Capillaries
Describe the passage of blood in the circulatory system.
1) Deoxygenated blood travels through the inferior / superior vena cava
2) Deoxygenated blood enters the right atrium
3) Blood passes through the tricuspid valve and enters the right ventricle
4) Blood moves through the pulmonary valve
5) Blood enters the pulmonary trunk and arteries where the blood is carried to the lungs
6) Blood loses carbon dioxide and gains oxygen in the pulmonary capillaries
7) Oxygenated blood enters the pulmonary veins
8) Blood enters the left atrium
9) Blood travels through the bicuspid valve and enters the left ventricle
10) Blood moves through the aortic valve; and into the aorta and systemic arteries
11) Oxygenated blood is pumped around the body
12) Blood loses oxygen and gains carbon dioxide in the systemic capillaries
What is the simple squamous epithelium of the heart tissue referred to as?
Endothelium
Describe the differences in the structures of arteries and veins.
Artery:
- No valves required as blood is already under high pressure
- Thick muscular walls to withstand high pressure of blood
Vein:
- Valves to ensure one-way flow of blood / venous return back to the heart (blood travels slowly as it does not have pulsatory pressure)
- Thin lining as pressure of blood is low
What are the two systems of arteries and veins in the body called?
- Arterial System
- Venous System
What is the main role of the lymphatic system?
To transport fluid from the interstitial space into the lymphatic capillaries
What does hydrostatic pressure do?
Hydrostatic pressure forces fluid into vessels (one way system)
What is the lymphatic system composed of?
- Lymph Vessels
- Lymphatic Tissues
- Lymphatic Organs
Describe the passage of fluid through the lymphatic system.
Capillaries -> Vessels -> Trunks -> Ducts
Where do the contents of the lymphatic system empty into?
The circulatory system at the junction of the left jugular and the left subclavian vein
Describe lymphatic trunks.
Lymphatic trunks serve a specific body area: jugular, subclavian, Broncho mediastinal, intestinal, lumbar
Describe lymphatic ducts.
- Largest lymph vessels (right lymphatic duct and thoracic duct)
- Carry lymph into venous circulation
What are the primary structures of the lymphatic system involved in? Provide examples.
- Involved in the formation / maturation of lymphocytes
- Thymus
- Red bone marrow
What are the secondary structures of the lymphatic system involved in? Provide examples.
- House lymphocytes and immune cells after formation
- Lymph nodes
- Tonsils
- Spleen
- Lymphatic nodules
- Mucus Associated Lymphatic Tissue (MALT) in the small intestine
What does the respiratory system provide?
The means necessary for gas exchange in cells
Describe the functions of the respiratory system.
- Air passageway
- Oxygen and carbon dioxide exchange site
- Odour detection
- Sound production
What is the respiratory system responsible for?
Gas exchange between the atmosphere and lungs
What does the respiratory system require the integration of?
- Musculoskeletal system
- Nervous system
- Cardiovascular system
What are the 2 structural regions of the respiratory system?
- Upper respiratory tract
- Lower respiratory tract
What are the 2 functional regions of the respiratory system?
- Conducting zone
- Respiratory zone
What is the conducting zone of the respiratory system?
Areas where the air is actually moving
What is the respiratory zone of the respiratory system?
Areas where air is being transported across membranes; where O2 and CO2 transfer
(This only comprises areas where there is alveolar surfaces present)
What is the advantage of having a complete nasal passageway in the upper respiratory tract?
- Allows time to warm / humidify air (this allows air to pass over olfactory receptors = detect odours)
- Protects delicate lung tissue as air is warmed before passing through the trachea
Describe the passage of air through the bronchial tree.
Mouth / Nose -> Pharynx -> Larynx -> Trachea -> Bronchi -> Lung -> Branches -> Alveoli
Describe the structure and location of lungs.
- Paired structures
- Within thoracic cavity
- Protected by rib cage
- Diaphragm lies inferiorly
How many lobes are in the right lung?
3
How many lobes are in the left lung?
2
Define ‘hilum’.
Entry / exit for blood vessels, bronchi and nerves
What do respiratory muscles help to do?
Alter the volume of thoracic cavity during inhalation (inspiration) and exhalation (expiration)
Describe the action of the muscles of quiet breathing.
- Diaphragm forms the rounded floor of the thoracic cavity and is dome shaped when relaxed. It alternates between the relaxed domed position and the contracted flattened position and changes the vertical dimensions of the thoracic cavity.
- External intercostals extend from a superior rib inferiomedially to the adjacent inferior rib. These elevate the ribs and increase the transverse dimensions of the thoracic cavity.
Describe the action of the muscles of force inspiration.
- Sternocleidomastoid attaches to sternum and clavicle; lifts rib cage
- Scalenes attach to ribs 1 and 2; elevates ribs 1 and 2
- Pectoralis minor attaches to ribs 3-5; elevates ribs 3-5
- Serratus posterior superior attaches to ribs 2-5 on its anterior surface; lifts ribs 2-5
- Erector spinae is a group of deep muscles along the length of the vertebral column; extends the vertebral column
Describe the action of the muscles of forced expiration.
- Internal intercostals lie deep and at right angles to the external intercostals; depress the ribs and decrease the transverse dimensions of the thoracic cavity
- Abdominal muscles (primarily the external obliques and transversus abdominis) compress the abdominal contents, forcing the diaphragm into a higher domed position and the rectus abdominus pulls the sternum and rib cage inferiorly
- Transversus thoracis extends across the inner surface of the thoracic cage and attaches to ribs 2-6; depresses ribs 2-6
- Serratus posterior inferior extends between the ligamentum niches and the lower border of ribs 9-12; depress ribs 9-12
What is the pleura?
Sebaceous membranes
Name and describe the location of the two pleura.
- Visceral Pleura (adhered you the surface of the lungs)
- Parietal Pleura (adhered to the internal surface of the thoracic wall, diaphragm and mediastinum)
