Anatomy and Physiology Midterm Flashcards
Endocrine system, blood, cardiovascular system, blood vessels, respiratory system
Define hormone
Chemical messenger secreted by an endocrine gland, and transported in the blood, that acts on target cells.
Define endocrine glands
Gland that secretes hormones into the bloodstream; hormone secreting gland.
Define exocrine glands
Gland that secretes its products into a duct or onto an outside body surface.
Classify hormones based on structure and actions at a target cell.
- Steroid hormones
- Nonsteroid hormones
What are steroid hormones?
- Lipid soluble (from cholesterol)
- Travel in blood bound to plasma proteins
- Protein receptors are located inside the target cell
What is the action mechanism of steroid hormones?
- Hormone passes through the plasma membrane
- Binds with receptor in cytoplasm
- Enters nucleus and triggers gene transcription
What are nonsteroid hormones?
- Derived from amino acids
- Water soluble
- Not able to enter cell
What is the action mechanism of nonsteroid hormones?
- Hormone binds to membrane receptor
- Activates enzyme
- Produces a second messenger molecule
Identify the function of the hypothalamus.
Produces releasing and inhibiting hormones that affect the pituitary gland.
What hormones are secreted by the hypothalamus?
- Anti-diuretic (ADH)
- Corticotropin-releasing (CRH)
- Gonadotropin-releasing (GnRH)
- Growth hormone releasing (GHRH)
- Growth hormone inhibiting (GHIH)
- Oxytocin
- Prolactin releasing (PRH)
- Prolactin inhibiting (PIH)
- Thyrotropin-releasing (TRH)
What is the function of the pituitary gland?
Regulates other endocrine glands.
List hormones secreted by the anterior pituitary.
- Growth hormone (GH)
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
What hormones are stored in the posterior pituitary?
- Antidiuretic hormone (ADH)
- Oxytocin
What is the function of the pineal gland?
Regulates circadian rhythms (sleep-wake cycle).
What hormone does the pineal gland secrete?
Melatonin.
What is the function of the thyroid gland?
Controls metabolism, growth, and energy balance.
List hormones secreted by the thyroid gland.
- Thyroxine (T₄)
- Triiodothyronine (T₃)
- Calcitonin
What is the function of the parathyroid glands?
Regulates blood calcium levels.
What hormone is secreted by the parathyroid glands?
Parathyroid hormone (PTH).
What is the function of the adrenal glands?
Respond to stress, metabolism, and electrolyte balance.
List hormones secreted by the adrenal cortex.
- Cortisol
- Aldosterone
- Androgens
List hormones secreted by the adrenal medulla.
- Epinephrine
- Norepinephrine
What is the function of the pancreas?
Regulates blood sugar levels via endocrine and exocrine functions.
List hormones secreted by the pancreas.
- Insulin
- Glucagon
- Somatostatin
What are the functions of the gonads?
Regulate reproduction and secondary sex traits.
List hormones secreted by the ovaries.
- Estrogen
- Progesterone
What hormone is secreted by the testes?
Testosterone.
What is the function of the thymus?
Develops T cells (immune system).
What hormone does the thymus secrete?
Thymosin.
Describe the negative feedback mechanism of cortisol secretion.
Environmental stressors trigger hypothalamus to release CRH, leading to ACTH release from pituitary and cortisol release from adrenal glands, which then inhibits further release of CRH and ACTH.
What is the normal pH range of blood?
7.35 to 7.45.
What are the components of blood?
- Red blood cells (45%)
- White blood cells (<1%)
- Plasma (55%)
What is hematocrit?
Percentage of red blood cells in a given volume of blood.
What is the normal hematocrit value?
45% of blood volume.
What is the importance of erythropoietin?
Stimulates the production of RBCs and helps maintain a healthy number of RBCs.
Describe the structure and function of hemoglobin.
Type of protein found in RBCs that transports oxygen and some carbon dioxide.
What is blood typing based on?
Presence or absence of specific antigens on RBCs and corresponding antibodies in plasma.
What are the four blood types in the ABO system?
- Type A
- Type B
- Type AB
- Type O
What is the Rh blood group?
Determined by the presence or absence of the Rh surface factor on red blood cells.
What is erythroblastosis fetalis?
Red blood cell destruction in the fetus due to Rh incompatibility.
Describe the process of hemostasis.
Involves blood vessel spasm, platelet plug formation, and blood coagulation.
What are the three steps following a blood vessel injury?
- Blood vessel spasm
- Platelet plug formation
- Blood coagulation
What triggers the life cycle of a red blood cell?
Low O2 levels in blood stimulate kidneys to produce erythropoietin.
What happens to aged and damaged red blood cells?
Engulfed by macrophages, hemoglobin is broken down into amino acids and recycled.
What are the coverings of the heart?
Pericardium, consisting of fibrous pericardium and serous pericardium.
What are the three layers of the heart wall?
- Epicardium
- Myocardium
- Endocardium
What are the four chambers of the heart?
- Right Atrium
- Right Ventricle
- Left Atrium
- Left Ventricle
What are the functions of heart valves?
Ensure one-way blood flow and prevent backflow.
List the major blood vessels connected to the heart.
- Superior Vena Cava
- Inferior Vena Cava
- Pulmonary Arteries
- Pulmonary Veins
- Aorta
What are the two types of Atrioventricular (AV) valves?
Tricuspid Valve and Mitral (Bicuspid) Valve
What is the function of the Semilunar (SL) Valves?
Prevent backflow of blood from arteries into ventricles
What is the role of Chordae tendineae and papillary muscles?
Help prevent AV valve prolapse during contraction
What do the Superior and Inferior Vena Cava do?
Bring deoxygenated blood from the body to the right atrium
What is the function of Pulmonary Arteries?
Carry deoxygenated blood from the right ventricle to the lungs
What do Pulmonary Veins carry?
Oxygenated blood from the lungs to the left atrium
What does the Aorta do?
Carries oxygenated blood from the left ventricle to the entire body
What is the Sinoatrial (SA) Node known as?
The ‘Pacemaker’ of the heart
What is the function of the Atrioventricular (AV) Node?
Delays signal to allow atrial contraction
What does the AV Bundle (Bundle of His) do?
Conducts signals to ventricles
What is the role of Purkinje Fibers?
Distribute impulses through ventricles for contraction
Trace the flow of blood through the heart chambers starting from the superior and inferior vena cava.
Right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary trunk, pulmonary arteries, pulmonary capillaries, pulmonary veins, left atrium, mitral valve, left ventricle, aortic semilunar valve, aorta
What supplies blood to the myocardium?
Left and right coronary arteries
How does blood return to the right atrium from cardiac tissues?
Through branches of the cardiac veins into the coronary sinus
What is Automaticity in cardiac muscle?
The ability to generate its own action potentials without external stimulation
What is Excitability in cardiac muscle?
The ability to respond to electrical stimuli
What is Conductivity in cardiac muscle?
The rapid spread of action potentials through the heart
What does Contractility refer to in cardiac muscle?
The ability of cardiac fibers to generate forceful contractions
What is the purpose of the long Refractory Period in cardiac muscle?
Prevents tetany, ensuring rhythmic heartbeats
What are Intercalated Discs?
Structures that allow electrical impulses to spread rapidly between cardiac muscle cells
What is the function of the SA Node?
Initiates contractions in the right atrium
What does the electrocardiogram (ECG) record?
The electrical events occurring in the myocardium throughout a cardiac cycle
What does the P wave represent in an ECG?
Atrial depolarization, leading to atrial contraction
What does the QRS complex represent in an ECG?
Ventricular depolarization and atrial repolarization
What does the T wave correspond to in an ECG?
Ventricular repolarization
Define cardiac output (CO).
CO = heart rate (HR) x stroke volume (SV)
What are the three layers of an artery?
- Tunica interna
- Tunica media
- Tunica externa
What is the main function of arteries?
Carry oxygenated blood away from the heart
What are veins characterized by?
Thinner walls, larger lumen, and valves to prevent backflow
What is the structure of capillaries?
One-cell-thick endothelium with no tunica media or externa
What is the role of capillaries?
Allow exchange of gases, nutrients, and waste between blood and tissues
What is blood pressure?
Force per unit area exerted by blood on the wall of a blood vessel
What is blood flow?
Volume of blood flowing through a vessel or organ in a given period
What factors contribute to resistance in blood flow?
- Viscosity
- Total vessel lengths
- Vessel diameter
What are baroreceptors?
Sensors located in the aortic arch and carotid arteries that sense changes in blood pressure
What is the role of the renin-angiotensin system?
Helps regulate blood pressure through hormonal controls
What is hydrostatic pressure?
Drives the passage of fluids and small molecules out of the capillary
What is colloid osmotic pressure?
Causes tissue fluid to return to the bloodstream
What do pulmonary arteries and veins do?
Carry deoxygenated blood to the lungs and oxygenated blood back to the heart, respectively
What are the major structures of the upper respiratory system?
- Nose
- Nasal Cavity
- Paranasal Sinuses
- Pharynx
What are the major structures of the lower respiratory system?
- Larynx
- Trachea
- Bronchial Tree
- Alveoli
What is the function of the nasal cavity?
Humidify, warm, and filter air
What is the role of the larynx?
Voice box and passageway for air
What occurs during gas exchange?
Oxygen enters the blood and carbon dioxide is expelled in the alveoli
Trace the flow of air from the nose to the pulmonary alveoli.
Nose → Pharynx → Larynx → Trachea → Primary bronchi → Bronchioles → Alveolar ducts → Alveoli
What are pulmonary alveoli?
Sites of gas exchange where oxygen (O₂) enters the blood and carbon dioxide (CO₂) is expelled
Alveoli are clusters of tiny air sacs at the distal ends of alveolar ducts.
Where does gas exchange occur?
Only in the alveoli
Alveoli are tiny sacs clustered at the distal ends of alveolar ducts.
What is the respiratory membrane?
A semi-permeable membrane involved in gas exchange consisting of:
* Simple squamous epithelial cells of the alveolus
* Endothelial cells of the capillary
* Fused basement membranes of these layers
Gas exchange occurs easily through this membrane.
How do gases diffuse across the respiratory membrane?
From an area of high pressure to an area of low pressure
O₂ will diffuse into the blood if its pressure is higher in alveolar air than in blood.
What happens to carbon dioxide during gas exchange?
CO₂ will diffuse out of the blood if its pressure is higher in blood than in alveolar air
This process is part of the gas exchange in the alveoli.
Define ventilation.
The movement of air into and out of the lungs
This involves two main processes: inspiration and expiration.
What occurs during inspiration?
Air moves into the lungs due to atmospheric pressure
This happens when pressure inside the lungs decreases.
What causes the decrease in lung pressure during inspiration?
Increasing lung volume
The thoracic cavity size increases as the diaphragm contracts.
What muscles are involved in forced inspiration?
External intercostal muscles contract
This is in addition to the diaphragm contraction.
What is the process of expiration?
Forces of expiration are due to elastic recoil of lung and muscle tissues
The diaphragm relaxes and abdominal viscera pushes diaphragm upward.
Is resting expiration a passive or active process?
Passive process
Forced expiration uses internal intercostal muscles and abdominal muscles.
What factors affect breathing?
Factors include:
* Lung tissue stretch
* Emotional state
* Physical activity
* Chemicals
These factors help control the depth and rate of breathing.
What is the role of chemoreceptors in breathing?
They detect changes in CO2 and H+ levels
Increased CO2 (drop pH) leads to increased breathing rate and depth.
How is oxygen transported in the blood?
Over 98% is carried bound to hemoglobin of RBC
This produces oxyhemoglobin.
What factors increase the release of oxygen from hemoglobin?
Factors include:
* Increased concentration of CO2
* Increased blood acidity
* Increased blood temperature
These conditions promote the release of O2 in areas where its concentration is low.
What are the three methods of carbon dioxide transport?
CO2 is transported by:
* Dissolved in blood plasma (7%)
* As carbaminohemoglobin (23%)
* As bicarbonate ions (70%)
Bicarbonate ions are the most important form.
What is the chemical reaction for carbon dioxide transport as bicarbonate?
CO2 + H2O ~ H2CO3
Carbonic acid releases H+ and bicarbonate ions (HCO3-).
What happens to bicarbonate ions in the blood?
They diffuse into plasma
CO2 is mainly transported in the blood plasma as HCO3-.
