Quiz 11 - Blood Flashcards
composition and functions of blood
blood acts as transport medium to distribute substances to and from body tissues
basis functions of blood
distribution
regulation
protection
distribution by blood
transports:
- O2 from lungs and nutrients from GI tract to cells
- metabolic wastes from cells to lungs and kidneys for elimination
- hormones from endocrine glands to target organs
regulation by blood
maintains:
- body temperature by absorbing and distributing heat
- pH in body tissues using buffer systems
- fluid volume in circulatory system
protection by blood
prevents:
- blood loss by initiating clot formation when a vessel is broken
- infections by synthesizing and utilizing antibodies and white blood cells against pathogens
components of blood
plasma plus formed elements and hematocrit (Hct)
hematocrit
% of RBCs in centrifuged blood sample
- when centrifuged, blood separates into heavier formed elements on bottom and lighter plasma on top
average Hct for men and women
men ~46%
women ~ 42%
physical characteristics of blood
- more dense than water (viscous)
- alkaline pH = 7.4
- temp = 38C
- accounts for ~7% of body weight
- avg volume: males ~5L, women ~4L
components of plasma
water (90% of plasma) plasma proteins (8%)
types of plasma proteins
albumin
fibrinogen
globulins
albumin
regulates osmotic pressure (water balance)
fibrinogen
clotting proteins
globulins
transport lipids and antibodies
substances transported by blood
respiratory gasses
nutrients
hormones
electrolytes
formed elements
erythrocytes
leukocytes
platelets
structure of erythrocytes
- biconcave shape (increases surface area, stackable, flexible)
- no nucleus (unable to divide, grow, or synthesize proteins)
- > 97% hemoglobins
- no mitochondria (ATP is generated anaerobically)
function of erythrocytes
carry O2 from lungs to tissue and carry CO2 from tissues to lungs
hemoglobin
major protein of RBCs that carries oxygen
- reg pigment: oxygenated (red), deoxygenated (dark red)
- 4 heme molecules: each with an iron that can bind one oxygen
erythropoietin
hormone released by kidneys which stimulates red blood cell production
release of erythropoietin is triggered by…
- hypoxia due to decreased RBCs
- decreases in oxygen availability
- increase tissue demand for oxygen
fate and destruction of erythrocytes
- life span of a RBC = 100-120 days
- dying and damaging RBCs are engulfed by macrophages in spleen or liver
- heme and global are separated and the iron recycled
leukocytes
- important in body’s defense against foreign invaders
- less numerous than RBCs
- make up 1% of total blood volume
types of leukocytes
neutrophils eosinophil basophil lymphocyte monocyte
neutrophils
- multi-lobed nuclei
- most abundant of WBCs
- phagocytize bacteria
- 1st of the WBCs to arrive at injury site during inflammation
eosinophil
- bi-lobed nuclei
- 1-4% of WBCs
- release enzymes that digest large parasites
- lessen severity of allergies
basophil
- most rare of WBCs
-
lymphocyte
- > 25% of WBCs
- primary cells of lymphatic system found mostly in lymphoid tissues (some circulate in blood)
- become B and T cells, important in immune system
monocyte
- 4-*% of WBCs
- largest of leukocytes
- arrive at injury site shortly after neutrophils, entering tissue and become macrophages
platelets
cell fragments
- structure: small fragments broken off from megakaryocytic in bone marrow
- function: forms platelet plug that seals injured blood vessel wall
